Projection system having low astigmatism

Projection system with low astigmatism

Field of invention

The present invention is generally directed to systems for displaying information, and more particularly to reflective projection systems.

Background of the invention

A typical optical imaging system includes a transmission or reflection type of imager, also referred to as a light valve or light valve array that enhances the beam. A typical transmission type light valve is translucent and allows light to pass therethrough. In other words, the reflective light valve can only reflect selected portions of the input beam to form an image. The main benefit provided by reflective light valves is that they can be placed behind the reflective surface as a control circuit and can drive advanced integrated circuit technology so that the application of existing base materials is not limited by their opacity. By using a reflective liquid crystal microdisplay as a developer, a new potential economy and a compact liquid crystal display (LCD) projector structure will be possible.

Many reflective LCD monitors rotate the polarization of the incident light. In other words, the polarized light that can be reflected by the imager can exhibit the darkest state if its polarization state is completely uncorrected. That is, it is given a certain degree of polarization rotation to provide a desired gray scale effect. A 90° rotation provides the brightest state for these systems. Therefore, polarized beams are often used as input beams for reflective LCD developers. A satisfactory streamlined configuration includes providing a folded optical path between a polarizing beam splitter (PBS) and the imager, wherein the illumination beam and the image of the projection reflected by the imager are shared by the PBS. The same physical space between the image and the imager. The PBS separates the incident polarized rotating image light. A single imager can be used to form a monochrome image or a color image. When the illumination is separated Multi-wave beams of different colors, basically a dual-purpose imager is used to form a color image. An image is applied to each beam individually and then recombined into a complete color image.

It is generally desirable to use the light generated by the light source as much as possible and to successfully pass through the image system using a low focal length optical aperture. There is a problem in that the formation of the "polar series connection" which is associated with the conventional PBS is required to set a smaller limit on the number of apertures of the optical aperture of the conventional optical imaging system. Conventional PBS, sometimes referred to as a MacNeille polarizer, used in a projector system, stacks inorganic dielectric films at Brewster's angle. Light with s-polarity is reflected, and light in the p-polar state is transmitted through the polarizer. However, it is difficult to obtain wide-angle performance when using these polarizing plates, and due to the Bruce angle condition, it is strictly limited that a pair of materials can be joined together only at an incident angle. When the incident angle leaves the Bruce angle range, it develops into a spectrally inconsistent light leakage phenomenon. This light leakage phenomenon is particularly useful when the incident angle of the film stack is more common than the Brewster angle. In addition, if a folding optical path projector incorporates p- and s-bias polarities, the disadvantages of comparison will appear.

Since the projection system usually projects light in a light cone manner, most of the light cannot be completely incident on the polarizing plate located at the Bruce angle, which causes polarization of the light beam. When the number of focal lengths of the system decreases, the number of times of the depolarization effect increases, and it is more enlarged in the subsequent reflection of the color reflective film, for example, in a dichroic mirror. We have confirmed that the problem of the reversal to the cascade is to effectively limit the focal length of the projection system and thus limit its luminous flux.

Summary of invention

There are still many needs for optical display systems, including true wide-angle effects, fast optical components that view or display high-contrast images with low optical aberrations.

In general, the present invention relates to a device that can be used to reduce astigmatism in a projection system, and in particular to substantially reduce astigmatism in an LCD projection system. In particular, the present invention employs an image cone of light, including effective reduction of astigmatism in a polarizing beam splitter.

A particular embodiment of the invention refers to a projection system having a light source that can be used to generate light. An image light cone includes at least a first reflective imager and a first polarizing beam splitter for applying an image to the light emitted by the light source. The first polarizing beam splitter can be used to reduce the astigmatism effect of the image light reflected from the first reflective imager. A projection lens system projects a low astigmatism image from the image cone.

Another embodiment of the invention refers to a projection system having a light emitting device and an image light cone for applying an image to the light emitted by the light emitting device. The image cone device includes at least the first imager device and a first polarization beam splitter device that separates light in a polarization mode. At least one beam splitter must be used to reduce the astigmatism in the image light. A projection lens imaging unit projects a low astigmatism image from the image cone device end.

Another embodiment of the present invention is a polarizing beam splitter, and a layer between the covers is disposed with a multilayer film and a polarized photosensitive film. a low astigmatism element can be disposed at a position between the opposite outer surfaces of the cover so as to be able to be lowered The astigmatism effect of the polarizing film.

Another embodiment of the invention refers to a projection system having a light source that emits light. An image light cone includes at least a first reflective imager and a fast polarizing beam splitter that adds an image to the light emitted by the light source. The first polarizing beam splitter includes a multilayer film polarizer disposed at a position between the caps and a low astigmatism element that can be used to reduce the astigmatism effect introduced by the polarizing film. A projection lens system projects an image onto the light emitted by the image cone.

The above summary of the present invention is not intended to be exhaustive The data and detailed description are intended to illustrate specific examples of these embodiments.

The present invention will be further described by reference to the embodiments of the embodiments illustrated in the accompanying drawings, in which: FIG. 1 is a schematic diagram of one embodiment of a projection unit having a single reflective type of imager architecture; Schematic diagram of another embodiment of a projection unit having a dual reflection type imager architecture; FIGS. 3A and 3B are diagrams showing different directionalities associated with one color of a polarizing beam splitter; FIG. 4 is a projection of the present invention BRIEF DESCRIPTION OF THE DRAWINGS FIG. 5 is a schematic view of another embodiment of a projection system of the present invention; FIG. 6 is a schematic view showing an embodiment of a color crucible of the present invention; and FIG. 7 is another embodiment of a color crucible of the present invention. Schematic diagram 8 is a schematic view of another embodiment of a color crucible according to the present invention; FIG. 9 is a schematic view of a projector having a combined light () color spectroscope according to an embodiment of the present invention; FIGS. 10A and 10B illustrate In the embodiment of the invention, a schematic diagram of different directivity of a combined light splitting mirror and a polarizing beam splitter; FIG. 11 is a schematic diagram of an embodiment of a polarizing beam splitter of the present invention; A schematic diagram of another embodiment of a projector according to the present invention; FIG. 13 is a schematic diagram of an embodiment of a dual-mirror projector of the present invention; and FIG. 14 is an embodiment of a polarizing beam splitter according to another embodiment of the present invention. FIG. 15 is a schematic diagram of an embodiment of a polarizing beam splitter having a wedge-shaped component in the present invention; FIG. 16 is a schematic diagram of a projection system using at least one diffused-light polarizing beam splitter in an embodiment of the present invention; 17 is a comparison diagram of wavelengths and contrasts drawn by a multilayer film polarizer according to an embodiment of the present invention; FIG. 18 is a dual-developer projection using a diffused light-type polarizing beam splitter according to an embodiment of the present invention. System schematic; and Figure 19 In one embodiment of the present invention, a schematic view of another type of astigmatism of the projection system using the polarizing beam splitter drop.

Although the present disclosure has been modified several times and has various alternative forms, the various features thereof have been presented by way of example and will be described in a more detailed manner. However, it will be apparent to those skilled in the art that the present invention is not limited by this particular embodiment. in. Rather, the invention is to cover all modifications and equivalents, and all alternatives are also in the spirit and scope defined by the appended claims.

<u style="single">Detailed description</u>

The present invention is applicable to optical developers and, in particular, to optical projector systems that are suitable for low focal lengths, which produce high quality, low aberration projected images.

The terminology of an optical display system as used herein includes a wide range of optical systems that produce images that can be viewed through a slide projector, such as front, rear projection systems, projection displays, head-up displays, Optical computing systems, optical interconnect systems and other viewing and display systems.

A wide-angle Cartesian polarized beam splitter (PBS) disclosed in U.S. Patent Application Serial No. 09/312,917, issued May 17, 1999, which is incorporated herein by reference. ); this is also attached for reference. The Cartesian PBS is a polarized beam splitter in which the polarization of the split beam is considered to be invariant, usually at right angles to the major axis of the PBS film. Conversely, if a non-Cartesian PBS is used, the polarization of the split beam is substantially dependent on the angle of incidence of the beam on the PBS.

An example of a Cartesian PBS is a multilayer film, a reflective polarized beam splitter (MRPB), which can be formed by an alternating layer of isotropic and birefringent materials. If the plane of the film is considered to be the xy plane and the thickness of the film is measured along the z-direction, then the z-index is the birefringence The refractive index of a material, if the light system with an electrical vector is parallel to the z-direction. Similarly, the x-index is the refractive index of the birefringent material, and if the light system having an electric vector is parallel to the x-direction, and the y-index is the refractive index of the birefringent material, if there is one The light system of the electric vector is parallel to the y-direction. The x-index of the birefringent material is substantially the same as the index of refraction of the isotropic material, in view of the difference between the y-index of the birefringent material and the isotropic material. If the thickness of the film layer is chosen correctly, the visible light reflected from the film will be polarized in the y-direction and the light will be polarized in the x-direction.

An example of an MRPB film is a matched z-index beam splitter (MZIP) film, wherein the z-index of the birefringent material is substantially the same as the x-index or y-refraction of the birefringent material. rate. The MZIP film is fully described in U.S. Patent Nos. 5,882,774 and 5,962,114, the entire disclosure of which is incorporated herein by reference. As an alternating layer, as described in U.S. Patent Application Serial No. 09/878,575.

One embodiment of a system 110 using a display is shown in FIG. 1, and includes a light source 112, such as an arc lamp 114, having a mirror 116 that can be used to direct light 118 forward. The light source 112 can also employ a solid state light source, such as a light emitting diode or a laser source. The system 110 also includes a Cartesian PBS 120, such as a wire grid beam splitter or an MRPB film. Light rays having y-polarity, the polarization of which is performed in a direction parallel to the y-axis, is indicated by a circle of x. a light having an x-polarity whose polarization is in a direction parallel to the x-axis Lines are marked with an arrow mark. The solid line is used to indicate the incident light, and the dashed line is used to indicate the light reflected back from the 126, which has a changed polarization state. In lighting PBS Prior to 120, the light provided by source 112 is adjusted by means of an adjustable optical cymbal 122. The accommodating optical cymbal 122 can change the characteristics of the light emitted by the light source 112 to become a desired feature of the projection system. For example, the accommodating optical cymbal 122 can change the divergence of light, the polar state of the light, and the spectrum of the light. The adjustable optical port 122 can include, for example, one or more sets of lenses, a polarized converter, a front beam splitter, and/or a filter to eliminate unnecessary ultraviolet or infrared light. . In some embodiments, the accommodating optical cymbal 122 can have a low focal length number, for example, equal to or greater than 2.5, so that most of the light source 112 can be used.

The y-polariser element of the light can be reflected by the PBS 120 to the end of the reflective display 126. The liquid crystal mode of the display 126 may be a smectic type, a nematic type or some other suitable type of reflective type image display. If the imager is of the smectic type, then the imager 126 will likely be a fermented liquid crystal display (FLCD). The imager 126 can reflect and modulate an image beam having an x-bias polarity. The reflected x-polarized light is transmitted through the PBS 120 and projected by the projection lens system 128, the design of which is substantially optimized to allow each unique optical system to be configured for use in the lens system 128. All components between the image and the monitor (s). A controller 152 is coupled to the display 126 end to enable control of the mode of operation of the display 126. Basically, the controller 152 can actuate the different of the display 126 The pixels are such that an image can be produced in the reflected light.

Another embodiment of a projection system 200 is shown in FIG. The system uses a light source 210, such as an arc lamp 211, having a curved mirror 213 that directs light to the end of the adjustable optical port 215. In the illustrated embodiment, the adjustable optical port 215 includes a collimating lens 217, a first array of lenslets 219, a second array of lenslets 221, and a collecting lens 227. Between the second array lens 221 and the collecting lens 227, the adjustable optical port 215 can include an optional polarizing converter 223, such as a Geffkcken type design. Depending on the conversion efficiency of the polarization converter 223, it is advantageous in that the front dichroic mirror 225 can be selectively disposed at the rear end of the polarization converter 223. The pair of array lenses 219 and 221 are nominally capable of receiving collimated light from the end of the collimating lens 217. The polarization converter 223 and the front beam splitter 225 are capable of polarizing light incident on the PBS 250 in accordance with a desired polarization state. It is noted that the illumination optics may include more or fewer optical components if compared to this particular illustrative embodiment.

Array lenses 219 and 221, and concentrating lens 227, can shape and homogenize the oblique light to uniformly illuminate the reflective developers 226, 228 and 230. The PBS 250 redirects the y-polarized light to the three sets of reflective images 226, 228 and 230. The PBS 250 typically includes an MRPB film 252, such as an MZIP film, which can be freely erected, disposed between the plies, or loaded between the crucibles 254, as described herein. The laminate or crucible 254 can be constructed of glass and can be referred to as the cover of the MRPB film 252.

In a dual image system, a color pupil 236 separates the light into individual ribbons that are coupled to the respective imagers. For the above three display structure To illustrate, the Color 236 system typically separates light into basic bands: red, green, and blue. Intervening lenses, such as field lenses 238, 240 and 242, can be inserted at the location between each of the imagers and color pupils 236 to further optimize the optical response of the system. The cameras 226, 228, and 230 modulate the polar state of the light to various degrees during reflection, and must depend on the particular image information. The color pupil 236 can then recombine the red, green, and blue images and transmit the combined image light to the Cartesian PBS 250, which can analyze the image with the only fully-passable x-polarized light. The y-polarized light will be redirected back to the source 212. Light passing through the PBS 250 can be collected by the projection lens system 234 and then focused onto a screen (not shown) for viewing. A selective rear beam splitter 244 can be inserted between the PBS 250 and the projection lens system 234. It should be noted that other optical structures can also be used with a duplex imager.

In the illustrated embodiment, the color 236 is a Phillips® available from Optical Coatings Laboratory, Inc. Obtained from Santa Rosa, California. For clarity of illustration, the color 236 shown in the figures is configured in a conventional orientation such that the axes of rotation 258 of the first and second color selection faces are parallel to the axis 256 of the Cartesian PBS 250, As shown in Figure 3A. The axis of rotation is an axis that rotates the plane around it and from its true position to a position perpendicular to the direction of light travel. In conventional types of beamsplitters, this relative relationship between the axis of rotation of color selection surface 258 and the axis of rotation 256 of the PBS is often indispensable, and a Cartesian PBS 250 can also allow color 236 to Beam The main shaft 262 is rotated around, so that the first and second developers 226 and 230 are guided to be perpendicular to each other, and the s-polarized light nominally from the PBS is associated with the color The color selection surface of 236 becomes p-polarized. The associated configuration of rotation is as shown in FIG. 3B, wherein the axis of rotation 258 of the color selection surface is perpendicular to the axis of rotation 256 of the PBS 250. This rotation configuration is described in U.S. Patent Application Serial No. 09/746,933, entitled "Using Wide-Angle Cartesian Polarizing Beamsplitters and Color Separating and Reconstructing Reflex Reflective LCD Projection Systems", by David JW Aastuen and Charles L. Bruzzone, filed on December 22, 2000, incorporated herein by reference.

The use of a Cartesian PBS 120 or 250 allows the projection system to exhibit a dynamic range of at least 100:1 in the visible range, wherein the accommodating optical 215 has a focal length of approximately 2.5. Further, an element disposed between the adjustable optical 215 and the projection lens system 234 may be referred to as an image light cone. A typical image light cone includes at least one polarizing beam splitter and one or more sets of imagers. If more than one set of imagers is used, the image cone can also include color separation and combined optical , such as color , two-color splitter, combined light Minute spectroscope or the like. Components and so on. The image cone does not include a lens, except that an optional field lens is disposed between a dichroic element and the imager. The image light cone can be telecentric, in which a cone of light incident on the image is constantly illuminated on the surface of the imager. A typical telecentric imager cone does not contain a field lens.

An example of a Cartesian PBS 250 is an MRPB film 252, such as an MZIP film, encased between crucibles 254. In order to minimize For the birefringence effect caused by the thermal induction of a high intensity beam, 254 is preferably constructed using a low stress-optical index material. One of the most appropriate materials is glass, trade name SF57 (Schott glass) or PBH55 (Ohara glass). The refractive indices of both SF57 and PBH55 glasses are about 1.85.

The refractive index of a typical MRPB film 252 is less than that of the surrounding 254. For example, the MZIP film has a refractive index of about 1.56, and its typical thickness is about 125 μm. When the PBS 250 was assembled, the MRPB film was adhered to the enamel panel with a thickness of about 50 μm thick and matched to a refractive index of about 1.56. It has been found that one type of adhesive is particularly suitable for the MRPB film. Norland 61 is manufactured by Norland Corporation. Together, the PBS film 252 and the adhesive can constitute a sloping plate having a refractive index of about 1.56 and a thickness of 225 μm. And oblique to the direction of propagation of the light at an angle of approximately 45°. This relatively low index laminate, placed inside the relatively high index 254, will cause the astigmatic effect of the image light. The astigmatism effect is a problem with the light emitted by the imager.

The formula for calculating the astigmatism effect of an inclined plate having a refractive index n in a medium having a refractive index n' is:<maths><img file="TW577235B_D0001.tif" /></maths>

Where t is the thickness of the sheet material and A is the angle between the central array of the beam and the sheet material. The astigmatism effect is the result of the sagittal section and the tangential differential shift of the light due to the refractive index of the oblique sheet material passing through it being different from the refractive index of the surrounding material.

The numerical values of n and n' are closely related to the wavelength. Therefore, the value of the astigmatism effect is also related to the wavelength due to dispersion. The relationship between the refractive index and the wavelength of the MZIP film, basically, a film including a polyester and a copolymer and SF57 glass, etc., are provided in Tables I and II, respectively.<tables><img file="TW577235B_D0002.tif" /></tables><tables><img file="TW577235B_D0003.tif" /></tables>

Using the formula (I), the astigmatism effect caused by the film of thickness 225 μm in the SF57 glass crucible is calculated for different colors: red light (645 nm) 169 μm, green light (546 nm) 181 μm, blue light (480 nm) 196 μm. In many cases, the astigmatism effect in the edge light is completely corrected and can be accompanied by a reduction in the astigmatism effect of the blue and red portions of the light. The observer will see an image with virtually no astigmatism, each of which The astigmatism is less than the depth of field of the projection lens system. Therefore, it is not necessary to completely eliminate the astigmatism effect of all wavelengths. When the single value of the astigmatism effect is low, it can be assumed that the astigmatism value in the green light is about 546 nm. In other methods, the astigmatism effects of different bands can be individually corrected.

A first method that can be used to eliminate the astigmatism effect is to provide a relatively low refractive index slanted plate with a relatively high refractive index material disposed around it, and the light propagates through a second slanting plate, the refractive index of which is It is lower than the surrounding material and is a rotating shaft that tends to be perpendicular to the first inclined plate. The second inclined plate can be constructed of any suitable solid, liquid or gaseous material. If the second sloping plate and the first slanting plate are identical, including the index of refraction and thickness, then it should be inclined at the same angle to the first ply to minimize astigmatism. If the second layer is not identical to the first layer, the intensity of the astigmatism introduced by the second layer is preferably the same as that introduced by the first layer, so that the astigmatism effect is completely eliminated. . This must select the angle and thickness of the second ply and the difference in refractive index between the second ply and the surrounding material. According to the design case described below, the spherical aberration and the offset are very small, so they can be ignored in practical applications. However, this spherical aberration and biasing in an optical system may need to be compensated for. Since the astigmatism compensation measure may increase other aberrations, it is better to use partial compensation for astigmatism in order to achieve aberration balance.

A second method that can be used to eliminate the astigmatism effect, wherein the first slanted plate has a lower refractive index than the surrounding material and introduces a second slanted plate having a higher refractive index than the surrounding material. The constituent material of the second inclined plate can be taken Use solid, liquid or gaseous materials. Basically, the second inclined plate inclined to a rotating shaft is parallel to the rotating shaft of the first inclined plate. This requires choosing the thickness, refractive index and tilt angle of the material to compensate for the astigmatism effect. A particular embodiment using this method to eliminate astigmatism will be described later.

The methods shown herein that can be used to reduce the astigmatism effect are applicable to projection systems having a wide range of focal lengths and are believed to be particularly advantageous for projection systems having a low focal length. The methods discussed herein can be used to reduce astigmatism or to substantially correct astigmatism effects. In many cases, the astigmatism effect does not need to be completely eliminated, but only needs to be reduced to a value that is less than the depth of field of the projection lens system. Basically, the depth of field increases with the number of focal lengths, so the correction of the astigmatism effect becomes increasingly important for low focal length projection systems. The term "sufficiently corrected" means that the astigmatism effect is reduced to a value less than the depth of field used by the projection lens system.

Although the discussion here is directed to reducing the astigmatic effects produced in MRPB PBS, it is worth noting that the methods discussed below for reducing the astigmatism effect are also very effective in reducing the astigmatism of other components of the projection system. it works.

Reducing the astigmatism effect can be achieved by appropriate color defects. Referring again to FIGS. 3A and 3B, in general, when the rotating shaft 258 and the rotating shaft 256 are perpendicular to each other, the astigmatism correction can be accomplished in the color crucible 236 using a laminate having a refractive index relatively lower than that of the surrounding material. Conversely, when the rotation axis 258 of the color selection surface is parallel to the rotation axis 256 of the PBS, the refractive index can be utilized in the color The astigmatism correction is done above the laminate of the surrounding material.

First, we discuss a particular embodiment of a white flour surface that employs a second slanted plate having a relatively low refractive index. Color 236 of different design methods can also be used, and several of them use 3 or 4 sets of to separate the light incident into 2 or 3 sets of ribbons. Often, the color chirp 236 separates light incident into the red, green, and blue components. In the Phillips crucible structure, as shown in FIG. 4, the color crucible 400 is composed of three sets of crucibles 402, 404 and 406. Light ray 410 entering first enthalpy 402 is incident on first filter 412, which reflects light in the first color band and transmits light in the second and third color bands. The light of the first ribbon 414 is completely reflected into the first pupil in the input surface 416. Since an air gap 417 is present between the input surface 416 and the PBS 450, the light is directed to the first developer 426.

Light transmitted into the second aperture 404 is incident on the second filter 418, which reflects the light 420 in the oblique second ribbon and transmits the light 424 in the third ribbon. The light 420 reflected by the second filter 418 is completely transmitted through the internal gap 422, a typical air gap, reflected between the first and second turns 402 and 404, and is guided to the second Developer 428. Light 424 transmitted through second filter 418 is directed through third 406 of third developer 430.

Basically, the first ribbon is blue, the second ribbon is red and the third ribbon is green. However, this is not static, and different ribbons can have different colors.

a gap 422 between the first and second turns 402 and 404, in the conventional It is still very small, typically ranging from 10 μm to 25 μm, which is sufficient to cause a total reflection inside the second ribbon. However, the size of the gap 422 can be increased to provide astigmatic effect compensation, as discussed further in the following examples.

<u style="single">Example 1</u>

The color crucible 400 is composed of a low birefringence glass, PBH55, which has a refractive index of 1.85. The angle of incidence of light incident on the central array of air gaps 422 is 21°. The first ribbon is blue, the second ribbon is red and the third ribbon is green. The color crucible 400 is at a rotational position opposite the PBS 450, so the s-polarized light system nominally from the PBS 450 forms a p-polarization in the color crucible 400.

The ruler 6 inch of the air gap is adjusted to a value of 181 μm in order to compensate for an astigmatism effect. Prior to adjustment, the PBS/color assembly used in the projector system projects a horizontal and vertical line onto a screen. It can be focused on a horizontal or vertical line, but not both. If, for example, the horizontal line is focused at a position 178 cm from the projection lens and the vertical line is focused at a distance of 105 cm, the focal length ratio is 1.7:1. If the best focal length is used, the two sets of lines will be greatly blurred at the same time.

Adjusting the gap 422, the first second crucibles 402 and 404 are separated and then separated by a standard size Monosized Microsphere glass bead provided by Duke Scientific Corp., Palo Alto, CA. A 100 μm air gap 422 is used for recombination. The glass beads have a diameter of 100 μm.

After recombination with the 100 μm air gap 422, the astigmatism effect of the red 6-color light and the green light of the system was measured again. The vertical line is focused at 135 cm, whereas the horizontal line is focused at 178 cm with a focal length ratio of 1.32:1. In addition, the qualitative appearance of the line is greatly improved when the focal length is optimized, wherein the gap 422 is 10 μm.

The gap 422 can be adjusted to 140 μm by replacing 100 μm spacer glass beads, also supplied by Duke Scientific. When measuring the astigmatism effect, it would be difficult to quantify the difference value of the focus existing between the vertical and horizontal lines. Obviously, the light from the sagittal section will be focused at 160 and 170 cm from the projector with a focal length ratio of less than 1.1:1. When focusing again to provide the best overall focus, no blurring is seen in the vertical or horizontal lines.

It should be noted that adjusting the air gap 422 does not affect the astigmatic effect of the light ray 414 in the first color band. A qualitative test was performed to determine if red and green alone performed the astigmatism correction procedure resulting in an acceptable image. Blue, red, and green images are carefully aligned and different contrasts are carefully observed. Most people agree that any blue blurred area can only be viewed by carefully examining the white lines in the dark background, rather than examining the black lines in a bright background. If it is recommended to reduce the blue astigmatism effect, it may not be as important as reducing the green and red astigmatism effects. The possible reason is that since the precision of the blue sensory organs in the human eye is lower than that of the green and red sensory organs, the normal resolution of the blue image is worse than the green or red image.

However, the astigmatism effect of the first ribbon can be corrected if used as shown in Figure 5. The method shown therein is similar to the color enamel shown in Fig. 4 except that the first 402 is formed by two portions 402a and 402b, and the air gap 502 is disposed therebetween. For the reasons required for manufacturing, a blunt end 504 must be placed at the acute end of the crucible 402b. Preferably, the gap 502 is sized and positioned such that the air gap 502 does not obstruct the light 410 from the PBS 450 from entering the color crucible 400. At the same time, the size and location of the gap 502 may also prevent the gap 502 from appearing in the ray path of the first ribbon until the ray 414 has been completely reflected from the interior away from the input surface 416. When the above formula (I) is used, the width of the air gap 502 should be about 0.875 mm, and an astigmatism effect of 196 μm is compensated at an angle of about 32.25°, while the astigmatism correction value may be different for other gaps 422. The value. If the result is more likely to cause other aberrations than the larger interval, a smaller gap can be used, which causes less aberration to partially compensate for the astigmatism effect. It will be appreciated from the skilled expertise in the art that it may optimize the imagery, either by optical software on a computer, or by experience.

It should be noted that the air gaps 422 and 502 are merely examples of low refractive index materials on the sheet of the bismuth glass, air, surrounding with high refractive index materials, and the like. The gaps 422 and 502 are not only able to fill the air, although the use of air is considerable because it provides a large refractive index to the tantalum material. Gap 422 and 502 can also fill another material having a relatively low refractive index, in addition to air. However, it should be understood that the difference between the refractive indices, such as the second enthalpy 404 and the gap 422, must be sufficient to maintain the total amount of the ray 420. Partial reflection, even when gap 422 is not filled with air. Similarly, the other gaps discussed below do not need to be filled with air, but only need to be filled with a material having a refractive index that is less than the material surrounding the gap.

Another method that can be used to correct the astigmatism effect can be referred to the description in FIG. In this embodiment, a dovetail 662 is disposed between the color crucible 600 and the PBS 650 with a gap 664 formed between the dovetail 662 and the color crucible 600. Color 600, typically a conventional Philippine , consisting of first, second, and third 602, 604, and 606, respectively, and the first and second 602 and 604 A total internal reflection gap 622 is formed between them. In the illustrated embodiment, the third weir 606 also includes an all-in-one reflective surface 656. This is not static and the third volume 606 can be constructed using a geometry that does not require a total reflection surface.

In a conventional dovetail system, the air gap 664 present between the dovetail 662 and the first weir 602 is just sufficient to allow the first band of light 614 reflected within the first weir 602. Has total internal reflection. However, the air gap 664 between the dovetail 662 and the first weir 602 can optionally have a larger width to substantially reduce and correct the astigmatism effect that occurs in the PBS 650. The width of the gap 664 can be selected in accordance with formula (I).

For example, the astigmatism effect in PBS 650 is 181 μm, and the wedge angle of the dovetail 662 is 10°. Equation (I) suggests that the astigmatism effect that must be corrected by an air gap 664 is approximately 2.104 mm.

It should be noted that even if the low-index laminate has been described as an air gap in conjunction with Figures 4-6, other materials can be used if they have a low refractive index. For example, a low index polymer film. In addition, it is also possible to use a gap combination between the colored crucibles and a gap between the colored crucibles and the dovetails to compensate for the astigmatism effect. It is further noted that the reduced astigmatism effect can be achieved in different embodiments of the color enamel , rather than merely the embodiments set forth herein.

The second method described above for correcting the astigmatism effect in the PBS is to utilize a plane of high refractive index that is tilted against an axis that is parallel to the axis that tends to the PBS beam splitter film. This method is useful if the color does not rotate against the PBS, so the nominal s-polarized light from the PBS is also the nominal s-polarized light in the color .

A particular embodiment of the method is illustrated in Figure 7, wherein the system is shown as a color crucible 700 that is comprised of first, second, and third crucibles 702, 704, and 706, respectively. of. The high index laminate 760, constructed of a transparent material, has a refractive index higher than the first and second turns 702 and 704, which is disposed on the output surface of the first turn 702. The air gap 722, which is substantially about 10 [mu]m wide, is provided between the high index laminate 760 and the second weir 704 so that the light of the second ribbon can be internally reflected in the second weir 704 The output surface 727 ends.

If the first filter 712 is disposed on the second surface 762 of the high-index layer 760, the light in the first ribbon 714 passes through the first 702 end. The high index laminate is up to 2 times, wherein the light 720 in the second ribbon and the light 724 in the third ribbon can only pass through the high index laminate 760 once, when it is from the second and third End 704 and Before 706 is reflected out. Therefore, the astigmatism correction value of the light of the first color band is different from the correction value of the second and third color bands. Since the observer's sensory organ is less responsive to the blue light in the image, if compared to the green light and its red light, as demonstrated above, this embodiment can properly compensate for the astigmatism effect if the first ribbon is Blue light.

If the first filter 712 is disposed on the outer surface 703 of the first turn, as previously described, the light 714 in the first ribbon does not pass through the high index plate 760, thus the first ribbon The light 714 in it confirms that the astigmatism cannot be corrected. As described above, the light ray 714 in the first color band is blue, and the astigmatism correction for the green light and the red light can only provide sufficient correction effect to the observer.

In another embodiment, as shown in Figure 8, the first weir 702 is separated into two portions 702a and 702b. A second high index layer 862 can be disposed between the weir portions 702a and 702b, and the thickness, azimuth angle and refractive index thereof can be selected to reduce the thickness in the first ribbon. Astigmatism effect. This embodiment is particularly useful if the filter 712 is disposed between the first defect portion 702a and the high index plate 760. Therefore, the color 800 can be provided to correct all three ribbons.

The astigmatism correction may also be achieved in a combined -type spectroscope/beam splitter. Figure 9 shows an embodiment of a portion of a projector 900 that uses a combined light splitter beam splitter and a beam splitter. Light ray 902 from a light source (not shown) is incident on the compositing beam splitter 904, which separates the light 902 into three color bands. The light ray 906 in the first color band passes through the combined light splitting mirror 904 and is transmitted to the end of the first mirror 908. The light ray 910 in the second color band is incident into a plane close to the second mirror 912 by the combined light splitting mirror 904. Light ray 914 in the third ribbon is reflected in a direction opposite the plane of a third mirror. Optical elements that can be used to operate the third ribbon are not shown in the drawings for clarity. In a projector 900 utilizing three sets of PBS, the back focus length can be shortened, thus permitting the use of a simplified projection lens system. In addition, the weight of the projection lens system required to match the depth of field angle can be simultaneously reduced.

The first and second mirrors 908 and 912 can reflect light in the first and second ribbons, respectively, and lead to the first and second polarizing beamsplitters 916 and 918. The first and second mirrors may be mirrors, such as multilayer film mirrors or metal mirrors, or reflective beamsplitters that reflect light toward the first and second polarizing beamsplitters 916 in accordance with a desired polarization state. 918.

The light in the first color 906 can be reflected by the first PBS 916, which has an MPBR film 917 directed toward a first reflective display 920 that reflects the light 906 in the first ribbon. The polarity of the selected portion of the 906 wavelength can be rotated to generate an image beam 922 in the first ribbon, the first ribbon being transmitted through the first PBS 916 and illuminated to the combined light () Type beam splitter 924 end. Similarly, light ray 910 in the second ribbon is reflected by second PBS 918 to the end of second reflective imager 926. The second reflective imager 926 can generate a developer beam 928 in the second ribbon and pass through the second PBS 918 toward the merged beam splitter 924.

It should be noted that the projector 900 also includes a grid mirror (not shown) a third PBS (not shown) and a third imager (not shown) to generate an image beam 930 in the third ribbon that is opposite the plane of the object. The direction is directed to the end of the combined light splitting mirror 924. The three image beams 922, 928 and 930 can be combined in a combined light splitting mirror to produce a three color image beam 932 that is substantially projected onto a screen by a set of projection optical pupils.

A more detailed diagram of a combined light splitting mirror 924 is shown in Figure 10A, which shows one of the combined light splitting beams in the plane of the image beams 922, 928 and 930. Cross section. The combined light splitting mirror 924 can be recombined by four sets of right angles 1002, 1004, 1006 and 1008, etc., each having different reflective coatings, such as a multilayer film, an attractive reflective coating. And configured in an interface of 1002-1008. Paints 1010 and 1012 can reflect image beam 928 in the second ribbon while coatings 1014 and 1016 are image beams 930 that can be reflected in the third ribbon.

The two sets of sheet materials 1020 and 1022 can be inserted into the positioning in the combined light splitting mirror 924 such that the light in each of the image beams 922, 928 and 930 is in addition to the first image beam 922. A small portion of the central portion will pass through one of the sheet materials 1020 or 1022, but only one. In the illustrated embodiment, the first sheet of material 1020 is disposed between the fourth crucible 1008 and the first crucible 1002, and the second sheet of material 1022 is disposed between the first and second crucibles 1002 and Between 1004.

As shown in the embodiment shown in Figures 9 and 10A, the axis of rotation of the MPBR film 917 and the axes of the sheet materials 1020 and 1022 are perpendicular to each other. Therefore, sheet material The refractive indices of 1020 and 1022 can be chosen to be less than the refractive index of 1002-1008. For example, a crucible composed of SF57 glass, if the sheet materials 1020 and 1022 are composed of a low index glass such as BK7, it has a reaction index of 1.517. The thickness of the sheet materials 1020 and 1022 is preferably selected to at least partially compensate for the astigmatism effect produced in the PBS. For example, if the astigmatism effect is 181 μm, the astigmatism effect is corrected by using 1002-1008 composed of SF57 glass and sheet materials 1020 and 1022 composed of BK7, and the thickness of the sheet material is 150 μm. We can assume that the incident angle of the combined light splitting mirror 924 is 45°.

The central portion of the first image beam 922 has a width d1, and its entire width cannot pass through any of the sheet materials 1020 and 1022 at all, so that it is impossible to correct the astigmatism effect. Basically, the area of the central portion is smaller than the opposite mesh of the beam 922, so the intensity of the light is not sufficient to correct the astigmatism effect, only a few percent of the total intensity. The central portion may not be able to correct the astigmatism effect, or may be blocked, for example using a black paint, which produces less than 5% power loss. The total power of the uncorrected central portion of beam 922 is reduced if the light in the ribbon contained in beam 922 produces a small astigmatic effect, such as blue light, in the observer's eye.

Another embodiment of a light combining beam splitter 1050 is shown in Figure 10B. A strip of light 1070 is incident into the PBS 1054 and reflected to the end of the imager 1072, which rotates the polarities of the central portion of the light 1070 to form image light 1074. The image light 1074 can be transmitted through the PBS 1054 to the end of the combined light splitting mirror 1050. Have shadows in one or more sets of ribbons The image light 1076 is directed into the combined light splitting mirror 1050 and combined with the image light 1074.

In this embodiment, the axis of rotation of the MRPB film 1052 in the PBS 1054 is parallel to the axis of rotation of the sheet materials 1056 and 1058. Therefore, the refractive indices of the sheet materials 1056 and 1058 are selected to be larger than the refractive index of 1060-1066, which constitutes the combined light splitting mirror.

The glass selected for use as the combined light splitting mirror 1050 is not limited to a high index, and thus the beam splitter 1050 can be constructed by a more common glass type, such as BK7. If the astigmatism effect induced by PBS 1054 is about 181 μm, the thickness of the sheet materials 1056 and 1058 which can be used to achieve the corrected astigmatism effect must be calculated to be about 1.1 mm, wherein the sheet materials 1056 and 1058 are made of PBH 71. The constructed 1060-1066 is composed of BK7.

Another particular embodiment for modifying the astigmatism effect in a projection system is shown in Figure 11, which employs a laminate of a relatively high refractive index material to configure a relatively high refractive index laminate. In PBS 1100.

The PBS 1100 is composed of two sets of bismuths 1102 and 1104 having two levels, an MRPB/adhesive layer 1106 and a high index layer 1108, etc., which are interposed between the ridges 1102 and 1104. The refractive index of the high index layer 1108, n₂, is higher than the refractive indices of the 1102 and 1104, n₀. Wherein the refractive index of the MRPB/adhesive layer 1106 is n₁The following relationships can be maintained as appropriate: n₂&gt;n₀&gt;n₁. The thickness of the high index layer 1108, d2, can be selected to reduce the astigmatism effect of the high index layer 1108, which is introduced by the MRPB/adhesive layer 1106. For example, if 1102 and 1104 are refracted by 1.85 The MRPB/adhesive layer 1106 composed of PBH55 glass and having a thickness of 225 μm has a refractive index of 1.56, and the astigmatism effect is 181 μm. The value of this astigmatism effect can be compensated by using PBH71 glass having a thickness of 3.8 mm, which has a refractive index of 1.92, as is the case with the high index layer 1108. It should be noted that an adhesive layer can attach the high index layer to the tip end, so that the effect of the adhesive layer can be ignored. The phenomenon of dispersion occurring in the PBS 1100 may cause a discoloration effect in which the light is erroneously placed in the light of another wavelength. The color change effect can be reduced by using, for example, a second PBS immediately following the first PBS, wherein the second PBS is directed to transmit image light and provides a color change effect that can be used to compensate for the presence of Discoloration in a PBS 1100.

The PBS 1100 can also be used if there is only one set of developers and there is no color . One of the benefits of using only a single imager is that there is no need to align the imager made up of images with another imager, in this case a dual-view projector. Another benefit is that there is no need to configure a color splitter/beam splitter, such as a color , x-, or similar component, so that the projector's back focus length can be shortened and a low focal length can be used. Projection lens systems, for example, are reduced to f/1.8 or even smaller.

In general, a single-panel camera must work with a color scheme, such as a color ring or a fast-tuning 7-color filter. Therefore, only about one-third of the light is incident on the imager, and it can be used at any time in the three-color ribbon, so it requires more light transmission in a single panel projector. Efficiency, even more than one or three panel projectors. With a focal length of f/1.8, the system etendue will It is 2.7 times larger than a projector with f/3.0, and the total light transmission amount of the low focal length projector is increased. In addition, projectors with lower focal lengths have a shorter coherence length, resulting in fewer spots.

An embodiment of a dual vision projector projection system 1600 is shown in Figure 16, wherein the astigmatism effect is achieved by providing astigmatic effect compensation of the PBS itself. Light 1602 is emitted from a source 1604. Light source 1604 may be an arc or incandescent lamp, or any other suitable source that produces appropriate light to project an image. Light source 1604 can be surrounded by a mirror 1606, such as an elliptical mirror (as shown), a parabolic mirror, or the like to increase the amount of light that is directed to the projector end.

Basically, light 1602 is processed prior to being separated into different ribbons. For example, light 1602 can pass through the optional pre-beam splitter 1608 so that only the light learned is directed to the projector end. The front beam splitter is a reflective beam splitter, so it can reflect light and, in the undesired state of the pole, it will be redirected to the end of the light source 1604 for recycling. The light 1602 can also be homogenized, so that the machine can provide illumination uniformly in the projector. One method is to achieve homogenization of light 1602 by passing light 1602 through a reflective tunnel 1610, although it is noted that other homogenization methods may be employed.

In the illustrated embodiment, the homogeneous ray 1612 will pass through the first lens 1614 to reduce the divergence angle. Light ray 1612 is then incident on first color separator 1616, which may be, for example, a galvanic thin film filter. The first color splitter 1616 can be separated from the residual light 1620 Light 1618 in the ground ribbon.

Light 1616 in the first ribbon may also pass through a second lens 1622 and selectively through a third lens 1623 to control divergence of light 1618 incident in the first ribbon of first PBS 1624. . Light 1618 can pass through first PBS 1624 and be transmitted to a first display 1626 end. The image light 1628 reflected from the imager is in a biased state and is transmitted through the PBS 1624 to the end of a combined light splitting mirror 1630. The PBS 1624 provides compensation for the astigmatism effect to reflect the image light. For example, PBS 1624 may be similar to PBS 1100 as shown in FIG. The imager 1626 may include one or more sets of compensation elements, such as a retarding element, to provide additional polarization of the poles and thus maximum contrast in the image light.

The remaining light 1620 passes through a third lens 1632, and the remaining light 1620 is incident on the second color separator 1634, such as a thin film filter or the like, to produce a beam in a second ribbon. 1636 and produces a beam 1638 in a third ribbon. Light 1636 in the second ribbon is directed through a second PBS 1642 and to a second display 1640 end. The second PBS 1642 can provide a compensating effect for the astigmatism effect on the light in the second color band. The second display 1640 directs the image light 1644 in the second ribbon to the end of the merged color splitter 1630.

Light ray 1638 in the third color band can be directed to a third display 1646 end via a third PBS 1648. The third PBS 1648 can provide compensation for the astigmatism effect to the light in the third ribbon. The third imager 1646 guides the image light 1650 to the combined light color in the third color band. The beam splitter 1630 ends.

The image light rays 1628, 1644, and 1650 in the first, second, and third color bands can be combined in a combined light ray splitting mirror 1630 and can be guided to the image by a series of color image beams. Projection optics 1652 end. A polarization-rotating optical 1654, such as a half-wave retarded laminate or the like, can provide PBS 1624, 1642 and 1648 and a combined light concentrating mirror 1630 to enable color splitting in the combined light The polarity of the combined light is controlled in mirror 1630. In the illustrated embodiment, the polarization-rotating optical 1654 is disposed between the compositing color splitting mirror 1630 and the first and third PBSs 1624 and 1648, and the like.

It should be noted that variations in the illustrative embodiments may be used. For example, instead of first reflecting light to the imager and then transmitting the image light, the PBS can first transmit the light to the imager end and then reflect the image light.

The projection system shown in Figure 16 has several benefits. One of the benefits comes from the fact that the duplex film PBS uses a wide-angle Cartesian beam splitter instead of the McNeille beam splitter. Thus, the duplex film PBS will be able to use a fast illumination optics, for example with a 2.5 focal length or even less, so that the overall efficiency of the projection system will also increase. Another benefit comes from the fact that the duplex film PBS can be individually optimized for their respective ribbons, so that the polar contrast of the image light in each ribbon is high. As a result, the projection system can operate without the rear beam splitter. In addition, only a single front beam splitter is used to process all the ribbons instead of one. Other front beamsplitters are used to process each of the ribbons. Another benefit of this embodiment is that the duplex layer PBS is quite sluggish for diagonal pairs, so the projection system 1600 can be more easily aligned.

In addition, since the PBS can be optimized with their respective color bands, there is little light leakage in the dark state, so the image contrast can be improved. Shown in Figure 17 is the ratio of the wavelength (x-axis) function of the projection system 1600 to the contrast (y-axis). In order to obtain the data provided in Figure 17, the imager is replaced by a quarter-wave mirror. A quarter-wavelength mirror is a combination of a quarter-wave retarder and an aluminum mirror. The directionality of the quarter-wave retarder in one direction causes the reflected light to be free of polarization, so that the reflected light is directed back to the source through the PBS. The reorientation of the quarter-wave retarder causes the poles of the reflected light to rotate, so that all of the reflected light is directed to the projection lens, via PBS. As expected, the projected image has a high contrast ratio and can drop below 400 nm in the 425 nm-700 nm wavelength range.

Another embodiment of a projector 1800 is shown in FIG. This projector basically uses two sets of developers. The light illumination optics will be given the same reference number if they are similar to the projector 1600 described above.

The pre-polarized, homogenized light 1612 passes through a first dispersion deceleration lens 1614 and is incident into a first color separator 1810. The color separator 1810 may be a thin dielectric film filter. Light 1818 in the first ribbon is directed to the first PBS 1820 end. Light 1818 can pass through another lens 1822 or lens system. Light 1818 is directed to first imager 1824 End, which adds an image to the reflected light 1826. The image light passes through the PBS 1820 and is then incident on the end of the color beam splitter 1828.

Light 1830, separated from the first ribbon, is treated as a second ribbon and will be directed to the second PBS 1832 end, which directs light 1830 to the second developer 1834. Light 1830 can pass through one or more sets of 1831 so that its divergence can be controlled. The imager 1834 can apply an image to the reflected light 1836. Image light 1836 is then combined with image light 1826 in color beam splitter 1828. The light 1830 in the second ribbon can be modulated by a color modulator 1838, for example by passing through a color ring and then rotated by an electric motor 1840. The color wheel includes transmission filters 1842 and 1844 that can process at least two different sets of colored sub-bands. Thus, light 1830 can be temporarily modulated into the first and second color sub-bands. As shown in the example, the light 1818 in the first ribbon may be blue when the light 1830 in the second ribbon is green and red. In the above example, the color wheel basically has an alternating green and its red transmission filter, so at any time, the color modulated light 1846 is transmitted to the second PBS. If the 1832 is not green, it is red light. In another embodiment, the light 1818 in the first ribbon is red light when the light 1830 in the second ribbon is green and blue. It should be noted that other methods can also be used to color modulate the light 1830. For example, the color modulator 1838 can be a photoelectric color modulator, such as the high-transmission color switch titled "Continuous Color Projection System", published in the SID 2000 Digest, which was presented on April 9, 2000. , invented by GD Sharp et al.

The developers 1824 and 1834 can be operated by a controller 1850 to display a suitable image at the correct time. The color modulator 1838 can also be controlled by the controller 1850 so that the color of the light 1846 transmitted by the color modulator can be displayed in synchronization with the image by the developer 1834.

The PBSs 1820 and 1832 can provide a compensating effect of the astigmatism effect, for example, according to the method described above in FIG. Other methods that can be used to reduce the astigmatism effect can also be employed, as described in FIG.

Another embodiment of a three-mirror projection system 1900 is shown in FIG. The elements of the projection system 1600 are similar to those of the projection system 1900 and are given the same number.

In this embodiment, the first and second PBSs 1924 and 1942 are formed by a cover 1950 having a refractive index close to that of the multilayer polarizing film 1952. This is particularly advantageous for light in the ribbon because it does not require the use of a high blue transparency polarizing film, such as a PET based polarizing film. In other words, we have found that PET films are less susceptible to fading than other types of multilayer films when illuminated with blue light, and a PET-based multilayer film is often used as a blue ribbon. The blue ribbon is also very sensitive to the thermally induced birefringence effect, so it is preferred to use a PBS closure in a blue ribbon that has a low index of photoelasticity. Therefore, a relatively high index of glass material is typically used in the blue ribbon to enable the use of a PET based multilayer film to reduce thermal birefringence. As a result, PBS 1948 in the blue ribbon is still likely to include a compensating effect of the astigmatism effect.

A high optical power multilayer film can be used due to the green and red ribbons, for example A PEN-based film, a low refractive index glass cover can also be used in these ribbons to reduce the astigmatism introduced by PBS 1924 and 1942. For example, if the closure of PBS 1924 and 1942 is composed of SF12 glass with a refractive index n = 1.62, the astigmatism effect will be small, about 17 μm, when the multilayer film is a PEN based material. Therefore, the light in the green red ribbon can be used with PBS that does not provide astigmatism compensation. PBS 1948 can also be used in the blue ribbon, for example, PBH55 glass is used as a cover, and PBH71 is used to make a glass sheet material.

The length of the light path between the imager and the projection optical aperture 1652 can be set to be approximately equal to each of the opposing bands of light. This can be achieved, for example, by setting the physical separation between each of the imagers and the color beam splitter 1630 to a different value, or by using a glass cover of a different thickness or the like.

Another method that can be used to compensate for astigmatism in the system is to use only a single imager, as shown in Figure 12. Light 1202 from a light source (not shown) can be formed by inserting a MRPB film 1208 into the glass crucible 1210 by a PBS 1206 and reflecting it to the end of the imager 1204. Image light 1212 reflected from imager 1204 is transmitted through PBS 1206. The image ray 1212 is astigmatic light as it passes through the PBS 1206.

The image ray 1212 can pass through an astigmatism-correcting filter 1214 that inserts a relatively low refractive index film 1216 between two relatively high refractive index 1218. The plane of the film 1216 is rotated about a rotating shaft 1220 which is perpendicular to the axis of the MRPB film 1208 in the PBS 1206. 1222. The thickness and angle of the film 1216 can be selected to reduce or substantially modify the astigmatism effect of the PBS 1206 or other components of the projection system.

In one embodiment, the filter 1214 is constructed using an MRPB film 1208 similar to the MRPB film 1216 and is inserted in a glass crucible 1218 similar to the glass crucible 1210 in the PBS 1206. In this example, the MRPB film 1216 is oriented to transmit image light 1212. The second MRPB film 1216 can also be used as a post-beam splitter, so that by reducing the transmitted light, it is in a biased state and is blocked by the PBS 1206 to increase its contrast.

The optical conditions of the first MRPB film 1208, i.e., high transmission in one polarization state and high reflectivity in the other polarization state, are high, so high contrast can be obtained in the image beam 1212. This means that only the best performing section of the MRPB film process length is suitable for use as the first MRPB film 1208. However, the optical condition of the second MRPB film 1216 is more flexible and is primarily used as a compensating effect for astigmatism and for clarity, since it is not the primary means of producing contrast. The absorbance that can be used to transmit light is in the range of 100:1-10:1. Therefore, the second MRPB film 1216 can be formed by a sub-performed section of the MRPB film process, thereby increasing the usable section of the MRPB film process length.

Filter 1214 can also be a PBS thick layer of MacNeille. Therefore, it is possible to use MacNeille PBS in this embodiment because it can only be used for transmission, and the light reflected by the MacNeille PBS is mixed with a polar state which can be ignored. Second filter when using MacNeille PBS can be made of BK7 glass.

It should be noted that an embodiment of an astigmatism correction operation is shown in FIG. 12, which can be successfully achieved in a dual-developer imager cone, in which a color separator/splitter system is disposed in the PBS. Between 1206 and the imager.

Another particular embodiment of the astigmatism correction operation is to effectively correct the astigmatism effect of the projector 1300, the main components of which are two sets of developers, as shown in FIG. In this embodiment, light rays 1302a and 1302b from a light source (not shown) are incident into individual Cartesian PBSs 1304a and 1304b. Different beams 1302a and 1302b can be produced by separating light from a source that produces a set of bands using a reflective dichroic filter or any other suitable method. The PBSs 1304a and 1304b can utilize individual MRPB films 1306a and 1306b to reflect light in a particularly polarized state. Light rays 1308a and 1308b reflected from PBS 1304a and 1304b are directed to the individual imagers 1314 and 1318. The image light 1312a reflected by the first imager 1314 is transmitted to the end of the dichroic beam splitter 1310 through the PBS 1304a. The light 1312b reflected by the second imager 1318 can pass through the PBS. 1304b is transmitted to the end of the dichroic beam splitter 1310. The image light 1312a in the first ribbon is transmitted through the two-color splitter 1310, and the image light 1312b in the second ribbon is reflected by the two-color splitter 1310 to combine the first image light 1312a, and A combined image light output 1320 is produced.

The dichroic beam splitter 1310 is composed of two sets of 1322 and 1324. Typically it is a glass crucible. The crucibles 1322 and 1324 are composed of a material having a first refractive index. Each of the crucibles 1322 and 1324 has a plurality of opposing layers 1326 and 1328 of high index material, such as high index glass. A two-color film 1330 is disposed between the two-layer sheets 1326 and 1328, which is composed of a high index material.

The layers 1326 and 1328 of the high index material may be specifically selected to have a thickness that substantially reduces astigmatism effects such as those caused by PBS 1304a and 1304b. Laminates 1326 and 1328 are selected to have the same thickness as previously described. Layers 1326 and 1328 can also be selected such that one of the plates is thicker than the other, as shown in FIG. The latter embodiment is advantageous, for example, it is determined that the astigmatism correction operating system of one ribbon must be more than the other ribbons. For example, a ribbon with a shorter wavelength range is determined to require less astigmatism correction than a ribbon with a longer wavelength range. If the first ply 1326a has a thickness d1 and the second ply 1328a has a thickness d2, the light 1312a in the first ribbon passes through a thickness d1+d2 that bonds the high index material. In other words, the light 1312b in the second ribbon passes through a thickness of 2 x d2 in combination with the high index material. Therefore, when d1&gt;d2, the image light 1312a in the first color band requires more astigmatism correction than the image light 1312b in the second color band.

In addition to adding a high index or low index sheet material to the optical system, the astigmatism effect can also be reduced by introducing a wedge element into the optical system. A particular embodiment of a wedge member that can be used to reduce the astigmatism effect is shown in Figure 15, wherein the PBS 1500 is shown as consisting of two sets of glass crucibles 1502 and 1504, and an MRPB film 1506 is Was inserted between them. Light ray 1508 from a light source (not shown) is reflected by MRPB film 1506 to at least one of the display 1510 ends. If more than one set of display 1510 is used, then a color 1512 must also be placed between the PBS 1500 and the dual viewfinder.

A wedge plate 1514 is disposed at a position between the MRPB film 1506 and one of the turns 1502 and 1504. The wedge plate 1514 can be constructed from any suitable transparent material. For example, the wedge plate 1514 can be constructed of glue or polymer. In a particular embodiment, the wedge plate 1514 is constructed of a stable optical adhesive, such as Norland 61, which adheres the MRPB film 1506 to the crucible 1504.

This embodiment will be further explained as follows with an example. If the glass crucibles 1502 and 1504 are composed of SF57 glass and have a MRPB film/adhesive layer having a thickness of 225 μm, the wedge angle necessary for correcting the astigmatism effect, α, is between 0.15° and 0.25°. The formula is used to calculate the formula, ZEMAX. If the height of one is h, the formula can be used to calculate the wedge thickness of the broad side of the wedge 1514, w, which is:<maths><img file="TW577235B_D0004.tif" /></maths>Where h = 35 mm, the calculated thickness, w, is 129 μm, so the length of the light path at the center end of the PBS is equal to 65 μm. The wedge may be constructed of an optical adhesive by placing a 129 μm spacer on one side of the crucible 1504 and filling the remaining space of the wedge with an optical adhesive. The optical adhesive can then be treated with ultraviolet light.

The spacer may be a glass or plastic sphere disposed only along the tapered broad side of the wedge. Alternatively, the spacers may also be framed to form a relief in MRPB. The film 1506 is either attached to the PBS crucible 1504. If the manufacturing tolerance is very high, the spacers may not be disposed at all. There is a machine that automatically creates the gap so that the wedge can be filled with the adhesive by simply tilting one of the turns in the process.

Another shape of the cymbal 1502 can be adjusted to correct for non-parallel paths of the PBS 1500 in the image.

One of the benefits of using the wedge element 1514 to correct the astigmatism effect is that the total thickness of the PBS is less than, for example, the embodiment shown in Figure 11, wherein a high index laminate is added to the ray path until it exceeds 2.8. Mm. Since the wedge angle is small, the wedge 1514 can be constructed simply by an adhesive that adheres the MRPB film 1506 to the crucibles 1502 and 1504. It is not necessary to use additional optical components, such as sheet materials, in the wedge PBS assembly. It should be noted that the compensation of the wedge astigmatism effect can be applied to other components, such as in a two-color splitter/beam splitter or a combined light splitter.

It should be noted that a single projector projection system, as shown in Figure 15, can also be configured in different types of low astigmatism PBS. For example, PBS 1500 can be replaced with a PBS, such as PBS 1100, as shown in FIG. Likewise, the low astigmatism PBS 1500 can be used in a dual vision projector projection system, such as the dual vision projector projection system shown in Figures 16 and 18, respectively.

As described above, the present invention is applicable to display devices and is believed to be particularly useful for reducing astigmatism effects in a projection system, such as using a polymeric multilayer film, a reflective polarizing dichroic mirror film or the like. Splitting mirror. A general-purpose polymeric multilayer film, a reflective polarizing dichroic mirror film, is a multilayer film with a matching index. The invention can also be used to reduce astigmatic effects that occur in other components of the projection system. Moreover, the present invention is applicable to projection systems having a wide range of focal lengths, but is believed to be particularly useful for projection systems of a low focal length.

The present invention is not to be considered as limited to the details of the invention described herein. The various modifications, equivalents, and various structures and the like of the present invention are intended to be directed to the various techniques disclosed in the subject disclosure. The scope of the patent application is intended to cover the modifications and devices described above.

Component symbol comparison table

110. . . system

112. . . light source

114. . . Arc lamp

116. . . Reflector

118. . . Light

120. . . Polarizing beam splitter (PBS)

122. . . Adjustable optical

126. . . Reflective imager

128. . . Lens system

152. . . Controller

200. . . Projection system

210. . . light source

211. . . Arc lamp

213. . . Reflector

215. . . Adjustable optical

217. . . Collimating lens

219. . . First array lenslet

221. . . Second array lenslet

223. . . Bipolar converter

225. . . Front beam splitter

226. . . Reflective imager

227. . . Condenser lens

228. . . Reflective imager

230. . . Reflective imager

234. . . Projection lens system

236. . . Color

238. . . Field lens

240. . . Field lens

242. . . Field lens

244. . . Rear beam splitter

250. . . Polarizing beam splitter (PBS)

252. . . Multilayer reflective polarizing beam splitter film

254. . .

256. . . Rotating shaft

258. . . Rotating shaft

262. . . Spindle

400. . . Color

402. . . First

402a, b. . . part

404. . . Second

406. . . Third

410. . . Light

412. . . First filter

414. . . Light

416. . . Input surface

417. . . Air gap

418. . . Second filter

422. . . gap

424. . . Light

426. . . First imager

428. . . Second imager

430. . . Third imager

450. . . Polarizing beam splitter (PBS)

502. . . gap

504. . . Blunt end

600. . . Color

602. . . First

604. . . Second

606. . . Third

614. . . Light

622. . . Reflection gap

650. . . Polarizing beam splitter (PBS)

656. . . Complete internal reflective surface

662. . . Wedge

664. . . Air gap

700. . . Color

702. . . First

702a, b. . . part

704. . . Second

706. . . Third

712. . . First filter

714. . . Light

720. . . Light

722. . . Air gap

724. . . Light

727. . . Output surface

760. . . High index board

762. . . Second surface of the high index plate

800. . . Color

862. . . Second high index board

900. . . Projector

902. . . Light

904. . . X cube beam splitter

906. . . Light

908. . . First mirror

910. . . Light

912. . . Second mirror

914. . . Light

916. . . First polarizing beam splitter

917. . . MRPB film

918. . . Second polarized beam splitter

920. . . First reflection imager

922. . . Imaging beam

924. . . X cube beam splitter

926. . . Second reflection imager

928. . . Imaging beam

930. . . Imaging beam

932. . . Image beam

1002. . . Right angle

1004. . . Right angle

1006. . . Right angle

1008. . . Right angle

1010. . . coating

1012. . . coating

1014. . . coating

1016. . . coating

1020. . . First sheet material

1022. . . Second sheet material

1050. . . X cube beam splitter

1052. . . MPBR film

1054. . . Polarizing beam splitter (PBS)

1056. . . Sheet material

1058. . . Sheet material

1060. . .

1062. . .

1064. . .

1066. . .

1070. . . Light

1072. . . Imager

1074. . . Image light

1076. . . Image light

1100. . . Polarizing beam splitter (PBS)

1102. . .

1104. . .

1106. . . MRPB/adhesive layer

1108. . . High index layer

1202. . . Light

1204. . . Imager

1206. . . Polarizing beam splitter (PBS)

1208. . . MPBR film

1210. . . Glass crucible

1212. . . Image light

1214. . . Astigmatic effect correction filter

1216. . . film

1218. . .

1220. . . Rotating shaft

1222. . . Rotating shaft

1300. . . Projector

1302a, b. . . Light

1304a, b. . . Polarizing beam splitter (PBS)

1306a, b. . . MPBR film

1308a, b. . . Light

1310. . . Two-color spectroscope

1312a, b. . . Image light

1314. . . Imager

1318. . . Imager

1322. . .

1324. . .

1326. . . High index board

1328. . . High index board

1330. . . Two-color film

1500. . . Polarizing beam splitter (PBS)

1502. . . Glass crucible

1504. . . Glass crucible

1506. . . MPBR film

1508. . . Light

1510. . . Imager

1512. . . Color

1514. . . Wedge plate

1600. . . Duplex projector projection system

1602. . . Light

1604. . . light source

1606. . . Beam splitter

1608. . . Pre-splitting mirror

1610. . . Reflective tunnel

1612. . . Homogeneous light

1614. . . First lens

1616. . . First color separator

1618. . . Light

1620. . . Residual light

1622. . . Second lens

1623. . . Third lens

1624. . . First PBS

1626. . . First imager

1628. . . Image light

1630. . . X cube color beam splitter

1632. . . Third lens

1634. . . Second color separator

1636. . . Light

1638. . . beam

1640. . . Second imager

1642. . . Second PBS

1644. . . Image light

1646. . . Third imager

1648. . . Third PBS

1650. . . Image light

1652. . . Projection optics polar rotating optics

1654. . . Polar rotating optics

1800. . . Projector

1810. . . Color separator

1818. . . Light

1820. . . First PBS

1822. . . lens

1824. . . First imager

1826. . . reflected light

1828. . . Color beam splitter

1830. . . Light

1831. . . lens

1832. . . Second PBS

1834. . . Second imager

1836. . . Image light

1838. . . Color modulator

1840. . . motor

1842. . . Transmission filter

1844. . . Transmission filter

1846. . . Color modulated light

1850. . . Controller

1900. . . Three-image projector projection system

1924. . . First PBS

1942. . . Second PBS

1948. . . Polar spectroscope

1950. . . Cover

1952. . . Multilayer polarizing film

D1, d2. . . thickness

h. . . thickness

W. . . Wedge thickness

α. . . Wedge angle