Light source device, and two-dimensional image display unit

The present invention relates to a light source device and a two-dimensional image display device, and more particularly to a light source device that realizes miniaturization of the two-dimensional image display device and a small two-dimensional image display device using the light source device.

In recent years, a two-dimensional image display device (laser display device) capable of vivid color expression has attracted attention. This uses three coherent light sources (for example, a laser light source) of red, green, and blue, and has a configuration as shown in FIG. 13, for example.

In FIG. 13, 600 is a two-dimensional image display device using a conventional laser light source. The two-dimensional image display device 600 includes a red, green, and blue laser light source 601a, 601b, 601c, a beam expander 602a, 602b, 602c, an optical integrator 603a, 603b, 603c, a mirror 604a, 604c, and a diffuser. It has 606a, 606b, 606c, diffuser plate moving means 605a, 605b, 605c, spatial light modulation elements 607a, 607b, 607c, field lenses 608a, 608b, 608c, dichroic prism 609, and projection lens 610. ing.

In this two-dimensional image display device 600, the light from the red, green, and blue laser light sources 601a, 601b, and 601c is magnified by the beam expanders 602a, 602b, and 602c, respectively, and passes through the optical integrators 603a, 603b, and 603c. The optical paths of the red and blue lights that have passed through the optical integrators 603a and 603c are bent 90 degrees by the mirrors 604a and 604c, and the green light that has passed through the optical integrators 603b is the field lenses 608a and 608a, respectively. The spatial light modulators 607a, 607b, 607c are irradiated through the 608b, 608c and the diffuser plates 606a, 606b, 606c. The light from the three types of laser light sources 601a, 601b, 601c passes through the optical integrators 603a, 603b, 603c, and the illuminance distribution on the spatial light modulation elements 607a, 607b, 607c becomes constant. The light independently modulated by the spatial light modulation elements 607a, 607b, and 607c is combined by the dichroic prism 609 to form a coaxial beam propagating in the same optical path, and is further magnified and projected by the projection lens 610 to screen 61. Imaged on top. At that time, since the laser beam coherence is high, speckle noise is superimposed on the image projected on the screen 61. In order to prevent this, the diffuser plates 606a, 606b, 606c are swung by the diffuser plate moving means 605a, 605b, 605c so that the speckle noise is time-averaged.

However, in the conventional two-dimensional image display device 600 as shown in FIG. 13, a beam expander and an optical integrator are used to magnify the light from the three types of laser light sources 601a to 601c and make the light intensity distribution uniform. Are required for each of the three. Further, in order to make the light from the three types of laser light sources parallel to each other and to be a coaxial beam propagating in the same optical path, it is also necessary to arrange many lenses and mirrors in the device. For this reason, the conventional two-dimensional image display device has a problem that the entire device becomes large-scale.

In order to solve this problem, the optical system of the two-dimensional image display device, for example, as shown in FIG. 14, first uses a dichroic mirror to emit light emitted from three color laser light sources of red, green, and blue. After mixing, it is conceivable to allow the beam expander and optical integrator to pass through.

In FIG. 14, 700 is a two-dimensional image display device using a conventional laser light source. The two-dimensional image display device 700 includes a red, green, and blue laser light source 701a, 701b, 701c, collimating lenses 704a, 704b, 704c, first and second dichroic mirrors 705a, 705b, and a beam expander 702. It has an optical integrator 703, a projection lens 710, and a liquid crystal panel 71.

Here, in the dichroic mirror, a multilayer film is laminated on a glass substrate, and the transmittance differs depending on the wavelength. The first dichroic mirror 705a of the two-dimensional image display device 700 shown in FIG. 15 reflects light having a wavelength shorter than that wavelength and allows only long wavelength light to pass through, with a wavelength of about 580 nm as a boundary. The dichroic mirror 705b of No. 705b reflects light having a wavelength shorter than that wavelength and allows only long wavelength light to pass through the wavelength of about 490 nm.

In the two-dimensional image display device 700 using such a conventional laser light source, first, the light emitted from the red, green, and blue laser light sources 701a, 701b, 701c is collimated by the collimating lenses 704a, 704b, 704c, and the light is collimated. The collimated light is converted into a coaxial beam that is parallel to each other and propagates in the same optical path by the first and second dichroic mirrors 705a and 705b, and then incident on the beam expander 702. Then, the light incident on the beam expander 702 is expanded in the beam expander 702 and then passes through the optical integrator 703. The optical integrator 703 has two fly-eye lenses 703a and 703b in which rectangular element lenses are two-dimensionally arrayed, and a collimating lens 703c, and each of the first fly-eye lenses 703a. The light on the element lens is imaged on the two-dimensional space light modulation element by the second fly-eye lens 703b, whereby the light intensity distribution on each element lens is multiplexed on the two-dimensional space light modulation element. The light intensity distribution on the two-dimensional spatial light modulation element becomes uniform.

Then, the light that has passed through the optical integrator 703 and has a uniform light intensity distribution is imaged on the liquid crystal panel 71 by the projection lens 710.<patcit num="1"><text>Japanese Unexamined Patent Publication No. 10-293268</text></patcit>

<p> In this way, as shown in FIG. 13, the light emitted from each of the laser light sources 601a to 601c is magnified by the beam expanders 602a to 602c, and the light intensity distribution is made uniform by the optical integrators 603a to 603b, and then the dichroic filter is used. As shown in FIG. 14, the light emitted from each of the laser light sources 701a to 701c is first combined by the first and second dichroic mirrors 705a and 705b to form a coaxial beam, rather than being combined by the prism 609 to form a coaxial beam. After making a beam, it is possible to reduce the scale of the entire two-dimensional image display device by expanding it with the beam expander 702 and making the light intensity distribution uniform with the light integrator 703.</p><p> However, even if the entire optical system of a conventional two-dimensional image display device is configured as shown in FIG. 14, the number of parts is still large and the device scale is still large for mounting on a small device such as a mobile phone. There is also a big problem.</p><p> The present invention has been made to solve the above problems, and an object of the present invention is to provide an ultra-small light source device that can be mounted on a small device and a small two-dimensional image display device using the light source device. To do.</p>

<p> In order to solve the above problems, the light source device of the present invention is emitted from at least two coherent light sources and at least one coherent light source so that each light emitted from the at least two coherent light sources propagates in the same optical path. It is provided with a diffracting unit that diffracts the light.</p><p> As a result, the light emitted from the plurality of coherent light sources can be easily combined in the diffractometer, and the light source device can be miniaturized.</p><p> Further, in the light source device of the present invention, the propagating optical paths of the respective lights emitted from the at least two coherent light sources overlap each other on the diffractometer. This makes it possible to further reduce the size of the light source device.</p><p> Further, in the light source device of the present invention, the central axis of the propagation optical path of each light emitted from the at least two coherent light sources intersects at one point on the diffractive part. This makes it possible to further reduce the size of the light source device.</p><p> Further, in the light source device of the present invention, the at least two coherent light sources are installed on the same submount.</p><p> As a result, it is possible to dissipate heat from three light sources by radiating heat from one submount, and there is also an effect that heat radiating from the light source in the light source device can be realized by a simple configuration.</p><p> Further, in the light source device of the present invention, the coherent light source is a coherent light source that emits red light, a coherent light source that emits green light, and a coherent light source that emits blue light. This makes it possible to provide a small light source device that lights RGB light.</p><p> Further, in the light source device of the present invention, the light emitted from at least one coherent light source among the coherent light sources passes through the diffracting portion without being diffracted by the diffracting portion.</p><p> As a result, the manufacturing process of the diffractive portion can be reduced, so that the light source device can be provided at a lower cost.</p><p> Further, in the light source device of the present invention, the diffraction section is composed of one diffraction element, and the diffraction element is at least one so that each light emitted from the at least two coherent light sources propagates in the same optical path. It diffracts the light emitted from the coherent light source. This makes it possible to make the diffractometer compact and to make the light source device ultra-miniaturized.</p><p> Further, in the light source device of the present invention, the diffraction element further includes a lens action.</p><p> As a result, each light emitted from the plurality of coherent light sources can irradiate the coplanar region above the diffraction element.</p><p> Further, the light source device of the present invention includes a first diffracting element that diffracts at least one received light so that at least two received lights propagate in the same optical path, and at least two coherents. A second diffraction that diffracts the light emitted from at least one coherent light source among the light sources so that the central axis of the propagation light path of the light from each coherent light source intersects at one point on the first diffractive element. It is composed of an element.</p><p> As a result, it is possible to provide a small light source device that can easily combine the light from the plurality of coherent light sources into a coaxial beam in the diffractive unit at a lower cost.</p><p> Further, in the light source device of the present invention, the second diffraction element further comprises a lens action, and the second diffraction element collects each light emitted from the at least two coherent light sources. Each light diffracted by the second diffraction element irradiates the same region of the first diffraction element.</p><p> Thereby, each light emitted from the plurality of coherent light sources can irradiate the same region of the first diffraction element provided above the second diffraction element.</p><p> Further, in the light source device of the present invention, the diffraction element is a volume hologram, and the volume hologram receives each light emitted from the at least two coherent light sources and changes the propagation direction of each light. A plurality of gratings are multiplexed.</p><p> As a result, it is possible to realize ultra-miniaturization of the light source device in which the light from the plurality of coherent light sources is simply converted into a coaxial beam and combined in the diffractive unit.</p><p> Further, in the light source device of the present invention, the diffraction element is divided into regions, and each light diffracted in each divided region of the diffraction element irradiates the same plane region.</p><p> As a result, the diffraction element can be provided with the function of an optical integrator, and the intensity distribution of the light applied to the space can be made uniform.</p><p> Further, in the light source device of the present invention, the diffraction element is divided into regions in a grid pattern. This makes it possible to further make the intensity distribution of the light applied to the space even.</p><p> The two-dimensional image display device of the present invention diffracts the light emitted from at least two coherent light sources and the light emitted from at least one coherent light source so that each light emitted from the at least two coherent light sources propagates in the same optical path. It includes a diffracting unit and a two-dimensional spatial light modulation element provided in the space above the diffracting unit and receiving each light diffracted by the diffracting unit into a coaxial beam.</p><p> As a result, the two-dimensional image display device that displays the light emitted from the light source device can be miniaturized.</p><p> Further, the two-dimensional image display device of the present invention includes a control unit that controls the operation of the at least two coherent light sources, and the at least two coherent light sources emit a coherent light source that emits red light and a green light. A coherent light source and a coherent light source that emits blue light, and the control unit controls the three coherent light sources so as to emit light sequentially in a time-divided manner.</p><p> As a result, moving images can also be displayed on the two-dimensional image display device.</p>

<p> According to the light source device of the present invention, in a light source device having a plurality of coherent light sources, since each light source emitted from the coherent light source is diffracted so as to propagate in the same optical path, the plurality of coherent light sources are provided. It is possible to make the optical system that combines each light from the light source into a coaxial beam into a compact size, and to provide an ultra-small light source device.</p><p> Further, according to the light source device of the present invention, the light emitted from at least one coherent light source among the plurality of coherent light sources is made to pass through the diffracting unit without being diffracted. The number of diffractions to be converted can be reduced, and the light source device can be constructed at low cost.</p><p> Further, according to the light source device of the present invention, the diffraction section is composed of two first and second diffraction gratings, and the second diffraction grating is the light from a plurality of coherent light sources, and these lights are the first. Since it is assumed that the same region of the diffraction element is diffracted and the first diffraction grating is diffracted so that each light passing through the second diffraction element becomes a coaxial beam, the light is diffracted from a plurality of light sources. It is possible to provide a small light source device capable of easily combining the light of the above into a coaxial beam.</p><p> Further, according to the light source device of the present invention, since the plurality of coherent light sources are provided on the same submount, the heat treatment of the plurality of light sources can be performed by the heat treatment of one submount, and the light source device can be used. It also has the effect of facilitating heat dissipation.</p><p> Further, according to the light source device of the present invention, the diffractive portion is divided into regions, and each of the divided regions of the diffractive portion is formed with a plurality of gratings and has a concave lens action. In addition to being able to easily combine each light emitted from the coherent light source into a coaxial beam, the intensity distribution of the light emitted from the diffractive part can be made uniform. Further, as the diffracting unit having an optical integrator that makes the intensity distribution of the light emitted from the diffracting unit uniform, a diffracting unit that is smaller in size and cheaper in material than the conventional lens array can be used. It can be realized at low cost.</p><p> Further, according to the two-dimensional image display device of the present invention, since the light source device is miniaturized by using a diffraction element, the two-dimensional image display device can be miniaturized.</p><p> Further, according to the two-dimensional image display device of the present invention, since the diffractive part of the light source device also has the function of an optical integrator, a fly-eye lens conventionally required for uniform light intensity distribution is used. Even without it, the output light of the light source device has a uniform intensity distribution, the two-dimensional image display device having a uniform intensity distribution of the light source light can be further miniaturized, and the number of components of the two-dimensional image display device can be reduced. Can also be reduced. As a result, a two-dimensional image display device having a uniform intensity distribution of light source light can be easily assembled and inexpensive.</p>

<figref num="1">FIG. 1 is a side view (FIG. (A)) and a plan view (FIG. (B)) showing the configuration of the light source device according to the first embodiment of the present invention.</figref><figref num="2">FIG. 2 is a diagram showing a method of manufacturing a diffraction portion according to the first embodiment of the present invention, and is a process of manufacturing a grating that diffracts the emitted light of a green, blue, or red laser light source (FIGS. (a) and (b)). , Figure (c)) is shown.</figref><figref num="3">FIG. 3 is a side view (FIG. (A)) and a plan view (FIG. (B)) showing another configuration of the light source device according to the first embodiment of the present invention.</figref><figref num="4">FIG. 4 is a side view (FIG. (A)) and a plan view (FIG. (B)) showing still another configuration of the light source device according to the first embodiment of the present invention.</figref><figref num="5">FIG. 5 is a side view (FIG. (A)) and a plan view (FIG. (B)) showing the configuration of the light source device according to the second embodiment of the present invention.</figref><figref num="6">FIG. 6 is a diagram showing a method of producing a second volume hologram of the diffracting portion according to the second embodiment of the present invention, and is a process of producing a grating that diffracts the emitted light of the green, blue, and red laser light sources (FIG. (a). ), Figure (b), Figure (c)).</figref><figref num="7">FIG. 7 is a diagram showing a method for producing a first volume hologram of the diffraction unit according to the second embodiment of the present invention, and is a process of producing a grating that diffracts the emitted light of the green, blue, and red laser light sources (FIG. (a). ), Figure (b), Figure (c)).</figref><figref num="8">FIG. 8 is a side view (FIG. (A)) and a plan view (FIG. (B)) showing the configuration of the light source device according to the third embodiment of the present invention.</figref><figref num="9">FIG. 9 is a diagram showing a method of forming a grating for green light of the diffraction unit according to the third embodiment of the present invention, and is a process of interferometrically exposing four divided regions arranged in a row (FIGS. (a) to 9). (d)) is shown.</figref><figref num="10">FIG. 10 is a diagram showing a method of forming a grating for blue light of the diffraction unit according to the third embodiment of the present invention, and is a process of interferometrically exposing four divided regions arranged in a row (FIGS. (a) to 10). (d)) is shown.</figref><figref num="11">FIG. 11 is a diagram showing a method of forming a grating for red light of the diffraction unit according to the third embodiment of the present invention, and is a process of interferometrically exposing four divided regions arranged in a row (FIGS. (a) to 11]. (d)) is shown.</figref><figref num="12">FIG. 12 is a diagram showing a configuration of a two-dimensional image display device according to a fourth embodiment of the present invention.</figref><figref num="13">FIG. 13 is a diagram showing a configuration example of one of the conventional two-dimensional image display devices.</figref><figref num="14">FIG. 14 is a diagram showing another configuration example of the conventional two-dimensional image display device.</figref>

Code description

10,10a, 10b, 10c Submount 11a, 11b, 11c, 21a, 21b, 21c, 601a, 601b, 601c, 701a, 701b, 701c Laser light source 12a, 12b, 12c Prism 32 division area 32a, 32b, 32c Grating 20,220,320 Diffractive part 221 First volume hologram 222 Second volume hologram 222a, 222b, 222c Grating 30,607a, 607b, 607c, 707 Spatial light modulation element 51,61 Screen 71 Liquid crystal panel 100,100a, 100b, 200,300 Light source device 500,600,700 Two-dimensional Image display device 510,710 Projection lens 520 Control unit 530 Video signal switching unit 540 Laser switching unit 550a, 550b, 550c Laser driving unit 560,608a, 608b, 608c Field lens 602a, 602b, 602c Beam expander 603a, 603b, 603c Optical integrator 604a , 604c mirror 605a, 605b, 605c Diffusing plate rocking means 606a, 606b, 606c Diffusing plate 609 Dichroic prism 610 Projection lens 704a, 704b, 704c Collimating lens 705a, 705b Dichroic mirror

Hereinafter, embodiments of the present invention will be described.

(Embodiment 1) In the first embodiment, one diffractive element diffracts the light emitted from three coherent light sources emitting red, blue, and green light so as to form a coaxial beam. A light source device that combines each light will be described. In the following description, the "coaxial beam" means light propagating in the same optical path, and the "optical axis" means the central axis of the optical path.

FIG. 1 is a diagram showing a configuration of a light source device according to the first embodiment, FIG. 1A is a side view, and FIG. 1B is a plan view.

In FIG. 1, 100 is the light source device of the first embodiment, and the light source device 100 is used as a light source of a two-dimensional image display device. The light source device 100 includes a coherent light source, here, three semiconductor lasers (hereinafter, simply referred to as "laser light sources") 11a to 11c that emit red light, blue light, and green light, and the laser light sources 11a to 11c. It has a submount 10 such as a silicon substrate that is directly mounted. Further, the light source device 100 is provided above the submount 10, and emits light emitted from at least one coherent light source, here, two laser light sources 11a, 11b, 11c, from the three coherent light sources. A diffracting unit 20 that diffracts all light so as to form a coaxial beam, and light emitted from the three laser light sources 11a, 11b, and 11c provided on the submount 10 illuminate the same region of the diffracting unit 20. As such, it has prisms 12a, 12b, 12c that reflect the light emitted from the laser light sources 11a, 11b, 11c. A spatial light modulation element 30 that spatially changes the amplitude of each light made into a coaxial beam by the diffraction unit 20 is provided above the diffraction unit 20.

Each of the laser light sources 11a to 11c is an end face emitting laser, the red light and green light laser light sources 11a and 11c are arranged on one straight line, and the blue light laser light source 11b is on a straight line orthogonal to the straight line. It is arranged. As shown in FIG. 1, the reflecting surfaces of the prisms 12a, 12b, 12c are the optical axis of the emitted light from the laser light sources 11a, 11b, 11c reflected by the reflecting surface and the emission from the laser light source 11b. The reflection angle is set so that the optical axis of the emitted light intersects at one point on the diffraction unit 20.

In the first embodiment, the diffraction unit 20 is composed of one volume hologram. A plurality of gratings are formed on the volume hologram by diffracting each light emitted from each of the laser light sources 11a to 11c into a coaxial beam. In the volume hologram of the first embodiment, the light passing through the diffracting unit 20 illuminates the same region of the spatial light modulation element 30 provided above the diffracting unit 20. It also has a lens function to collect light.

Hereinafter, a method for manufacturing the diffraction unit 20 according to the first embodiment will be described.

FIG. 2 is a diagram showing a method for producing a volume hologram of the first embodiment, FIG. 2 (a) is a method for forming a grating for light emitted from a laser light source 11c of green light, and FIG. 2 (b). Shows a method for forming a grating for light emitted from a blue light laser light source 11b, and FIG. 2 (c) shows a method for forming a grating for light emitted from a red light laser light source 11a.

For example, a light source Lg1 and a light source Lg2 having the same wavelength as the green light laser light source 11c are used to form a grating corresponding to the light emitted from the green light laser light source 11c. At this time, the light sources Lg1 and Lg2 emit laser light generated from the same light source and further divided. For example, light from one laser light source may be introduced into an optical fiber, further divided into two fibers by a fiber coupler, and the emission end faces of the two fibers may be arranged at the positions of Lg1 and Lg2. Further, the light source Lg1 is arranged so that the optical position with respect to the volume hologram 20 coincides with the laser light source 11c shown in FIGS. It is arranged at the center of projection projected on the entire light receiving surface of the light modulation element 30. In the first embodiment, since the spatial light modulation element 30 is located directly above the diffracting unit 20, the light source Lg2 is arranged on a straight line perpendicular to the light emitting surface of the diffracting unit 20 (FIG. 2 (a). )reference). Then, the volume hologram is coherently exposed by the light emitted from the light sources Lg1 and Lg2. As a result, interference fringes are recorded on the volume hologram to form a Bragg grating that diffracts and focuses the light emitted from the laser light source 11c.

A light source Lb1 and a light source Lb2 having the same wavelength as the blue light laser light source 11b are used to form a grating corresponding to the light emitted from the blue light laser light source 11b. At this time, the light sources Lb1 and Lb2 emit laser light generated from the same light source and further divided. For example, light from one laser light source may be introduced into an optical fiber, further divided into two fibers by a fiber coupler, and the emission end faces of the two fibers may be arranged at the positions of Lb1 and Lb2. Further, the light source Lb1 is arranged so that the optical position with respect to the volume hologram 20 coincides with the laser light source 11b shown in FIG. 1, and the light source Lb2 is arranged at the same position as the light source Lg2 (see FIG. 2 (b)). ). Then, the volume hologram is coherently exposed by the light emitted from the light sources Lb1 and Lb2. As a result, interference fringes are further recorded on the volume hologram to form a Bragg grating that collects the light emitted from the laser light source 11b.

A light source Lr1 and a light source Lr2 having the same wavelength as the red light laser light source 11a are used to form a grating corresponding to the light emitted from the red light laser light source 11a. At this time, the light sources Lr1 and Lr2 emit laser light generated from the same light source and further divided. For example, light from one laser light source may be introduced into an optical fiber, further divided into two fibers by a fiber coupler, and the emission end faces of the two fibers may be arranged at the positions of Lr1 and Lr2. Further, the light source Lr1 is arranged so that the optical position with respect to the volume hologram 20 coincides with the laser light source 11a shown in FIG. 1, and the light source Lr2 is arranged at the same position as the light source Lg2 (see FIG. 2 (c)). ). Then, the volume hologram is coherently exposed by the light emitted from the light sources Lr1 and Lr2. As a result, interference fringes are further recorded on the volume hologram to form a Bragg grating that diffracts and focuses the light emitted from the laser light source 11a.

It should be noted that the interference exposure of the volume hologram needs to be performed three times so that the grating for the emitted light of each of the three laser light sources is formed in one volume hologram. Therefore, each interference exposure is performed on the volume hologram. The light intensity is such that the constituent photosensitive material is completely exposed by three exposures.

Next, the action and effect will be described. In the light source device 100, when light is emitted from the red light, blue light, and green light laser light sources 11a to 11c provided on the submount 10, the light emitted from the three laser light sources 11a, 11b, and 11c is emitted. Is reflected by the prisms 12a, 12b, 12c on the submount 10 so that the optical axes of the emitted lights intersect at one point on the diffractometer 20.

Then, the red, blue, and green laser beams from the respective laser light sources 11a, 11b, and 11c are combined in the diffraction unit 20 so as to form a coaxial beam as shown in FIG. 1 by grating according to each light. Therefore, the same region of the spatial light modulation element 30, that is, the light receiving surface is irradiated. That is, the red light, blue light, and green light emitted from the laser light sources 11a, 11b, and 11c reflected by the prism are diffracted and condensed as they pass through the diffracting unit 20, respectively. As a result, the combined light emitted from the three laser light sources from the diffractometer 20 irradiates the light receiving surface which is a fixed region of the spatial light modulation element 30.

As described above, according to the first embodiment, in the light source device, the three laser light sources 11a to 11c and the light emitted from the laser light sources 11a to 11c are combined so as to form a coaxial beam. Since it is equipped with a diffractometer 20 composed of a volume hologram of the above, it is possible to miniaturize the optical system that converts the light emitted from the three laser light sources into a coaxial beam, which makes it possible to make a small device such as a mobile phone. It is possible to realize an ultra-compact two-dimensional image display device that can be mounted.

Further, since the three light sources are arranged on the same submount 10, it is possible to dissipate the heat of the three light sources by the heat of one submount 10, and the heat treatment of the light source in the light source device can be performed. It also has the effect of being easy to do.

Further, in the first embodiment, the end face emitting lasers are used for the three light sources 11a to 11c, and the blue light laser is arranged on a straight line orthogonal to the straight line connecting the green light laser and the red light laser. However, the arrangement of the laser light source is not limited to this.

For example, a surface emitting laser may be used as the blue light laser, and this may be arranged between the green light laser and the red light laser. 3 (a) and 3 (b) are side views and plan views of the light source device 100a showing the light source device 100a having such a configuration, and have the same reference numerals as those of FIGS. 1 (a) and 1 (b) in FIG. Indicates the same as that in the light source device 100.

In this case, the number of prisms installed on the submount 10 can be reduced, and the light source device 100 can be made inexpensive.

Further, in the first embodiment, the semiconductor laser chip which is the laser light source is provided on the same submount 10, but the laser light source is a semiconductor as shown in the light source device 100b shown in FIGS. 4 (a) and 4 (b). The laser chips may be mounted on separate submounts 10a to 10c. 4 (a) and 4 (b) are side views and plan views of the light source device 100b, and the same reference numerals as those in FIGS. 1 (a) and 1 (b) in FIG. 4 are those in the light source device 100. Shows the same thing as.

By mounting the semiconductor laser chips as the three light sources on separate submounts 10a to 10c in this way, the degree of freedom in the layout of the three light sources is increased, and it is easy to design the light source device in a small device. It has the effect of being able to.

Further, in the first embodiment, the diffraction unit 20 has been described as having a condenser lens function, but if the light passing through the diffraction unit 20 is within the plane of the spatial light modulation element 30, the diffraction unit 20 It is not necessary to collect each light at. In this case, since it is not necessary to form a grating that collects the light emitted from the laser light source 11b on the volume hologram, the step of manufacturing the volume hologram can be reduced, and the apparatus can be provided at a lower cost. Can be done.

Further, in the first embodiment, the case where the number of coherent light sources is three has been described as an example, but the number of light sources may be at least two or more. For example, when four or more coherent light sources are provided, a light source that can express a wider range of vivid colors by providing light such as bluish green or yellow in addition to red light, blue light, and green light. Can be provided.

Further, in the first embodiment, the light source device is used as a light source of the two-dimensional image display device, and the spatial light modulation element 30 spatially changes the amplitude of the light from the diffractometer 20. However, the light source device of this embodiment is not limited to the light source of the two-dimensional image display device, and the spatial light modulation element other than the two-dimensional image display device spatially changes the phase of the light from the diffractometer 20. It can also be used as a light source for an apparatus that changes to.

(Embodiment 2) In the first embodiment, the case where the diffraction grating is composed of one diffraction element has been described, but in the second embodiment, the diffraction grating is composed of two diffraction elements. The case where it is done will be described.

First, the configuration of the light source device according to the second embodiment will be described. 5A and 5B are views showing the configuration of the light source device according to the second embodiment, FIG. 5A is a side view, and FIG. 5B is a plan view.

In FIG. 5, 200 is the light source device of the second embodiment, and the light source device 200 includes a submount 10 such as a silicon substrate and red light, blue light, and green light provided on the submount 10. Three semiconductor laser light sources (hereinafter, simply referred to as laser light sources) 21a to 21c that emit each of them and those provided above the submount 10 are emitted from the three laser light sources 21a to 21c. It is provided with a diffractometer 220 that diffracts each light into a coaxial beam. A spatial light modulation element 30 that spatially changes the amplitude of the light made into a coaxial beam in the diffraction unit 220 is provided above the diffraction unit 220.

Here, the three laser light sources 21a to 21c are surface emitting lasers that emit light from the upper surface of the laser chip, and these are arranged along one straight line on the submount 10.

Then, in the second embodiment, the diffraction unit 220 is composed of two volume holograms (first and second volume holograms) 221, 222.

The second volume hologram 222 is provided above the sub-mount 10 and emits light from each of the three laser light sources 21a to 21c on the first volume hologram 221 provided further above. The optical axes of the emitted lights are diffracted so as to intersect at one point, and the emitted lights are condensed so as to irradiate the same region of the first volume hologram 221. Therefore, in the second volume hologram 222, a plurality of lights corresponding to the respective lights so as to irradiate the same region of the first volume hologram 221 with each light emitted from the laser light sources 21a to 21c. A grating, specifically, a grating 222a for red light, a grating 222b for blue light, and a grating 222c for green light are formed.

The first volume hologram 221 further diffracts the light emitted from each light source diffracted by each of the second volume holograms 222 to form a coaxial beam. Therefore, the first volume hologram 221 is formed with a plurality of gratings that diffract the light emitted from each light source that has passed through the second volume hologram 222 so as to form a coaxial beam.

In the second embodiment, in order to further reduce the size of the light source device 200, the arrangement intervals of the light sources 21a to 21c are narrowed, and as shown in FIG. 5, the light emitted from each of the light sources is emitted. Overlap on the second volume hologram 222. Therefore, in the second volume hologram 222, the gratings 222a to 222c for red light, blue light, and green light are partially overlapped and formed.

Hereinafter, a method for manufacturing the diffraction unit 220 according to the second embodiment will be described.

FIG. 6 is a diagram showing a method for producing a second volume hologram according to the second embodiment, FIG. 6 (a) shows a method for forming a grating for green light, and FIG. 6 (b) shows a method for forming a grating for blue light. As for the forming method, FIG. 6 (c) shows the grating forming method for red light. Further, FIG. 7 is a diagram showing a method of producing the first volume hologram of the second embodiment, FIG. 7 (a) shows a method of forming a grating for green light, and FIG. 7 (b) shows a method of forming a grating for green light. FIG. 7 (c) shows a method for forming a grating for red light.

First, a method for producing the second volume hologram 222 will be described. The second volume hologram 222 is diffracted so that the optical axes of the emitted light from the light sources 21a to 21c intersect at one point on the first volume hologram 221, and the emitted light is diffracted on the first volume hologram 221. It collects light so as to irradiate the same area of.

For example, a light source Lg1 and a light source Lg2 having the same wavelength as the green light laser light source 21c are used to form a grating corresponding to the light emitted from the green light laser light source 21c. At this time, the light sources Lg1 and Lg2 emit laser light generated from the same light source and further divided. For example, light from one laser light source may be introduced into an optical fiber, further divided into two fibers by a fiber coupler, and the emission end faces of the two fibers may be arranged at the positions of Lg1 and Lg2. Here, the light source Lg1 is arranged so that the optical position with respect to the volume hologram 222 coincides with the laser light source 21c shown in FIGS. 5 (a) and 5 (b), and the light source Lg2 is arranged in the second volume hologram 222. The area irradiated by the light emitted from the light source Lg1 is placed at the center of projection for magnified projection on the entire surface of the first volume hologram 221 (see FIG. 6 (a)). Then, the second volume hologram 222 is coherently exposed by the light emitted from the light sources Lg1 and Lg2. As a result, interference fringes are recorded on the second volume hologram 222 to form a Bragg grating 222c that diffracts and focuses the light emitted from the laser light source 21c. Then, at the time of this interference exposure, the region other than the exposed region is shielded by a light-shielding mask having an aperture having a shape corresponding to the divided region.

A light source Lb1 and a light source Lb2 having the same wavelength as the blue light laser light source 21b are used to form a grating with respect to the light emitted from the blue light laser light source 21b. At this time, the light sources Lb1 and Lb2 emit laser light generated from the same light source and further divided. For example, light from one laser light source may be introduced into an optical fiber, further divided into two fibers by a fiber coupler, and the emission end faces of the two fibers may be arranged at the positions of Lb1 and Lb2. Here, the light source Lb1 is arranged so that the optical position with respect to the second volume hologram 222 coincides with the laser light source 21b shown in FIGS. 5A and 5B, and the light source Lb2 is the second volume hologram. The region irradiated by the light emitted from the light source Lb1 in 222 is arranged at the projection center where the entire surface of the first volume hologram 221 is magnified and projected (see FIG. 6 (b)). Then, the second volume hologram 222 is coherently exposed by the light emitted from the light sources Lb1 and Lb2. As a result, interference fringes are recorded on the second volume hologram 222 to form a Bragg grating 222b that diffracts and focuses the light emitted from the laser light source 21b. Then, at the time of this interference exposure, the region other than the exposed region is shielded by a light-shielding mask having an aperture having a shape corresponding to the divided region.

A light source Lr1 and a light source Lr2 having the same wavelength as the red light laser light source 21a are used to form a grating corresponding to the light emitted from the red light laser light source 21a. At this time, the light sources Lr1 and Lr2 emit laser light generated from the same light source and further divided. For example, light from one laser light source may be introduced into an optical fiber, further divided into two fibers by a fiber coupler, and the emission end faces of the two fibers may be arranged at the positions of Lr1 and Lr2. Here, the light source Lr1 is arranged so that the optical position with respect to the volume hologram 222 coincides with the laser light source 21a shown in FIGS. 5 (a) and 5 (b), and the light source Lr2 is arranged in the second volume hologram 222. The area irradiated by the light emitted from the light source Lr1 is arranged at the center of projection for magnified projection on the entire surface of the first volume hologram 221. Then, the second volume hologram 222 is coherently exposed by the light emitted from the light sources Lr1 and Lr2. As a result, interference fringes are recorded on the second volume hologram 222 to form a Bragg grating 222a that diffracts and focuses the light emitted from the laser light source 21a. Then, at the time of this interference exposure, the region other than the exposed region is shielded by a light-shielding mask having an aperture having a shape corresponding to the divided region.

In the second embodiment, the light sources are arranged close to each other so that the emitted light partially overlaps on the second volume grating 222. Therefore, in the produced second volume grating 222, The adjacent Bragg grating 222a and Bragg grating 222b, and the adjacent Bragg grating 222b and Bragg grating 222c partially overlap.

Next, a method for producing the first volume hologram 221 will be described. The first volume hologram 221 diffracts and condenses the emitted light from the light sources 21a to 21c that have passed through the second volume hologram 222 so as to become coaxial light.

For example, in order to form a grating corresponding to the light emitted from the green light laser light source 21c, as shown in FIG. 7A, the lens Lc, the light source Lg2 having the same wavelength as the green light laser light source 21c, and the light source Use with Lg3. At this time, the light sources Lg2 and Lg3 emit laser light generated from the same light source and further divided. For example, light from one laser light source may be introduced into an optical fiber, further divided into two fibers by a fiber coupler, and the emission end faces of the two fibers may be arranged at the positions of Lg2 and Lg3. Here, the lens Lc collects the divergent light from the light source Lg3 so that it incidents the first volume hologram as parallel light. The light source Lg2 arranges the region where the grating 222c is formed in the second volume hologram 222 at the projection center for magnifying and projecting the entire surface of the first volume hologram 221. Then, the first volume hologram 221 is coherently exposed by the light emitted from the light sources Lg2 and Lg3. As a result, interference fringes are recorded on the first volume hologram 221 to form a Bragg grating that diffracts the light emitted from the laser light source 21c.

As shown in FIG. 7 (b), the interference exposure of the first volume hologram 221 is obtained by using the light sources Lg1 and Lg2 shown in FIG. 7 (a) as the light sources Lb2, having the same wavelength as the blue light laser light source 21b. It is performed by replacing the light source Lb3, and further, as shown in FIG. 7 (c), the light sources Lg1 and Lg2 shown in FIG. 7 (a) are replaced with the light source Lr2 and the light source Lr3 having the same wavelength as the red light laser light source 21a. Do. As a result, the grating that diffracts the light emitted from the laser light source 21b of blue light and the light emitted from the laser light source 21a of red light on the first volume hologram 221 is converted into a Bragg grating with respect to the laser light source 21c of green light. Form in multiple layers. At this time, the light source Lb2 arranges the region where the grating 222b is formed in the second volume hologram 222 at the projection center for magnifying and projecting the entire surface of the first volume hologram 221, and the light source Lr2 uses the second volume hologram. The region in 222 where the grating 222a is formed is arranged at the projection center where the entire surface of the first volume hologram 221 is magnified and projected.

Since the interference exposure of the first volume hologram needs to be performed three times so that the grating for the emitted light of each of the three laser light sources is formed in one volume hologram, each interference exposure is a volume hologram. The light intensity is such that the photosensitive material constituting the above is completely exposed by three exposures.

Next, the action and effect will be described. First, laser light is emitted from the red light, blue light, and green light laser light sources 21a to 21c provided on the submount 10, and each laser light is applied to the second volume hologram 222 of the diffractometer 220. Laser.

Then, each light emitted from each of the laser light sources 21a to 21c is diffracted and collected by the gratings 222a to 222c for red light, blue light, and green light when passing through the second volume hologram 222, respectively. Be lit. As a result, the optical axes of the respective lights intersect at one point on the first volume hologram 221 and irradiate the same region of the first volume hologram 221.

Then, each light diffracted and condensed by each of the second volume holograms 222 propagates in the same optical path when passing through the first volume hologram 221 as shown in FIG. 5 (a). It is diffracted to form a beam, combined, and irradiates the same region of the spatial light modulation element 30.

As described above, according to the second embodiment, in the light source device, the volume hologram in which the light emitted from the three laser light sources 21a to 21c and the laser light sources 21a to 21c are combined so as to form a coaxial beam. Since the diffractometer 220 is provided, it is possible to realize an ultra-small two-dimensional image display device that can be mounted on a small device such as a mobile phone, as in the first embodiment.

Further, in the second embodiment, the diffraction unit 220 is composed of the first and second volume holograms 221 and 222, and the second volume hologram 222 emits light emitted from the three laser light sources. The optical axis of the emitted light is diffracted so as to intersect at one point on the first volume hologram 221, and the first volume hologram 221 transmits three laser beams from the second volume hologram 222 to the spatial light modulation element 30. Since the diffraction is performed so as to irradiate the same region, it is not necessary to align the optical axes of the light incident on the diffraction unit 220 from each light source on the diffraction unit 220, and the direction is perpendicular to the submount such as a surface emitting laser. A light source that emits light can be arranged directly on the submount 10. As a result, the configuration of the light source device can be simplified and its assembly can be easily performed. This leads to cost reduction of the light source device.

Further, in the second embodiment, since the three light sources 21a to 21c are provided on the same submount 10, it is possible to dissipate heat from the three light sources by dissipating heat from one submount 10. Therefore, there is also an effect that the heat treatment of the light source can be easily performed in the light source device.

In the second embodiment, the second volume hologram 222 has a configuration in which the boundary portions of the adjacent gratings 222a to 222c are slightly overlapped, but the second volume hologram 222 is a grating for each light. May be multiplexed so that most of them overlap. In this way, the scale of the device can be reduced.

On the contrary, the second volume hologram 222 may be formed by forming gratings for each light so as not to overlap each other. In this way, the scale of the light source device becomes a little larger, but since a distance can be secured between the light sources installed on the same submount 10 and the light sources, there is an effect that the heat dissipation of the light source can be efficiently performed.

Further, in the second embodiment, it has been described that the second volume hologram 222 has a lens action, but the irradiation region of the light passing through the second volume hologram 222 is in the plane of the first volume hologram 221. If it fits, it is not necessary to condense each light with the second volume hologram 222. In this case, since only two different gratings 222a and 222c for diffracting the emitted light from the two laser light sources 21a and 21c need to be multiplexed on the second volume hologram 222, the volume hologram is multiplexed. The number of gratings to be made can be reduced, and the device can be provided at a lower cost.

Further, in the second embodiment, the case where the number of coherent light sources is three has been described as an example, but the number of light sources may be at least two or more.

(Embodiment 3) The light source device of the third embodiment also has the function of an optical integrator that makes the light intensity distribution of the light emitted from each laser light source uniform in the diffractive part of the light source device of the first embodiment. It is a light source.

8A and 8B are views showing the configuration of the light source device according to the third embodiment, FIG. 8A is a side view, and FIG. 8B is a plan view.

In FIG. 8, 300 is a light source device according to the third embodiment, and the light source device 300 is a red light, blue light, green light laser light source 11a, 11b, similar to the light source device 100 of the first embodiment. 11c, prisms 12a, 12b, 12c that reflect the emitted light of the red and green laser light sources 11a, 11c, the submount 10 that supports these laser light sources and the prism, and the prisms 12a, 12b, 12c. It has a diffractometer 320 through which the emitted light of the laser light sources 11a, 11b, and 11c is passed. Here, the laser light sources 11a to 11c, the prisms 12a to 12c, and the submount 10 are the same as those in the first embodiment.

Then, in the third embodiment, the diffracting unit 320 diffracts the incident light and equalizes the light intensity distribution thereof, and is composed of one volume hologram.

The volume hologram 320 is divided into a plurality of regions, and here, a 16-divided volume hologram 320 will be described as an example.

In the volume hologram 320, 16 divided regions 32 are arranged in four vertical and horizontal rows. Then, in each divided region 32, gratings that diffract the light emitted from the light sources 11a to 11c incident on each region so as to illuminate the entire light irradiation surface of the spatial light modulation element 30 are formed in a plurality of manners. There is. Here, each region of the volume hologram 320 has a concave lens action that expands the divergence angle of the incident light.

The light emitted from each light source incident on each divided region of the 16-divided volume hologram is diffracted by the grating formed in each of the 16 regions of the volume hologram to form a coaxial beam. Each light output from each of the 16 regions of the volume hologram irradiates the same region of the spatial light modulation element 30 provided above the diffraction unit 320.

In FIG. 8 (a), the optical path of the light emitted from the blue light source 11b is mainly displayed for simplification of the figure, but the light emitted from the red and green light sources 11a and 11c is also displayed. Similarly, it is incident on each divided region of the diffraction unit 320, diffracted and diverged by the grating formed in each divided region, and irradiates the same region of the spatial light modulation element 30.

Hereinafter, a method for manufacturing the diffraction unit 320 according to the third embodiment will be described. FIG. 9 is a diagram showing a method of forming a grating for diffracting the light emitted from the laser light source of green light on the volume hologram of the third embodiment, and FIG. 10 is a diagram showing the volume hologram of the third embodiment. FIG. 11 is a diagram showing a method of forming a grating that diffracts the light emitted from the blue light laser light source, and FIG. 11 shows the light emitted from the red light laser light source on the volume hologram of the third embodiment. It is a figure which shows the method of forming the grating which diffracts.

In the volume hologram 320 of the third embodiment, it is necessary to individually form a grating in each of the 16 divided regions. Therefore, in order to form a grating that diffracts the light emitted from the green light laser light source 11c, as shown in FIGS. 9 (a) to 9 (d), the light source Lg1 having the same wavelength as the green light laser light source 11c is used. , Light source Lg2 is used. At this time, the light sources Lg1 and Lg2 emit laser light generated from the same light source and further divided. For example, light from one laser light source may be introduced into an optical fiber, further divided into two fibers by a fiber coupler, and the emission end faces of the two fibers may be arranged at the positions of Lg1 and Lg2. Further, in the interference exposure using these light sources, the light source Lg1 is fixed at a position where the optical position with respect to the volume hologram 320 coincides with the laser light source 11c shown in FIGS. , The position is changed for each division area 32.

For example, by arranging the light sources Lg1 and Lg2 as shown in FIGS. 9 (a) to 9 (d) and performing interference exposure four times, one row of the 16 divided regions of the volume hologram 320 Gratings 32c are formed in the four regions lined up in. In the interference exposure of each region, the light source Lg2 is arranged at the projection center where each region of the volume hologram 320 is magnified and projected onto the spatial light modulation element 30. Therefore, by performing the four interference exposures shown in FIGS. 9 (a) to 9 (d) for each row of the divided regions in the volume hologram 320, all 16 divided regions 32 of the volume hologram 320 are covered. A grating 32c is formed that diffracts the light emitted from the green light laser light source 11c. At the time of interference exposure of each of the divided regions 32, the regions other than the exposed regions are shielded by a light-shielding mask having an aperture having a shape corresponding to the divided regions.

As shown in FIGS. 10 (a) to 10 (d), the grating that diffracts the light emitted from the blue light laser light source 11b is a light source Lb1 and a light source Lb2 having the same wavelength as the blue light laser light source 11b. The light source Lb1 is fixed at a position where the optical position with respect to the volume hologram 320 coincides with the laser light source 11c shown in FIGS. 8 (a) and 8 (b), and the light source Lb2 is set for each divided region. It is formed by changing its position. At this time, the light sources Lb1 and Lb2 emit laser light generated from the same light source and further divided. For example, light from one laser light source may be introduced into an optical fiber, further divided into two fibers by a fiber coupler, and the emission end faces of the two fibers may be arranged at the positions of Lb1 and Lb2.

In this case as well, by the four interference exposures shown in FIGS. 10 (a) to 10 (d), blue light was emitted to four regions arranged in a row among the 16 divided regions 32 of the volume hologram 320. A grating 32b that diffracts the light emitted from the laser light source is formed, and by performing these four interference exposures for each row of the divided regions in the volume hologram 320, all 16 divided regions 32 of the volume hologram 320 are formed. A grating 32b that diffracts blue light is formed on the surface. Further, also in this case, in the case of the interference exposure of each of the divided regions, the regions other than the exposed region are shielded from light.

Similarly, as shown in FIGS. 11 (a) to 11 (d), the grating that diffracts the light emitted from the red light laser light source 11a is a light source Lr1 having the same wavelength as that of the red light laser light source 11a. Interference exposure using Lr2 is fixed by the light source Lr1 at a position where the optical position with respect to the volume hologram 320 coincides with the laser light source 11a shown in FIGS. It is formed by changing the position each time. At this time, the light sources Lr1 and Lr2 emit laser light generated from the same light source and further divided. For example, light from one laser light source may be introduced into an optical fiber, further divided into two fibers by a fiber coupler, and the emission end faces of the two fibers may be arranged at the positions of Lr1 and Lr2.

In this case as well, the red lasers were applied to the four regions arranged in a row among the 16 divided regions 32 of the volume hologram 320 by the four interference exposures shown in FIGS. 11 (a) to 11 (d). A grating 32a that diffracts the light emitted from the light source is formed, and by performing these four interference exposures for each row of the divided regions, red light is diffracted over all 16 divided regions 32 of the volume hologram 320. Grating 32a is formed. Further, also in this case, in the case of the interference exposure of each of the divided regions, the regions other than the exposed region are shielded from light.

Next, the action and effect will be described. When light is emitted from the red light, blue light, and green light laser light sources 11a to 11c, the light emitted from the laser light sources 11a, 11b, 11c is emitted by the prisms 12a, 12b, 12c provided on the submount 10. It is reflected and these reflected lights illuminate the diffractometer 320. At this time, the light emitted from the laser light sources 11a to 11c has the same optical axis on the diffracting unit 320 and irradiates the same region of the diffracting unit 320.

Then, when the three lights from the red light, blue light, and green light laser light sources 11a to 11c pass through the diffracting unit 320, the red light that has passed through this region in each divided region 32 of the diffracting unit 320. , The optical axes of the blue and green lights are aligned, and the light is diffracted and diverged so as to illuminate the same region, that is, the entire surface of the spatial light modulation element 30. As a result, the spatial light modulation element 30 is irradiated with light having a uniform light intensity distribution obtained by combining laser light of each color.

As described above, according to the third embodiment, the diffraction unit 320 is divided into two-dimensional regions, and each divided region of the diffraction unit 320 is individually diffracted and diverged from the light emitted from each light source. Since each light source light that has passed through the region of 3 becomes a coaxial beam and is multiplexed so as to irradiate the entire light irradiation region of the spatial light modulation element 30, an optical system that converts the light emitted from the three laser light sources into a coaxial beam is provided. It is possible to provide an ultra-compact light source device that can be miniaturized and can have a uniform intensity distribution of each light source light on the spatial light modulation element 30.

Further, although the lens array constituting the conventional optical integrator is expensive to process, the volume hologram can be produced by using a small and inexpensive photosensitive material (polymer), as in the third embodiment. Further, if the diffractometer 320 made of the volume hologram also has the function of the optical integrator, the cost of the apparatus can be reduced.

In the third embodiment, the case where the diffraction unit 320 is composed of one volume hologram has been described as an example, but the diffraction unit has two volumes as in the second embodiment. It may be composed of a hologram. In this case, if the first volume hologram 221 shown in FIG. 5 is configured to be region-divided as shown in the third embodiment, each of the first volume holograms 221 on the spatial light modulation element 30 is similar to the third embodiment. The effect of making the light intensity distribution of the light source light uniform can be obtained.

Further, in the third embodiment, the case where the diffraction unit 320 is divided into 16 is taken as an example, but the region division of the diffraction unit is not limited to 16 divisions, and 64 divisions, 128 divisions, and further divisions are possible. Further, it is also possible to divide the region of the diffraction unit into different numbers of vertical and horizontal arrangements of the divided region according to the planar shape of the spatial light modulation element.

(Embodiment 4) Hereinafter, a two-dimensional image display device using the light source device described in the first to third embodiments will be described. FIG. 12 is a diagram showing a configuration of a two-dimensional image display device according to the fourth embodiment.

In FIG. 12, 500 is the two-dimensional image display device of the fourth embodiment, and the two-dimensional image display device 500 is a light source device 300 having laser light sources 11a, 11b, 11c for red light, blue light, and green light. And the laser drive units 550a to 550c for red light, blue light, and green light that drive each laser light source in the light source device 300, and the laser switching unit 540 that switches the drive of each laser drive unit 550a to 550c. And the video signal switching unit 530 that switches the red video signal, blue video signal, and green video signal input from the outside and outputs them to the spatial light modulation element 30, and outputs the control signal so that each RGB image is displayed in sequence. Then, the control unit 520 that controls the laser switching unit 540 and the video signal switching unit 530, the field lens 560 that makes each laser light output from the light source device 300 a focused light speed close to the parallel light beam, and the space. It has a projection lens 510 that receives the light emitted from the light modulation element 30 and projects it on the screen 51. Here, the light source device 300 is the same as that of the third embodiment.

Next, the operation of the two-dimensional image display device 500 configured as described above will be described. First, the video signal switching unit 530 sequentially switches the input red video signal, blue video signal, and green video signal according to the control signal output from the control unit 520, and outputs the input to the spatial light modulation element 30.

Further, the laser switching unit 540 drives the laser driving units 550a to 550c for red light, blue light, and green light according to the control signal from the control unit 520, and the red, blue, and green lasers. Light sources 11a to 11c are turned on in sequence.

As a result, the light emission from the laser light source of each color and the formation of the image of each color by the spatial light modulation element 30 are performed in synchronization. Specifically, in the light emitting state of the red light laser light source 11a, a red video signal is supplied to the spatial light modulation element 30 to modulate the red light, and in the light emitting state of the blue light laser light source 11b, the above. A blue video signal is supplied to the spatial light modulation element 30 to modulate the blue light, and in the light emitting state of the green light laser light source 11c, the green video signal is supplied to the spatial light modulation element 30 to modulate the green light. Is done.

Then, the image formed by the modulation of the light of each color by the spatial light modulation element 30 is projected on the screen 51 by the projection lens 510.

When displaying a moving image, it is necessary to display an image with a large number of frames in a short time, for example, an image of 30 frames per second, but in order to realize this with the device 500, the image is displayed at 30 frames per second. If the control unit 520 controls each light source 11a to 11c to emit light several times during one frame of the image to be displayed, the image of each color cannot be separated when observed by the human eye. Therefore, the user can observe a full-color natural moving image.

As described above, according to the fourth embodiment, the light source device of the two-dimensional image display device 500 is a coaxial beam of three laser light sources 11a to 11c and the light emitted from the laser light sources 11a to 11c. Since it has a diffractometer 320 made of a volume hologram that harmonizes with each other, the optical system that converts the light emitted from the three laser light sources into a coaxial beam can be miniaturized, thereby displaying a two-dimensional image. The device can be miniaturized.

Further, according to the fourth embodiment, since the diffracting unit 320 of the light source device 300 also has the function of an optical integrator, an optical integrator composed of a fly-eye lens, which has been conventionally required for uniform light intensity distribution. Even if the light source device is not used, the output light of the light source device has a uniform intensity distribution. As a result, the 2D image display device having a uniform intensity distribution of the light source can be made smaller, the number of components of the 2D image display device can be reduced, and the 2D image is easy to assemble and inexpensive. A display device can be realized.

The light source device and the two-dimensional image display device of the present invention are useful for use in a small image projection device, a portable information terminal, a notebook personal computer, or the like.