Procedure and apparatus for the examination of optical components, particularly ophthalmic components, and device for the illumination of transparent objects under examination.

The invention relates to a method and apparatus for testing optical components, in which each of the component to be tested and an image is produced to be detected by image analysis, errors in the depicted object, and an illumination means for illuminating clear-transparent test objects.

In the production and quality control of optical components, in particular of ophthalmic devices such as contact lenses, the test is still conducted visually. In this context, for example, can be made to the DIN 58 223 regulations. The visual quality control is a subjective test only, which is dependent on people and daily fluctuations is subjected. This results in testing the quality inevitably shifts the quality standards, and it can not achieve sufficient reproducibility of the quality of products. In addition, the possibilities of automation, particularly in the mass production of such components, significantly impaired.

From EP 0359084 A2 it is known in the contact lens manufacturing, to detect the presence or absence of scratches and the like. On the curved surface of the lens through an optical projector device, and an image processing device. From the mentioned publication does not, however, as the projector means and the image processing means are trained to use them for a reproducible quality control, particularly in the automated production of optical components, can.

Regarding the illumination of test objects is known to illuminate objects in a microscope by means of "dark field illumination". In a dark field illumination such an object is illuminated by a light source and an illumination optics (condenser) so that the illumination light bundle does not enter into the beam path of the microscope. Becbachtet is then only the light scattered from the object into the beam path of light.

There are illumination optics for dark field illumination are known in which a central aperture disk is arranged in the beam path, which covers the central part of the illumination light beam. A condenser lens falls then a ring-shaped illumination light beam which is collected by the edge portions of the condenser lens in the plane of the object, and then bypasses the Strahlengana of the microscope optics laterally.

It is also a so-called. "Kardioidkondensor" is known in which a ring-shaped illumination light beam to an object-side concave surface of a first lens is totally reflected. The deflected beam is incident so outward light on a substantially cylindrical outer surface of a second lens. From this lateral surface, the light beam is totally reflected again. The second lens collects the light reflected from the edge inward bundle again in the plane of the object. From there, the light beam (pages 707-708 Grimsehls physics textbook, 11th ed. (1943) Vol.2, Verl. BG Teubner,) running back tapered at the optical path of the microscope over. In these known arrangements is the illumination of objects in a microscope with a steady illumination optics.

Starting from this prior art, it is an object of the invention to provide a method and apparatus for testing optical components that contribute to the automation of the inspection steps and the preparation of the optical components. It is a further object of the invention to provide an illumination device for illuminating clear-transparent test objects for the study of the test objects for errors, which allows to make the error clearly. Test objects can thereby be optical elements such as lenses or eyeglasses, contact lenses, etc.. The invention is in particular the object of such a lighting device such that it allows an automatic fault analysis by observing the test objects by means of an electronic image pickup device and image processing.

The object is achieved in the invention in method terms that a planar contrast image is produced from the respective component to be tested and the image area of ​​the respective visualized errors for quality control by comparison to one or more limit values ​​is determined.

Device this object is achieved with the invention in that an optical imaging device is provided which has a contrast imager, and also an image processing device is provided which includes an image pickup device having an image sensor that can perform a face determining the errors detected respectively in contrast image.

In the invention, an illumination device is used that allows the simultaneous contrast display at all to be examined component structures of interest as planar structures. Combined with this illumination device is therefor an image pickup device for use with an optical image sensor. The image pickup device can be optionally equipped with an imaging optical system, with which the contrast image can be taken. The contrast image is transmitted to an image processing device. For this purpose, it is advantageous to divide the contrast image in picture elements (pixels). With use of a CCD image sensor as this division is already predetermined in pixels by the construction or design of the CCD. The picture elements are implemented using a conversion means into digital image signals, which can be stored and processed. In this way, an analysis of the structural features of the optical component to be inspected (an area determination), and hence the fault detected in each contrast image possible. Advantageously, a binary image is generated for this reaction at first.

To generate the contrast image, a dark field illumination of the component to be tested is carried out in a preferred manner. With the aid of correspondingly scattered light of the component to be tested against a dark background and is illuminated with the aid of a camera, optionally containing the image sensor. The image sensor is preferably configured as a CCD. In this way, a dark field illumination image is taken from the illuminated specimen. Such an image is a high-contrast display of errors, these errors occur as faces on the contrast image display in appearance. For example, involved in a dark field illumination the error as bright spots in certain areas against a dark (black or gray), non-faulty background is. These errors can and scratches, holes, bubble inclusions, cracks, adhering fragments and soiling or loss points like., act. These errors arise as surfaces in the scene. However, it is also Randfehler of the specimen which are represented as planar structures, are determined. It may be the edge outbreaks webbed, cracks, adhering to the edge fragments, soiling and fading parts at the rim and Randi homogeneity.

The image areas of the respective detected errors can be divided into pixels (picture elements surface). By the number of the respective image surface elements (pixels), the extent of each error or all of the error can be determined. It can be provided for this purpose, a sample / counting device with which can be a counting of the pixels perform. The determined number of pixels for each image area of ​​fault detected is compared with a predetermined number of pixels. This predetermined number of pixels represents a quality standard which the candidate has to be observed, represents.

In examining the specimen can also be divided into different zones are defined for the different thresholds as quality standards. For example, when considering a contact lens for the optical zone and the lenticular different quality standards in the form of predetermined image areas shall be established. The quality of the edge of the lens can also be determined based on the shape of the planar image of the contact lens edge.

In a preferred manner can already come in the course of the individual production steps in the manufacture of the optical component for use the invention. It can refer to the error detection and quality control according to the invention may be integrated with one or more of the manufacturing steps, so that you have a continuous automatic quality control during manufacture of the optical component. One can pretend this for each manufacturing step corresponding quality standards, so that you win for each of the manufacturing steps reproducible quality controls in automated manufacturing. The invention can be used advantageously in the quality control of optical components such as optical lenses, especially ophthalmic devices, such as ophthalmic lenses, contact lenses, intraocular lenses and the like., Used. Here, an automatic final inspection and, as already explained, a continuous automatic quality monitoring during the production of the components can be achieved.

For example, in the contact lens manufacturing both a dry testing can be performed by hydrated contact lenses (test on air) and a Naßprüfung (examination in storage solution). If the components are housed in transparent containers, it is possible to perform a final check of the inserted components.

In the above-mentioned illumination device, a light source and an illumination optical system for illuminating the test objects are provided in the dark field illumination. The illumination geometry of the illumination optics is adjustable for adaptation to the test object.

In this Heise, by appropriate adjustment of the illumination optics is adapted to the dimensions and shape of the test object illumination can be achieved, what mistakes as voids, cracks, or the like. can appear as clear contrasts. The so appearing contrasts can be detected by an electronic image pickup device and evaluated by means of image processing for error detection. It has been shown that such a presentation of errors clear-transparent test objects as contrasts by means of a dark field illumination is possible, but that it is necessary for that purpose, to make the illumination optics adjustable. Further embodiments of the invention are subject of the dependent claims.

Reference to the figures the invention is explained in more detail by exemplary embodiments.

It shows:<ul><li>Fig. 1 shows schematically an image analysis apparatus which is an embodiment of the invention;</li><li>Figure 2 is a represented by the Bildananlysevorrichtung of Figure 1 image of the specimen with schematically drawn-dimensionally reproduced errors..;</li><li>Figure 3 is a positioning scheme in the image analysis of a form of a contact lens under test.;</li><li>Figure 4 zoning in a form of a contact lens specimen.</li><li>Figure 5 is a detection scheme for margin error on a form of a contact lens specimen.</li><li>Fig. 6 is a graph of Figure 5 in accordance with the detected error margin.</li><li>7 schematically shows different manufacturing steps in manufacturing a contact lens with integrated automatic test steps.</li><li>Figure 8 shows schematically different manufacturing steps of another manufacturing process for contact lenses with integrated automatic test steps. </li><li>Figure 9 is a final inspection for using the method of packaging according to the invention suitable, in particular for contact lenses in a plan view.</li><li>Fig. 10 is a sectional pictorial view of the package shown in Fig. 9;</li><li>11 is a block diagram of an image analysis device shown in FIG. 1. and</li><li>Fig. 12 is a longitudinal section of a lighting device.</li></ul>

In FIG. 1, an apparatus is shown, which serves for the testing of optical components. A component to be tested 6 is located on a holding and transport device 8. A lighting device 1 includes a contrast imager 5, which can be designed as a dark field illumination device. Using a light source 18 whose light is repeatedly reflected and scattered, the component to be tested 6 is illuminated against a dark background 19th

For the processing of the image contrast or darkfield image represented in this way an image processing device 2 is provided. This image processing device 2 includes an image pickup device 3 with an image sensor 4. It may here for example, a video camera, the image sensor 4 is formed as a CCD.

The video camera can be connected to a monitor, not shown, on which the sheet-like contrast image can be made visible. If the image sensor is a CCD, you automatically due to the CCD structure, an image division into picture elements (pixels), for example, 500 x 700, ie there is here by itself an image segmentation. By means of a reading and converting means 7, the individual pixels of the contrast of the image can be scanned and converted into binary signals, which are then stored and processed further as will be explained below.

An exemplary embodiment of a contrast image 12 of a specimen is shown in the form of a binary image in FIG. 2. It may be the contrast image 12 of a test contact lens here, for example. Error on the surface make height of the specimen 6 or enclosed errors are shown areally in the contrast image 12th This is, for example, the error 13, 14, 15, 16 and 17-dimensionally shown This may represent holes, bubbles, inclusions, adhering fragments etc..

As FIG. 2 shows this error areally shown are bzh. Error surfaces into individual picture elements, called pixels, divided. Such a division may be carried out in cooperation with the reading and conversion means 7, for example by means of the image sensor 4 (CCD).

On the device 7, an image analysis device 9 (image classification, pixel count, pixel comparison) is connected. This measures the number of pixels, for example, by counting. For this purpose the image analysis device may 9 (23 pixel counter in Figure 11) having a correspondingly formed counter.

Referring to Fig. 11, which schematically illustrates a block diagram for the functional units included in the image analysis device 9, the operation of the image analyzing means 9 will be explained.

An image capture memory 20 receives from the read-out means 7 (Fig. 1) captured by the video camera and the image sensor 4 of the image pickup device 3 image of the component under test 6. This image may have the form shown in FIG. 2. In order for the quality control that centered component to be tested 6 and arranged properly in the image forming apparatus 1 and image processing apparatus 2, an alignment and centering controller 22 is connected to the image capture device 20th The controller 22 controls the holding and transporting means 8 (Fig.l) accordingly, if the candidate is 6 not arranged centered. For positioning the lens in the square array 3 shown in the Fig. The lens edge is first detected which the outer boundary of the search field is when positioning is then "outside-in" of wanted.

Since contact lenses usually have an engraving, it is necessary to omit this engraving in the examination, as it would otherwise cause a fault indication. For this purpose, the square box shown in FIG. 3 is divided into eight sectors. In the illustrated embodiment, positioning is performed so that the engraving is arranged in half in the two sectors II and III. One half of the engraving is to the left of the twelve o'clock position, and the other half of the engraving is to the right of the twelve o'clock position, both engraving halves have the same distance to the twelve o'clock position. So that the test specimen 6 is properly positioned, the holding and transfer means 8 may comprise an xy-displacement device.

If the component to be tested 6 is formed from different areas or parts, are sufficient for the different quality standards or be required, it is advantageous, appropriate zoning on captured image (Fig. 2) of the component to be tested 6 make.

In FIG. 4, such a Zoning is for example shown schematically for a contact lens. By an area which is detected by a radius r1, an optics zone OZ is set the contact lens. By radii r2 and r3 is a auszublendende signature zone in engraving angle range is set.

By an area between radii r1 and r4 a lenticular zone LZ is defined, and by the radius r4 of the edge R of the lens is defined.

For optical OZ and the lenticular zone LZ, different error limits can fix, the maximum permissible error for the optical zone OZ set lower than the maximum permissible error for the lenticular zone LZ. Also for the edge R, a boundary error limit be set; For example, the longitudinal and / or transverse dimensions may not be greater than 50 microns. However, the margin of error, in the invention even lower, for example at 20 microns, are recognized. This also applies to the MPE in the optical region OZ and in the lenticular LZ. Depending on how high the quality of the contact lens or the component to be tested should be 6, the margin of error (fault threshold) is set.

WHILE the areal zones of the picture corresponding assigned error thresholds are set, can be carried out for the contact lens edge R on the principle illustrated in Figures 5 and 6 error detection. It can here individually different criteria or overall considered. One criterion may be whether the radius is different to a certain boundary point of a mean radius Rm over a predetermined radius deviation Δ Rg / 2 out or not. Furthermore, it can be considered as a criterion for determining whether the total aid exceeding a certain threshold to strong radius deviations or not. Finally, are still under investigation as a criterion whether the curve shape of the rim is very different from a circular shape or not, as shown, for example, between the two curve parts C1 and C2 and between the curve portions C3 and C4 in Fig. 5. Fig. 6 shows, for example, that approximately at 150 ° radius a strong deviation exists. In FIG. 5, this is with R1 - R2 shown. From Fig. 6 is also the strong deviation of the edge from the circular shape between the cam members C3 and C4 is erkenntlich.Ferner from FIG. 6 also has a strong variation in the radius range of about 260 ° to 300 ° recognizable.

The mentioned error can be in the image analysis device 9 (FIG. 1) by means of a storage device 21 (Fig. 11), in which the zoning shown in Fig. 4 is set to capture in cooperation with threshold storing. For example, a threshold value memory 27 for the lenticular zone LZ a limit value memory 28 and for the edge R a third threshold value memory 29 are provided for the optical zone OZ. For the respective zones associated pixel counter 23 are available. The pixel counter, which specify values ​​for the error variables in the respective zones, these values ​​provide to comparators 24, 25 and 26, which are connected with the described associated threshold memories 27, 28 and 29th The comparison result may be stored in a buffer memory 30 for the respective zones and optionally reproduced together with the captured image in the image capture memory 20 on a monitor.

Furthermore, depending on the respective comparison results of the comparators 24, 25 and 26 either through the latch 30 or directly Aussortierer 11 (Fig. 1) is driven. This Aussortierer 11 is connected to the holding and transport device 8 or in operative connection. This is illustrated by a dashed line in FIG. 1 schematically. The component to be tested 6 is then left in dependence on the holding and transport device 8, when it is sufficient according to the comparison result to the quality requirements. The component to be tested 6 is then transferred to the next processing station. If the component 6 does not satisfy the quality requirements, it is removed by the action of Aussortierers 11 from the holding and transport device eighth

An embodiment of the device for illuminating the test object, for example for illumination of the contact lens is shown in Fig. 12. There is a central first reflector body is designated 110th The first reflector body 110 has a flat, upper end face 112th The upper end face 112 extends perpendicular to an axis system 114. Subsequently to the end surface 112, the reflector body 110 a to the system axis 114 coaxial, cylindrical envelope surface 116. On the bottom of the reflector body 110 forms a convex-conical first reflector 118. The axis of the reflector cone 118 coincides with the system axis 114th

Below the reflector body 110 is placed 120 on the system axis 114 is a light source. From the light source 120 is incident on the central light beam 122 konvexkonischen, first reflector 118. The light beam 122 is radially fanned out from the first reflector 118th In the drawing, the peripheral beams 124 and the longitudinal axis of the system 114 extending central ray 126 of the beam 122 are shown before and after reflection on the first reflector 118th

The radially apart range of light beam 122 is incident on a second reflector 128. The second reflector 128 is concave-cylindrical and coaxial to the system axis 114. The second reflector 128 is attached to a second reflector body 130th The second reflector body has an annular, planar end face 132nd located inside the cylindrical reflector 128 adjoins the end face 132nd On the outer side, the reflector body 130, then 134 coaxially with the reflector 128 on the end face 132, a cylindrical outer surface. Subsequent to the cylindrical outer surface 134 forms the reflector body 130 has a tapered portion 136 on the conical section 136 is adjoined by a cylindrical, provided with an external threaded portion 138 on. On the inside joins the cylindrical reflector 128 at a conical section 140th Below the reflector body 130 forms a bottom face 142 with a central opening 144. This opening 144 protrudes, the light source 120 into the interior of the reflector body 130th

On the upper end surface 132 of the reflector body 130 is a clear transparent plate 146, which forms with its flat top a support 148 for the test objects. The defined by the support 148 support plane is perpendicular to the system axis 114 and accordingly parallel to the end face 112 of the first reflector body 110. The plate 148 is up and down with anti-reflection layers 150, 152 is provided. The concave-cylindrical second reflector 128 reflects the light beam 122 range of radially apart so that there is almost grazing collected in the center of the support 148 in a light spot.

The second reflector body 130 is provided with the provided externally threaded section 138 in an internally threaded 154, screwed cup-shaped housing part 156th The housing part 156 carries in on the system axis 114 a sock 158 for the light source 120. In addition, are the base of the pot-shaped housing part 156 supporting rods 160 mounted, carrying the first reflector body 110th The supporting rods 160 are guided through aligned openings in the floor of the housing part 156 and by a transverse bore 162 of the clamping screws 164th The clamping screw 164 seated in radial threaded holes 166 in the bottom of the housing portion 156 between said aligned apertures. The clamping screws 164 can be solved. Then the supporting rods 160 and thus the first reflector body 110 are adjustable in height relative to the cup-shaped housing part 156th There is an adjustment of the reflector body 110 relative possible to the light source 120th The housing part 156, the light source 120 and the first reflector body 110 form a coherent assembly 170 as a whole via the internal thread 154 and provided with Aussenge-threaded portion 138 of the second reflector body 130 relative to the second reflector body 130 and thus ZU the second reflector 128 and the support 148 is adjustable in the direction of the system axis 114 (or vice versa).

This adjustment of the light spot generated in the support plane is adapted to the dimensions of the test objects once. Furthermore, the device can be adjusted so as to give optimum contrast for error detection.

The reflectors 118 and 128 may be formed specular. The surfaces of the first and second reflectors 118 and 128, but may also be formed partially diffuse-reflecting.

An alternative solution may consist in that the light source is a PTC-ring light. The adjustability of the illumination geometry can then be that the radiation characteristic of the PTC ring light can be adapted to the geometry of the test object.

With the Figungen 7 and 8 will now be even demonstrated on two different manufacturing processes for contact lenses, as the inventive image analysis in combination with other image processing method in the production process at different production Range or may be steps integrated so -that an automatic expiration of the total production of the contact line is achieved.

In Fig. 7 a so-called full mold process which includes a molding of the contact lens is shown in its individual steps with integrated automatic inspection using image analysis according to the invention. Fullmoldverfahren are known (eg., EP 0367513 and Where 87/04390).

In a manufacturing step 31, the mold inserts (optical tools), which consist of high-grade metals / alloys, for example, by machining. Here is an initial step can already be 32 performed using an image analysis. This test step can examine the surface quality of the mold inserts and the geometry of the mold inserts. the mold inserts are then inserted into an injection mold in a step 33rd Here, too, may be carried out an optical inspection by means of image analysis in a test step 35 to verify the surface quality and the installation dimensions.

This is followed by the production of plastic molds, ie, the two mold halves (Molds), in which the contact lens is to be manufactured by molding, of (production step 34). Again, a test step 36 with integrated image analysis, so that the surface quality, the geometry (distortion and the like.) And freedom from dust of the mold halves produced can be checked. This is followed by the dispensing of the polymerization of the contact lens material and the closing of the two mold halves joins in a step 37th Here can also be integrated into a test step 38, in which the correct closing, and the presence can be determined by air bubbles with the help of the illustrated image analysis.

It is then in a step 39, the polymerization of the contact lens material, which is enclosed by the two mold halves. In this case, can be monitored in this context, in a checking step 40, in the closed mold which is transparent, not only the course of the polymerization, but also the Polymerisationsschwund of the polymerized material and a suitable adjustment of the two mold halves Optionally, depending on the result of the image analysis and the adjustment of the two mold halves are controlled to compensate for the Polymerisationsschwundes in accordance with the established Polymerisationsschwund.

In a further production step 41, the opening of the two mold halves takes place. As part of an integrated test step 42 can here an interim control are carried out in terms of gross errors, such as cracks, dents and the like. The manufactured lens body.

In the subsequent manufacturing step 43, the contact lens is removed from the mold, and it may be a dry test can be performed to the contact lens by means of the image analysis described in a test step 44th This is followed the hydration of the lens body can be followed in a single production step 45th In a further production step 46, the lens (dry or hydrated) in vials or in so-called Foilpacks 68, which are shown in Figures 9 and 10, is introduced.

Then can be checked in a checking step 47, if the lens was placed in the storage container 69th This is part of a so-called presence check. Furthermore, it can be monitored whether the liquid level is correct in the storage container. Furthermore, the cleanliness of the preservative fluid and the lens itself can be monitored. Furthermore, lens quality and power of a final inspection may be subjected. The explained at test 47 tests may be performed using the image analysis described above. Subsequently, the container (Fig. 9, 10) are closed with the cover films 71 by welding.

In FIG. 8, a turning process is illustrated, with the likewise, a contact lens can be produced. In this rotation process, a button is cut from a rod of contact lens material and inserted into a chuck of a lathe in a single production step 48th Turning machines are known. It is made for example to German Patent 31 10 624 at the moment. In a test step 49 can be checked, for example, using the image analysis described above, the button in terms of material inclusions, its dimensions (Trimmaße) out. In one production step 50 is produced by rotating using a rotating tool in a lathe inner curve IK on the button. In a subsequent test step 51, by image analysis, the rotary screen and the surface quality and possibly also the geometry for which a well-known Moire process can be put to use, are reviewed.

In a further production step 52, the polishing of the inner curve IK done. Optionally, can be verified in a test step 53, the polishing image, the surface quality and again the geometry of the inner curve.

It then takes the Aufritten of buttons on a mandrel of the lathe in a single production step 54. In this case, the button is cemented with its inside curve to the spindle. Here, too, can be carried out in a check step 55 using an optical image analysis, the quality and the dimensions of the wax layer, which is used for cementing, as well as the concentricity and a vertex determination.

Subsequently, the outer curve AK is rotated in a single production step 56th The rotary screen, the geometry and the center thickness of the finished lens can be checked in a test step 57th

It then takes place in one manufacturing step 58, the polishing of the outside curve AK. In a test step 59 then the polishing image, the geometry and the center thickness of the contact lens can be checked. The test step 57 can be omitted in this case also.

In a manufacturing step 60, the contact lens is abgekittet of the cap of the automatic lathe. In one production step 61 the curling of the contact lens is performed. In a subsequent production step 62, the cleaning of the contact lens is performed. a test step 63 can be followed by cleaning the contact lens, in which with the aid of image analysis (eg Fig. 1) a dry examination of the contact lens is performed.

This is followed as a manufacturing step 64 of the engraving of the contact lens. In these the apparent for example from figures 3 and 4, then engraving is engraved in the contact lens body. This is then followed as a production step 65 to a surface treatment of the contact lens. This has the particular advantage that the surface of the lens for the tear fluid is made wettable. In a checking step 66, the examination of wettability can then also be performed using the image analysis (for example Fig.1). By Bildanalvse läßtsich namely to determine whether is carried out on the surface of droplet formation, or if the lens surface is wetted surface of the liquid.

In a further manufacturing step, 67 inserting the lens for example in Foilpacks occurs (Fig. 9, 10). Thus, for the then, wei connect at the full mold process shown in Fig. 7, a test step that corresponds to the test step 47th Thereafter, the welding of the cover sheets is carried out on the container.

From the above explanation, in particular in connection with Figures 7 and 8, shows that a complete monitoring and thus automate 100% can be achieved in the manufacture of optical components using optical image analysis. This is particularly true in the manufacture of contact lenses. This is the desired product quality through constant monitoring (in-process control) of the entire production sequence guarantees, so that may be waived under certain circumstances to a final inspection. especially for manufactured in large numbers and contact lenses (disposable lenses) Such monitoring is of advantage. The guaranteed by the invention quality control is based on a definable standard of quality and is thus a reproducible and objective quality control.