WO2014072021A1

WO2014072021A1 - Quality inspection of an ambiguous image of a lens structure

Info

Publication number: WO2014072021A1
Application number: PCT/EP2013/003168
Authority: WO
Inventors: Georg Kruse
Original assignee: Giesecke & Devrient Gmbh
Priority date: 2012-11-06
Filing date: 2013-10-21
Publication date: 2014-05-15
Also published as: DE102012021725A1; EP2917897A1; EP2917897B1

Abstract

The present invention discloses a device and a proceedings for inspecting the quality of an ambiguous image of a lens structure (4) which is arranged on a support (2), characterized in that the support (2) is mounted on a holder (6), wherein the holder (6) is rotated by a motor (8). A light source (10) illuminates the lens structure (4) while an optical recording device (12) records at least one image of the lens structure (4) while the holder (6) is turning. A data processing device (14) evaluates the at least one recorded image of the lens structure (4) with regard to its colour values and controls the motor (8).

Description

C u m b e a c tio n s a c tio n s

The invention discloses an apparatus and method for checking the quality of a tilted image of a lens structure which is placed on a support, e.g. a portable data carrier is located.

For labeling a carrier by means of a laser, one uses movable deflection mirrors via an electrical control. The distance between carrier and laser is usually relatively large. Consequently, such a method is very sensitive to disturbances.

During a laser inscription for the representation of images, it is customary to work in raster mode, ie the image is written in a well-defined and uniform distance from one another line by line or line by line using a pulsed laser in serial processing. The eye of the beholder no longer sees the individual halftone dots on the finished label, but depending on the size of the dots and the distance to each other and depending on the ratio of black dots to a light background, a more or less strong gray. If either the laser or the mirror or the carrier, for example a card, is moved irregularly during a laser inscription, for example by coupling in mechanical vibrations or vibrations, then the spacing of the screen dots changes accordingly. Depending on the type and duration of the disturbance, dark, ie a smaller dot pitch, or light, ie a larger dot pitch, stripes in the lasered image result. Accordingly, stripe structures can result if an electrical coupling, for example a 50 Hz hum, disturbs the drive or positioning logic of the deflection mirrors. Other effects that can lead to stripe structures in the laser image are, for example, laser power fluctuations, ie dot size changes, during laser marking.

In addition to stripes, there are quality defects in the form of more or less punctiform or patchy dark or light structures in the area of lasered images or, in severe cases, also in the area of lasered letters. The causes are usually rather complex and may be due to locally limited inclusions in the card, e.g. Losses are explained, depending on the used printing ink (s) incl. UV printing up to short-term effects in the range of the laser, such as e.g. incorrectly set first pulse suppression etc.

Corresponding quality-reducing effects, which lead to streaking or staining, are also found in personalization processes using printing technology (for example, ink jet printing).

Within ongoing card personalization under production conditions, the challenge now is to determine if a personalized card or passport is a good or a bad ("reject") document. As criterion for this one can determine eg number and respective size of the disturbances. If the number or size of the disturbances now exceeds a predetermined amount, the corresponding document (card, passport) is rejected as a reject. The examination of the quality of information to be displayed in a data carrier, which are executed in the form of a tilted image of a lens structure in a portable data carrier, is carried out by a subjective visual examination and evaluation of, for example, the contrast, the tilting behavior or the overall intensity.

For a carrier, all suitable carriers come into question. In particular, portable data carriers are used as carriers. Lens structures are placed on portable data carriers, such as e.g. Credit cards, health cards, passports, identity cards, visa, banknotes, entrance tickets, SIM cards, etc. applied.

A disadvantage of the subjective examination is that neither an objective evaluation of the quality of the information to be displayed is possible nor an objective comparison between two lens structures, which each represent a tilted image, is possible.

WO 2010/043443 A discloses a method and a device for the inspection of lens structures. Here, the brightness values or color values represented by a lens structure are checked at two different angles without an inscription being applied. Thus, for example, defects in or near the lens surface can be detected. In principle, it is possible to sort out cards which have bad lenses before labeling cards with lens structures. However, the costs for producing the cards have already been incurred. A conclusion on the problem causing the quality reduction is in most cases no longer possible at this stage. An examination of the quality of representation of incorporated into the lens structure Infomation taking into account the tilting behavior is not possible here.

To check and evaluate the shape and design of lens structures, the lens parameters are determined by geometric measurement of the lens parameters, e.g. measured by means of a height sensor. However, this test method only checks the geometric or optical properties of the lens structures and provides no information about the tilting behavior and the quality of the representation of written infomations. However, tilting behavior, display quality, sharpness and contrast are determined by a complex interplay between lens parameters, design of the label, e.g. Resolution, color, and map design determined. A final assessment of the quality of the tilting behavior of the lens structures or the quality of the information represented by the tilting behavior of the lens structure is therefore only at the end product, i. on already produced carrier with applied lens structure possible.

The object of the invention is to find a solution for overcoming the disadvantages of the prior art.

In particular, it is an object of the invention to find a solution to allow an objective assessment of the quality of presentation of the tilting effect of a lens structure. The object of the invention is achieved by the independent claim and the independent claim. Advantageous embodiments are described in the dependent claims. To achieve the object, the invention discloses a device for checking the quality of a tilted image of a lens structure, which is arranged on a carrier, characterized in that the device comprises

a holder for fixing the carrier,

a motor to rotate the mount,

a light source to illuminate the lens structure,

an optical pickup device for picking up at least one image of the lens structure during rotation of the holder,

a data processing device for evaluating the at least one image taken by the optical pickup device for color values and for controlling the motor.

An advantageous embodiment is characterized in that the motor is a stepping motor to rotate the holder gradually by a defined angle. Another advantageous embodiment is characterized in that the optical recording device is a camera.

A further advantageous embodiment is characterized in that the device has a shield against extraneous light.

A further advantageous embodiment is characterized in that at least the holder and / or the light source and / or the optical detection device are set up such that a distance and / or an angle to the lens structure can be variably adjusted. Another advantageous embodiment is characterized in that the optical detection device is a microscope.

Another advantageous embodiment is characterized in that the light source generates a white or a colored light.

Another advantageous embodiment is characterized in that the carrier is a portable data carrier.

In order to achieve the object, the invention further discloses a method for checking the quality of a tilted image of a lens structure which is arranged on a support, characterized in that the method comprises at least the following steps

- fixing the carrier on a holder,

turning the holder by means of a motor,

illuminating the lens structure with a light source, taking at least one image of the lens structure during the rotation of the holder by means of an optical recording device,

evaluating the at least one image captured by the optical pickup device with regard to its color values and controlling the motor by means of a data processing device.

An advantageous embodiment is characterized in that at least one field to be measured is defined in the lens structure to be tested. Another advantageous embodiment is characterized by the fact that in at least two fields to be measured, the fields are the same or different sizes. Another advantageous embodiment is characterized in that at least one test pattern is introduced into the lens structure.

A further advantageous embodiment is characterized in that the test pattern comprises at least two surfaces which have the same or different color values.

A further advantageous embodiment is characterized in that the test pattern comprises at least two surfaces which are the same or different in size.

Another advantageous embodiment is characterized in that the test pattern is introduced into the lens structure by means of a laser.

A further advantageous embodiment is characterized in that the color values are evaluated for all the images which are taken by the lens structure during rotation of the holder for at least one surface and / or test pattern to be measured.

A further advantageous embodiment is characterized in that at least one image is taken of the lens structure per an angular position to be determined during the rotation. The present invention provides an objective measuring method which makes it possible to objectively judge the quality of the presentation of information by means of the tilting effect of a lens structure. The measuring method can be carried out, for example, by means of suitably prepared carriers having a lens structure, with which the assessment of an expected quality of a production batch can be carried out. Furthermore, the invention makes it possible, on the one hand, to check the quality of lens-producing production means, such as laminating sheets. Conversely, the invention makes it possible to sort out unsuitable means of production. On the other card designs, such as film thicknesses, film coatings, etc., are tested for their basic suitability for the representation of tilting effects.

Heretofore, carriers having tilting lens structures have been tested by positioning a lens-structured carrier by hand relative to a fixed light source. The carrier was tilted about the transverse axis and tested with the naked eye, the tilting image of the lens structure on a tilting out. For testing purposes, a lens structure to be tested is applied to a carrier, such as a credit card or a passport page. Optionally, a test pattern can be introduced into the lens structure, for example by means of a laser. Subsequently, the lens structure to be tested is measured with the above-described device and methods described above, and checked. The determined color value is then displayed as a function of the angle at which the optical detection device has taken pictures from the lens structure. A measurement curve showing the course of the color values as a function of the angle which lies between the rotated holder and the optical detection device is assessed on the basis of defined criteria. As a rule, the trace has a so-called Gaussian shape. A broad and flat curve means poor quality. A narrow and high curve means a good quality.

The test pattern according to the invention consists of different light to dark gray areas. Alternatively, the surfaces may also be black or white or any other suitable color. Furthermore, so-called gray wedges may be included in the test pattern. A gray wedge has a stepless progression from light to dark, e.g. from black to white. The test pattern according to the invention is introduced into the lens structure by means of a laser. When introducing a so-called calibrated laser system is used, which a defined laser power or a defined color value, e.g. a gray value. For example, a so-called dot-per-inch value (dpi value) is also defined. For example, the test pattern is centered within the lens structure. The test pattern has a scaling of, for example, 1: 1. This means that a grid of, for example, square areas has an area of 0.64 x 0.64 square millimeters. This can be used, for example, to measure or control the lens width.

To test the carrier with a lens structure with tilting effect, the carrier is mounted on a holder. The holder is rotated by a motor. Advantageously, a stepping motor is used. A stepper motor has the advantage that the holder is rotated stepwise, whereby each the step corresponds to a certain angle. The angle can be adjusted. The smaller the angle, the better the accuracy of the data to be evaluated. An optical pickup device captures at least one image of the lens structure during rotation. Advantageously, at least one image is taken for each angular step by which the holder is rotated. After taking the images for at least a partial rotation, at least one area to be measured in the images is defined, so called "regions of interest (ROI)." Advantageously, a plurality of ROI's are defined, where at least one ROI is recommended for a light, eg white one , and define a dark, eg black, area in the image.The ROIs advantageously have the same area size and before the evaluation of the captured images, it is checked whether the ROIs for each measured angle or each image are correctly positioned.

For each ROI, the color value, e.g. Gray value, black level, white level, etc., determined for each angle of rotation of the holder with the lens structure. From these values, it is then advantageous to determine an average over all images for the respective ROI, e.g. a mean gray value or a mean white value for the respective ROI. The color values determined are entered into a diagram via the angle and evaluated, as described above.

Thus, an objective quality inspection of a tilting image of a lens structure is possible with the present invention.

A great advantage of the invention is that any quality-reducing effects are detected early, for example, before a mass production, since the quality inspection prepared by means of accordingly so-called test specimens are performed, which are corresponding carriers with lens structure with tilting effect.

The method can be used to determine the cause of quality-reducing effects associated with tilting images. For example, critical laminating sheets can be checked and replaced if necessary.

After eliminating the cause of a quality reduction, the reject rate is reduced and the corresponding costs are avoided.

The device and method are expandable. Thus, e.g. the positions of lenses, their radii or the angular accuracy of inscribed in the lens structure, for example, rectangular structures are checked and measured. Further extensions are, for example, the examination of the quality of representation of metallic structures in the data carrier, such as a hologram or a kinegram or a security thread. In the following, embodiments of the invention will be described in detail with reference to the accompanying drawings.

1 shows the basic structure of a device according to the invention,

FIG. 2 shows exemplary measured curves for color values determined according to the invention, in this case gray values, of two patterns which are plotted over the angle when taking the picture, FIG. 3 shows a test pattern according to the invention,

FIG. 4 shows an inventive image of a lens structure with an area to be measured according to the invention, so-called region of interest (ROI).

Figure 1 shows the basic structure of a device according to the invention. The device according to the invention for checking the quality of a tilting image of a lens structure 4, which is arranged on a carrier 2, comprises a holder 6, for fixing the carrier 2. The holder 6 is rotated by a motor 8. A light source 10 illuminates the lens structure 4. An optical pickup device 12 picks up at least one image of the lens structure 4 during rotation of the holder 6. A data processing device 14 evaluates the at least one image taken by the optical recording device 12 regarding its color values and controls the motor 8. The data processing device 14 is provided with suitable contact-bound and / or contactless communication links with the motor 8, the light source 10 and the optical pickup device 12 connected.

The motor 8 is advantageously a stepper motor to turn the holder 6 stepwise by a defined angle. The device according to the invention has a shield against extraneous light. The shield is not shown for reasons of clarity. The shield consists of an opaque material. Advantageously, the shield can be opened and closed be used to insert a to be tested carrier 2 with lens structure 4 in the holder 6 and to remove from this.

At least the holder 6 and / or the light source 10 and / or the optical detection device 12 are arranged so that a distance and / or an angle to the lens structure 4 are variably adjustable.

The optical pickup device 12 is advantageously a microscope or a camera. Advantageously, the optical recording device 12 comprises a combination of a microscope and a camera. The optical pickup device 12 is capable of taking frames and / or taking continuous pictures in the form of a film.

Positioning aids are advantageously located in the optical pickup device 12, e.g. to display a target cross, a frame, a grid or similar in the picture to be taken.

In a step preceding the taking of an image, a calibration of the optical pickup 12 may be performed with the aim of obtaining a mm scale instead of a scale of a number of pixels. For this purpose, for example, instead of a carrier 2 to be tested, a mm scale is applied and this is taken with the optical recording device 12 _; on, so-called "teaching / learning" of the optical recording device 12. The mm scale can then be reached by simple conversion. The scale thus determined can then be superimposed on the picture taken and remains valid as long as the focus and the working distance of the optical recording device 12 to the carrier 2 to be checked does not change. In principle, you can also superimpose a reference image such as a gray wedge on the captured image.

By means of image processing in particular certain color values, brightness, etc. can be suppressed or enhanced.

Furthermore, one can use image filtering, e.g. by Sobel filter, etc., e.g. Highlight edges, e.g. to obtain a machine evaluable criterion. This makes it possible to realize the fully automatic measurement of, for example, a test pattern 16 applied to a carrier 2 or the detection / measurement of print marks.

The light source 10 produces a white or a colored light or a light of a suitable wavelength, e.g. infrared or ultraviolet. Furthermore, the generated light is uniform and diffuse.

The carrier 2 is a portable data carrier, such as e.g. a chip card, a passport, an ID card, a driver's license, a credit card, a health card, a visa, a document of value, a banknote etc.

The present invention further discloses a method for checking the quality of a tilted image of a lens structure 4, which is arranged on a support 2. For this, at least one surface 26 to be measured, so-called "region of interest", abbreviated to ROI, is defined in the lens structure 4 to be inspected, with at least two surfaces 26 to be measured, the surfaces 26 being equal or different in size Test pattern 16 is incorporated into the lens structure 4. The test pattern 16 comprises at least two areas which have the same or different color values at least two surfaces which are equal or different in size. The test pattern 16 is advantageously introduced into the lens structure 4 by means of a laser.

During or subsequent to a rotation of the holder 6, the color values are evaluated for all and / or at least one surface 26 and / or test pattern 16 to be measured over all images taken by the lens structure 4. The color values can be evaluated with regard to the brightness and / or the color information. Advantageously, at least one image is taken of the lens structure 4 per one angular position to be determined during the rotation. For example, if the motor 8 is a stepper motor and the holder 6 rotates in three degree increments, at least one image from the lens structure 4 is picked up by the optical pickup 12 for every three degree increment.

After the images have been taken by the optical recording device 12, the images are evaluated.

In the simplest embodiment, only one area 26 to be measured or a portion of each image of a sequence of captured images is evaluated.

The area to be measured 26 (ROI) is positioned the same for all images of the sequence, so that the area to be measured 26 is completely within the test pattern 16 for each angular position to be measured. Depending on the angle, different color values result for the pictures of a sequence. Alternatively, several subregions of each image of a sequence can be evaluated. If one evaluates for each image a plurality of differently positioned surfaces 26 to be measured and compares the results of each image with one another, it is possible, for example, to obtain statements regarding the uniformity of the lens structure 4 to be tested.

By means of a respective surface 26 to be measured in the white and in the black region of the test pattern 16 of each image of a sequence inscribed in the lens structure 4, a so-called white balance for the optical recording device 12 can be achieved, for example by subtraction of the determined gray or color values. This is useful if the optical recording device used does not have a manual white balance.

With the method described here, it is also possible to eliminate effects that occur, e.g. result from an uneven illumination of the lens structure 4 to be tested during the image acquisition or the image sequence.

For example, the invention may be used to qualify personalization devices for portable data carriers, such as credit cards, identity cards, etc. On the one hand, this can happen during the initial acceptance of such systems, but on the other hand, it can also be used in ongoing production in order to determine possible quality defects in personalization. Corresponding tests are also carried out after a plant has been repaired in order to prove that it has been successfully repaired or adjusted before resuming production. For this purpose, a prepared and geometrically defined test pattern 16, eg a test grid, and a well-defined map, eg of reference material, having dimensions and properties according to ISO 7810 are used.

The equipment to be qualified writes the test pattern 16 on a support 2, e.g. a credit card. This test pattern 16 is then checked for correct size, tilt, distortion, etc.

A further test step in the qualification and acceptance of personalization systems is the control of the gray value calibration, in particular in the case of laser systems, or the color calibration, in particular in personalization systems with printing technology.

In this case, it is checked whether the Personalisierungsanlage the full extent of all gray values between black and white, or in Farbwerte the full Farbumf ang can represent, and whether the representation of the gray values, in particular the color values, stable, i. without drift, e.g. over a whole production day is possible.

In addition, several systems of the same type can be adjusted to the same quality.

The verification of a gray value calibration can be carried out, for example, by comparing a carrier 2 with lens structure 4 described with a so-called gray wedge 20 against a reference card, which consists of the same card material, in which case a reference material is necessary. A gray wedge 20 is a stepless progression from a light to a dark color, eg a stepless progression from black to white. Comparison by visual inspection is common but inaccurate. A comparison By contrast, by means of densitometer, although accurate, but very expensive and is carried out only in exceptional cases. With the invention described herein, it is possible to perform such a comparison quickly, easily and objectively.

FIG. 2 shows exemplary measurement curves of two patterns for color values determined according to the invention, in this case gray values which are plotted over the angle when taking the picture. The measurement curve of pattern 1, whose measuring points are marked with squares, is narrow and high and indicates a good quality. Accordingly, the measurement curve of pattern 2, whose measurement points are marked with circles, shows a broad and low profile and thus a poorer quality than the measurement curve of pattern 1. For representing and interpreting the measurement points, one carries the respectively measured color values, e.g. Brightness, above the respective angle at which the optical pickup device 12 has received the lens structure 4. The result is a curve corresponding to a typical lens structure 4 in approximately a Gaussian bell curve with a, in multi-level Kippbil- countries corresponding to several, pronounced peak / n. Areas far outside the angle at which the test pattern 16, i. a "black" area has been written in, usually have a high brightness, i. small gray values, areas within the angle under which the test pattern 16 was inscribed, have a low brightness, ie large gray values.

The evaluation of the substrate 2 to be tested with lens structure 4 takes place relative to threshold values for the contrast which are to be determined in advance, ie the difference between the light and dark areas, corresponding to FIG Height of the top, as well as the contrast, ie the width of the top.

Measured values below this threshold give poor quality above this threshold. More specifically, a high tip means good quality and a flat tip means poor quality. ,

With a narrow tip, a large change in contrast occurs with little change in the viewing angle. At a wide peak, the contrast changes only slightly with a larger change in the viewing angle, the lens structure 4 shows only a small reaction. Correspondingly, a narrow tip means a good, a wide tip a bad quality.

In the case of multi-level tilt images, it is also possible to determine a selectivity between the individual tilt images by evaluating the maxima and minima of the curve.

Test results show that for significantly different lens radii, the shape of the measured curve is different. Accordingly, the quality criterion for a good or a bad lens structure 4 is different for different lens radii.

Further quality criteria may be a uniformity or continuity of the measurement curve as well as a respective standard deviation of the gray values. Unsteady or noisy curves indicate disturbances within the surface 26 to be measured, which are visible only at certain angles, eg lens inclusions, air bubbles or incompletely shaped lenses, eg lamination marks. A large standard deviation, ie a low measurement accuracy, indicates strongly noisy gray values, caused for example by an uneven lens surface. In the following, further possibilities for evaluating recorded images will be described. If one takes more than one image per angular position, a so-called subsequence of images, then one can vary within a subsequence, for example, the position of the surface 26 to be measured and / or change the aperture, focus, shutter speed, etc. of the camera and consequently with methods, which are known from digital image processing extend the respective surface to be measured 26, for example, to achieve higher depth of field or greater brightness dynamics, so-called focus stacking technique or high dynamic range technology.

The device according to the invention is initially to be used as a separate device. In principle, however, the device according to the invention can also be installed in the form of a module in personalization systems and then used for process control or quality assurance.

FIG. 3 shows a test pattern 16 according to the invention.

The test pattern 16 includes four areas 18, each comprising black and white squares. In each case, a gray wedge 20 runs horizontally, the gray wedge 20 being dark on the outside and becoming lighter towards the center of the test pattern 16. In the middle of the test pattern 16 are a black strip 22 and a white strip 24, with both strips 22 and 24 arranged vertically.

The test pattern 16 consists in the simplest case of a black area with a certain size, for example 5 x 5 square millimeters. In principle, the larger the area 26 to be measured of the test pattern 16, the lower is the measurement error. The test pattern 16 is present, for example, in the form of a file, for example as a JPG or TIF-coded picture.

A carrier 2 with lens structure 4 to be tested is subjected to a step preceding the actual measurement under defined conditions, such as e.g. fixed ink or laser power defined, dpi value, etc., described with a test pattern 16, printed or lasered. The test pattern 16 is thereby e.g. inscribed in the lens structure 4 by means of a laser beam at an angle in a region of the carrier 2 to be tested. As a result, in the simplest case, a single-stage tilt image is generated, which is sufficient for the measuring method described here.

In an extended embodiment, the test pattern 16 may be supplemented with white or gray areas. This is e.g. the setting of the laser power for the labeling process easier.

If the test pattern 16 contains geometrically defined elements, e.g. square or circular surfaces or checkerboard-like patterns, so it can also be tested for distortion, faithfulness of the personalization or absolute size of the lens structure 4.

In a further embodiment, a plurality of possibly different test patterns 16 are defined, which are inscribed at different angles in the carrier 2 to be tested and completely or partially overlap. This results in a multiple tilt effect, which can also be tested with the method described here.

In principle, a corresponding test pattern 16 can also be preceded by a lamination of a carrier 2 to be tested in the form of a card benefit by printing. tecrinik be applied during application of a design print. In this way, different types of tilting images are generated.

FIG. 4 shows a photo of a section of a lens structure 4 with a surface 26 to be measured according to the invention, a so-called region of interest (ROI).

The surface 26 to be measured may take any suitable form. Here a square shape was chosen. A round or polygonal or asymmetrical shape can also be selected for the surface 26 to be measured if this corresponds to the requirements for a measurement to be performed.

LIST OF REFERENCE NUMBERS

2 carriers

4 lens structure

6 bracket

8 engine

10 light source

12 optical recording device

14 data processing device

16 test patterns

18 area with black and white squares

20 gray wedge

22 black stripes

24 white stripes

26 area to be measured, region of interest (ROI)

Claims

Patent claims

1. A device for checking the quality of a tilting image of a lens structure (4), which is arranged on a support (2), characterized in that the device comprises

a holder (6) for fixing the carrier (2),

a motor (8) to rotate the support (6),

a light source (10) for illuminating the lens structure (10),

an optical pickup device (12) for picking up at least one image of the lens structure (4) during rotation of the holder (6),

a data processing device (14) for evaluating the at least one image recorded by the optical recording device (12) with respect to its color values and for controlling the motor (8).

2. Apparatus according to claim 1, characterized in that the motor (8) is a stepping motor to rotate the holder (6) gradually by a defined angle.

3. Device according to one of claims 1 to 2, characterized in that the device has a shield against extraneous light.

4. Device according to one of claims 1 to 3, characterized in that at least the holder (6) and / or the light source (10) and / or the optical recording device (12) so arranged are that a distance and / or an angle to the lens structure (4) are variably adjustable.

5. Device according to one of claims 1 to 4, characterized in that the optical recording device (12) is a microscope.

6. Device according to one of claims 1 to 5, characterized in that the light source (10) generates a white or a colored light.

7. Device according to one of claims 1 to 6, characterized in that the carrier (2) is a portable data carrier.

8. A method for checking the quality of a tilted image of a lens structure (4), which is arranged on a carrier (2), characterized in that the method comprises at least the following steps

- Fix the carrier (2) on a holder (6),

turning the holder by means of a motor (8),

illuminate the lens structure (4) with a light source (10),

receiving at least one image from the lens structure (4) during the rotation of the holder (6) by means of an optical recording device (12),

- Evaluating the at least one of the optical recording device (12) recorded image with respect to its color values and controlling the motor (8) by means of a data processing device (14).

9. The method according to claim 8, characterized in that at least one field to be measured (26) in the lens structure to be tested (4) is defined.

10. The method according to any one of claims 8 to 9, characterized in that at least two fields to be measured (26), the fields (26) are equal or different in size.

11. The method according to any one of claims 8 to 10, characterized in that at least one test pattern (16) is introduced into the lens structure (4).

12. The method according to claim 11, characterized in that the

Test pattern (16) comprises at least two surfaces which have the same or different color values.

13. The method according to claim 11, characterized in that the

Test pattern (16) comprises at least two surfaces which are the same or different sizes.

14. The method according to any one of claims 11 to 13, characterized in that the test pattern (16) is introduced by means of laser in the lens structure (4).

15. The method according to any one of claims 8 to 14, characterized in that over all images which are recorded during rotation of the holder (6) of the lens structure (4) for at least one surface to be measured (26) and / or test pattern (16) the color values are evaluated.

16. The method according to any one of claims 8 to 15, characterized in that at least one image of the lens structure (4) is taken per an angular position to be determined during the rotation.