Measuring optical properties of a transparent object

Abstract

The invention relates to a measuring device (1), a system, a measuring method and a computer program (5) for determining optical properties of a transparent object (8). In order to be able to determine the optical properties of a transparent object (8) in a particularly simple manner, a measuring method is proposed which has the following steps: during an acquisition process, the imaging (30, 31, 32) of a test pattern (3) is acquired, wherein the acquisition process comprises the acquisition of test patterns (21, 22) imaged by the object (8) with the object (8) in at least two different positions (11, 12), wherein the distance of the object positions (11, 12) from one another is known and the relative positions of the image acquisition means (10) to one another and to the display means (2) remain unchanged during the acquisition process; and during a determination process, the optical properties of the object (8) are determined from the imaging (30, 31, 32) of the test pattern (3) acquired during the acquisition process without knowledge of the geometry, position and orientation of the object (8) in such a way that the test patterns (20, 21, 22) acquired during the acquisition process are compared with one another.

Description

Technical Field

[0001] This invention relates to a measuring device, system, measuring method, and computer program for determining the optical properties of transparent objects. Background Technology

[0002] Determining the refractive power of eyeglasses is a standard task in ophthalmic optics practice. Typically, eyeglasses with unknown power are measured manually using a so-called vertex powermeter. This is difficult to perform and yields unreliable results, especially with modern progressive lenses, which are not the relatively simple single-vision lenses, as they also depend on the operator's skill. Progressive lenses, now the standard vision correction for older patients, are position-dependent lenses that typically have a distance portion in the upper region and a near portion (reading portion) in the lower region. In principle, aberrations occur in the transition region between the distance and near portions, and lens manufacturers attempt to combat these aberrations through a variety of lens designs. However, this indicates that not every patient will be suited to every lens design, thus often requiring investigation into the cause of patient dissatisfaction in ophthalmic optics practice. One possible cause is manufacturing defects in the eyeglasses. For example, the positions of the distance and near reference points must be adapted to the position of the patient's pupil. Therefore, there is a need to determine the optical characteristics of eyeglasses in a simple way and correlate these characteristics with the patient. These goals are being attempted using modern measuring equipment and methods. While simple vertexmeters can only perform point measurements, more advanced devices based on wavefront measurements have been able to display the refractive power distribution over a limited local area of ​​the lens. However, a drawback is that, due to technical and optical limitations, this cannot be performed across the entire surface, especially in the intended use position of the glasses. Therefore, using known solutions, measurements can only be taken over a limited local area of ​​the entire surface, determined by the maximum aperture of the sensor used. Furthermore, determining the distance point, and especially the near point, has failed due to the inability to fully capture the global characteristics of the lens. Summary of the Invention

[0003] One object of the present invention is to provide a technique by which the optical properties, particularly the refractive properties, of transparent objects can be measured in a particularly simple manner.

[0004] This objective is achieved through the subject matter of the independent claims. Advantageous embodiments of the invention are given in the dependent claims or derived from the following description and / or drawings.

[0005] A measuring apparatus for determining the optical properties of a transparent object according to the present invention comprises: a display device for displaying a test pattern; a plurality of image acquisition devices for acquiring images of the test pattern, wherein the image acquisition devices acquire test patterns imaged by the object at at least two different positions of the object during the acquisition process, wherein the distance between the positions of the object is known, and the relative positions of the image acquisition devices to each other and to the display device remain unchanged during the acquisition process; and a computer unit having a computer program for determining the optical properties of the object, wherein the computer program, during the determination process, without knowing the geometry, position, and orientation of the object, determines the optical properties of the object from images of the test patterns acquired by the image acquisition devices during the acquisition process by comparing the test patterns acquired during the acquisition process with each other.

[0006] The system for measuring the optical properties of a transparent object according to the present invention includes such a measuring device and a transparent object positioned between the display device and the plurality of image acquisition devices.

[0007] The measurement method for determining the optical properties of a transparent object according to the present invention comprises the following steps: a) acquiring an image of a test pattern during an acquisition process, wherein the acquisition process includes acquiring a test pattern imaged by the object in at least two different positions, wherein the distance between the positions of the objects is known, and the relative positions of the image acquisition devices to each other and to the display device remain unchanged during the acquisition process; and b) during a measurement process, determining the optical properties of the object from the image of the test pattern acquired during the acquisition process without knowing the geometry, position, and orientation of the object, by comparing the test patterns acquired during the acquisition process with each other.

[0008] The computer program according to the present invention includes computer program instructions that, when executed by a computer unit, cause the computer unit to perform the measurement steps of the above-described method.

[0009] The advantages and embodiments described below in conjunction with the device according to the invention are also meaningfully applicable to the system according to the invention, the method according to the invention, and the computer program according to the invention, and vice versa.

[0010] This invention utilizes photogrammetry principles and is based on the application of the transmission deflection method (transmission deflection measurement). A test pattern is imaged of the object under test. Here, refraction at the surface of the transparent object causes displacement and / or distortion of the imaged pattern, depending on the object's geometry. The optical properties of the object, particularly its refractive effect, can be inferred from the deflection (skewness) of the transmitted light. Therefore, the deflection of the transmitted light is measured. For this purpose, the imaged pattern is captured by a suitable image acquisition device (e.g., a digital camera). From the detected changes in the pattern (e.g., in the form of displacement and / or distortion), the optical properties of the object, such as local refractive power, local surface tilt, or local prismatic effect, are determined. Preferably, at least one refractive power distribution is determined from the local pattern changes.

[0011] The present invention is particularly useful for determining the optical properties of thin, transparent objects. In other words, the object under test is preferably a thin optical element. This is specifically understood as an optical element whose optical action can be represented by a single principal surface. For thin optical elements, the optical properties can be determined particularly easily using the present invention. However, the present invention can also be used in principle for other objects, particularly optical elements whose distance between principal surfaces is much smaller than the measurement distance, and those that only approximately behave as thin optical elements or whose optical behavior can at least approximately be represented by a single principal surface. The object must be sufficiently transparent such that sufficient light for measurement can pass through it.

[0012] The test pattern used can be any number of virtually any pattern elements in any arrangement. For example, dots, lines, or other elements that can be presented in isolation from each other are suitable as pattern elements.

[0013] This invention allows for the rapid and comprehensive measurement of optical elements in transmission, particularly for determining their optical properties, especially local refractive power. The invention is applicable to a wide variety of optical elements. It is particularly advantageous to apply this invention to eyeglasses, especially progressive eyeglasses. More precisely, in this case, the optical element under study is formed by a lens mounted in the frame of the eyeglasses. In short, the object of measurement is the assembled eyeglasses. However, the invention can also be applied to a single lens as the object of measurement. Hereinafter simply referred to as eyeglasses. A pair of eyeglasses here exemplarily represents an intentionally refractive optical element designed to achieve a specific optical effect, particularly refractive effect. The invention is also particularly advantageous to apply to vehicle windows, especially windshields. Windshields here exemplarily represent an unintentionally refractive optical element that should not have an optical effect, particularly refractive effect. In all cases, the invention is based on detecting local beam direction changes caused by the optical element and using them to evaluate the optical effect and thereby assess the quality of the optical element. For eyeglasses, the purpose of examining the optical properties is to identify the aforementioned lens characteristics that are important to the optometrist. For windshields, measuring local refractive power is prescribed for safety reasons. The purpose of examining optical properties here is to check optical uniformity, especially to identify defects and optical irregularities, such as streaks, refractive index jumps, etc.

[0014] The technical solution according to the present invention is characterized by its ability to measure any transparent object, especially thin transparent objects. It can also measure multiple objects simultaneously. If the object is a pair of eyeglasses, both lenses can be studied at the same time.

[0015] The technical solution according to the invention is characterized by the ability to acquire optical properties across the entire surface of an object. In particular, the invention allows for the determination of local refractive power (full-surface refractive power distribution) over substantially the entire aperture of an optical element (e.g., a spectacle lens), whereas methods known in the prior art typically cannot acquire the entire spectacle lens as a measurement surface due to the nature of the methods themselves.

[0016] The technical solution according to the present invention is characterized in that the acquisition of optical properties is independent of the optical effects of the object. In particular, it is not necessary to know the material of the object being measured or its refractive power. If the object is a pair of eyeglasses, then the type of lens (monofocal, multifocal, progressive) is also unnecessary to consider.

[0017] The technical solution according to the present invention is characterized by the ability to acquire optical properties solely based on the optical action of an object, without knowing its geometric parameters. In other words, to determine the optical properties of an object, it is not necessary to know its geometric properties (outer contour, radius of curvature, thickness). In particular, it is not necessary to know the geometry of the object's optically active surface to determine the object's refractive effect.

[0018] The technical solution according to the invention is characterized in that the measurement result depends neither on the measured position (exact position) of the object nor on its orientation. Therefore, neither needs to be known. The object position is understood here as the location of the object being measured in the measurement field. The object can be located at any distance between the display device and the image acquisition device. For the determination of the optical properties of the object according to the invention, only the displacement of the object between the acquired and imaged object positions needs to be known. In other words, only the distance between the object positions needs to be known, in the simplest case, the difference in object positions along the optical axis (z-axis). No markings or further information on the object are required for the measurement. In particular, no other information is acquired besides the imaged test pattern.

[0019] If the object under study is a pair of eyeglasses, the present invention allows for measurements to be taken at the point of use of the eyeglasses, that is, at the point where the lenses are actually used.

[0020] This invention relates to the measurement of the refractive power of optical elements, particularly the distribution of refractive power across the entire aperture of the element. Using this invention, the full-surface, position-resolved refractive power distribution of an optical element can be determined in a particularly simple manner.

[0021] If the object is a pair of eyeglasses, this invention allows for the display of the actual refractive power distribution in a particularly simple manner and the identification of characteristic points in the lens relative to the edges, such as the distance point and near point. Therefore, optometrists can be provided with crucial information about the reasons for customer dissatisfaction. Simultaneously, it provides optometrists with a measurement method that can, in a quality control sense, acquire, quantify, and display the relationship between the achieved lens position and orientation and the identified, frame-specific, and patient-measured fit points. In particular, the relationship between the positions of the near and distance points and the identified edges can be determined and displayed. Simultaneously, the corresponding local refractive power and possibly other parameters at these points can be determined and displayed, and compared with the design values ​​(“prescription”) of the relevant lens.

[0022] According to a preferred embodiment of the invention, the measuring device includes a positioning device for achieving different positions of the object between the display device and the image acquisition device. Preferably, the computer program is also designed to control the positioning device to perform different positions of the object during the acquisition process.

[0023] According to a preferred embodiment of the invention, the image acquisition devices are designed such that they acquire, during the acquisition process, an unchanged, i.e., unaltered reference test pattern displayed by the display device, untouched by the object. This acquisition serves as a blank measurement for calibration of the measurement process. The number of image acquisition devices depends on the number of objects under test. The display device is advantageously an electronic display, allowing the number, arrangement, and shape of the displayed pattern elements to be easily changed as needed.

[0024] According to a preferred embodiment of the invention, the computer program is designed to determine local pattern variations for a plurality of object positions (preferably for each object position) during the measurement process, i.e., variations of the test pattern imaged by the object relative to the reference test pattern used as a comparison test pattern.

[0025] According to a preferred embodiment of the invention, the computer program is designed to determine, during the measurement process, a change in a test pattern imaged by the object arranged in a first object position relative to a plurality of other test patterns as comparison test patterns for a plurality of object positions (preferably for each object position), the other test patterns being imaged by the object position of the object when the object is located in a position different from the first object position.

[0026] According to a preferred embodiment of the invention, the computer program is designed such that it preferably determines, during the measurement process, only within the edge limits of the object, the change of the test pattern imaged by the object relative to the comparison test pattern.

[0027] According to a preferred embodiment of the invention, the computer program is designed to determine, during the measurement process, the variation of a test pattern imaged by the object relative to a comparison test pattern for multiple imaging groups, wherein each imaging group is formed by the imaging neighborhood of individual pattern elements of the test pattern, and each imaging group represents a face element of the object, i.e., an element of the main face of the object. An imaging group can be formed, in particular, by an N×N neighborhood, such as a 2×2, 3×3, or 4×4 neighborhood, wherein each neighborhood has an actual center point or a virtual center point formed by the pattern elements. This means that the variation is not determined for individual pattern elements of the test pattern, i.e., not by comparing individual pattern elements, but rather the variation is always determined based on a set of pattern elements (imaging groups) in the test pattern imaged by the object. The number of neighborhoods thus determines the number of data points for subsequent evaluation. The variation is determined for multiple such neighborhoods. In other words, instead of studying the distortion and / or displacement of individual pattern elements of the test pattern, the study is on the offset variation of the pattern elements of the test pattern, and thereby the distortion and / or displacement of the test pattern.

[0028] By considering the neighborhood (i.e., the region of adjacent pattern elements), the problem of limited resolution in the measurement method is solved. According to another preferred embodiment of the invention, the resolution is further improved by evaluating the offset of pattern elements in the overlapping imaging group.

[0029] For each imaging group (neighborhood) consisting of at least 2×2 pattern elements, a local affine transformation matrix can be calculated between the preimage (test pattern) and the image (the image of the preimage through optical elements), which mathematically approximates the local optical effect. According to a preferred embodiment of the invention, the computer program is designed such that, during the measurement process, for the plurality of surface elements considered, for the plurality of imaging groups considered, preferably for each imaging group, it determines the local affine transformation matrix for each pair of test patterns to be compared. Here, each pair of test patterns includes, on the one hand, a test pattern imaged by the object from one object position, i.e., altered by the object, and on the other hand, a comparison test pattern, wherein the comparison test pattern is either an unchanged reference test pattern or a test pattern imaged by the object from another object position. If the imaged test pattern is compared with the reference test pattern, the transformation matrix transforms the reference test pattern, representing the unchanged initial state, into the test pattern imaged by the object, representing the altered state. If a comparison is made between two test patterns that are imaged by objects at different object positions, the transformation matrix transforms the first test pattern (which is imaged by an object arranged in the first object position) into another test pattern (which is imaged by an object when the object is in an object position different from the first object position).

[0030] According to a preferred embodiment of the invention, the computer program is designed such that, during the measurement process, for at least one imaging group, preferably for each imaging group, it determines the principal axis direction and scaling ratio along the two principal axes from a transformation matrix determined for that imaging group, and thereby determines the local refractive power of the surface element represented by that imaging group.

[0031] According to a preferred embodiment of the invention, the computer program is designed such that, during the measurement process, for at least one imaging group, preferably for each imaging group, it determines a local translation from a transformation matrix determined for that imaging group, and thereby determines the local prism of the surface element represented by that imaging group.

[0032] According to a preferred embodiment of the invention, the computer program is designed to generate a refractive power map of the transparent object using at least one determined optical property of the object after the measurement process. Preferably, the computer program generates a position-resolved refractive power map relative to the edge boundaries of the object.

[0033] According to a preferred embodiment of the invention, the computer program is designed to generate a composite image to display the superposition of the generated refractive power map with the edge boundaries of the object. In other words, if the object being measured is a pair of eyeglasses, the fitted eyeglasses can be measured and traced back to the actual edge geometry. The optometrist can then, for example, directly identify whether the eyeglasses have been properly edged, i.e., whether they are correctly mounted in the frame.

[0034] In this context, it has proven particularly advantageous if the distribution of refractive power is displayed in the form of a composite image of the refractive power within the defined limits of the measured object and the actual limits of the measured object.

[0035] According to a preferred embodiment of the invention, the computer program is designed to determine the edge limits of the object from an image of the test pattern acquired during the acquisition process, either before or after the measurement process. Preferably, the computer program determines the edge limits using an image processing algorithm.

[0036] According to a preferred embodiment of the invention, the transparent object is an object with a desired optical function, particularly fitted eyeglasses, wherein the eyeglasses are preferably in their use position.

[0037] According to a preferred embodiment of the invention, the transparent object is an object that does not have the intended optical function, particularly an extended, substantially flat object, especially the windshield of a motor vehicle. Attached Figure Description

[0038] Other embodiments, features, and combinations of features of the present invention are set forth in the following description of embodiments of the invention, wherein these embodiments relate to assembled eyeglasses and windshields as objects of measurement. However, the descriptions, features, and combinations of features given in this context are not limited to these objects of measurement, but are also directly or accordingly applicable to other optical elements, or can be adapted to other optical elements. The accompanying drawings show:

[0039] Figure 1 A simplified perspective view of the measuring equipment is shown;

[0040] Figure 2 A simplified schematic diagram of the measuring device is shown;

[0041] Figure 3 The reference test pattern is shown;

[0042] Figure 4 A test pattern is shown, imaged by the object in the first object position;

[0043] Figure 5The test pattern is shown as an image of the object at the second object position;

[0044] Figure 6 The image shows a composite image created by overlaying the generated refractive power map with the edge boundaries. Detailed Implementation

[0045] All accompanying drawings are not drawn to scale and are intended to be schematic only, showing only the main components. The same reference numerals are used herein to denote elements that have the same or similar function.

[0046] The examples described below involve generating refractive power maps for progressive lenses. Figure 1 and Figure 2 As schematically shown, the measuring device 1 includes a self-emissive display 2, such as a TFT screen, as a display device for displaying the test pattern 3. The displayed test pattern 3 (here in a simple dot matrix form) is... Figure 3 As shown in the figure, the dot matrix comprises multiple regularly arranged dotted pattern elements 23.

[0047] The measuring device 1 includes a computer unit 4 with a computer program 5 for providing a test pattern 3 by controlling a display 2 connected to the computer unit 4.

[0048] The mounted eyeglasses 8, arranged on the shooting bracket 7, serve as the measurement object. For the eyeglasses 8 with two lenses 9, two measurement fields are set up in this example. The measuring device 1 includes two digital cameras 10 serving as image acquisition devices, such that one camera 10 is assigned to each measurement field (binocular measuring device). These measurement fields can overlap. Alternatively, multiple cameras 10 can be set up for each lens 9 or each measurement field. The additional data generated in this way can be used to improve the quality of the measurement results.

[0049] The glasses 8 are placed in the first object position 11 located between the display 2 and the camera 10. For subsequent optical characteristic measurements, the absolute position of the shooting bracket 7 and any angle (tilt, oblique) of the measuring object 8 are irrelevant.

[0050] Cameras 10 are arranged at a fixed, known distance relative to display 2. The relative positions of cameras 10 to each other and to display 2 remain unchanged during the acquisition process. The distances between cameras 10 are not important, especially not related to the distance of the spectacle lens 9 in the sense of channel-type centering.

[0051] The cameras 10 are designed such that their focal planes correspond to the plane of the display 2, and each of the two cameras 10 captures the entire object 8, i.e., the two lenses 9 of the glasses. Figure 2 In the image, a single beam path 13 is shown only symbolically for each lens 9 and camera 10.

[0052] In this example, to simplify the evaluation of the measurement data, the optical axes of the camera 10 are arranged parallel to each other and are assigned to the lens 9 of the eyeglasses 8 and aligned with its center.

[0053] Camera 10 images the display 2 or a portion thereof and acquires an image of the test pattern 3. In other words, the test pattern 3 of the eyeglasses 8 displayed on the display 2 is imaged onto the sensor of camera 10. Here, both lenses 9 are acquired simultaneously. The number of pattern elements 23 captured by camera 10 is irrelevant to the measurement results. The number of captured pattern elements 23 only affects the lateral resolution of the measurement. For extremely reduced lens 9, the number of pattern elements 23 that can be acquired becomes very small. In this case, the density of pattern elements 23 in the test pattern 3 can be increased.

[0054] The camera 10 captures an image of test pattern 3 (imaging). First, the camera 10 captures an image 30 of test pattern 3 without alteration, i.e., the pattern unaltered by the lens 9, see [link to image 30]. Figure 3 The unchanged test pattern 3 is used as a reference test pattern 20. Thus, it can be seen that when there is no refractive element between the display device 2 and the camera 10, the positions of each pattern element 23 of the test pattern 3 in the image acquired by the camera 10 are known.

[0055] Subsequently, camera 10 captures at least two images 31 and 32 showing the test pattern 3 altered by glasses 9, see [link / reference] Figure 4 , Figure 5 For measurements requiring sufficient accuracy for spectacle lenses, two images taken at different distances from the measuring object 8 to the measuring device 1 are sufficient. For spectacle lenses, sufficient accuracy is within 1 / 16 diopter.

[0056] When the glasses 8 are at the first object position 11, the camera 10 captures the first altered image 31. The first altered test pattern 21 in the image is... Figure 4 As shown in the figure. As can be identified here, the pattern element 23 of the first test pattern image 21 located inside the edge limit 18 is slightly offset relative to the corresponding pattern element 23 in the image 30 of the reference test pattern 20.

[0057] Subsequently, the measuring device 1 is modified so that the glasses 8 are positioned in a second object position 12 between the display 2 and the camera 10. For this purpose, the shooting bracket 7 moves along the z-direction 17 between the display 2 and the camera 10. Since the glasses 8 is fixed relative to the shooting bracket 7, the distance between the different object positions 11, 12 corresponds to the distance between the corresponding positions of the shooting bracket 7. In an alternative variation, the display 2 and the camera 10 are mounted at a fixed, aligned distance from each other and configured as a motion unit, moving along the z-direction 17 relative to the shooting bracket 7, which is stationary in this case, to establish the desired object positions 11, 12.

[0058] The difference between the second object position 12 and the first object position 11 lies in a significant Δz. In the example shown, the second object position 12 is closer to the camera 10, and... Figure 2 The distance (Δz) between the positions 11 and 12 of the objects is known and is the only information needed to determine the optical properties of the glasses 8, apart from the image data captured by the camera 10.

[0059] The computer unit 4, which has computer program 5, is also used to control the moving unit (not shown), which serves as a positioning device for occupying different object positions 11, 12 by moving the shooting bracket 7 along the z-direction 17 or, in an alternative variation, by moving the display-camera unit relative to the stationary shooting bracket 7 along the z-direction 17.

[0060] When the glasses 8 are in the second object position 12, the camera 10 captures a magnified second alteration image 32. The imaged second alteration test pattern 22 is in... Figure 5 As shown in the image. (and) Figure 4 Compared to the first altered test pattern 21, it shows a stronger offset relative to the reference test pattern 20 and an enlargement of the pattern elements 23 within the edge boundary 18.

[0061] exist Figure 3 , Figure 4 and Figure 5 In the test pattern 3 shown, there is no pattern element at the center of the pattern. This empty position 24 is used in subsequent image processing to more easily assign a location to be studied within the measurement field. In an alternative variant not shown, to achieve this purpose, a test pattern containing non-point-like pattern elements is used, these pattern elements having different shapes depending on their position within the test pattern.

[0062] Computer unit 4, equipped with computer program 5, is also used to evaluate the measurement results acquired by camera 10. The characteristics of the measured object 8 are determined by analyzing the captured images 30, 31, and 32 using computer program 5. Computer program 5 contains algorithms for performing necessary calculations and determining the required data.

[0063] First, the defined edge 18 of the lens 9, i.e., the visible edge of the lens within the frame, is determined from the measured image data. In further evaluation, the variation of test patterns 21, 22 relative to the reference test pattern 20 is determined only within said edge boundary. From this edge boundary, an edge line 19 can be determined, which serves as the border of the refractive power map 29 or is inserted into the composite image 33, see [reference]. Figure 6 The determined edge 18 position is also used as a boundary condition for the expected value of the measured surface position of the corresponding spectacle lens 9.

[0064] After the defined edge 18 of the lens 9 is determined, for each of the two lenses 9, the test patterns 21, 22 modified by the lens under test 8 are compared with the unchanged reference test pattern 20 for each object position 11, 12 to determine the local pattern changes.

[0065] Test pattern 3 consists of pattern elements 23 in the form of dots, which are located on the intersection of equidistant horizontal and vertical lines (Cartesian lattice). Therefore, each single point has four direct horizontal and vertical neighbors, as well as four additional diagonal neighbors, which together form the so-called 8-neighborhood.

[0066] First, the image location of pattern element 23 in the image is searched. Individual pattern elements 23 are no longer considered here; instead, imaging groups are considered, where each imaging group is formed by a 3×3 neighborhood of pattern element 23. Here, each imaging group 25 represents a face element of a lens 9. In other words, the face element to be evaluated for each lens 9 is defined by selecting the neighborhood of pattern element 23 in the images 30, 31, and 32 acquired by camera 10.

[0067] Next, the corresponding centroids of imaging groups 25 are determined. Then, it is determined how much these centroids are offset relative to the target position, i.e., the calibrated zero position. Then, for each imaging group 25, i.e., for each 3×3 neighborhood, a local affine transformation matrix is ​​determined that transforms the undisturbed initial state (calibrated state) into a perturbed state (state with refractive elements), where, for example, at least five of the nine pattern elements in the neighborhood must be present. This is performed on all imaging groups 25 representing surface elements within the previously determined boundaries.

[0068] However, the exact location of the refractive element 8 and the angle at which the refractive surface is located are unknown. But since the refractive surfaces of the lens 9, which are considered to be made of the same material, are adjacent to each other, i.e., geometrically connected, their principal surfaces must be continuously differentiable (continuity condition). Taking this into account, an essentially unique solution for the corresponding principal surface positions is obtained, and thus the refractive power of the refractive surface is derived.

[0069] After the transformation matrix is ​​determined, the direction and magnitude of the local refractive power of the surface elements represented by the considered imaging group 25, i.e. the corresponding 3×3 neighborhood, are determined from it using a suitable algorithm of computer program 5.

[0070] Although the family of possible principal surfaces of the lens 9 can be determined in this way, the angle of the refractive surface remains unknown when evaluated using only a single measurement at a single object position 11. The angle, and thus the position of the principal surface, can only be determined by evaluating the results of at least one second measurement (where the lens 8 is in a different object position 12, i.e., other positions where the principal surface exists).

[0071] Then, the transformation parameters (principal axis direction, scaling factor, displacement) are derived from the transformation matrices calculated for each 3×3 neighborhood and each object position 11, 12, and are calculated using a suitable algorithm of computer program 5. In other words, the coefficients of each individual local affine transformation matrix provide information about the average lateral displacement (translation) of the corresponding group of pattern elements (neighborhood) as well as the scaling factor of their respective effective principal axes and the orientation of these principal axes.

[0072] The local pattern displacements from the two object positions 11 and 12 can be converted into local prisms. In other words, the local translations are irrelevant to the current refractive power calculation, but they can be used to calculate the local prisms and their orientation.

[0073] The two scaling ratios along the two principal axes represent the magnification (reduction). Using the local scaling ratios along the effective principal axes (determined at the two object positions 11 and 12), the local refractive power at each location is calculated using a suitable algorithm in computer program 5. The refractive power is then inversely derived from the two magnifications (i.e., the two object positions) using the imaging equation. In other words, the paired principal axis scaling ratios from two different object positions 11 and 12 (but at the same position on the lens 9) are converted into a basic refractive power in that section using the imaging equation. The same applies to the paired scaling ratios of the secondary principal axes. The spherical power, the spherical equivalent (average), and the cylindrical power (difference) are then calculated from the two local refractive powers (principal and secondary principal axes) along the corresponding sections. Thus, the orientation of the cylindrical power is also known.

[0074] The position-resolved measurements of spherical power, cylindrical power, axis, and prismatic effect obtained in this manner, relative to the actual edge of lens 9, i.e., low-order refractive power, can be displayed as a refractive power map 29 for assessing centering, cylindrical position, and other patient-specific parameters, and in this way for quality assurance and for determining the cause of individual patient intolerance. For this purpose, a refractive power map 29 showing the distribution of refractive power values ​​is generated. The refractive power map 29, together with the determined edge line 19, is combined in a composite image 33.

[0075] In the case of measuring spectacle 8, the display includes a refractive power map 29 of the two lenses 9 relative to the spectacle frame. The refractive power map 29 can display the spherical equivalent, minimum and maximum principal sections, spherical power, cylindrical power, cylindrical axis, and prismatic effect. See [link to relevant documentation]. Figure 6 The diagram shows the refractive power map of the progressive lens calculated by measurement. The upper diagram shows the spherical equivalent value, and the lower diagram shows the cylindrical power. The border of the refractive power map 29 shown through the edge line 19 corresponds to the actual shape of the eyeglass frame. This allows the refractive power value to be directly correlated with the patient's actual viewpoint, which can be obtained, for example, through a video centering system.

[0076] The calculated results, particularly the determined refractive power map 29 and / or composite image 33, are displayed by means of a suitable display device 6 (e.g., a second display) for direct use by the optometrist. The computer program 5 is also accordingly designed to display these results by controlling the second display connected to the computer unit 4.

[0077] All optical properties can be determined in this way over essentially the entire aperture of the lens. Because the evaluation is performed on a neighborhood basis rather than point-by-point, the optical properties of regions immediately adjacent to the geometric edges of the lens can only be predicted by extrapolation.

[0078] In another embodiment of the invention, not shown, the windshield of a motor vehicle is used as both an optical element and a measurement object. All the technical features and characteristics of the measuring device 1 and the measuring method given above in conjunction with the measuring object glasses 8 are also applicable to the measuring object windshield. However, according to a preferred embodiment, only a single camera 10 is used, which, together with the display 2, forms a C-shaped arc-shaped display-camera unit mounted on a robotic arm. Different object positions 11, 12 of the measurement object relative to the camera 10 are achieved by moving the C-shaped arc around the stationary measurement object; in other words, by traveling around the measurement object. Here, multiple defined positions are approached in a three-dimensional trajectory. During the measurement process for multiple imaging groups, a suitable transformation matrix corresponding to the measuring device is determined for each pair of test patterns to be compared.

[0079] When using this C-curve system, which is also applicable to other large objects, in addition to the calculations and data analysis described above in conjunction with the measurement of glasses 8, attitude-related misalignment correction is also required to account for the curvature of the C-curve caused by gravity, which depends on the position of the C-curve in space and affects the measurement results.

[0080] All features presented in the specification, subsequent claims, and drawings, whether individually or in any combination, are essential to this invention. Each of these features or combinations thereof may constitute an independent invention, the claims of which are expressly reserved.

[0081] When giving a combination of features that defines the invention, each feature from the description of the embodiments is not necessarily required to be combined with one or more or all other features specified in the description of the embodiments; in this regard, each sub-combination of features of one or more embodiments is explicitly disclosed.

[0082] Furthermore, the physical characteristics of a device can be reformulated as method characteristics and used, and the method characteristics can also be reformulated as physical characteristics of a device and used. Features reformulated in this way are implicitly disclosed.

[0083] The device according to the invention is designed to perform the described method, particularly and at least to perform the measurement step, i.e., to measure the optical properties of an object during the measurement process. Preferably, the device is a computer unit (data processing unit, computer) designed to perform all the steps related to data processing according to the method described herein, or the device comprises such a computer unit. The computer unit preferably has multiple functional modules, each designed to perform a specific function or multiple specific functions according to the described method. The functional modules can be hardware modules or software modules. In other words, with regard to the computer unit, the invention can be implemented in the form of computer hardware, computer software, or a combination of hardware and software. If the invention is implemented in software, i.e., a computer program, then when the computer program is executed on a computer with a processor, all the described functions are implemented by computer program instructions. Here, the computer program instructions are implemented in any programming language in a manner known per se and can be provided to the computer in any form, for example, as data packets transmitted over a computer network or as a computer program stored on a data carrier.

[0084] List of reference numerals in the attached diagram:

[0085] 1. Measuring equipment

[0086] 2 monitors

[0087] 3 Test Pattern

[0088] 4. Computer Unit

[0089] 5. Computer Programs

[0090] 6. Other display devices

[0091] 7. Shooting tripod

[0092] 8. Glasses

[0093] 9. Eyeglass lenses

[0094] 10 cameras

[0095] 11 First object position

[0096] 12. Second object position

[0097] 13 Beam Path

[0098] 14 (empty)

[0099] 15 (empty)

[0100] 16 (empty)

[0101] 17 z direction

[0102] 18. The edge of the eyeglass lens

[0103] 19. Edge line

[0104] 20 Reference Test Pattern

[0105] 21 First change to the test pattern

[0106] 22. Second change to the test pattern

[0107] 23 Pattern Elements

[0108] 24 Vacant Positions

[0109] 25 imaging groups (N×N neighborhood)

[0110] 26 (empty)

[0111] 27 (empty)

[0112] 28 (empty)

[0113] 29. Refractive power map

[0114] 30. Image of the reference test pattern

[0115] 31 The first image of the changed test pattern

[0116] 32. Second, change the image of the test pattern.

[0117] 33. Composite image.

Claims

1. A measuring device (1) for determining the optical properties of a transparent object (8). The measuring device includes a display device (2) for displaying the test pattern (3). The measuring device includes several image acquisition devices (10) for acquiring images (30, 31, 32) of the test pattern (3), wherein, The image acquisition device (10) acquires test patterns (21, 22) imaged by the object (8) when the object (8) is in at least two different positions (11, 12) during the acquisition process, wherein the distance between the object positions (11, 12) is known, and the relative positions of the image acquisition devices (10) to each other and to the display device (2) remain unchanged during the acquisition process. The measuring device includes a computer unit (4) having a computer program (5) for determining the optical properties of the object (8), the computer program (5) determining the optical properties of the object (8) from the images (30, 31, 32) of the test pattern (3) acquired during the acquisition process without knowing the geometry, position and orientation of the object (8), by comparing the test patterns (20, 21, 22) acquired during the acquisition process with each other.

2. The measuring device (1) according to claim 1, wherein the measuring device includes a positioning device for achieving different positions of the object (8) between the display device (2) and the image acquisition device (10), wherein, The computer program (5) controls the positioning device to perform different positioning of the object (8) during the acquisition process.

3. The measuring device (1) according to claim 1 or 2, wherein, The image acquisition device (10) acquires an unchanged reference test pattern (20) during the acquisition process.

4. The measuring device (1) according to claim 3, wherein, The computer program (5) determines, during the measurement process, the changes of the test patterns (21, 22) imaged by the object (8) relative to the reference test pattern (20) used as a comparison test pattern for several object positions (11, 12).

5. The measuring device (1) according to any one of claims 1 to 4, wherein, The computer program (5) determines, during the measurement process, the variation of a test pattern (21) imaged by the object (8) arranged in the first object position (11) relative to a plurality of other test patterns (22) as comparison test patterns for a plurality of object positions (11, 12), the other test patterns (22) being imaged by the object (8) when the object (8) is located in an object position (12) different from the first object position (11).

6. The measuring device (1) according to claim 4 or 5, wherein, The computer program (5) determines, during the measurement process, the change of the test pattern (21, 22) imaged by the object (8) relative to the comparison test pattern (20) within the edge limit (18) of the object (8).

7. The measuring device (1) according to any one of claims 4 to 6, wherein, The computer program (5) determines, during the measurement process, the changes of the test patterns (21, 22) imaged by the object (8) relative to the comparison test pattern (20) for multiple imaging groups (25), wherein each imaging group (25) is formed by the neighborhood of the imaging of each pattern element (23) of the test pattern (3), and each imaging group represents a face element of the object (8).

8. The measuring device (1) according to claim 7, wherein, The computer program (5) determines, during the measurement process, a local affine transformation matrix for each of the imaging groups (25) to be compared with each other for each test pattern (20, 21, 22).

9. The measuring device (1) according to claim 8, wherein, The computer program (5) determines the principal axis direction and scaling ratio along the two principal axes from the transformation matrix determined for at least one imaging group (25) during the measurement process, and thereby determines the local refractive power of the surface element represented by the imaging group (25).

10. The measuring device (1) according to claim 8 or 9, wherein, The computer program (5) determines local translations from a transformation matrix determined for at least one imaging group (25) during the measurement process and thereby determines local prisms of the surface elements represented by the imaging group (25).

11. The measuring device (1) according to any one of claims 1 to 10, wherein, The computer program (5) generates a refractive power map (29) of the object (8) using at least one determined optical property of the object (8) after the measurement process.

12. The measuring device (1) according to claim 11, wherein, The computer program (5) generates a composite image (33) to display the superposition of the generated refractive power map (29) with the edge boundary (19) of the object.

13. The measuring device (1) according to any one of claims 1 to 12, wherein, The computer program (5) determines the edge limit (18) of the object (8) from the image of the test pattern (3) acquired during the acquisition process.

14. A system for measuring the optical properties of a transparent object (8), the system comprising a measuring device (1) according to any one of claims 1 to 13 and comprising a transparent object (8) positioned between the display device (2) and the plurality of image acquisition devices (10).

15. The system according to claim 14, wherein, The transparent object (8) is an object with the intended optical function, particularly an assembled pair of glasses, wherein the glasses are preferably in their use position.

16. The system according to claim 14, wherein, The transparent object (8) is an object that does not have the expected optical function, especially an extended, substantially flat object, particularly the windshield of a motor vehicle.

17. A measurement method for determining the optical properties of a transparent object (8), the measurement method comprising the following steps: During the acquisition process, images (30, 31, 32) of test patterns (3) are acquired, wherein the acquisition process includes acquiring test patterns (21, 22) imaged by the object (8) when the object (8) is in at least two different positions (11, 12), wherein the distance between the object positions (11, 12) is known, and the relative positions of the image acquisition devices (10) to each other and to the display device (2) remain unchanged during the acquisition process. During the measurement process, the optical properties of the object (8) are determined from the images (30, 31, 32) of the test patterns (3) acquired during the acquisition process without knowing the geometry, position and orientation of the object (8), by comparing the test patterns (20, 21, 22) acquired during the acquisition process with each other.

18. A computer program, including computer program instructions, which, when executed by a computer unit (4), cause the computer unit to perform the determination step of the method according to claim 17.

Images