Method and apparatus for determining the refractive power of an optically transparent article

Abstract

The present invention relates to a method and apparatus for determining the refractive power of an optically transparent article (2), and preferred uses thereof. The refractive power of the article (2) in a first deflection direction (AH) and at least one other deflection direction (AV) in a measurement area (MB) is measured by an optical measuring device (4), defining the orientation and position of the article (2), the viewpoint (42, 52), and the line of sight direction (BR). The intersection of the defined line of sight direction (BR) and one local measurement area (MF[i]) on the article (2) and the visual angle (ε) formed by the line of sight direction (BR) and the measurement direction (MR) within the confirmed local measurement area (MF[i]) are confirmed. For the refractive power, an amplification constant is determined based on the identified visual angle (ε) and the refractive index (n) of the article (2), and the refractive power in the line of sight direction (BR) is confirmed by applying the amplification constant to the local refractive power value B[i] of the local measurement area (MF[i]).

Description

Technical Field

[0001] The present invention relates to a method and an apparatus for determining the refractive power of an optically transparent article, particularly a sheet-like article, such as sheet glass, as recited in claims 1 and 10, the sheet-like article being capable of being implemented in a flat or preferably curved form. Furthermore, the present invention relates to a preferred use of this method and / or apparatus for verifying the refractive power of a windshield at any viewing angle, as recited in claim 16.

Background Art

[0002] When an optically visible light ray passes through an optically transparent article having a refractive index different from that of the surroundings, this optical ray is refracted and generally deflected according to the laws of optics. In the case of a uniform sheet-like transparent article having surfaces in a parallel orientation, a visible light ray directed perpendicular to the sheet passes through the sheet without refraction. A visible light ray directed at a viewing angle other than 90° with respect to the sheet is shifted parallel in the direction of the ray, and as a result, the image appears shifted laterally.

[0003] If the sheet is non-uniform, has curvature, and / or has non-parallel surfaces (even if only locally), the incident parallel visible light rays undergo different refractions, which, as in the case of a lens, leads to image distortion. The strength of the distortion is explained by the refractive power B in the deflection direction, usually in the unit of diopter (dpt). The refractive power ("strength of distortion") also varies depending on the line-of-sight direction in which the visible light ray is incident on the optical article.

[0004] The optical power of a flat glass plate with an uneven surface is described in Kerkhof, Optische Wirkungen von Flachglas mit unebenen Oberflachen [Optical Power of Flat Glass Plates with Uneven Surfaces], Glasstechnische Berichte, issue 25, pages 71 to 83, Verlag der Deutschen Glastechnischen Gesellschaft Frankfurt (Main), 1952, under the premise that the glass plate is a series of many glass prisms with very small wedge angles of the refractive surface for various angles of incidence of visible light, based on refractive geometry. The refractive surface is the plane in which the incident and refracted visible light exist.

[0005] Knowing the local surface shapes on both sides of a sheet of transparent material allows us to estimate the refractive plane and determine a single refractive force for a given line of sight towards the transparent material. However, this is non-uniform in transparent materials, and this can also cause optical refraction regardless of the local surface shapes of the incident and exit surfaces of the transparent material. Furthermore, determining the surface shape of transparent materials, such as plate glass, especially curved plate glass like car windshields, is extremely complex and time-consuming.

[0006] One possible iterative method for verifying the surface shape of plate-like or layered articles is described in International Publication No. 2022 / 189327A1. This involves providing a hypothetical surface shape as an initial shape and defining multiple measurement points on the initial shape. The spatial locations of the measurement points are optically determined by illuminating the surface and detecting the reflected radiation. The deviation of the detected radiation at the measurement points from the expected radiation from the initial shape is repeatedly checked until the measured values ​​match the expected values ​​within a certain accuracy value. The verified surface shape is then used to simulate the refractive power distribution. Given a known surface shape, the refractive power can, in principle, also be verified from a defined line of sight direction. Due to the expenditure and evaluation complexity associated with the measurement method, such a method is not suitable for optical quality control of optically transparent articles on industrial production lines.

[0007] Furthermore, a refractive force measurement method is known that involves imaging a known pattern through a transparent object and quantitatively evaluating the distortion of the pattern by the object in the image. The pattern may be, for example, a pattern of multiple lines having a predetermined spacing. Then, from the change in the spacing in a particular deflection direction, it is possible to determine the refractive force in that deflection direction, as described in DIN 52305 (Identification of deflection angle and refractive value of safety plate glass for vehicle glazing). The pattern may also consist of a regular arrangement of circles of a known diameter, and the change in the diameter of the circles in at least one deflection direction is evaluated (refer here to safety glazing materials to ECE R43, Agreement on the Adoption of Unified Rules for Approval of Automotive Equipment and Parts). The problem with the above measurement is that the measurement is performed from a predetermined line of sight direction. If the refractive force of an object is to be confirmed from different line of sight directions with respect to the object, for example, from a predetermined viewpoint (e.g., the driver's position) in different line of sight directions through the windshield, multiple measurements are required. However, the advantage of measurement is that the actual refractive power of the article is confirmed, thereby identifying non-uniformities of the article itself, such as foreign matter or defects, in addition to the surface shape and surface orientation, and that theoretical models are used as little as possible. [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] In light of this background, the problem that the present invention seeks to address is to propose a way to determine, as accurately as possible, the actual refractive power of an optically transparent article, such as a curved glass panel like the windshield of an automobile, from any line of sight through the article, and the determination of the refractive power is intended to be made possible, in particular, by measurement at the speed of a typical production line in the case of a transported article. [Means for solving the problem]

[0009] For this purpose, the method proposed by the present invention particularly comprises the following steps, which can be optionally carried out in another technically advantageous way or sequence.

[0010] (a) The step of measuring the refractive power of a transparent article in a first deflection direction and at least one other deflection direction in a measurement area using an optical measuring device in a relatively predetermined measurement direction, wherein the measurement area of ​​the article is divided into a plurality of measurement areas, and local refractive power values ​​(also called local refractive power values ​​B[i]) are determined for each measurement area (also called local measurement area MF[i]) from the sum of that / all measurement areas. All of the local refractive power values ​​B[i] are congruent to form a refractive power map of the article, i.e., local refractive power values ​​B[i] for each measurement area MF[i].

[0011] Therefore, a refractive force map showing local refractive force values ​​B[i] describes the refractive force over the entire measurement area of ​​the article, where each refractive force value B[i] includes the refractive force value B(AH) for the first deflection direction and the refractive force value B(AV) for each of the other measured deflection directions. In the case of measuring the refractive force B with respect to the first and second deflection directions, therefore, the local refractive force value B[i] can be described or formed as a 2-tuple of the form [B[i](AH),B[i](AV)]. If there are three or more deflection directions, the result is a corresponding n-tuple for n deflection directions.

[0012] One important aspect of local refractive power values ​​B[i] is that they represent the actual refractive power with respect to visible light in the measurement direction, particularly in the first deflection direction and at least one second deflection direction (different from the first direction). Local refractive power values ​​B[i] therefore account for deflection in three-dimensional space and are not limited to refractive planes confirmed by modeling. Furthermore, the measured refractive power is without assumptions or models regarding the surface geometry of the incident and exit surfaces of the transparent article. This is valid for any (local) surface geometry of the article.

[0013] (b) The step of defining the orientation and position of the article, the viewpoint, and at least one line of sight direction (BR) from that viewpoint through the measurement area of ​​the article in a common coordinate system. As a result, the line of sight direction of visible light passing through the article is clearly defined. By defining the viewpoint with respect to the article, it is also possible to define different (at least two or more) line of sight directions through the article, corresponding to a typical use in which a user views an article that is fixed in place, such as through the windshield of a car, from viewpoints in different directions. Then, the measurement direction (predetermined with respect to the article) with respect to the line of sight is also known in this common coordinate system. Thus, any line of sight direction from a viewpoint through the article can be defined and the refractive force in this line of sight can be identified.

[0014] (c) The steps of confirming the intersection of the defined line of sight direction and the single local measurement area MF[i], and determining the viewing angle ε between the line of sight direction and the measurement direction within the confirmed local measurement area (MF[i]).

[0015] (d) The step of specifying an amplitude constant D of the refractive force as a function of a specified viewing angle ε and the refractive index n of the article, wherein the amplification constant D includes a constant value DH of the refractive force in a first deflection direction B(AH) and each constant value DV of the other deflection direction B(AV).

[0016] The refractive index n is the refractive index relative to air, which can be found, for example, in a table or measured by a common measurement method known to those skilled in the art. "Air" represents the surrounding environment in which the measurement is taken. This can, in principle, be any surrounding environment, particularly gaseous or liquid. In many typical applications, this is ordinary ambient air. The amplification constant D can therefore also be described or formed as an n-tuple according to the local refractive force value B[i]. From the 2-tuple, therefore, the notation [DH,DV] for the amplification constant D is obtained. Thus, the amplification constant embodied as an n-tuple describes the refractive force from the line of sight in each of the deflection directions. For example, when refractive values ​​B are measured in two deflection directions AH and AV, and the viewing angle ε lies in the plane defined by the measurement direction MR and the deflection direction AH, the amplification constant D includes the deflection value DH in the deflection direction AH and the deflection value DV in the deflection direction DV. When there are multiple deflection directions AVi, multiple amplification constants DVi can be applied to correspond to multiple or all of the deflection directions AVi, thereby allowing us to determine the refractive force or the respective deflection for each deflection direction AVi. The refractive force is therefore determined for different deflection directions in three-dimensional space.

[0017] (e) A step of confirming the refractive power in the line of sight by applying the amplification constant D to the local refractive power value B[i] of one measurement area at the intersection with the defined line of sight direction BR of the confirmed local measurement area MF[i].

[0018] The present invention allows for the determination and / or evaluation of the refractive force B through an article in essentially any line of sight direction BR, regardless of the measurement direction MR (relating to the article) in which the local refractive force value B[i] was measured. This enables the determination of not only the two-dimensional deflection of visible light in a plane (refracting surface) defined by the direction and deflection of visible light, but also the three-dimensional deflection of visible light incident on the article at any angle. This requires only one measurement of the refractive force from the measurement direction when the refractive force of the article has been measured or confirmed in at least two deflection directions AH and AV in multiple different deflection directions. Thus, it is possible to optically evaluate the refractive force of an article in different line of sight directions from only one measurement in a given measurement direction. In prior art evaluations, the article had to be measured separately in each line of sight direction.

[0019] Therefore, the method proposed by the present invention is not only easier and faster to perform, but also enables comprehensive optical evaluation of an article even during production on a production line where the article is transported over an optical measuring device, and also during a process in which the entire measurement area of ​​the article is scanned and the refractive power is determined from the measurement direction. Measurement from different directions cannot be performed on a production line. After the measurement is performed, the optical evaluation can be performed in a computing unit, and the evaluation results can be output and / or stored.

[0020] The measurement area in which refractive power is measured can be the entire object or a partial area of ​​the object.

[0021] Each measurement area is a partial region of the article (meaning a localized partial region of the entire measurement area). For each local measurement area, the refractive force values ​​in at least two deflection directions are determined by measurement. Preferably, the individual local measurement areas congruently and precisely form the entire measurement area. In other words, the measurement area is divided into local measurement areas, and the sum of all local measurement areas forms the measurement area of ​​the article. Local measurement areas can be positions where the measurement direction intersects with the article, i.e., positions where the article is placed within the optical measuring device.

[0022] Each local measurement area MF[i] can preferably be defined by the refractive power B[i] value in at least one deflection direction (or more different deflection directions). Thus, a measurement area is an area region for which the optical measuring device identifies one value of the refractive power in at least one deflection direction (or more deflection directions) and spatially assigns it. By identifying each value of the refractive power for each measurement area, the refractive power B of the entire measurement area MB is identified as a refractive power map BK showing the value of the refractive power B[i], where [i] is the index of the single defined individual measurement area MF[i]. The optical measuring device can create the refractive power map BK by scanning the measurement area MB of the optical article ().

[0023] Preferably, the measurement area is defined as an area perpendicular to the measurement direction, regardless of the actual orientation of the surface of the optically transparent article whose refractive power is being identified. The measurement area can be understood or used as the focal plane of a lens in which the measurement ray is deflected. Preferably, the measurement direction may coincide with the optical axis of the lens of the measuring device, typically an optical camera. This case can be easily explained. However, this is purely a matter of definition regarding how the measurement direction is defined, whether the measurement direction and the first deflection direction lie in another (i.e., a particularly specified) common plane, and / or whether the measurement direction actually coincides with the optical axis of the camera lens. To those skilled in the art, other mathematical explanations are also possible and it is clear that these can be converted to one another by an optical-trigonometric examination. Such explanations are also covered by the spirit of the present invention. However, for clarity, the explanation will be limited to this terminology.

[0024] In principle, any optical measuring device capable of determining the refractive power of an optically transparent article at a given measurement point in a given spatial direction can be used for this purpose. Such optical measuring devices are known. Preferred examples of particularly advantageous measuring devices that enable high-speed measurement of large articles, such as flat glass, such as curved flat glass, will be discussed later. These are particularly suitable for measuring and checking flat glass online on a production line.

[0025] The smallest feasible measurement area is predetermined by the maximum resolution of the optical measuring device. Larger measurement areas can be defined, for example, as multiple feasible minimum measurement areas.

[0026] According to one preferred configuration of this method, the line-of-sight direction can be selected such that, according to the present invention, the viewing angle ε is within the plane defined by the measurement direction and the first deflection direction. As a result, the amplification constant D enables the refractive force B in this deflection direction to be accurately determined. This can achieve particularly high accuracy because the line-of-sight direction is exactly included within the deflection plane of the first deflection direction for which the amplification constant DH is determined. At least one other amplification constant DV for at least one other deflection direction is also specifically specified for the line-of-sight direction within this plane.

[0027] When this method is applied in accordance with the present invention, the viewing angle ε can also be made such that the line-of-sight direction (BR) is projected into the plane defined by the measurement direction and the first deflection direction and / or another deflection direction or a plurality of, or individual, other deflection directions.

[0028] Alternatively, according to the present invention, the viewing angle ε can therefore also be determined from the projection onto the corresponding plane. This projection of the line-of-sight direction is specified as the component of the line-of-sight direction in the (first or another) deflection direction. If the projection of the line-of-sight direction also has components in other deflection directions for which the refractive force is measured, the refractive force can also be determined by applying the amplification constants for these components of the line-of-sight direction accordingly. Then, for these other deflection directions, the refractive force can be determined in the same way as the above method, particularly by performing the method multiple times, and the deflection direction in which the component under consideration in the deflection direction is included is regarded as the first or main deflection direction in each case. Then, the different refractive values in each of the deflection directions can be superimposed, for example, by linear combination or simple or weighted addition.

[0029] The local refractive power value B[i] can be determined, optionally, from a linear combination of the local refractive power values in the directions of the first and second, or more generally, a plurality of deflection directions, from a function F of different local refractive power values F(B[i](AH), B[i](AV)) for each deflection direction, for example, from a linear combination of B[i](AH) and B[i](AV) with predetermined coefficients f(AH) and f(AV), that is, F = f(AH)·B[i](AH)+f(AV)·B[i](AV).

[0030] The coefficients f(AH) and f(AV) can be predetermined as fixed values. As a result, for example, the importance or significance that varies depending on the specific application is assigned to different deflection directions. It is also conceivable to explain the coefficients f(AH) and f(AV) as the weighting of the individual refraction directions AH, AV from the relative magnitude of the viewing angle ε(AH,AV) in the plane defined by the projection of the measurement direction and the line-of-sight direction defined by the respective deflection directions AH, AV. One possible calculation formula is

Equation

[0031] As a result, it is also possible to take into account the case where the line-of-sight direction is not exactly in the plane defined by one of the measurement direction and the deflection direction (considering the projection).

[0032] Another possibility of calculating the refractive power using the formula F is to calculate the coefficients from the relative weighting of the local refractive power values in different deflection directions AH, AV in a way basically similar to that already described with respect to the projection of the viewing angle ε. This is, for example, the following formula

Equation

[0033] The functions described above should be understood as specific possible configurations according to the present invention, and the present invention is not intended to be limited to these configurations. Those skilled in the art can combine or adapt them accordingly. Other, more complex functions, such as constants or polynomials, are also conceivable, rather than the functions described as linear combinations.

[0034] The advantage of the present invention in determining the local refractive power value from a function F of the different local refractive power values ​​for each deflection direction, depending on all or more deflection directions, is that the refractive power characteristics are also taken into account when the line of sight direction is not precisely in the plane defined by the measurement direction MR and one of the deflection directions (taking projection into account), and / or when one visible ray is deflected in different deflection directions AH, AV by a surface structure of a glass plate that cannot be explained by a cylindrical lens in the defined deflection direction, for example. As a result, a scalar local refractive power value B[i] for the measurement area MF[i] is obtained.

[0035] Referring to such values ​​may be advantageous for specific applications, as it can optionally supplement the indication of a refractive power map showing different refractive power values ​​for different deflection directions for a particular line of sight. According to the present invention, the refractive power value for a given line of sight is obtained by applying the amplification constant D(DH,DV) to the measured refractive power value, as described above.

[0036] According to the present invention, in one configuration of the proposed method, the value of one amplification constant D of the deflection directions AH and AV can be determined as a function of the viewing angle ε, under the assumption of a transparent article having a wedge angle between the incident and exit surfaces, and the wedge angle of the lens accurately explains the deflection in the one deflection direction under consideration from the deflection directions AH and AV to the one deflection direction under consideration. This can be done in this way for each of the polarization directions to determine the refractive power in that direction. The local refractive power of an optically transparent article can be explained fairly well and with high reliability by such a simple optical model.

[0037] According to one preferred specific configuration of the method according to the present invention, the amplification constant D in the plane defined by the measurement direction and the deflection direction is

number

number

[0038] The amplification constants DH and DV describe the refractive index of the lens as a function of the viewing angle ε, which is qualitatively shown in Figure 6. DH describes the amplification constant in the direction of the lens's tilt with respect to the viewing angle ε, i.e., when the line of sight direction is in the plane defined by the measurement direction MR and the deflection direction AH. As expected, a high amplification constant DH appears when the tilt between the lens and the line of sight is large (i.e., at a large viewing angle ε). In comparison, for the deflection direction perpendicular to the tilt, a smaller amplification constant DV is obtained across the entire tilt range (angle range of the viewing angle ε).

[0039] For a lens with a refractive power of 10 mdpt, measurements at a viewing angle ε = 55° yield a refractive value of approximately 41 mdpt. This corresponds to the amplification constant of 4.1. Figure 8 shows the amplification constant of approximately 4.2. Therefore, a high degree of accuracy in estimating the amplification constant is obtained precisely within a moderate angular range that is relevant in practice.

[0040] The method according to the present invention was also checked for a particularly preferred application, namely the determination of the refractive force of an automobile windshield. In this application, the local refractive force value B[i] of a selected measurement area MF[i] of a windshield placed perpendicular (vertically) with respect to the measurement direction MR in the longitudinal deflection direction AH (with an inclination angle of 0° around the horizontal rotation axis) was measured by an optical measuring device. The windshield was also oriented symmetrically with respect to the measurement direction MR, such that the windshield is oriented perpendicular (horizontally) with respect to the measurement direction MR (with a yaw angle of 0° around the longitudinal rotation axis). The terms “horizontally” and “vertically” are, in principle, arbitrary and, as used herein, refer to the normal mounting position in an automobile on a flat road.

[0041] In a longitudinal plane extending in the measurement direction MR, according to the method proposed by the present invention, the amplification constant D was confirmed by applying the aforementioned formulas for amplification constants DH and DV for different viewing angles ε and different line-of-sight directions (all of which are also located in this longitudinal plane).

[0042] To verify these formulas, in the measurement setup, the windshield was rotated by a viewing angle ε (by the tilt angle) according to the application of the method according to the present invention, around a horizontal rotation axis perpendicular to the vertical plane extending in the measurement direction MR through the selected measurement area MF[i], and the local refractive power value B[i] of the selected measurement area MF[i] was measured using an optical measuring device. The amplification constant D(exp) was experimentally confirmed from the quotient between the local refractive power value B[i] measured at each viewing angle ε and the initial local refractive power value B[i] (ε=0°) without rotation by the tilt angle.

[0043] Figure 9 shows the profile of the amplification constant DH(theo) confirmed (theoretically) by the proposed method, compared with the amplification constant DH(exp) obtained from measurements.

[0044] For viewing angles ε of approximately 55° or 60°, which are of interest at actual installation locations, the values ​​confirmed by the method according to the present invention correspond with high accuracy to the actually measured values. This opens up the possibility of applying the method of the present invention to the optical quality control of transparent articles, especially large articles, where the optical properties, particularly refractive power, related thereto are evaluated from different viewing directions. One important application of the method proposed by the present invention, and of optical measuring devices configured to carry out this method, is the measurement of plate glass, particularly automotive plate glass, such as windshields, which have specifications related to refractive power.

[0045] A preferred aspect of the present invention is that the measurement direction can correspond to a preferred line of sight through an optically transparent article. The preferred line of sight can be predetermined, for example, by the typical mounting configuration of the article. In one particularly preferred application of this method, an automobile windshield can be used as the optically transparent article, which is rotated by an angle of inclination of 40 to 75°, particularly 55 to 60°, from the vertical orientation around a horizontal axis of rotation N (along the longer side of the windshield). This angle of inclination can be measured or defined as the angle between the normal of the sheet at the center of the windshield and the measurement direction MR. An advantage of positioning a transparent article in this manner within the optical measuring device when performing the method according to the present invention is that the viewing angle ε between the measurement direction MR and the line of sight BR is minimized for applications of high practical relevance. Typically, the error when determining the amplification constant D in applications of the proposed method is much smaller the viewing angle ε is. This preferred arrangement of optically transparent articles according to the present invention therefore improves the accuracy of the method proposed by the present invention.

[0046] In one particularly preferred configuration of this method, a curved windshield, in an orientation predetermined by the transport device, can be transported as an optically transparent article through an optical measuring device, the optical measuring device can be positioned, or is positioned such, that the measuring direction of the optical measuring device with respect to the installation position of the windshield in the vehicle is in the horizontal plane of the vehicle and oriented in the direction in which the vehicle is moving straight ahead. With such a configuration of this method, the measurement of refractive force is carried out in a manner that closely resembles subsequent usage conditions and / or quality control requirements. In the case of an automobile, the driver generally looks through the glass in the direction of travel of the vehicle, with a line of sight rotated by a visual angle ε in the horizontal plane. In the vertical direction, the visual angle (which is of great safety importance) changes only slightly, at least in the circumstances of a typical user.

[0047] Therefore, if the line of sight with respect to the measurement direction lies in a plane oriented parallel to the plane defined by the measurement direction MR and one of the deflection directions AH and AV, preferably the first deflection direction AH, then one preferred configuration or application of the method according to the present invention is met. This plane is preferably oriented parallel to the horizontal plane of the vehicle. According to the present invention, the refractive force is measured in a measurement direction such that the refractive force with respect to it is as close as possible to the line of sight direction BR confirmed by the method according to the present invention.

[0048] A preferred feature of the present invention is that the optical refractive power can be specified by an optical measuring device in the horizontal deflection direction as a (at least) first deflection direction (AH) and the vertical deflection direction as a second deflection direction (AV) with respect to the installation position of the windshield in an automobile. These are deflection directions that are particularly important for the qualitative evaluation of the refractive power of the sheet. Optionally, according to the present invention, another deflection direction AV can also be taken into consideration, thereby the rotation angle relative to the deflection directions around the measurement direction is not 90° but, for example, 45° or 30°. This allows for a more accurate description of the refractive power and optical refraction behavior of the article, particularly the windshield.

[0049] The present invention also relates to an apparatus for determining the refractive power (B) of an optically transparent article, having the features of claim 10, comprising an optical measuring device having a camera and illumination, wherein the camera records illumination through the transparent article, and the apparatus includes a holding and transport device for fixing the optically transparent article within the optical measuring device, the holding and transport device configured to move the optically transparent article within the optical measuring device for the purpose of scanning the entire measurement area, and a computing unit configured to perform a refractive power measurement and to perform the method according to the present invention as described in any one of claims 1 to 9. According to the present invention, the computing unit is configured to control the optical measuring device and to perform the method or part thereof by a suitable data processing program executablely installed on the computing unit.

[0050] An optical measuring device can be configured in which illumination generates a collimated beam (e.g., a laser beam), which is refracted by an object and recorded by a camera. The refraction of this object can be calculated from the deflection of the light beam captured by the camera. To generate a refractive power map, the light beam can be scanned across the entire measurement area MB of the part. Another alternative involves transmitting radiation from a point light source, or using it, through a sheet (object) and viewing the (area) intensity distribution on a screen behind the sheet (object). From the area distribution, the deflection or refraction in essentially any direction can be determined. The camera can record the screen, or it can directly act as a screen to capture the intensity of individual pixels of the camera.

[0051] According to one preferred embodiment of the present invention, faster scanning of the measurement area of ​​an article is possible. In this preferred embodiment, the optical measuring device has a column camera as the camera and a pattern having a known structure as illumination, the column camera records the pattern so that the pattern is imaged in the longitudinal direction of the column through an optically transparent article and is visible in the longitudinal direction of the column over the entire measurement area of ​​the article, and a holding and transport device moves the article perpendicular to the longitudinal direction of the column within the optical measuring device. In this configuration, the refractive power map can be generated by measurement as the article is continuously moved within the optical measuring device. This is particularly efficient and advantageous for applications on a production line.

[0052] Preferably, the illumination pattern can be a periodic line pattern whose structure is known. The refractive power can be determined by the deviation of the line pattern in the recorded image from the periodic structure. Methods relating to this are known to those skilled in the art.

[0053] According to one configuration of the present invention, the line pattern can be formed from two pairs of lines oriented perpendicular to each other, and each pair of lines consists of periodically arranged parallel lines. Preferably, the lines are oriented obliquely with respect to the longitudinal direction of the column of the column camera, preferably at an angle of 45°. This makes it possible to determine, in a simple and particularly accurate manner, the refractive power of an article in the longitudinal direction of the column and perpendicular to the longitudinal direction of the column, i.e., the first deflection direction and the second deflection direction perpendicular to the first deflection direction. In principle, other patterns, such as a circular pattern, can also be used. Furthermore, pairs of lines that are not perpendicular to each other can also be used, as long as these lines extend in two different directions from each other.

[0054] In one preferred embodiment, a column camera can be formed by light-sensitive pixels arranged adjacent to each other along the length of the column. In each case, one or more pixels can be arranged to cross the length of the column. When there is only one pixel (crossing the length of the column), the column camera is also called a linear array camera. Such a linear array camera has the advantage of requiring a minimum number of pixels to be processed each time an image is recorded. The same is, of course, true when multiple hardware pixels of the camera are combined to form a single effective pixel during evaluation.

[0055] This minimizes processing time when measuring refractive power. However, the pattern is only imaged in one dimension along the length of the column. Multiple pixels arranged across the length of the column, depending on the number of adjacent pixels, become more complex to evaluate and require longer processing times. The latter may be unusable on a production line or may limit production speed. Therefore, a linear array camera constitutes the solution according to the present invention, which is often preferred in practice. However, the advantage of multiple pixels arranged across the length of the column is that a two-dimensional section of the periodic pattern is recorded, thereby making it possible to easily evaluate refractive power in many different deflection directions. This may be advantageous for applications where accuracy requirements for verifying refractive power are stringent.

[0056] In this regard, according to the present invention, an image of a column camera having multiple pixels arranged to traverse the length of the column can be recorded, but for a single online evaluation on a production line, only one image of the pixels, i.e., the image of the linear array camera, is evaluated. For offline evaluation, it is possible to rely on a supplementary 2D image. This is the case, for example, when refractive effects at different viewing angles are intended to be evaluated and corrected during the evaluation of an image from an auxiliary camera having a field of view through a sheet. Further possible applications will be described.

[0057] In one particularly preferred embodiment of the present invention, the periodic line pattern of illumination and the image recording structure of the column camera can have different (spatial) periodicities. The different spatial periodicities of the pattern and the image recording structure produce an optical effect in the image recorded through a transparent article, such that the moiré effect (known and calculable to those skilled in the art) results in the superposition of regular patterns, yielding another periodic grid having a specific structure that does not exist in any of the individual patterns and also depends on the type of superposition procedure. Since the periodic line pattern and the image recording structure are known, the accuracy of confirming refractive power can be further improved by calculating the periodic grid that follows the moiré effect.

[0058] The present invention also relates to the following applications of the method and / or apparatus described above, particularly in any one of claims 1 to 9, and / or the apparatus described above, particularly in any one of claims 10 to 15, which confirm the refractive power of the windshield at a visual angle ε (other than zero) between the line of sight direction and the measurement direction, and measure the refractive power of the windshield from there, namely, To confirm the refractive power of the windshield from the driver's perspective at different viewing angles through the windshield. To determine the refractive power of the windshield for different line-of-sight directions within the recording angle covered by the auxiliary camera's lens, from the viewpoint of an auxiliary camera positioned on the windshield and recording through the windshield. It also relates to particularly advantageous uses for at least one of the two.

[0059] Such auxiliary cameras can be used, in particular, for measuring distances to vehicles ahead or for lane keeping assistance. To prevent excessive distortion in the image, which can lead to misinterpretation of the image, it is generally necessary that the refractive power of the windshield for different line-of-sight directions within the recording angle is within the margin of error. This is confirmed by the method and / or apparatus according to the present invention, and there is no need to perform measurements in different measurement directions. The same applies to different line-of-sight directions of the driver.

[0060] In the applications described with respect to auxiliary cameras, the determination of refractive force by the method and / or apparatus according to the present invention can also be used as a basis for correcting the image of the auxiliary camera, for example, in the case of distance measurement or lane keeping assistance.

[0061] Other advantages, features, and potential applications of the present invention are also evident from the following description and drawings relating to exemplary embodiments. In this case, the spirit of the invention includes all of the described and / or illustrated features together, or in any desired combination that is convenient for those skilled in the art, regardless of the exemplary embodiments described and / or illustrated or any combination thereof in the claims. [Brief explanation of the drawing]

[0062] [Figure 1] A schematic three-dimensional view of a device for determining the refractive power of an optically transparent article, according to one embodiment of the present invention, is shown. [Figure 2] Figure 1 is a schematic side view of the apparatus according to the present invention. [Figure 3] A windshield, as an optically transparent article having a measurement area in a measurement region, according to one preferred use of the present invention, is schematically shown in a plan view from the measurement direction. [Figure 4a] A schematic three-dimensional representation of the illumination pattern of a measuring device according to one embodiment of the present invention is shown. [Figure 4b] The pattern image shown in Figure 4a is schematically represented by a diagram viewed through an object with a refractive effect. [Figure 5a] A schematic three-dimensional representation of the illumination pattern of a measuring device according to another embodiment of the present invention is shown. [Figure 5b] The pattern image shown in Figure 5a is schematically represented by a diagram viewed through an object with a refractive effect. [Figure 6] A schematic diagram shows a common coordinate system for a measurement and evaluation device for performing the method according to the present invention for determining refractive power in an arbitrary line of sight direction, according to one embodiment. [Figure 7]A schematic diagram shows a common coordinate system for a measurement and evaluation device for performing the method according to the present invention for determining the refractive force in an arbitrary line of sight direction, according to another embodiment. [Figure 8] An example of constant values ​​DH and DV for amplification constants as functions of the viewing angle ε from 0° to 80° is shown. [Figure 9] Examples of constant values ​​DH theoretically confirmed by the present invention in the first deflection direction of the amplification constant for different viewing angles ε, and constant values ​​DH measured by the experimental apparatus in the first deflection direction are shown. [Modes for carrying out the invention]

[0063] In the drawings, the present invention is described based on one particularly preferred exemplary embodiment in which the method and apparatus according to the present invention are used to determine the refractive power of a transparent article embodied as a windshield. However, the present invention is not limited to this use, and the apparatus and method can be appropriately adjusted to correspond to other optically transparent articles. From the present invention, those skilled in the art will appropriately adjust the embodiments shown in the drawings and described in relation to specific exemplary embodiments within the scope of the expertise of those skilled in the art and the more general description above.

[0064] Figure 1 schematically shows one preferred embodiment of the apparatus 1 according to the present invention for determining the refractive power of an optically transparent article 2, thereby enabling the method according to the present invention, where the optically transparent article 2 is a car windshield 3. The terms article 2 and windshield 3 are used synonymously hereafter.

[0065] Apparatus 1 has an optical measuring device 4 including a camera 5 and illumination 6, the camera 5 recording the illumination 6 through a transparent article 2. The recording area 7 indicates that the camera 5 is embodied as a linear array or column camera, which records patterns 20, 30 of illumination 6 (shown in Figures 4a, 5a as an example) through a windshield 3, which is done so that patterns 20, 30 are imaged in the camera 5 along the length of the column and are visible along the length of the column 11 over the entire measuring area MB of article 2, i.e., in the example shown in the figure, extending from the upper horizontal edge of the windshield 3 to the lower horizontal edge of the windshield 3, covering the entire height of the windshield 3. Article 2 is transported in the transport direction 10 across the length of the column 11 within the optical measuring device 4.

[0066] Figure 2 shows a side cross-sectional view of the device 1. The device 1 is attached to the leg 8. In the open space below the camera 5 and the illumination 6 of the device 1, the windshield 3 is positioned such that the measurement direction MR corresponds to the user's preferred line of sight BR through the optically transparent article 2. In the case of the windshield 3, the measurement direction MR preferably corresponds to the horizontal line of sight of the driver of the vehicle in the direction of travel while moving straight ahead. As shown in Figures 1 and 2, the windshield is generally installed at an angle of inclination with respect to the orientation of the vehicle. Furthermore, the windshield 3 is generally curved itself, which is also schematically shown in Figures 1 and 2. The shape and orientation of the optically transparent article 2 are not important for the applications of the device and method according to the present invention. They do not need to be known. This also applies to the importance of both the surface shape and orientation of the incident and exit surfaces with respect to visible light, which is generally considered in geometrical optics, because the optical measuring device determines the actual refractive properties of an article 2 of any shape, particularly in a measurement direction MB predetermined by the measuring device.

[0067] The article 2 or windshield 3 is fixed to the holding and transporting device 9 of the apparatus 1 in a desired orientation with respect to the optical measuring device 4, and the holding and transporting device 9 is configured to move the optically transparent article 2 through the optical measuring device 4 for the purpose of scanning the entire measurement area. For this purpose, the holding and transporting device 9 moves the windshield 3 through the optical measuring device in a transport direction 10 preferably perpendicular to the longitudinal direction 11 of the column of the camera 5.

[0068] Apparatus 1 further includes a computing unit, which is not shown, and is used to perform the measurement of refractive power in the measurement direction MR using an optical measuring device 4, and to perform a method for determining the refractive power in the line-of-sight direction BR through article 2, the line-of-sight direction being particularly different from the measurement direction MR. This procedure will be described in more detail later.

[0069] To measure the refractive force using the measuring device 4, a measuring area MB is defined on the article 2, which is represented in Figure 3 by the sum of squares. In the example shown, the measuring area MB includes only a portion of the entire article 2. In this example, the edge region of the windshield 3 is excluded from the refractive force measurement. However, in other applications, the measuring area MB may also cover the entire article.

[0070] Each square in the measurement area MB represents a measurement area MF. Therefore, the measurement area MB is divided into multiple measurement areas MF, and the sum of all measurement areas MF (or, in other words, all measurement areas MF together) preferably exactly forms the measurement area MB. The shape of the measurement areas MF is not limited to the squares shown in the figure and can be appropriately selected by those skilled in the art depending on the application. The size and number of measurement areas MF for article 2 should be understood as examples (in a qualitative way) in the drawing. In actual applications, the number of measurement areas MF is typically greater, and the size of the measurement areas MF for article 2 is typically smaller. The minimum size of the measurement areas MF is determined by the resolution of the optical measuring device 4. For clarity in the figure, although each square in the figure represents a measurement area MF, only two measurement areas are designated by reference numeral MF.

[0071] For each measurement area MF[i], the local refractive force value B[i] is confirmed in the predetermined measurement direction MR for the article, and all of the local refractive force values ​​B[i] jointly form a refractive force map of article 2, the resolution of which is predetermined by the size and arrangement of the measurement area MF. The index[i] indicates the defined measurement area[i]. In the example shown here, the measurement direction MR is assumed to be perpendicular to the plane of the drawing, regardless of the curvature or inclination of article 2 with respect to the plane of the drawing.

[0072] The present invention includes identifying the refractive powers of a first deflection direction AH and at least one other deflection direction AV. The deflection directions AH and AV describe the actual refraction of visible light in the directions shown in the figure.

[0073] In the preferred exemplary embodiment shown herein, the first deflection direction AH represents the deflection due to horizontal refraction (relating to a typical mounting position of the windshield 3 in an automobile). Another (second) deflection direction AV describes the deflection due to vertical refraction (relating to a typical mounting position of the windshield 3 in an automobile). The measurement direction MR is perpendicular to the plane defined by the deflection directions AH and AV and is shown as a point in the measurement area MF[i] in Figure 3.

[0074] A method for determining the refractive force in the deflection direction, as performed by the optical measuring device 4, is essentially known to those skilled in the art, and consists of recording known patterns 20, 30 through the article 2 with the camera 5. In the case of a linear array camera, as described in this exemplary embodiment, the image of the pattern is obtained from a series of images taken over time as the article 20 is progressively transported within the measuring device 4. Examples of possible patterns 20, 30 are qualitatively shown in Figures 4a and 5a, in each case, first as a dot pattern and then as a line pattern, in their relative orientation with respect to the deflection directions AH and AV. Figures 4b and 5b show images of patterns 20, 30 recorded by the camera through the article 2, where distortion resulting from the optical refraction of the article 2, or windshield 3, in this specific example is visible at the locations indicated by ellipses. In addition to the known geometric arrangements of illumination patterns 20 and 30, article 2, and camera 3, it is possible to determine the refractive power of article 2 in each measurement area MF[i] for the measurement direction MR defined by the line of sight direction of camera 5, according to known geometric optics, taking into account the geometric shapes of patterns 20 and 30. The refractive power is measured and captured as an n-tuple of refractive power for each measurement area MF[i] in each deflection direction AH and AV. In the example of the figure shown with two deflection directions AH and AV, therefore, a 2-tuple of the form B[i] = [B][i](AH), B[i](AV)] is obtained for each local refractive power value B[i] in measurement area MF[i]. Thus, all measurement areas MF in the measurement region MB are combined to form a refractive power map of article 2.

[0075] Regarding the application of the method according to the present invention, as shown in Figure 6, the common coordinate system 40 is for measurement and evaluation devices. In one preferred configuration of the common coordinate system 40, particularly in the application of devices and methods for determining the refractive power of a windshield 3, the orthogonal axes of the coordinate system 40 can be the first deflection direction AH, the measurement direction MR of the optical measuring device 4, and another (second) deflection direction AV, thus forming a typical xyz coordinate system. In such a coordinate system 40, the use of the proposed method according to the present invention can be implemented in a particularly simple manner. However, in principle, those skilled in the art are free to use any coordinate system to describe the method and refractive power. Those skilled in the art can make such adjustments within the scope of their respective expertise.

[0076] In the coordinate system 40 of this figure, the coordinate plane 41 oriented parallel to the horizontal edge of the windshield 3 (as article 2) is defined by the measurement direction MR and the first deflection direction AH. When performing the method according to the present invention, the orientation and position of article 2, the viewpoint 42, and the line of sight direction BR from the viewpoint 42 across the measurement area MB of article 2 are defined. The line of sight direction BR can, in principle, be selected arbitrarily. The measurement direction MR is defined with respect to article 2 by the measuring device 4 and simultaneously determines the orientation of the coordinate system 40 in the embodiment described with respect to Figure 6. However, in principle, the coordinate system can be freely selected in space, and the measurement direction MR can also be described in terms of the coordinates of the coordinate system.

[0077] Subsequently, the intersection point of the defined line of sight direction BR in coordinate system 40 with a single local measurement area MF[i] is confirmed, and the viewing angle ε between the line of sight direction BR and the measurement direction MR in the confirmed local measurement area MF[i] is determined. Identifying the local measurement area MF[i] may also involve confirming the local refractive force values ​​B[i](AH) and B[i](AV) from the refractive force map, which have already been measured as described above.

[0078] In the measuring and evaluating apparatus, the amplification constant of the refractive force is then specified as a function of the specified viewing angle ε and the known refractive index n of article 2, the amplification constant including a constant value DH for the refractive force in the first deflection direction AH and a constant value D) for each of the other deflection directions AV. That is, in the example shown herein, the constant values ​​DH and DV are coincident with the local refractive forces B[i](AH) and B[i](AV). In the case of plate glass, the magnitude of the refractive index n relative to air is typically on the order of about n = 1.5 and is specified by the manufacturer of the plate glass or measured with a known measuring apparatus as is known to those skilled in the art.

[0079] In this example, the amplification constants DH and DV are defined as follows:

number

[0080] Using these amplification constants DH and DV for different deflection directions AH and AV, the local refractive force values ​​at the viewing angle ε are then calculated as B[i](AH,ε)=DH(ε)·B[i](AH) and B[i](AV,ε)=DV(ε)·B[i](AV), as shown in Figure 6.

[0081] In the example shown in Figure 6 for the windshield 3, the viewpoint 42 is in a horizontally oriented coordinate plane 41. The line of sight direction BR is the direction of the driver's line of sight when sitting at viewpoint 42 and looking horizontally (at a viewing angle ε) through the windshield in a horizontal plane (which coincides with the coordinate plane 41 in this example). By changing the viewing angle ε, the rotation of the driver's head in each line of sight direction can be simulated. In this configuration, the viewing angle ε is also called the yaw angle.

[0082] Figure 7 shows another example of the windshield 3 in a coordinate system 50 where the viewpoint 52 is in a vertically oriented coordinate plane 51. The line of sight direction BR is the driver's line of sight, seated at viewpoint 42 and looking through the windshield across an installation angle corresponding to the viewing angle ε in the horizontal plane (perpendicular to the coordinate plane 41 in this example). Different installation angles can therefore be simulated by changing the viewing angle ε. In this configuration, the viewing angle ε is also called the tilt angle.

[0083] Coordinate systems 40 and 50 can be converted to each other by swapping the designations of the first and second deflection directions AH and AV. The aforementioned formulas for DH and DV also apply. By continuously applying the method according to the arrangements shown in Figures 6 and 7 (the refractive force map is updated each time), it is possible to take into account different combinations of viewing angles in different deflection directions.

[0084] For viewpoints 42 and 52 that are not located within coordinate planes 41 and 51, the projection of the viewing angle ε onto each coordinate plane 41 and 51 can be taken into consideration accordingly.

[0085] Figure 8 shows the profiles of the (sizeless) amplification constants DH, DH for different viewing angles ε, as described in the previously mentioned forms relating to DH and DV. The viewing angle ε lies in coordinate planes 41, 51 defined by the measurement direction MR and the first deflection direction AH, as shown in Figure 5 or 6. As expected, as the viewing angle ε increases, the refractive effect and, consequently, the amplification constant also increases significantly. The refractive effect in the second deflection direction AV, perpendicular to the first deflection direction, remains almost constant in comparison.

[0086] Figure 9 shows a comparison of the calculated amplification constant DH(theo) with the experimentally confirmed amplification constant DH(exp) for the arrangement shown in Figure 7 (the tilt angle of the windshield 3 changes). The reference measurement of refractive power was confirmed for the windshield 3 placed vertically, i.e., when the measurement direction MR and the line of sight direction BR coincide in Figure 7. The calculated value of the amplification constant DH is confirmed as described above in the application of the method according to the present invention. For experimental comparison, the windshield 3 was oriented in the measuring device 4 such that the measurement direction MR corresponds to the line of sight direction BR each time for various viewing angles ε, according to the application of the present invention. For viewing angles ε < 40° (tilt), the deviation is negligible. As the viewing angle ε becomes larger, the deviation between the experiment and the method according to the present invention increases, but the refractive power values ​​confirmed with the amplification constant according to the present invention can be used as good estimates up to viewing angles of approximately 60° (which, for convenience, covers the actual range).

[0087] This simplifies quality control of the windshield 3 on the production line. In the case of an auxiliary camera, the refractive effect in different line-of-sight directions along multiple deflection directions can be easily estimated by placing the viewpoint at the mounting point of the auxiliary camera on the front of the windshield 3. [Explanation of Symbols]

[0088] List of reference codes 1. Apparatus for determining refractive power 2 Optically transparent articles 3. Windshield 4 Optical measurement device 5 Cameras 6 Lighting 7. Recording area 8. Legs of the device 9. Holding and transporting equipment 10 Transport direction 11. Camera column length direction 20 patterns 21 image patterns 22 Pattern distortion as a result of refraction 30 patterns 31 patterns of images 32. Pattern distortion as a result of refraction 40 Coordinate Systems 41. A plane (coordinate plane) defined by the measurement direction and the first deflection direction. 42 Perspectives 50 Coordinate Systems 51. A plane (coordinate plane) defined by the measurement direction and the first deflection direction. 52 Perspectives AH First deflection direction of refraction AV refraction's second deflection direction B[i] Local refractive power value BR line of sight direction DH is a constant value of the amplification constant D. DV is a constant value of the amplification constant D. ε viewing angle MB measurement area MF[i] Measurement Area MR measurement direction n refractive index

Claims

1. A method for determining the refractive power of an optically transparent article (2), A step of measuring the refractive power of the article (2) in a first deflection direction (AH) and at least one other deflection direction (AV) in a measurement area (MB) of the article (2) using an optical measuring device (4) in a predetermined measurement direction (MR) with respect to the article (2), wherein the measurement area (MB) of the article (2) is divided into a plurality of measurement areas (MF), a local refractive power value (B[i]) is confirmed for each of the measurement areas (MF[i]), and all of the local refractive power values ​​B[i] form a refractive power map; The steps include defining the orientation and position of the article (2), the viewpoints (42, 52), and the line of sight (BR) of the article (2) through the measurement area (MB) from the viewpoints (42, 52) within a common coordinate system (40), The steps include: confirming the intersection point of the defined line of sight direction (BR) and a single local measurement area (MF[i]), and identifying the viewing angle (ε) between the line of sight direction (BR) and the measurement direction (MR) within the confirmed local measurement area (MF[i]); A step of specifying the amplification constant of the refractive force as a function of the specified viewing angle (ε) and the refractive index (n) of the article (2), wherein the amplification constant includes a constant value (DH) for the refractive force in the first deflection direction (AH) and a constant value (DV) for each of the other deflection directions (AV), The step of confirming the refractive power in the line of sight direction (BR) by applying the amplification constant to the local refractive power value B[i] of the confirmed local measurement area (MF[i]), A method that includes this.

2. The method according to claim 1, characterized in that the viewing angle (ε) lies within a plane (41, 51) defined by the measurement direction (MR) and the first deflection direction (AH).

3. The method according to claim 1, characterized in that the visual field (ε) is in the projection of the line of sight direction (BR) onto a plane (41, 51) defined by the measurement direction (MR) and the first deflection direction (AH).

4. The method according to any one of claims 1 to 3, characterized in that the value of the amplification constant in one of the deflection directions (AH, AV) is determined as a function of the viewing angle (ε) under the premise that the transparent article (2) has a wedge angle between the incident surface and the exit surface.

5. The amplification constant in the plane (41, 51) defined by the measurement direction (MR) and the deflection direction (AH) is: [Math 1] The method according to any one of claims 1 to 4, characterized in that it is defined by the formula, wherein n is the refractive index of the transparent article (2) with respect to air.

6. The amplification constant in a plane perpendicular to the plane (41, 51) defined by the measurement direction (MR) and the deflection direction (AH) is: [Math 2] The method according to claim 5, characterized by being defined by

7. The method according to any one of claims 1 to 6, characterized in that the measurement direction (MR) corresponds to a preferred line of sight direction (BR) passing through the optically transparent article (2).

8. The method according to any one of claims 1 to 7, characterized in that a windshield (3) curved in a certain direction predetermined by a holding and transport device (9) as an article (2) is transported through the optical measuring device (4), and the optical measuring device (4) is positioned such that the measuring direction (MR) of the optical measuring device (4) with respect to the installation position of the windshield (3) in the automobile is in the vehicle horizontal plane and directed in the forward straight direction of the vehicle.

9. The method according to claim 8, characterized in that the optical refractive power is measured by the optical measuring device (4) with respect to the installation position of the windshield (3) in the automobile, in the horizontal deflection direction as the first deflection direction (AH) and in the vertical deflection direction as the second deflection direction (AV).

10. An apparatus for determining the refractive power of an optically transparent object (2), comprising an optical measuring device (4) having a camera (5) and an illumination (6), wherein the camera (5) records the illumination (6) through the transparent article (2), and comprising a holding and transporting device (9) for fixing the optically transparent article (2) within the optical measuring device (4), wherein the holding and transporting device (9) is configured to move the optically transparent article (2) through the optical measuring device (4) for the purpose of scanning the entire measuring area (MB) of the article (2), and also comprising a computing unit configured to perform the measurement of the refractive power and to perform the method according to the present invention as described in any one of claims 1 to 9.

11. The apparatus according to claim 10, wherein the optical measuring device (4) has a column camera as a camera (5) and a pattern (20, 30) of a known structure as illumination (6), the column camera records the pattern (20, 30) through the optically transparent article (2) in such a manner that the pattern (20, 30) is imaged in the column camera in the longitudinal direction (11) of the column such that it is visible over the entire measuring area (MB) of the article (2), and the holding and transporting device (4) moves the article (2) through the optical measuring device (4) perpendicular to the longitudinal direction (11) of the column.

12. The apparatus according to claim 11, characterized in that the pattern (30) is a periodic linear pattern.

13. The apparatus according to claim 12, characterized in that the line pattern is formed from two pairs of lines oriented perpendicular to each other, and each pair of lines consists of periodically arranged parallel lines.

14. The apparatus according to any one of claims 11 to 13, characterized in that the column camera is formed by photosensitive pixels arranged adjacent to each other in the longitudinal direction (11) of the column.

15. The apparatus according to any one of claims 12 to 14, characterized in that the periodic line pattern of the illumination (6) has a different periodicity from the image recording structure of the column camera.

16. The method according to any one of claims 1 to 9 and / or the apparatus according to any one of claims 10 to 15 for confirming the refractive power of the windshield (3) at a viewing angle (ε) between the line of sight direction (BR) and the measurement direction (MR) from which the refractive power of the windshield (3) can be confirmed, has the following applications, namely, The refractive power of the windshield (3) is to be confirmed from the driver's viewpoint (42, 52) in different lines of sight passing through the windshield (3). The refractive power of the windshield (3) is confirmed from the viewpoint of an auxiliary camera, which is positioned on the windshield (3) and records different line-of-sight directions (BR) within a recording angle covered by the lens of the auxiliary camera through the windshield (3). Use for at least one of the following purposes.

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