EP4680948A1 - Procédé et appareil de détermination de réfringence d'un objet optiquement transparent - Google Patents

Procédé et appareil de détermination de réfringence d'un objet optiquement transparent

Info

Publication number
EP4680948A1
EP4680948A1 EP24711871.4A EP24711871A EP4680948A1 EP 4680948 A1 EP4680948 A1 EP 4680948A1 EP 24711871 A EP24711871 A EP 24711871A EP 4680948 A1 EP4680948 A1 EP 4680948A1
Authority
EP
European Patent Office
Prior art keywords
measuring
refractive power
viewing
deflection
windshield
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP24711871.4A
Other languages
German (de)
English (en)
Inventor
Rolf Kubiak
Stefan Tasse
Marc-Andre THUROW
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Isra Vision GmbH
Original Assignee
Isra Vision GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Isra Vision GmbH filed Critical Isra Vision GmbH
Publication of EP4680948A1 publication Critical patent/EP4680948A1/fr
Pending legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/95—Investigating the presence of flaws or contamination characterised by the material or shape of the object to be examined
    • G01N21/958—Inspecting transparent materials or objects, e.g. windscreens
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/41—Refractivity; Phase-affecting properties, e.g. optical path length

Definitions

  • the invention relates to a method and a device for determining the refractive power of an optically transparent object, in particular a disk-shaped object such as a glass pane, wherein the disk-shaped object can be flat or preferably curved according to claims 1 and 10.
  • the invention also relates to a preferred use of the method and/or the device for determining the refractive power of a windshield from any viewing angle according to claim 16.
  • the optical effect of flat glass with an uneven surface was described in Kerkhof, Optical Effects of Flat Glass with Uneven Surfaces, Glass Technical Reports, Issue 25, pages 71 to 83, Publisher of the German Glass Technical Society, Frankfurt (Main), 1952, assuming that the glass plate is a result of many glass prisms with very small wedge angles of the refraction plane for different angles of incidence of the line of sight on the basis of refractive geometric considerations.
  • the refraction plane is the plane in which the incident line of sight and the refracted line of sight lie.
  • the plane of refraction can be estimated for a given viewing direction of the transparent object and the refractive power can be determined.
  • this can cause inhomogeneities in the transparent object that can also lead to optical refraction independent of the local surface shape of the entry and exit surfaces of the transparent object.
  • determining the surface shape of the transparent object e.g. a pane of glass, especially a curved pane of glass such as a windshield of a motor vehicle, is very complex and time-consuming.
  • a possible iterative method for determining the surface shape of a plate or layer-like object is described in WO 2022/189327 A1.
  • An assumed surface shape is provided as the initial shape and a large number of measuring points are defined on the initial shape.
  • the spatial position of the measuring points is determined optically by irradiating the surface and detecting the reflected radiation. From deviations of the detected radiation in a measuring point from the radiation expected from the initial shape, an adapted surface shape is iteratively determined until the measurements agree with the expectations within an accuracy value.
  • the determined The surface shape is then used to simulate a refractive power distribution. Due to the known surface shape, the refractive power can then in principle also be determined from defined viewing directions.
  • Such methods are not suitable for optical quality control of optically transparent objects in an industrial production line due to the effort involved in the measurement method and the evaluation effort.
  • a known pattern is imaged through the transparent object and a distortion of the pattern caused by the object in the image is quantitatively evaluated.
  • the pattern can, for example, be a pattern of parallel lines with a defined line spacing.
  • the refractive power in this deflection direction can then be determined from the variation of the line spacing in a certain deflection direction, as described, for example, in DIN 52305 (determination of the deflection angle and the refractive index of safety panes for vehicle glazing).
  • the pattern can also consist of a regular arrangement of circles of known diameter, with a variation of the circle diameter being evaluated in at least one deflection direction (cf.
  • the object of the invention is to propose a possibility for determining the actual refractive power of an optically transparent object, for example a pane of glass such as a curved windshield of a motor vehicle, as accurately as possible when looking through the object in any direction, wherein the determination of the refractive power should be possible by measuring, in particular, the speed of a conventional production line for a transported object.
  • an optically transparent object for example a pane of glass such as a curved windshield of a motor vehicle
  • the method proposed according to the invention comprises in particular the following steps, which may also be carried out in another technically reasonable manner or sequence.
  • the refractive power map with the local refractive power values B[i] describes the refractive power for the entire measuring range of the object, whereby each refractive power value B[i] contains a value for the refractive power B(AH) in the first deflection direction and a value for the refractive power B(AV) of each further measured deflection direction.
  • a local refractive power value B[i] can be described or formed as a 2-tuple of the form [B[i](AH), B[i](AV)]. If there are more than two deflection directions, a corresponding n-tuple results for n deflection directions.
  • the local refractive power values B[i] indicate the actual real refractive power for a line of sight in the measurement direction, namely in a first and at least one second (different from the first) deflection direction.
  • the local refractive power values B[i] therefore describe a deflection in three-dimensional space and are not limited to a model-determined refractive plane.
  • the measured refractive power is also free of assumptions and models regarding the surface shape of the entry and exit planes of the transparent object. This is valid for every (local) surface shape of the object.
  • the refractive index n is the refractive index of the object against the air, which is known, for example, from tabular overviews or can be measured using measuring methods known to the expert and customary in the field.
  • Air represents the environment in which the measurement takes place. This can basically be any environment, particularly gaseous or liquid. For many typical applications, this will be normal ambient air.
  • the gain factor D can therefore also be described or formed as an n-tuple, corresponding to the local refractive power value B[i]. For a 2-tuple, the notation [DH, DV] results for the gain factor D.
  • the gain factor formed as an n-tuple therefore describes the refractive power from one viewing direction in each of the deflection directions.
  • the amplification factor D includes a value DH for the deflection in the deflection direction AH and a value DV for the deflection in the deflection direction DV. If there are several deflection directions AVi, several amplification factors DVi can be applied accordingly for several or all of the deflection directions AVi in order to determine the refractive power or deflection in each of the deflection directions AVi. This determines the refractive power for different deflection directions in three-dimensional space.
  • the refractive power B through the object can be determined and/or evaluated in any viewing direction BR (relative to the object) regardless of the measuring direction MR (relative to the object) in which the local refractive power values B[i] were determined.
  • This not only determines a two-dimensional deflection of a line of sight in a plane (the refraction plane) that is spanned by the direction of the line of sight and the deflection direction, but also a three-dimensional deflection of a line of sight incident on the object at any angle.
  • the method proposed according to the invention is not only easier and faster to carry out, but also enables a comprehensive optical evaluation of an object during production in a production line in which the object is transported through an optical measuring device and the entire measuring area of the object is scanned and the refractive power is determined from one measuring direction. Measurements from different directions can be carried out in a production line. After the measurement has been carried out, the optical evaluation can be carried out in a computing unit and the evaluation result can be output and/or saved.
  • the measuring area for which the refractive power is measured can be the entire object or a part of the object.
  • Each measuring surface is a sub-area of the object (in the sense of a local sub-area of the entire measuring area).
  • a value of the refractive power is determined by measurement in at least two deflection directions.
  • the individual local measuring areas together form the entire measuring area.
  • the measuring area is divided into local measuring areas, with the totality of all local measuring areas forming the measuring area of the object.
  • the local measuring area can be located at the position where the measuring direction intersects with the object, i.e. where the object is arranged in the optical measuring device.
  • a single local measuring surface MF[i] can preferably be defined by a value of the refractive power B[i] in the at least one deflection direction (or several different deflection directions).
  • a measuring surface is therefore the surface area for which the optical measuring device determines exactly one value of the refractive power in the at least one deflection direction (or several deflection directions) and assigns it spatially.
  • the refractive power B for the entire measuring area MB is determined as a refractive power map BK with a value of the refractive power B[i], where [i] is the index of exactly one defined individual measuring surface MF[i].
  • the optical measuring device can scan the measuring area MB of the optical object () to create the refractive power map BK.
  • the measuring surface is defined as a surface that is perpendicular to the measuring direction, regardless of the actual orientation of the surface of the optically transparent object whose refractive power is being determined.
  • the measuring surface can be understood or used as the focal plane of a lens in which the deflection of the measuring beam takes place.
  • the measuring direction can coincide with the optical axis of an objective of the measuring device, typically an optical camera. This case is easy to describe. However, it is purely a question of definition how the measuring direction is defined and whether the measuring direction and the first deflection direction lie in a distinguished (i.e.
  • any optical measuring device that is able to determine the refractive power of an optically transparent object at a measuring point in a spatial direction can be used.
  • Such optical measuring devices are known.
  • Preferred examples of particularly advantageous measuring devices that allow rapid measurement of a large-area object, e.g. a glass pane, such as a curved glass pane, are described below. These are particularly suitable for measuring and checking glass panes online in a production line.
  • the smallest possible measuring area is determined by the maximum resolution of the optical measuring device.
  • a larger measuring area can be defined, e.g. as a multiple of the smallest possible measuring area.
  • the viewing direction can be selected according to the invention such that the viewing angle s lies in the plane spanned by the measuring direction and the first deflection direction.
  • the refractive power B can thus be determined in precisely this deflection direction using the amplification factor D. This achieves a particularly high level of accuracy because the viewing direction lies precisely in the deflection plane of the first deflection direction for which the amplification factor DH is determined.
  • the at least one other amplification factor DV for the at least one other deflection direction has also been determined precisely for a viewing direction in this plane.
  • the viewing angle s can lie in a projection of the viewing direction (BR) into the plane spanned by the measuring direction and the first deflection direction and/or the further or several or each of the further deflection directions.
  • the viewing angle s can also be determined according to the invention from the projection into the corresponding plane.
  • This projection of the viewing direction is referred to as the component of the viewing direction in the (first or further) deflection direction.
  • the refractive power can also be determined for these components of the viewing direction by appropriately applying the amplification factor.
  • the refractive power for these other deflection directions can then be determined analogously to the method described above, in particular by carrying out the method several times, whereby the deflection direction in which the component of the deflection direction under consideration lies is regarded as the first or main deflection direction.
  • the factors f(AH) and f(AV) can be fixed. This means that the different deflection directions are assigned a different importance or significance for a specific application, for example. It is also conceivable to describe the factors f(AH) and f(AV) as a weighting of the individual refraction directions AH, AV from the relative sizes of the viewing angles s(AH,AV) in the planes that are spanned by projections of the viewing direction, which is spanned by the measuring direction and the respective deflection direction AH, AV. A possible formula for the calculation can be where, if necessary, several summands or factors E(A7) and B[i]( ) are provided in the formula.
  • Another possibility for calculating the refractive power using a formula F can be to calculate the factors from a relative weighting of the local refractive power values in the different deflection directions AH, AV, basically comparable to the one explained above for the projections of the viewing angle s. This can be done, for example, using the formula This means that refractions in different deflection directions are also taken into account when the refraction occurs in different refraction directions AH, AV, for which the local refractive power values B[i](AH B[i](AV) were determined, regardless of the actual viewing direction.
  • the advantage according to the invention of determining the local refractive power values as a function of all or several deflection directions from a function F of the various local refractive powers in the respective deflection directions is that properties of the refractive power are also taken into account when the viewing direction is not exactly in the plane spanned by the measuring direction MR and one of the deflection directions (taking the projections into account) and/or a deflection of a line of sight occurs in different deflection directions AH, AV, for example due to a surface structure of the glass pane that cannot be described by a cylindrical lens in a defined deflection direction.
  • the result is then a scalar local refractive power value B[i] for a measuring surface
  • the value of the amplification factor D in one of the deflection directions AH, AV can be determined as a function of the viewing angle s, assuming a transparent object with a wedge angle between the entrance surface and the exit surface, where the wedge angle of the lens describes the deflection in the one of the deflection directions AH, AV under consideration. This can be done in this way for each of the deflection directions in order to determine the refractive power in this direction. It has been shown that the local refractive power of optically transparent objects can be described quite well and reliably using such simple optical models.
  • the amplification factor D in the plane spanned by the measuring direction and deflection direction can be defined by where n is the refractive index of the transparent object against air or the measuring environment. Accordingly, the amplification factor D in a plane that is perpendicular to the plane spanned by the measuring direction and deflection direction can be defined by
  • the amplification factors DH and DV describe the refractive power of a lens as a function of the viewing angle s, as qualitatively described in Fig. 6.
  • DH describes the amplification factor in the direction of the tilt of the lens relative to the viewing angle s, ie with a viewing direction in the plane spanned by the measuring direction MR and deflection direction AH.
  • a high amplification factor DH of the refractive power is shown with a strong tilt between the lens and the viewing direction (i.e. a large viewing angle s).
  • a - in comparison - small amplification factor DV results over the entire tilt range (angular range of the viewing angle s).
  • Fig. 8 shows an amplification factor of approximately 4.2. This results in a good accuracy in estimating the amplification factor, particularly in a medium angle range that is relevant in practice.
  • the method according to the invention was also tested for a particularly preferred application, determining the refractive power of a windshield of a motor vehicle.
  • the local refractive power value B[i] was measured in a selected measuring surface MF[i] of the windshield, which was (vertically) vertical relative to the measuring direction MR (tilt angle 0° around a horizontal axis of rotation) in the vertical deflection direction AH by an optical measuring device.
  • the windshield was also aligned symmetrically relative to the measuring direction MR in such a way that the windshield was (horizontally) vertical relative to the measuring direction MR (yaw angle 0° around a vertical axis of rotation).
  • the terms “horizontal” and “vertical” are fundamentally arbitrary and in this text refer to a normal installation position in a motor vehicle standing on a level road.
  • the gain factors D were determined according to the method proposed according to the invention in different viewing directions (all of which also lie in this vertical plane) for different viewing angles s by applying the formulas for gain factors DH and DV defined above.
  • the windshield was rotated in a measuring arrangement around a horizontal axis of rotation that was perpendicular to the vertical plane running in the measuring direction MR through the selected measuring surface MF[i] by the respective viewing angle s in accordance with the application of the method according to the invention (rotation by the tilt angle) and the local refractive power value B[i] in the selected measuring surface MF[i] was measured by the optical measuring arrangement.
  • Fig. 9 shows the course of the (theoretically) determined gain factors DH(theo) according to the proposed method in comparison to gain factors DH(exp) derived from the measurement.
  • the values determined according to the method according to the invention correspond to the actually measured values with great accuracy.
  • An important application of the method proposed according to the invention and of a method for carrying out the method The purpose of the optical measuring device is to measure glass panes, in particular glass panes for use in motor vehicles, such as windscreens, with specifications for the refractive power.
  • the measuring direction can preferably correspond to a preferred viewing direction through the optically transparent object.
  • a preferred viewing direction can be predetermined, for example, by a typical installation situation of the object.
  • a windshield of a motor vehicle can be used as the optically transparent object, which is rotated from a vertical orientation about a horizontal axis of rotation (along the longer side of the side of the windshield) by a tilt angle in the range between 40° and 75°, in particular between 55° and 60°. This tilt angle can be measured or defined as the angle between a window normal in the center of the windshield and the measuring direction MR.
  • the advantage of such an arrangement of the transparent object in the optical measuring device when carrying out the method according to the invention is that the viewing angle s between the measuring direction MR and the viewing direction BR is minimized for a practically relevant application.
  • the smaller the viewing angle s the smaller the error in determining the amplification factors D when applying the proposed method.
  • This preferred arrangement of the optically transparent object according to the invention therefore improves the accuracy of the method proposed according to the invention.
  • a curved windshield can be transported as an optically transparent object through the optical measuring device in an orientation predetermined by a transport device and the optical measuring device can be positioned such that the measuring direction of the optical
  • the measuring device is located in a horizontal vehicle plane relative to the installation position of the windshield in a motor vehicle and is directed in the direction of a vehicle driving straight ahead.
  • the viewing direction lies in relation to the measuring direction in a plane that is aligned parallel to the plane spanned by the measuring direction MR and one of the deflection directions AH, AV, preferably the first deflection direction AH.
  • This plane is preferably aligned parallel to the horizontal vehicle plane.
  • the optical refractive power can preferably be measured by the optical measuring device (at least) in a horizontal deflection direction as the first deflection direction (AH) and in a vertical deflection direction as the second deflection direction (AV) in relation to the installation position of the windshield in the motor vehicle.
  • AH first deflection direction
  • AV second deflection direction
  • these are particularly important deflection directions for the qualitative assessment of the window in relation to its refractive power.
  • further deflection directions AV can also be taken into account according to the invention, so that the angle of rotation of the deflection directions relative to one another around the measuring direction is not 90°, but for example 45° or 30°. This results in a more precise description of the refractive power and the optical refractive behavior of the object, in particular a windshield.
  • the invention also relates to a device for determining the refractive power (B) of an optically transparent object with the features of claim 10 with an optical measuring device having a camera and lighting, the camera recording the lighting through the transparent object, with a holding and transport device for fixing the optically transparent object in the optical measuring device, the holding and transport device being set up to move the optically transparent object through the optical measuring device for scanning the entire measuring area, and with a computing unit which is set up to carry out the measurement of the refractive power and to carry out the inventive method according to one of claims 1 to 9.
  • the computing unit is set up to control the optical measuring device and to carry out the above-described method or parts thereof by means of suitable data processing programs which are installed on the computing unit in such a way that they can be executed.
  • a collimated light beam is generated in the lighting device (e.g. a laser beam) which is refracted in the object and recorded by the camera.
  • the refraction of the object can be calculated from the deflection of the light beam recorded by the camera.
  • the light beam can scan the entire measuring range MB of the object.
  • Another alternative is to shine through the pane (object) from or with a point-shaped light source and to observe the (area-wide) intensity distribution on a screen behind the pane (object).
  • the deflection or refraction in basically any direction can be determined from the area-wide distribution.
  • a camera can record the screen or the serve directly as a screen and capture the intensity in the individual pixels of the camera.
  • the optical measuring device has a column camera as the camera and a pattern of a known structure as the illumination, the column camera recording the pattern through the optically transparent object in such a way that the pattern is imaged in the column camera in a column longitudinal direction in such a way that it is visible in the column longitudinal direction over the entire measuring area of the object, and that the holding and transport device moves the object perpendicular to the column longitudinal direction through the optical measuring device.
  • the refractive power map can be generated with a measurement in which the object is continuously moved through the optical measuring device. This is particularly efficient and advantageous for use in a production line.
  • the illumination pattern can be a periodic line pattern whose structure is known.
  • the refractive power can be determined by deviations in the periodic structure of the line pattern in the recorded image. Methods for this are known to those skilled in the art.
  • the line pattern can be formed from two pairs of lines, in particular aligned perpendicularly to one another, with each pair of lines being made up of periodically arranged parallel lines.
  • the lines are preferably aligned obliquely to the longitudinal direction of the column of the column camera, preferably at an angle of 45°. This enables a particularly precise determination of the refractive power of the object in the longitudinal direction of the column and perpendicular to the longitudinal direction of the column, ie in the first deflection direction and a direction perpendicular to the first deflection direction. second deflection direction in a simple way.
  • other patterns such as circular patterns, can also be used. Pairs of lines that are not perpendicular to each other can also be used, as long as the lines run in two different directions.
  • the column camera can be formed by light-sensitive pixels arranged next to one another in the longitudinal direction of the column.
  • One or more pixels can be arranged transversely to the longitudinal direction of the column. If there is only one pixel (transversely to the longitudinal direction of the column), the column camera is also referred to as a line camera.
  • Such a line camera has the advantage that the minimum possible number of pixels has to be processed per image recording. The same applies, of course, when combining several hardware pixels of the camera into one effective pixel during evaluation.
  • the pattern is only imaged one-dimensionally in the longitudinal direction of the column.
  • several pixels arranged transversely to the longitudinal direction of the column multiply the evaluation effort and lead to a longer processing time. This may not be available in a production line or may limit the production speed. Therefore, a line camera is often a preferred solution according to the invention in practice.
  • the advantage of several pixels arranged transversely to the longitudinal direction of the column is that a two-dimensional section of the periodic pattern is recorded, which enables simple evaluation in many different deflection directions of the refraction. This can be advantageous for applications with high requirements for the accuracy of determining the refractive power.
  • the invention can provide for images to be recorded by a column camera with several pixels arranged transversely to the column longitudinal direction, but for an online evaluation in the production line only the images of one of the pixels are evaluated, ie the image of a line camera. For an offline evaluation, the two-dimensional image can then be used in addition. This can be the case, for example, if refraction effects for different viewing angles are to be evaluated and corrected when evaluating an image from an assistant camera looking through the window. Possible applications will be explained below.
  • the periodic line pattern of the illumination and an image recording structure of the slit camera can have a different (spatial) periodicity. Due to the different spatial periodicity of the pattern and the image recording structure, an optical effect is created in the image recorded through the transparent object through the moiré effect (known per se and calculable by the person skilled in the art), in which the superposition of the regular patterns creates its own periodic grid, which has a special structure that is not present in any of the individual patterns and is also dependent on the type of superposition. Since the periodic line pattern and the image recording structure are known, the accuracy in determining the refractive power can be further increased by calculating the own periodic grid according to the moiré effect.
  • the invention also relates to a particularly advantageous use of the method described above, in particular according to one of claims 1 to 9 and/or the device described above, in particular according to one of claims 10 to 15, for determining the refractive power of a windshield at a viewing angle s (different from zero) between a viewing direction and a measuring direction under which the refractive power for the windscreen is measured, for at least one of the following applications:
  • Such assistance cameras can be used, among other things, to measure the distance to vehicles driving ahead or as a lane departure warning system.
  • the determination of the refractive power with the method and/or device according to the invention can also be used as a basis for correcting the images of the assistance camera, for example when determining the distance or a lane keeping assistant.
  • Fig. 1 schematically shows a three-dimensional view of a device for determining the refractive power of an optically transparent object according to an embodiment of the invention
  • Fig. 2 is a schematic side view of the device according to the invention shown in Fig. 1;
  • Fig. 3 schematically shows a windshield as an optically transparent object with measuring surfaces of the measuring area according to a preferred use of the invention in a plan view from the measuring direction:
  • Fig. 4a shows schematically a pattern of illumination of the measuring device in three dimensions according to an embodiment of the invention
  • Fig. 4b shows schematically an image of the pattern according to Fig. 4a in a view through the object with refraction effects
  • Fig. 5a schematically shows a pattern of illumination of the measuring device in three dimensions according to another embodiment of the invention
  • Fig. 5b schematically shows an image of the pattern according to Fig. 5a in a view through the object with refraction effects
  • Fig. 6 schematically shows a common coordinate system of the measuring and evaluation arrangement for carrying out the method according to the invention for determining the refractive power in any viewing direction according to an embodiment
  • Fig. 7 schematically shows a common coordinate system of the measuring and evaluation arrangement for carrying out the method according to the invention for determining the refractive power in any viewing direction according to a further embodiment
  • Fig. 8 an example of the factor values DH, DV of the amplification factor depending on the viewing angle s between 0° and 80°;
  • Fig. 9 shows an example of the factor value DH in the first deflection direction of the amplification factor determined theoretically according to the invention and the factor value DH in the first deflection direction measured in an experimental arrangement for different viewing angles s.
  • the invention is described using a particularly preferred embodiment in which a method according to the invention and a device according to the invention are used to determine the refractive power of a transparent object designed as a windshield.
  • the invention is not limited to this application and can also be used in a corresponding manner for other optically transparent objects with a suitably adapted device and a suitably adapted method.
  • the person skilled in the art will suitably adapt the embodiments shown in the drawing and described for the specific embodiment within the scope of his specialist knowledge and the more general description above. Fig.
  • FIG. 1 shows schematically a preferred embodiment of a device 1 according to the invention for determining the refractive power of an optically transparent object 2, with which the method according to the invention can be carried out, wherein the optically transparent object 2 is a windshield 3 of a motor vehicle.
  • the optically transparent object 2 is a windshield 3 of a motor vehicle.
  • object 2 and windshield 3 are used synonymously below.
  • the device 1 has an optical measuring device 4 with a camera 5 and a lighting 6, wherein the camera 5 records the lighting 6 through the transparent object 2.
  • the recording area 7 shows that the camera 5 is designed as a line or column camera which records a pattern 20, 30 of the lighting 6 (as shown by way of example in Figs. 4a, 5a) through the windshield 3 in such a way that the pattern 20, 30 is imaged in the camera 5 in a column longitudinal direction in such a way that it is visible in a column longitudinal direction 11 over the entire measuring area MB of the object 2, in the example shown therefore extending from an upper horizontal edge of the windshield 3 to a lower horizontal edge of the windshield 3 and covering the entire height of the windshield 3.
  • the object 2 is transported transversely to the column longitudinal direction 11 in a transport direction 10 through the optical measuring device 4.
  • Fig. 2 shows the device 1 in a sectional view from the side.
  • the device 1 is mounted on feet 8.
  • the windshield 3 is arranged in such a way that the measuring direction MR corresponds to a preferred viewing direction BR of a user through the optically transparent object 2.
  • the measuring direction MR preferably corresponds to a horizontal viewing direction of a driver of the vehicle in the direction of travel when driving straight ahead.
  • the windshield is usually angled relative to a vertical orientation by a tilt angle.
  • windshields 3 are usually curved, as is also schematically indicated in Fig. 1 and 2.
  • the object 2 or the windshield 3 is fixed on a holding and transport device 9 of the device 1 in the desired orientation relative to the optical measuring device 4, wherein the holding and transport device 9 is set up to move the optically transparent object 2 through the optical measuring device 4 for scanning the entire measuring area.
  • the holding and transport device 9 moves the windshield 3 in the transport direction 10 through the optical measuring device 4, which is preferably aligned perpendicular to the column longitudinal direction 11 of the camera 5.
  • the device 1 further comprises a computing unit (not shown in the drawing) which, according to the invention, is used to carry out the measurement of the refractive power in the measuring direction MR by means of the optical measuring direction 4 and to carry out the method for determining the refractive power in a viewing direction BR through the object 2 (in particular different from the measuring direction MR). This procedure is explained in more detail below.
  • a measuring area MB is defined on the object 2, which is represented in Fig. 3 by the total of squares is shown.
  • the measuring range MB only covers a part of the entire object 2.
  • the edge areas of the windshield 3 are excluded from the measurement of the refractive power in the example shown. In other applications, however, the measuring range MB can also cover the entire object.
  • Each of the squares in the measuring range MB represents a measuring surface MF.
  • the measuring range MB is therefore divided into several measuring surfaces MF, with the totality of all measuring surfaces MF (or in other words: all measuring surfaces MF together) preferably forming the measuring range MB.
  • the shape of the measuring surfaces MF is not limited to the squares shown in the drawing, but can be selected by the person skilled in the art to suit the application.
  • the size and number of measuring surfaces MF relative to the object 2 are also to be understood as examples (qualitative) in the drawing. In realistic applications, the number of measuring surfaces MF is typically larger and the size of the measuring surfaces MF relative to the object 2 is typically smaller.
  • a minimum size of the measuring surfaces MF results from the resolution of the optical measuring device 4. For the sake of clarity, only two measuring surfaces are designated with the reference symbol MF in the drawing, although each of the squares shown indicates a measuring surface MF.
  • a local refractive power value B[i] is determined in a measuring direction MR specified in relation to the object, whereby all local refractive power values B[i] together form a refractive power map for the object 2, the resolution of which is specified by the size and arrangement of the measuring surfaces MF.
  • the index [i] indicates a defined measuring surface [i].
  • the measuring direction MR should be perpendicular to the drawing plane, regardless of any curvature or tilt of the object 2 relative to the drawing plane.
  • the refractive power is determined in a first deflection direction AH and at least one further deflection direction AV.
  • the deflection directions AH, AV describe an actual refraction of a line of sight in the direction shown.
  • the first deflection direction AH describes a deflection by refraction in a horizontal direction (relative to a typical installation position of the windshield 3 in a motor vehicle).
  • the further (second) deflection direction AV describes a deflection by refraction in a vertical direction (relative to a typical installation position of the windshield 3 in a motor vehicle).
  • the measuring direction MR is orthogonal to the plane spanned by the deflection directions AH, AV and is indicated in Fig. 3 by a point in the measuring surface MF[i].
  • the measuring method for determining the refractive power in a deflection direction which is generally known to the person skilled in the art and is carried out by the optical measuring device 4, consists in recording a known pattern 20, 30 with the camera 5 through the object 2. With a line camera, as described in this embodiment, an image of the pattern is produced by temporally successive images as the object 20 is transported progressively through the measuring device 4.
  • Examples of possible patterns 20, 30 are shown qualitatively in Fig. 4a and 5a, once as a dot pattern and once as a line pattern, each in their relative orientation to the deflection directions AH, AV.
  • Fig. 4b and 5b images of the patterns 20, 30 through the object 2 taken by the camera are shown, which reveal distortions due to optical refraction in the object 2 or the windshield 3 in the specific example at the points marked by ellipses. Due to the known geometric From the arrangement of patterns 20, 30 in the illumination 6, object 2 and camera 3 as well as the geometric dimensions of patterns 20, 30, the refractive power of object 2 in each measuring surface MF[i] for the measuring direction MR determined by the viewing direction of camera 5 can be determined in accordance with known ray optics.
  • the refractive power is measured and recorded as an n-tuple of the refractive power for each of the measuring surfaces MF[i] in each of the deflection directions AH, AV.
  • this results in a 2-tuple of the form B[i] [B[i](AH), B[i](AV)] for the local refractive power values B[i] of each of the measuring surfaces MF[i].
  • the refractive power map of object 2 is thus formed for all of the measuring surfaces MF of the measuring range MB together.
  • a common coordinate system 40 is used for the measuring and evaluation arrangement.
  • orthogonal axes of the coordinate system 40 can be through the first deflection direction AH, the measuring direction MR of the optical measuring device 4 and the further (second) deflection direction AV and thus form a typical xyz coordinate system.
  • the application of the proposed method according to the invention is particularly easy to implement.
  • the expert is free to use any coordinate system to describe the method and the refractive power. The expert can make such adjustments within the scope of specialist knowledge.
  • a coordinate plane 41 is spanned by the measuring direction MR and the first deflection direction AH, which is aligned parallel to the horizontal edges of the windshield 3 (as object 2).
  • the orientation and position of the object 2 a viewing point 42 and a viewing direction BR from the viewing point 42 through the measuring range MB of the object 2.
  • the viewing direction BR can basically be chosen arbitrarily.
  • the measuring direction MR is defined by the measuring device 4 relative to the object 2 and, in the embodiment described with reference to Fig. 6, also determines the position of the coordinate system 40. In principle, however, the coordinate system can be freely selected in space and the measuring direction MR can also be described in coordinates of the coordinate system.
  • the intersection point of the specified viewing direction BR with exactly one local measuring surface MF[i] is then determined in the coordinate system 40 and the viewing angle s between the viewing direction BR and the measuring direction MR in the determined local measuring surface MF[i] is determined.
  • the local refractive power values B[i](AH) and B[i](AV) can also be determined from the refractive power map, which were previously measured as described above.
  • an amplification factor for the refractive power is then determined as a function of the specific viewing angle s and a known refractive index n of the object 2, whereby the amplification factor comprises a factor value DH for the refractive power in the first deflection direction AH and a factor value DV for each further deflection direction AV.
  • the amplification factor comprises a factor value DH for the refractive power in the first deflection direction AH and a factor value DV for each further deflection direction AV.
  • a factor value DH and a factor value DV matching the local refractive indices B[i](AH) and B[i](AV).
  • the gain factors DH and DV are defined in the example as follows:
  • the viewing point 42 lies in the horizontally directed coordinate plane 41.
  • the viewing direction BR is the viewing direction of a driver of the motor vehicle sitting at the viewing point 42, who is looking sideways (at the viewing angle s) through the windshield in a horizontal plane (which in the example shown here coincides with the coordinate plane 41).
  • the viewing angle s is also referred to as the yaw angle.
  • Fig. 7 shows another example of a windshield 3 for an arrangement with a coordinate system 50, in which the viewing point 52 lies in a vertically directed coordinate plane 51.
  • the viewing direction BR is the viewing direction of a driver of the motor vehicle sitting at the viewing point 42, who looks through the windshield in a horizontal plane (which in the example shown here is perpendicular to the coordinate plane 41) through an installation angle corresponding to the viewing angle s.
  • the viewing angle s is also referred to as the tilt angle. It is easy to see that the coordinate systems 40, 50 can be converted into one another by swapping the designations of the first and second deflection directions AH, AV.
  • projections of the viewing angle s into the respective coordinate plane 41, 51 can be considered in a corresponding manner.
  • Fig. 8 shows the course of the (dimensionless) amplification factors DH , DH for different viewing angles s, as described in the above forms for DH and DV.
  • the viewing angle s lies, as shown in Fig. 5 or 6, in the coordinate plane 41, 51 defined by the measuring direction MR and the first deflection direction AH.
  • the refractive effect and accordingly the amplification factor increase significantly at large viewing angles s.
  • the refractive effect in the second deflection direction AV perpendicular to the first deflection direction remains - in comparison - approximately constant.
  • Fig. 9 shows a comparison of the calculated amplification factor DH (theo) compared to an experimentally determined amplification factor DH (exp) for an arrangement according to Fig. 7 (various tilt angles of the windshield 3).
  • the reference measured values for the refractive power were determined for a vertically standing windshield 3, ie when the measuring direction MR and the viewing direction BR coincide in Fig. 7.
  • the calculated values for the amplification factor DH are determined as described above in application of the method according to the invention.
  • the windshield 3 in the measuring arrangement 4 was so aligned so that the measuring direction MR always corresponded to the viewing direction BR from the application of the method for the various viewing angles s.

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Abstract

L'invention concerne un procédé et un appareil pour déterminer la réfringence d'un objet optiquement transparent (2) et ses applications privilégiées. La réfringence dans une région mesurée (MB) de l'objet (2) dans une première direction de déviation (AH) et au moins une autre direction de déviation (AV) est mesurée au moyen d'un dispositif de mesure optique (4), et une orientation et une position de l'objet (2), d'un point de vue (42, 52) et d'une direction d'observation (BR) sont définies. Le point d'intersection de la direction d'observation définie (BR) et d'une zone de mesure locale précise (MF[i]) sur l'objet (2), et l'angle de vue (ε) compris entre la direction d'observation (BR) et une direction de mesure (MR) dans la zone de mesure locale identifiée (MF[i]) sont déterminés. Un facteur d'amplification de la réfringence est déterminé sur la base de l'angle de vue (ε) et de l'indice de réfraction (n) de l'objet (2), et la réfringence dans la direction d'observation (BR) est déterminée par application du facteur d'amplification à la valeur de réfringence locale B[i] de la zone de mesure locale (MF[i]).
EP24711871.4A 2023-03-15 2024-03-13 Procédé et appareil de détermination de réfringence d'un objet optiquement transparent Pending EP4680948A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102023106477.0A DE102023106477A1 (de) 2023-03-15 2023-03-15 Verfahren und Vorrichtung zur Bestimmung der Brechkraft eines optisch transparenten Objekts
PCT/EP2024/056669 WO2024189077A1 (fr) 2023-03-15 2024-03-13 Procédé et appareil de détermination de réfringence d'un objet optiquement transparent

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EP4680948A1 true EP4680948A1 (fr) 2026-01-21

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EP (1) EP4680948A1 (fr)
JP (1) JP2026509863A (fr)
CN (1) CN121488156A (fr)
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WO (1) WO2024189077A1 (fr)

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Publication number Priority date Publication date Assignee Title
DE3816392A1 (de) * 1988-05-13 1989-11-23 Ver Glaswerke Gmbh Verfahren zur bestimmung der optischen qualitaet von flachglas oder flachglasprodukten
DE29724139U1 (de) * 1996-10-18 2000-02-24 Innomess Gesellschaft für Messtechnik mbH, 45768 Marl Vorrichtung für die Ermittlung von optischen Fehlern in grossflächigen Scheiben
DE102013105570A1 (de) * 2013-05-29 2014-12-04 Isra Surface Vision Gmbh Verfahren zur Bestimmung der Brechkraft eines transparenten Objekts sowie entsprechende Vorrichtung
DE102014115336A1 (de) * 2014-10-21 2016-04-21 Isra Surface Vision Gmbh Verfahren zur Bestimmung eines lokalen Brechwerts und Vorrichtung hierfür
WO2022189327A1 (fr) 2021-03-12 2022-09-15 Saint-Gobain Glass France Procédé itératif de détermination de la forme de la surface d'un objet en feuille ou en couche avec précision de mesure élevée

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CN121488156A (zh) 2026-02-06

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