System for calibrating optical distortion

Abstract

According to the system for calibrating the optical distortion, provided by the invention, the optical distortion of the transparent part can be calibrated, and the accuracy of optical distortion measurement of the transparent part is improved. The system comprises a calibration element, and the optical distortion of the calibration element is a fixed value. Wherein the calibration coefficient of the system is related to the deviation between the first optical distortion and the fixed value, and the calibration coefficient is used for correcting the second optical distortion. The first optical distortion is the optical distortion, measured by the system, of the calibration element, and the second optical distortion is the optical distortion, measured by the system, of the transparent part to be measured.

Description

Technical Field

[0001] The present application relates to the field of optical distortion measurement, and in particular, to a system for calibrating optical distortion. Background Art

[0002] Optical distortion is defined as the rate of change of optical angle deviation caused by the non-uniformity of transparent parts. Common optical distortion test methods for transparent parts include grid photography, slide projection grid method, circular spot method, etc. However, when the non-uniformity of the transparent surface is too small or the surface of the transparent part is irregular, the consistency of the optical distortion measured by the above optical distortion test methods is poor and cannot be used to calibrate the optical distortion of transparent parts. Utility Model Content

[0003] The present application provides a system for calibrating optical distortion, which can improve the accuracy of optical distortion measurement of a transparent part to be measured.

[0004] In a first aspect, an embodiment of the present application provides a system for calibrating optical distortion. The system is used to calibrate the optical distortion of a transparent part to be measured, and the system includes: a calibration element, the optical distortion of the calibration element is a fixed value, wherein the calibration coefficient of the system is related to the deviation between the first optical distortion and the fixed value, and the calibration coefficient is used to correct the second optical distortion, the first optical distortion is the optical distortion of the calibration element measured by the system, and the second optical distortion is the optical distortion of the transparent part to be measured by the system.

[0005] Based on the above solution, the optical distortion of the optical system is calibrated by using the calibration element, so that when the optical system measures the optical distortion of the transparent component to be measured, the purpose of improving the measurement accuracy can be achieved.

[0006] In combination with the first aspect, in certain implementations of the first aspect, the system further includes: a grid generation module and a measuring device, the grid generation module being used to provide a background pattern and emitting a first imaging light to the calibration element or the transparent element to be measured; the calibration element or the transparent element to be measured being used to generate a second imaging light containing distortion based on the first imaging light from the grid generation module, and emitting the second imaging light to the measuring device; the measuring device being used to generate a measurement pattern based on the second imaging light, and the measurement pattern being used to calculate the surface distortion of the calibration element or the transparent element to be measured.

[0007] In combination with the first aspect, in some implementations of the first aspect, the second imaging light emitted by the calibration element includes at least two different transmission directions.

[0008] Based on the above solution, the second imaging light includes at least two different transmission directions, which can ensure the observation and measurement of optical distortion, making the measurement result more accurate.

[0009] In combination with the first aspect, in certain implementations of the first aspect, the calibration element includes a first surface, the first surface is an incident surface or an exit surface of the first imaging light, and the first surface is composed of two planes with an included angle greater than 0, so that the second imaging light generated after the first imaging light passes through the first surface propagates along a first direction and a second direction respectively.

[0010] In combination with the first aspect, in some implementations of the first aspect, the calibration element further includes a second surface, the second surface is opposite to the first surface, and the second surface is perpendicular to the optical axis of the system.

[0011] By arranging the second surface to be perpendicular to the optical axis, the calculation complexity of the optical distortion of the calibration element can be reduced, the calculation process can be simplified, and the calculation efficiency can be improved.

[0012] In combination with the first aspect, in some implementations of the first aspect, the calibration element is a prism.

[0013] In combination with the first aspect, in some implementations of the first aspect, the prism is a cylindrical prism. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Schematic diagram of the distortion obtained for grid photography.

[0015] Figure 2 A schematic structural diagram of a system 200 for calibrating optical distortion provided in an embodiment of the present application.

[0016] Figure 3 A side cross-sectional schematic diagram of a first calibration element 220 provided in an embodiment of the present application.

[0017] Figure 4 A side cross-sectional schematic diagram of a second calibration element 220 provided in an embodiment of the present application.

[0018] Figure 5 A side cross-sectional schematic diagram of a third calibration element 220 provided in an embodiment of the present application.

[0019] Figure 6 A schematic diagram of the principle of measuring optical distortion provided in an embodiment of the present application.

[0020] Figure 7 A schematic structural diagram of a specific test system 700 provided in an embodiment of the present application. DETAILED DESCRIPTION

[0021] The technical solution in this application will be described below in conjunction with the accompanying drawings.

[0022] In order to facilitate understanding of the embodiments of the present application, the following explanation is made.

[0023] First, the terms "first", "second", etc. and various numbers in the text descriptions or drawings of the embodiments of the present application shown below are only used for the convenience of description and are not used to limit the scope of the embodiments of the present application. For example, the first imaging light and the second imaging light are used to distinguish different imaging lights.

[0024] Second, the term "comprising" and any variations in the embodiments of the present application shown below are intended to cover non-exclusive inclusions. For example, a system, product or device comprising a series of units is not necessarily limited to those units explicitly listed, but may include other units that are not explicitly listed or inherent to these products or devices.

[0025] Third, in the embodiments of the present application, words such as "exemplarily" or "for example" are used to indicate examples, illustrations or descriptions, and the embodiments or designs described as "exemplarily" or "for example" should not be interpreted as being more preferred or more advantageous than other embodiments or designs. The use of words such as "exemplarily" or "for example" is intended to present related concepts in a specific way for easy understanding.

[0026] Fourth, in the embodiments of the present application, imaging light refers to light that carries an image (or image information) and is used to generate an image, and may also be referred to as image light, etc.

[0027] Fifth, in the drawings of the present application, the thickness, size and shape of each optical element have been slightly exaggerated for the sake of convenience. Specifically, the shapes of the optical elements shown in the drawings are shown by way of example, and the drawings are only examples and not drawn strictly to scale.

[0028] Sixth, unless otherwise defined, all terms (including technical terms and scientific terms) used in this application have the same meanings as commonly understood by ordinary technicians in the field to which this application belongs.

[0029] Modern high-performance aircraft have increasingly higher optical requirements for transparent parts. Among the optical properties of aircraft transparent parts, optical distortion is particularly important. This is because severe optical distortion can cause the target to jump and cause visual fatigue to the pilot. Therefore, it is crucial to measure the optical distortion of transparent parts and make corresponding corrections. The evaluation technology of optical distortion can be summarized into two categories: visual inspection method and instrument inspection method. The visual inspection method is that the inspector conducts a visual inspection of the transparent parts in a simulated pilot position. This method is easy to operate, but it cannot be quantified. At the same time, it is greatly affected by human factors. With the development of aviation technology, the optical distortion test of transparent parts has also developed from visual inspection to instrument inspection. At present, the test methods applied to the optical distortion of transparent parts mainly include grid photography method, slide projection grid method, circular spot method, etc. For example, Figure 1 The principle diagram of the distortion obtained by grid photography is as follows. The position of the maximum distortion area of ​​the grid line in the horizontal or vertical direction is determined on the film or printed photo, and the slope of the maximum distortion grid line ( Figure 1 However, when the unevenness on the surface of the transparent part is too small or irregular, the consistency of the optical distortion obtained by these methods is poor, which affects the calibration of the optical distortion of the transparent part.

[0030] In view of this, the present application provides a system for calibrating optical distortion, which realizes calibration of the optical distortion of a transparent part by calibrating the inherent optical distortion of the element, thereby improving the accuracy of measuring the optical distortion of the transparent part and improving the efficiency of calibrating the optical distortion of the transparent part.

[0031] Figure 2 FIG. 2 is a schematic structural diagram of a system 200 for calibrating optical distortion provided in an embodiment of the present application. Figure 2 As shown, the system is used to measure and calibrate the optical distortion of a transparent part 20 to be measured. The system 200 includes a grid generation module 210, a calibration element 220, and a measuring device 230. The grid generation module 210 is used to provide a background pattern and emit a first imaging light to the calibration element 220 or the transparent part 20 to be measured. The calibration element 220 or the transparent part 20 to be measured is used to generate a second imaging light containing distortion based on the first imaging light from the grid generation module 210, and emit the second imaging light containing distortion to the measuring device. The measuring device 230 is used to generate a measurement pattern based on the second imaging light containing distortion, and the measurement pattern is used to calculate the surface distortion of the calibration element 220 or the transparent part 20 to be measured.

[0032] It should be noted that in the present application, the optical distortion of the calibration element 220 is a constant value. That is, for the calibration element 220, no matter what measurement method is adopted, its optical distortion is constant and is the only constant value, which can be understood as the inherent optical property of the calibration element 220, or the known parameter that can be obtained. Therefore, when the calibration element 220 is applied to the measurement system of the optical distortion of the transparent part (including Figure 2 When the measurement system 200 shown, as well as other measurement systems not listed in the embodiments of the present application but including the calibration element 220, is used, the calibration element 220 can be used to correct the optical distortion measured by the measurement system, that is, the calibration element 220 is used to replace the transparent part to measure the optical distortion, and the calibration coefficient of the measurement system is obtained by the deviation between the optical distortion of the calibration element 220 measured by the measurement system and the known constant value. Subsequently, after the transparent part to be measured is measured, the calibration coefficient can be used to calibrate the measurement result of the optical distortion of the transparent part to be measured. In other words, the calibration element 220 is used to obtain the calibration coefficient of the system before measuring the optical distortion of the transparent part 20 to be measured. The calibration coefficient can be used to calibrate the measurement system so that the optical distortion of the calibration element 220 measured by the system is consistent with the constant value of the calibration element 220 itself.

[0033] It should be noted that in the description of this application, the measured optical distortion of the calibration element 220 is consistent with or the same as the set value of the calibration element 220 itself, but is not limited to being the same. The difference between the measured value and the customized value can be within the allowable error range.

[0034] First combine the following Figure 3 , Figure 4 and Figure 5 Three possible structures of the calibration element 220 provided in the embodiments of the present application are described.

[0035] Figure 3 FIG. 2 is a side cross-sectional schematic diagram of a first calibration element 220 provided in an embodiment of the present application. Figure 3 As shown, the calibration element 220 is an irregular prism. The calibration element 220 includes a first surface 310, which is the incident surface or the exit surface of the light beam (wherein, Figure 3 The first surface 310 is composed of two planes with an angle greater than 0 (i.e. Figure 3 The first surface 310 is composed of a plane 311 and a plane 312), so that the imaging light beam propagates along the first direction and the second direction after passing through the first surface 310.

[0036] Figure 4 FIG. 2 is a side cross-sectional schematic diagram of a second calibration element 220 provided in an embodiment of the present application. Figure 4As shown, the calibration element 220 is an irregular prism. The calibration element 220 includes a first surface 410, which is the incident surface or the exit surface of the light beam (wherein, Figure 4 The first surface 410 is composed of three surfaces, and the angle between two adjacent planes in the three surfaces is greater than 0, so that the light beam propagates in three directions after passing through the first surface 410. Figure 4 The angle between the plane 411 and the plane 412 is greater than 0, and the angle between the plane 412 and the plane 413 is greater than 0. After the imaging light beam passes through the first surface 410, it propagates along the first direction, the second direction and the third direction.

[0037] Figure 5 FIG. 2 is a side cross-sectional schematic diagram of a third calibration element 220 provided in an embodiment of the present application. Figure 5 As shown, the calibration element 220 is a prism with a constant optical distortion. The calibration element 220 includes a first surface 510, which is the incident surface or the exit surface of the light beam (wherein, Figure 5 The light exit surface in the middle. Figure 3 The calibration element 220 and Figure 4 Compared with the calibration element 220 in Figure 5 In the embodiment, the first surface 510 is composed of a non-vertical plane, that is, the angle between the surface 510 and the horizontal plane is not 90°, and the imaging light beam propagates along the first direction after passing through the first surface 510.

[0038] It is understandable that the above Figures 3 to 5 The calibration element 220 shown is only a partial example of the calibration element 220 applicable to the present application solution, but not all of them. That is, the calibration element 220 used in the measurement system of the present application is not limited to the above-mentioned Figures 3 to 5 Optionally, the calibration element 220 may also be a cylindrical prism, a prism with a free-form surface, or other optical elements with a constant optical distortion, such as a lens, etc., which is not limited in the present application.

[0039] It should be noted that in the above Figures 3 to 5In the calibration element 220 shown, for the sake of simplicity of calculation, the second surface of the calibration element 220 opposite to the first surface is set as a surface perpendicular to the optical axis of the system. At this time, after the light beam enters the calibration element 220, the deflection of the outgoing light beam will be introduced only by the first surface, thereby reducing the complexity of calculating the optical distortion of the calibration element 220, but the present application is not limited to this. When the second surface of the calibration element 220 opposite to the first surface is not a surface perpendicular to the optical axis, at this time, the deflected light emitted from the calibration element 220 needs to consider the translation of the light. In addition, it should be noted that in the present application scheme, the surface design and placement of the calibration element 220 surface need to make the second imaging light emitted from the calibration element 220 have at least two different propagation directions, so that the measuring device 230 can obtain patterns that do not match the two directions, thereby obtaining the optical distortion of the calibration element 220.

[0040] Next, combine Figure 3 The calibration element 220 shown illustrates the principle of measuring optical distortion of the measurement system 200 of the present application. Figure 6 As shown, the imaging light emitted by the grid generation module 210 is processed by the calibration element 220 to generate a measurement pattern containing distortion in the imaging of the measurement device 230. The optical distortion D (in mrad / cm) is calculated by the following formula.

[0041]

[0042] Wherein, B is the distance between the calibration element 220 or the transparent element 20 and the grid generation module 210, in centimeters (cm), C is the distance between the measuring device 230 and the grid generation module 210, in centimeters (cm), E is the distance between the measuring device 230 and the calibration element 220 or the transparent element 20, in centimeters (cm), R is the maximum distortion grid size change,

[0043] It should be noted that in Figure 6 In the schematic diagram shown, the grid generation module 210 generates a square pattern as an example for explanation, but the present application is not limited thereto. For example, in some other embodiments, the grid generation module 210 can also generate a circular pattern. Specifically, when the test system uses a square pattern, assuming that the maximum side length of the grid in the maximum distortion is 24 mm, and the length of the square in the original grid generation module 210 is 20 mm, then When the test system uses a circular pattern, assuming that the major axis of the circular spot at the maximum distortion is 6 mm, and the diameter of the circle in the original grid generation module 210 is 5 mm, then

[0044] It should also be noted that in order to more easily observe the change in grid length, that is, to observe the distortion area and improve the accuracy of measurement, Figure 6 When the calibration element 220 is placed, the deflection points on the first surface of the calibration element 220 can be set to have grids that do not overlap. At this time, the grid length in the distorted image acquired by the measuring device 230 becomes easy to observe.

[0045] Optionally, the measuring device 230 in the test system 200 may be an image sensor, such as a camera, etc., which is not limited in the present application.

[0046] It should be noted that the present application does not limit the specific structure of the grid generation module 210. For example, the grid generation module 210 may include a lighting device and a grid screen, or a projection screen that projects a grid pattern.

[0047] Exemplarily, when the grid generation module 210 is composed of a lighting device and a grid screen, and the measuring device 230 is a camera, Figure 7 1 is a schematic structural diagram of a specific test system 700 provided in an embodiment of the present application, and the test system is used to measure the transparent member 20 to be tested. Figure 7 As shown, the test system 700 includes an illumination device 710, a grid screen 720, a calibration element 730 and a camera 740, wherein the optical distortion of the calibration element 730 is a constant value D1, and the calibration element 720 can be the above-mentioned Figures 3 to 5Any calibration element 220, or other calibration elements applicable to the embodiments of the present application, can be specifically referred to the above description, which will not be repeated here. It can be understood that when the optical distortion of the transparent part 20 to be tested is measured, the optical distortion of the calibration element 730 is first measured and calibrated using the system 700, that is, the system 700 is adjusted according to the measurement result of the optical distortion of the calibration element 730, so that the measurement result of the optical distortion of the calibration element 730 by the system 700 is equal to D1. Then, based on the adjusted system, the calibration element 730 is replaced by the transparent part 20 to be tested, and the optical distortion of the transparent part 20 to be tested is measured. Specifically, when the system 700 is used to measure the optical distortion of the calibration element 730, the lighting device 710 is used to emit an illumination light beam to the grid screen 720. The grid screen 720 is used to generate a first imaging light based on the illumination light beam, and emit the first imaging light to the calibration element 730. The calibration element 730 is used to generate a second imaging light based on the first imaging light from the grid screen 720, and emit the second imaging light to the camera 740. The camera 740 is used to generate a first measurement pattern based on the second imaging light from the calibration element 730, and the first measurement pattern is used to calculate the optical distortion of the calibration element 730. When the optical distortion of the calibration element 730 calculated based on the first measurement pattern is the same as the known optical distortion D1 of the calibration element 730 itself, the calibration element 730 in the system 700 is replaced with the transparent part 20 to be measured, and the optical distortion of the transparent part 20 to be measured is measured. At this time, the lighting device 710 is used to emit an illumination beam to the grid screen 720. The grid screen 720 is used to generate a third imaging light based on the illumination beam, and emit the third imaging beam to the transparent part 20 to be measured. The transparent part 20 to be measured is used to generate a fourth imaging light based on the third imaging light from the grid screen 720, and emit the fourth imaging light to the camera 740. The camera 740 is used to generate a second measurement pattern based on the fourth imaging light from the transparent member 20 to be measured. The second measurement pattern is used to calculate the optical distortion of the transparent member 20 to be measured.

[0048] In the several embodiments provided in this application, it should be understood that the disclosed system can be implemented in other ways. For example, multiple components can be combined or integrated into another module, or some features can be ignored or not performed. The modules described as separate components may or may not be physically separated.

[0049] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A system for calibrating optical distortion, characterized in that: The system is used to calibrate the optical distortion of a transparent part to be tested, and the system comprises: a calibration element, the optical distortion of the calibration element is a constant value, Among them, the calibration coefficient of the system is related to the deviation between the first optical distortion and the fixed value, and the calibration coefficient is used to correct the second optical distortion. The first optical distortion is the optical distortion of the calibration element measured by the system, and the second optical distortion is the optical distortion of the transparent part to be measured by the system.

2. The system according to claim 1, characterized in that The system also includes: a grid generation module and a measurement device, The grid generation module is used to provide a background pattern and emit a first imaging light toward the calibration element or the transparent element to be measured; The calibration element or the transparent member to be measured is used to generate a second imaging light containing distortion based on the first imaging light from the grid generation module, and emit the second imaging light to the measuring device; The measuring device is used to generate a measurement pattern based on the second imaging light, and the measurement pattern is used to calculate the surface distortion of the calibration element or the transparent part to be measured.

3. The system according to claim 2, characterized in that The second imaging light emitted by the calibration element includes at least two different transmission directions.

4. The system according to claim 2 or 3, characterized in that: The calibration element includes a first surface, which is the incident surface or the exit surface of the first imaging light. The first surface is composed of two planes with an included angle greater than 0, so that the second imaging light generated after the first imaging light passes through the first surface propagates along the first direction and the second direction respectively.

5. The system according to claim 4, characterized in that The calibration element further comprises a second surface, the second surface being opposite to the first surface, the second surface being perpendicular to the optical axis of the system.

6. The system according to claim 1, characterized in that The calibration element is a prism.

7. The system according to claim 6, characterized in that The prism is a cylindrical prism.

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