Calibration system of microlens array

Abstract

The utility model discloses a calibration system of a microlens array. The calibration system comprises an energy generating device, an optical measuring device and a calibration processing device, the energy generating device can provide a plurality of image fields with different wavelengths; the optical measurement device comprises a front lens group, a micro lens array supporting structure and an optical acquisition unit which are sequentially arranged along an imaging light path; a microlens array to be calibrated is fixed on a microlens array supporting structure to form a light field imaging system, so that light field original images of a plurality of image fields with different wavelengths are obtained; the microlens array supporting structure can move in the direction close to or away from the energy generating device. The calibration processing device is used for obtaining optimized calibration parameters of the micro-lens array to be calibrated according to a plurality of image fields with different wavelengths and the light field original image; the calibration system provided by the utility model can implement comprehensive calibration of the microlens array in image fields with different wavelengths, and can meet various calibration test requirements.

Description

Technical Field

[0001] The utility model relates to the technical field of optical testing, and more specifically to a calibration system for a microlens array. Background Art

[0002] The emergence of light field cameras is a revolutionary development in the field of computational imaging. Light field cameras break through the limitation of traditional cameras that only record light intensity. They can not only obtain the position information of light, but also record the light angle information that is highly correlated with scene depth, target geometry, etc. Through signal processing algorithms, they can realize many functions such as taking pictures first and focusing later, and precise virtual viewpoint synthesis. They have broad application prospects in computer vision, robotics, medical imaging, industrial inspection and other fields.

[0003] The current mainstream light field camera is a light field camera based on a microlens array. It inserts a microlens array between the main lens and the image sensor, so that the light from the main lens passes through each microlens and is recorded by the image sensor, realizing the collection of four-dimensional light field data. Light field cameras based on microlens arrays have achieved many successful application cases in depth estimation, super-resolution reconstruction, refocusing, attitude estimation, etc. In order to support the above applications, accurate calibration of light field camera parameters is crucial, especially calibration of microlens array parameters.

[0004] The microlens array is composed of sub-lenses with diameters ranging from a few hundred nanometers to a few millimeters arranged in a certain order on a substrate, and the number of units ranges from thousands to tens of thousands. Ideally, the parameters of each microlens with the same focal length in the microlens array are the same, so their optical properties are also the same; however, the situation of each microlens in the array cannot be strictly controlled during the processing and manufacturing process, and some errors are inevitable, which leads to the refractive index of each microlens material being not safe and consistent, and the surface structure of each microlens is not completely consistent. In addition, there may be other defects or impurities in the microlens, which will eventually cause each microlens with the same focal length in the microlens array to be not completely the same, and the optical properties are also different, thereby affecting the overall imaging effect of the microlens array. The inconsistency of this microstructure and / or material between each microlens in the microlens array will be reflected in the different refractive indices of the light entering the microlens, causing the image formed by the microlens array when acquiring image fields of different wavelengths to have dispersion, blurring and other problems, seriously affecting the imaging quality. Especially when the light field camera based on the microlens array is applied to the unmanned driving scene in mines, due to the different ambient light during the day or at night (that is, the day and night scenes are image fields of different wavelengths), the image quality obtained by the light field camera based on the microlens array is poor, which reduces the accuracy of the depth perception data and thus affects the accuracy of the unmanned driving control.

[0005] Existing calibration systems mostly use a checkerboard calibration plate to calibrate the center point of the microlens array by directly acquiring a white image. The light field camera calibrated in this way generally has the problem of poor adaptability to different wavelengths.

[0006] In summary, at this stage, there is an urgent need to develop a microlens array calibration system to solve the above-mentioned technical problems. Utility Model Content

[0007] One purpose of the utility model is to provide a new technical solution for a calibration system of a microlens array.

[0008] The utility model provides a calibration system for a microlens array, the system comprising: an energy generating device and an optical measuring device arranged at a relative interval, and a calibration processing device connected to the energy generating device and the optical measuring device;

[0009] The energy generating device is capable of providing a plurality of image fields of different wavelengths;

[0010] The optical measurement device comprises a front lens group, a microlens array support structure and an optical collection unit which are sequentially arranged along an imaging optical path; a light field imaging system is formed by fixing a microlens array to be calibrated on the microlens array support structure to obtain a plurality of original light field images of image fields with different wavelengths; the microlens array support structure can be moved toward or away from the energy generating device to adjust the distance between the microlens array to be calibrated, the front lens group and the optical collection unit;

[0011] The calibration processing device is used to obtain the optimized calibration parameters of the microlens array to be calibrated according to the image fields of multiple different wavelengths and the original image of the light field.

[0012] Optionally, the optical measurement device also includes a rear lens group arranged between the microlens array support structure and the optical collection unit, and the rear lens group can be moved in a direction close to or away from the energy generating device to adjust the distance between the microlens array to be calibrated, the rear lens group and the optical collection unit.

[0013] Optionally, the front lens group and / or the rear lens group has a plurality of optional lens combinations, and each lens combination contains a different number and / or type of lenses.

[0014] Optionally, the optical collection unit can move towards or away from the energy generating device.

[0015] Optionally, the energy generating device may provide an image field in an ultraviolet light band, a visible light band, a near infrared band, a far infrared band or a terahertz wave.

[0016] Optionally, the light source of the energy generating device is a laser, a display, a heating coil or a terahertz light source.

[0017] Optionally, the energy generating device further comprises a filter arranged at the light output end of the light source, and the filter is an ultraviolet filter, a visible filter, an infrared filter, a far infrared filter or a terahertz filter.

[0018] Optionally, the energy generating device is a high color gamut LED display.

[0019] Optionally, the distance between the energy generating device and the optical measuring device is 50 cm to 1 m.

[0020] Optionally, the system further comprises a dark box, wherein the energy generating device and the optical measuring device are both arranged in the dark box.

[0021] According to an embodiment disclosed in the present utility model, a calibration system for a microlens array of the present utility model has the following beneficial effects:

[0022] The utility model provides a calibration system for a microlens array, comprising an energy generating device, an optical measuring device and a calibration processing device. The energy generating device is used to provide a plurality of image fields with different wavelengths, and a microlens array to be calibrated is installed on the optical measuring device through a microlens array supporting structure to form a light field imaging system to obtain light field original images of the image fields with multiple different wavelengths, so that the calibration processing device processes the light field original images to obtain optimized calibration parameters of the microlens array to be calibrated to complete the calibration. The utility model has a simple structure, can implement comprehensive calibration of microlens arrays under image fields with different wavelengths, and adopts a movable microlens array supporting structure to fix the microlens array to meet various calibration test requirements.

[0023] Other features and advantages of the present invention will become apparent from the following detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present invention and, together with the description, serve to explain the principles of the present invention.

[0025] Figure 1 A structural block diagram of a microlens array calibration system provided according to an embodiment;

[0026] Figure 2 The figure is a schematic diagram of the specific structure of a microlens array calibration system provided according to an embodiment.

[0027] Description of reference numerals:

[0028] Optical measuring device 1; front lens group 11; microlens array supporting structure 12; optical collection unit 13; rear lens group; energy generating device 2; calibration processing device 3; dark box 4. DETAILED DESCRIPTION

[0029] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention.

[0030] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

[0031] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0032] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0033] Since the condition of each microlens in the array cannot be strictly controlled during the processing and manufacturing process, some errors are inevitable, making the refractive index of each microlens material not completely consistent, and the surface structure of each microlens is not completely consistent. In addition, there may be other defects or impurities in the microlens, which will eventually cause each microlens of the same focal length in the microlens array to be not exactly the same. In other words, each microlens in the microlens array has a different refractive index for the incoming light, which affects the overall imaging effect of the microlens array. In particular, when using a microlens array to obtain image fields of different wavelengths, the resulting image has problems such as dispersion and blur, which seriously affects the imaging quality. However, in the prior art, the calibration system for the microlens array mainly uses a black and white calibration plate, and the center point of the microlens array is calibrated by obtaining a white image. The calibrated light field camera generally has the problem of poor adaptability to different wavelengths.

[0034] In order to solve the above technical problems, the present invention provides a microlens array calibration system. Figure 1-2 As shown, the system comprises: an energy generating device 2 and an optical measuring device 1 which are arranged relatively spaced apart, and a calibration processing device 3 connected to the optical measuring device 1;

[0035] The energy generating device 2 can provide multiple image fields with different wavelengths; the optical measuring device 1 includes a front lens group 11, a microlens array supporting structure 12 and an optical collection unit 13 which are sequentially arranged along the imaging light path; a light field imaging system is formed by fixing the microlens array to be calibrated on the microlens array supporting structure 12 to obtain the original light field images of the image fields with multiple different wavelengths; the microlens array supporting structure 12 can be moved toward or away from the energy generating device 2 to adjust the distance between the microlens array to be calibrated, the front lens group 11 and the optical collection unit 13; the calibration processing device 3 is used to obtain the optimized calibration parameters of the microlens array to be calibrated according to the image fields with multiple different wavelengths and the original light field images.

[0036] It should be noted that, in this embodiment, the front lens group scales the image field provided by the energy generating device so that the number of pixels occupied by the image field and the scaled image (the image transmitted through the front lens group) is in a relationship of a:b, where a and b can be in any multiple relationship, as long as the scaled image can completely cover the microlens array.

[0037] In this embodiment, the microlens array to be calibrated is detachably mounted on the optical measurement device via a microlens array support structure, which facilitates the light emitted from the front lens group to the microlens array to be calibrated, and also facilitates the transmission of the light passing through the microlens array to be calibrated to the subsequent parts. Among them, the microlens array support structure has a variety of structural forms, such as a support seat or a support rod, which are not specifically limited here. In this embodiment, the microlens array support structure is moved to drive the microlens array to be calibrated to move, thereby changing the distance between the microlens array to be calibrated, the front lens group and the optical acquisition unit, so as to adapt to the calibration requirements of various different microlens arrays.

[0038] In this embodiment, the optical acquisition unit refers to an optical acquisition system including an image sensor (such as CCD, CMOS, etc.), which is used to record and store the light passing through the microlens array for calibration by the calibration processing device.

[0039] In this embodiment, the energy generating device provides multiple image fields of different wavelengths, and the image distribution matrices of the image fields can be the same or different.

[0040] In this embodiment, the calibration processing device can be a high-performance processor, a computer or a cloud platform, which is not specifically limited here. In addition, in this embodiment, the calibration processing device can also be connected to the energy generating device to control its operation.

[0041] In addition, in this embodiment, the calibration process can be performed in a dark environment or a bright environment.

[0042] Optionally, the optical measurement device 1 in the calibration system of the microlens array of the present embodiment further includes a rear lens group 14 disposed between the microlens array support structure 12 and the optical collection unit 13, and the rear lens group 14 can be moved in a direction close to or away from the energy generating device 2 to adjust the distance between the microlens array to be calibrated, the rear lens group 14, and the optical collection unit 13. In the present embodiment, the distance between the microlens array to be calibrated, the rear lens group, and the optical collection unit is changed by moving the rear lens group, thereby meeting the calibration requirements of various different microlens arrays.

[0043] It should be noted that when the microlens array is produced according to the size of the image sensor, there is no need to set a rear lens group. When it is mass-produced, a rear lens group can be set. The rear lens group scales the image transmitted by the microlens array to be calibrated so that the number of pixels occupied by the transmitted image and the scaled image on the optical collection unit satisfies the relationship of c:d, where c and d can be in any multiple relationship, as long as the light after scaling is not larger than the optical collection unit.

[0044] Optionally, the front lens group 11 and / or the rear lens group 14 in the calibration system of the microlens array of this embodiment have a plurality of optional lens combinations, and the number and / or lens types contained in each lens combination are different. It should be noted that in this embodiment, the front lens group and the rear lens group both refer to one or a group of lenses, and the type of lenses contained can be a convex lens or a concave lens (of course, the lens can also be an adjustable liquid lens). The specific front lens group or rear lens group is determined according to the calibration test requirements. For example, the front lens group can use a full-frame 300mm lens.

[0045] Optionally, the optical collection unit 14 in the microlens array calibration system of this embodiment can move towards or away from the energy generating device 2. In this embodiment, the optical collection unit is generally installed in a fixed structure and does not need to be moved, but in special cases, a flexible connection can be used to achieve movement within a small range.

[0046] Optionally, in the microlens array calibration system of this embodiment, the image sensor in the optical collection unit 13 is connected to the microlens array to be calibrated through a micrometer-level structure, so that the light passes through the microlens and forms a clear and uniform image on the image sensor.

[0047] Optionally, the energy generating device 2 in the calibration system of the microlens array of this embodiment can provide an image field of ultraviolet light band, visible light band, near infrared band, far infrared band or terahertz wave. It should be noted that, according to the calibration test requirements, the image fields of different wavelengths provided by the energy generating device can be ultraviolet light band, visible light band, near infrared band, far infrared band or terahertz wave, for example: the ultraviolet light band can be 200nm, 300nm; the visible light band can be 480nm blue light wavelength, 580nm yellow light wavelength, 650nm red light wavelength; the near infrared band can be 750nm, 850nm; the far infrared band can be 5um, and the terahertz wave can be 30um.

[0048] Optionally, the light source of the energy generating device 2 in the calibration system of the microlens array of this embodiment is a laser, a display, a heating wire or a terahertz light source. It should be noted that the energy generating device in this embodiment can be a laser emitting a specific ultraviolet, visible or near-infrared wavelength, a display emitting visible or near-infrared wavelength, a heating wire emitting a far-infrared wavelength in a specific pattern, a terahertz light source emitting terahertz waves, etc.

[0049] Optionally, the energy generating device 2 in the calibration system of the microlens array of this embodiment further includes a filter arranged at the light-emitting end of the light source, and the filter is an ultraviolet filter, a visible filter, an infrared filter, a far-infrared filter or a terahertz filter. It should be noted that the filter in this embodiment can be a filter that only allows light of a specific wavelength to pass through or a filter that allows light of a specific wavelength range to pass through; the filter can be an optically coated filter or a filter of a special material with filtering characteristics, for example: a germanium filter can be used for the far-infrared band.

[0050] Preferably, the energy generating device 2 in the calibration system of the microlens array of this embodiment is a high color gamut LED display. In this embodiment, the energy generating device is preferably a high color gamut LED display (such as a 28-inch 4K display) with an image output function to ensure that the output content is consistent with the input file, and to facilitate the rapid switching of the display content; pure color data is selected as the display content, preferably RGB three-color monochrome pictures, which are displayed in sequence during acquisition.

[0051] Optionally, in the calibration system of the microlens array of this embodiment, the distance between the energy generating device 2 and the optical measuring device 1 is 50 cm to 1 m. It should be noted that in this embodiment, the distance between the energy generating device and the optical measuring device can be 50 cm, 60 cm, 70 cm, 80 cm, 90 cm or 1 m, and of course can be other values, which are determined according to specific calibration test requirements and are not specifically limited here.

[0052] Preferably, in order to reduce the calibration cost and improve the calibration effect, the calibration system of the microlens array of this embodiment further includes a dark box 4, and the energy generating device 2 and the optical measuring device 1 are both arranged in the dark box 4, so as to perform the calibration operation in a dark environment. It should be noted that the material of the dark box in this embodiment can be acrylic material or metal material, which is not specifically limited here.

[0053] In summary, the calibration system of the microlens array of the embodiment of the utility model includes an energy generating device, an optical measuring device and a calibration processing device; the energy generating device is used to provide multiple image fields with different wavelengths, and the microlens array to be calibrated is installed on the optical measuring device through the microlens array supporting structure to form a light field imaging system to obtain the light field original images of the image fields with multiple different wavelengths, so that the calibration processing device processes the light field original images to obtain the optimized calibration parameters of the microlens array to be calibrated to complete the calibration. The structure is simple, and the comprehensive calibration of the microlens array under the image fields with different wavelengths can be implemented. Moreover, the microlens array is fixed by the movable microlens array supporting structure to meet various calibration test requirements.

[0054] Please note that the technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, all possible combinations of the technical features in the above embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification. The above embodiments only express several implementation methods of the present application, and their descriptions are relatively specific and detailed, but they cannot be understood as limiting the scope of the utility model patent. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present application, several variations and improvements can be made, which all belong to the scope of protection of the present application. Therefore, the scope of protection of the patent in this application shall be based on the attached claims.

[0055] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

[0056] Although some specific embodiments of the present invention have been described in detail by way of examples, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present invention. It should be understood by those skilled in the art that the above embodiments may be modified without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the appended claims.

Claims

1. A microlens array calibration system, characterized in that: The system comprises: relative spacing An energy generating device and an optical measuring device are provided, and a calibration processing device connected to the optical measuring device; The energy generating device is capable of providing a plurality of image fields of different wavelengths; The optical measurement device comprises a front lens group, a microlens array support structure and an optical collection unit which are sequentially arranged along an imaging optical path; a light field imaging system is formed by fixing a microlens array to be calibrated on the microlens array support structure to obtain a plurality of original light field images of image fields with different wavelengths; the microlens array support structure can be moved toward or away from the energy generating device to adjust the distance between the microlens array to be calibrated, the front lens group and the optical collection unit; The calibration processing device is used to obtain the optimized calibration parameters of the microlens array to be calibrated according to the image fields of multiple different wavelengths and the original image of the light field.

2. The microlens array calibration system according to claim 1, characterized in that: The optical measurement device also includes a rear lens group arranged between the microlens array support structure and the optical collection unit, and the rear lens group can be moved in a direction close to or away from the energy generating device to adjust the distance between the microlens array to be calibrated, the rear lens group and the optical collection unit.

3. The microlens array calibration system according to claim 2, characterized in that: The front lens group and / or the rear lens group have a plurality of optional lens combinations, and each lens combination contains a different number and / or lens type.

4. The microlens array calibration system according to claim 1, characterized in that: The optical collection unit can move towards or away from the energy generating device.

5. The microlens array calibration system according to claim 1, characterized in that: The energy generating device can provide an image field in the ultraviolet light band, the visible light band, the near infrared band, the far infrared band or the terahertz wave.

6. The microlens array calibration system according to claim 1, characterized in that: The light source of the energy generating device is a laser, a display, a heating coil or a terahertz light source.

7. The microlens array calibration system according to claim 6, characterized in that: The energy generating device further comprises a filter arranged at the light output end of the light source, and the filter is an ultraviolet filter, a visible filter, an infrared filter, a far infrared filter or a terahertz filter.

8. The microlens array calibration system according to claim 6, characterized in that: The energy generating device is a high color gamut LED display.

9. The microlens array calibration system according to any one of claims 1 to 8, characterized in that: The distance between the energy generating device and the optical measuring device is 50 cm to 1 m.

10. The microlens array calibration system according to any one of claims 1 to 8, characterized in that: The system further comprises a dark box, wherein the energy generating device and the optical measuring device are both arranged in the dark box.

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