WO2022213427A1 - 一种光源及其设置方法、光学检测方法及系统 - Google Patents

一种光源及其设置方法、光学检测方法及系统 Download PDF

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Publication number
WO2022213427A1
WO2022213427A1 PCT/CN2021/089097 CN2021089097W WO2022213427A1 WO 2022213427 A1 WO2022213427 A1 WO 2022213427A1 CN 2021089097 W CN2021089097 W CN 2021089097W WO 2022213427 A1 WO2022213427 A1 WO 2022213427A1
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light
image
light source
camera
characteristic data
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PCT/CN2021/089097
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English (en)
French (fr)
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于常青
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武汉精测电子集团股份有限公司
武汉精立电子技术有限公司
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Publication of WO2022213427A1 publication Critical patent/WO2022213427A1/zh

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    • 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
    • G01N21/8806—Specially adapted optical and illumination features
    • 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
    • G01N21/01—Arrangements or apparatus for facilitating the optical investigation
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B47/00—Circuit arrangements for operating light sources in general, i.e. where the type of light source is not relevant
    • H05B47/10—Controlling the light source
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B47/00—Circuit arrangements for operating light sources in general, i.e. where the type of light source is not relevant
    • H05B47/10—Controlling the light source
    • H05B47/155—Coordinated control of two or more light sources
    • 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
    • G01N21/8806—Specially adapted optical and illumination features
    • G01N2021/8835—Adjustable illumination, e.g. software adjustable screen
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2201/00—Features of devices classified in G01N21/00
    • G01N2201/06—Illumination; Optics
    • G01N2201/061—Sources

Definitions

  • the invention belongs to the technical field of optical detection, and in particular relates to a light source and its setting method, an optical detection method and a system.
  • the composition of product appearance defect detection equipment usually includes lighting source, light source controller, industrial camera, lens and image analysis and processing software.
  • the function of the lighting source is to reveal the defects on the product, and the basic principle of displaying defects is to highlight the defect area.
  • area array light-emitting devices such as LCD, OLED, Mini LED, and Micro LED, which are currently mainly used for image display, are highly flexible and controllable light sources in terms of their own characteristics.
  • These light-emitting devices not only break through the limitations of conventional surface light sources in structural form, and can realize curved, spherical or free-form surfaces, but also in terms of light-emitting characteristic data, such as the color and light-emitting intensity of light-emitting units can be controlled at the micron level.
  • light-emitting characteristic data such as the color and light-emitting intensity of light-emitting units can be controlled at the micron level.
  • a form of illumination light source related to the technology of the present invention is to place a transmissive template with a variable or fixed pattern in front of the light source, and the pattern on the template is illuminated on the projection plane by the light source and the projection optical system. Structured light is mainly used for 3D contour detection.
  • Another form is the commonly used projector and projector, which is used to display playback images and videos. It can project rich images on the illuminated plane, but its purpose is to display the projected image, and it is not based on the projected image. Perform feedback adjustment function.
  • the present invention provides a light source and its setting method, optical detection method and system, which can improve the detection of the detected object illuminated by it by adjusting the luminous intensity distribution of the area array illumination light source. precision.
  • a method for setting a light source comprising:
  • adjusting the luminous intensity distribution of the light source according to the image grayscale distribution characteristic data includes:
  • the light intensity of the light-emitting unit corresponding to the image sub-region will be increased, and if the average gray value of the image sub-region is higher than the set threshold range, the light intensity will be decreased. The light intensity of the light-emitting unit corresponding to the image sub-region.
  • obtaining the image grayscale distribution characteristic data of the standard sample within the field of view of the camera includes:
  • the initial luminous intensity of the light emitting unit is set to be the same, the area array light emitting device is imaged or projected onto the surface of the standard sample in the illumination area, and the surface of the standard sample is photographed with a camera to obtain image grayscale distribution characteristic data.
  • adjusting the luminous intensity distribution of the light source according to the image grayscale distribution characteristic data includes:
  • the grayscale reference value is the grayscale value when the image is in a balanced state, and the balanced state is that the average brightness value of the image reaches a preset value and the absolute value of the brightness difference between sub-regions of the image is less than the first preset threshold value.
  • the feedback matrix is set according to the deviation, specifically:
  • the deviation is a negative number and the absolute value of the deviation is greater than the second preset threshold, enhancing the light-emitting intensity of the light-emitting unit corresponding to the sub-region of the image proportionally according to the deviation;
  • the deviation is a positive number and the absolute value of the deviation is greater than the second preset threshold, reducing the light-emitting intensity of the light-emitting unit corresponding to the image sub-region proportionally according to the deviation;
  • obtaining the image grayscale distribution characteristic data of the standard sample within the field of view of the camera includes:
  • the pre-stored data includes the image grayscale distribution characteristic data of the standard sample within the camera's field of view, or, pre-stored data obtained from the standard sample's image grayscale distribution characteristic data within the camera's field of view.
  • the setting rule of the feedback matrix is that for the average gray value of the image sub-area is lower than the set threshold range, the light intensity of the light-emitting unit corresponding to the image sub-area is increased, and the average gray value of the image sub-area is higher than the set threshold. If the threshold value is within the range, the light intensity of the light-emitting unit corresponding to the sub-region of the image is reduced.
  • adjusting the luminous intensity distribution of the light source according to the image grayscale distribution characteristic data includes:
  • the obtained image is in a balanced state, where the average brightness value of the image reaches a preset value and the absolute value of the brightness difference between sub-regions of the image is smaller than the first preset threshold.
  • the light emitted by the area array light emitting device is imaged or projected to the illumination area through the optical component, so that each sub-area of the illumination area and each light emitting unit of the area array light emitting device have an optical conjugate relationship.
  • an optical detection method is provided, and the optical detection method includes the above-mentioned light source setting method, and
  • the method also includes:
  • the method also includes:
  • the adjustable parameters of the camera module After adjusting the luminous intensity distribution of the light source according to the image grayscale distribution characteristic data, adjust the adjustable parameters of the camera module, so that the image brightness reflected by the standard sample is adjusted to a balanced state, and the balanced state is that the average brightness value of the image reaches the preset value and The absolute value of the luminance difference between the sub-regions of the image is smaller than the first preset threshold.
  • the adjustable parameters of the camera module include one or more of exposure time, aperture size and gain.
  • a light source is provided, the light source is an area-array light-emitting device, and the area-array light-emitting device includes a light-emitting unit with a controllable luminous intensity,
  • the light source is used to illuminate the inspected product, and the luminous intensity distribution of the light source is adjusted through the feedback matrix obtained according to the image grayscale distribution characteristic data of the standard sample within the field of view of the camera.
  • an optical detection system comprising:
  • a camera for adjusting the adjustable parameters of the camera module after adjusting the luminous intensity distribution of the light source according to the image grayscale distribution characteristic data so that the image brightness reflected by the standard sample is adjusted to a balanced state, where the balanced state is the average brightness value of the image
  • the preset value is reached and the absolute value of the luminance difference between the sub-regions of the image is less than the first preset threshold.
  • a light source and its setting method, optical detection method and system of the present invention which adjust the luminous intensity distribution of the area array illumination light source according to the image grayscale distribution of the detected product within the field of view of the camera, and adjust the brightness distribution after compensation. It is fed back to the light source to perform illumination that compensates for the brightness distribution, so that the image reaches a state of uniform grayscale. On this basis, the brightness of the image can also be adjusted by adjusting the parameters of the camera.
  • the unit technology is mature, such as imaging technology, projection technology, light-emitting element display technology, and image grayscale analysis technology, so it is convenient for engineering realization and productization, and because the difference in illumination light intensity is increased, a single frame image can be obtained beyond its own dynamics.
  • the detection capability of a wide range does not require multiple exposures of the tested product with high contrast, which saves the detection time, thereby improving the detection efficiency and reducing the cost.
  • 1 is a schematic diagram of the mapping relationship between the area array light-emitting device and the lighting area according to the technical solution of the present invention
  • FIG. 2 is a schematic diagram of a projection pattern of an area array light-emitting device according to the technical solution of the present invention
  • 1-area array light-emitting device 2-imaging/projection optical assembly, 3-illumination area, 4-light-emitting unit and 5-illumination sub-area.
  • Lcos Liquid Crystal on Silicon, that is, liquid crystal on silicon.
  • a light source setting method includes the following steps:
  • the light source used in this method is an area array light-emitting device
  • the area array light-emitting device includes a light-emitting unit with a controllable luminous intensity, so that different light-emitting units illuminate different areas of the product to be detected, because each area of the product to be detected is different.
  • the reflection characteristic data is different
  • the image grayscale distribution characteristic data of the standard sample within the camera's field of view is obtained by taking pictures with the camera
  • the image grayscale distribution characteristic data is the distribution of the grayscale corresponding to each pixel point.
  • the grayscale distribution corresponding to the pixel points can be used to obtain the image grayscale distribution characteristic data of the standard sample within the camera's field of view, and the luminous intensity distribution of the light source can be adjusted through the image grayscale distribution characteristic data. If the intensity value is lower than the set threshold range, the light intensity of the light-emitting unit corresponding to the image sub-area is increased, and the average gray value of the image sub-area is higher than the set threshold range, then the light intensity corresponding to the image sub-area is reduced.
  • the light intensity of the light-emitting unit is adjusted, and the adjusted light source is used to illuminate the inspected product, which can avoid over-saturation of the image of the high-reflection area of the inspected product, and at the same time improve the image brightness of the low-reflection area, so that whether it is a high-reflection area or a low-reflection area Defects in the reflective area can be displayed simultaneously.
  • FIG. 1 is a schematic diagram of the mapping relationship between the area array light-emitting device and the lighting area according to the technical solution of the present invention.
  • the area array light-emitting device 1 is composed of a plurality of light-emitting units 4.
  • the types of the area-array light-emitting device include Mini LED, OLED, Micro LED, Lcos, etc. It can be a combination of multi-color sub-light-emitting units, such as RGB units, and the area array light-emitting device can independently control the light-emitting and light-emitting intensity according to the light-emitting unit or the light-emitting sub-unit under the driving of the driving circuit.
  • the light emitted by the area array light-emitting device 1 is imaged or projected to the illumination area 3 through the imaging/projection optical assembly 2.
  • the illumination sub-area 5 of the illumination area has an optical conjugate relationship with the light-emitting unit 4, and the illuminance on it is determined by the corresponding light-emitting unit.
  • the luminous intensity is determined, the object to be detected is placed in the illumination area, and the imaging photo of the surface of the detected object is taken by the camera for subsequent analysis.
  • acquiring image grayscale distribution characteristic data of the standard sample within the camera's field of view includes: setting the initial luminous intensity of the light-emitting unit to be the same, and using a camera to photograph the surface of the standard sample to obtain image grayscale distribution characteristic data.
  • the image of the standard sample within the field of view of the camera may be obtained by photographing in advance, or may be obtained by on-site photographing, wherein the initial luminous intensity of the light-emitting unit in the light source when the image is photographed can be set according to requirements, for example, setting
  • the area array light-emitting device is uniform light-emitting, that is, the intensity of each light-emitting unit is set to be the same, and the light intensity is half of its maximum light-emitting intensity.
  • the area array light-emitting device is imaged or projected onto the surface of the standard sample in the illumination area, and the image grayscale distribution characteristic data can be obtained by taking pictures of the surface of the standard sample with a camera.
  • the reflection coefficient is wavelength-dependent, for example, a test object with red and blue areas is illuminated with the same intensity of red light, the red area has a higher reflection and appears as a high grayscale (or overexposure) in the image, and the blue Areas appear as low grayscale (or underexposed).
  • the red area has a higher reflection and appears as a high grayscale (or overexposure) in the image, and the blue Areas appear as low grayscale (or underexposed).
  • the area array light-emitting device adopts uniform light field illumination, uses the camera to take an image of the sample surface (the first standard product of the product), dims the light-emitting unit of the area array light-emitting device corresponding to the bright area of the imaged image, and dims the dark area of the imaged image.
  • the light-emitting unit of the corresponding area array light-emitting device is brightened until the average grayscale of the imaged image is within the preset effective range (the preset effective range is the range that can achieve effective image detection, such as 50% of the image saturation value.
  • the projected light field since the projected light field is not uniform, it can increase the brightness of the illumination area corresponding to the area with low reflectivity, and increase the illumination area corresponding to the area with high reflectivity
  • the brightness of the sensor is reduced, and the luminous intensity of the area array light-emitting device is compensated in an active form so that the reflection intensity of the surface of the detected object is within the effective range that can be detected.
  • adjusting the luminous intensity distribution of the light source according to the image grayscale distribution characteristic data includes: acquiring the correspondence between each sub-region of the image and the light-emitting unit; acquiring the average gray value of each sub-region of the image and the preset For the deviation between the grayscale reference values, a feedback matrix is obtained according to the deviation, and the luminous intensity of the corresponding light-emitting unit is adjusted according to the feedback matrix.
  • the grayscale reference value is the grayscale value when the image is in a balanced state, and the balanced state is that the average brightness value of the image reaches a preset value and the absolute value of the brightness difference between sub-regions of the image is smaller than the first preset threshold value.
  • the absolute value of the difference between the average gray value of the image sub-region and the gray reference value is calculated, and the absolute value is greater than the first
  • the preset threshold range that is, the average gray value of the sub-region of the image is too large or too small, then adjust the luminous intensity of the corresponding light-emitting unit proportionally according to the difference, if the deviation is negative and the absolute value of the deviation is greater than the second preset threshold , it means that the average gray value of the image sub-area is small, and the illumination intensity of the corresponding area needs to be increased.
  • the luminous intensity of the light-emitting unit corresponding to the image sub-area can be proportionally enhanced, thereby improving the image of the low-reflection area of the detected product. If the deviation is a positive number and the absolute value of the deviation is greater than the second preset threshold, it means that the average gray value of the sub-region of the image is relatively large, and the illumination intensity of the corresponding area needs to be reduced. The luminous intensity of the light-emitting unit corresponding to the sub-region of the image is proportionally reduced, thereby reducing the gray value of the image in the high-reflection region of the detected product.
  • the grayscale reference value is the grayscale value when the image is in a balanced state
  • the balanced state is that the average brightness value of the image reaches the preset value and the absolute value of the brightness difference between the sub-regions of the image is less than the first preset threshold value, which is regarded as a
  • effective image detection can be achieved, for example, 50% to 80% of the saturation value of the image, corresponding to the gray levels 128 to 204 in the example.
  • the above adjustment process can be an iterative process, and the image grayscale distribution characteristic data of the standard sample within the field of view of the camera is updated according to the adjusted luminous intensity, so as to obtain the updated feedback matrix.
  • the image is in a balanced state, and the balanced state is that the average brightness value of the image reaches a preset value and the absolute value of the brightness difference between sub-regions of the image is smaller than the first preset threshold value.
  • the value of the feedback matrix corresponding to the surface array light-emitting device can be made more accurate, so that the acquired image grayscale distribution characteristic data can be more accurate.
  • the corresponding iteration parameters such as controlling the number of iterations or the error between two iterations
  • the iteration is terminated, so that the value of the feedback matrix corresponding to the area array light-emitting device is more accurate, so that the acquired image grayscale distribution characteristic data is more accurate.
  • the brightest and darkest regions have defects whose reflection coefficients are not much different from the background where they are located. When illuminated with a uniformly distributed light field, there may be bright regions.
  • the area array light-emitting device When overexposed, other areas are normal, or the dark area is underexposed and other areas are normal, use the above method to take pictures in the setting state where the area array light-emitting device is set to emit uniform light, analyze the image, and transmit the intensity distribution feedback matrix to the area array.
  • Light-emitting device adjust the illumination intensity of each area (feedback compensation), you can cycle to capture images and adjust the illumination intensity of each area until the illumination intensity of each area reaches the ideal state required for image processing; at this time, the feedback matrix is recorded and compensated to the area array Light emitting device, as a setting for detection of defects in this product, this area.
  • acquiring the image grayscale distribution characteristic data of the standard sample within the camera's field of view may also be: acquiring pre-stored data, where the pre-stored data includes the image grayscale of the standard sample within the camera's field of view Distribution characteristic data, or, pre-store the feedback matrix obtained according to the image grayscale distribution characteristic data of the standard sample within the field of view of the camera and used to adjust the light intensity of each light-emitting unit; the setting rule of the feedback matrix is: If the average gray value of the area is lower than the set threshold range, the light intensity of the light-emitting unit corresponding to the image sub-area is increased, and the average gray value of the image sub-area is higher than the set threshold range, then the corresponding image sub-area is reduced. The light intensity of the light-emitting unit.
  • the reflection characteristic data of each area on the surface of the standard sample for light is known, for example, the reflection coefficient of each area on the surface of the standard sample for light is known, you can set the corresponding light-emitting unit according to the reflection coefficient of each area on the surface of the standard sample.
  • the initial luminous intensity specifically, if the reflection coefficient of the corresponding area is large, the light intensity corresponding to the area will be smaller, and if the reflection coefficient of the corresponding area is small, the light intensity corresponding to the area will be increased, so as to obtain The image reaches a state of preliminary equilibrium.
  • the above-mentioned adjustment process may be an iterative process, obtaining an initial feedback matrix according to pre-stored data, setting the initial luminous intensity of the light source according to the initial feedback matrix; updating the image gray of the standard sample within the field of view of the camera according to the initial luminous intensity. degree distribution characteristic data to obtain the updated feedback matrix; through iteration, the obtained image is in a balanced state, and the balanced state is that the average brightness value of the image reaches the preset value and the absolute value of the brightness difference between the sub-regions of the image less than the first preset threshold.
  • the value of the feedback matrix corresponding to the area array light-emitting device can be made more accurate, so that the acquired image grayscale distribution characteristic data can be more accurate.
  • the iteration is terminated when it is within the set range, so that the value of the feedback matrix corresponding to the area array light-emitting device is more accurate, so that the acquired image grayscale distribution characteristic data is more accurate.
  • FIG. 2 is a schematic diagram of a projection pattern of an area array light-emitting device according to the technical solution of the present invention.
  • the known gray distribution characteristic data is the reflection coefficient of the detected object, and the reflection coefficient of the detected object is area a: 10, area b: 128, area c: 160, and area d: 240.
  • the coefficient is 0, all the incident light is absorbed without reflection; when the reflection coefficient is 255, 100% of the incident light is reflected.
  • Setting the reflection coefficient range from 0 to 255 also corresponds to the gray value of the image captured by the camera from 0 to 255. If the gray value of the image pixel exceeds 255, it is saturated or overexposed, and if it is less than 50, it is underexposed.
  • the illumination intensity of each sub-area of the illumination area is adjusted according to the distribution of the reflection coefficient of the sample surface. For example, set the illumination intensity of each sub-area of the illumination area as area a: 10x255, area b: 255, area c: 255 and area d. : 0.5x255, then the reflection intensity of each sub-area (the gray value corresponding to the image captured by the camera) is area a: 100, area b: 128, area c: 160 and area d: 120.
  • the reflection intensities (gray values) of each area of the tested object are respectively a area: 10, b area: 128, c area : 160, area d: 240, when there is a defect in the tested product (taking the reflection coefficient of the defect differing from the background area by 10% as an example), the gray value corresponding to the defect in each area (taking the reflection coefficient decreasing by 10% as an example)
  • Area a: (1-10%)*10 9
  • Area b: (1-10%)*128 115
  • Area c: (1-10%)*160 144
  • Area d: (1- 10%)*240 216
  • the grayscale difference between the substrate and the defect in each area is: a:1, b:13, c:16, d:24. Therefore, compared with areas b, c, and d, the difference between the defects in area a and the base gray level is as small as 1 gray level. If the image noise of the camera
  • the present invention also provides an optical detection method, which includes the above-mentioned light source setting method.
  • an optical detection method which includes the above-mentioned light source setting method.
  • by outputting the projection pattern to the area array light emitting device so that the area array light emitting device emits light according to the projection pattern, and is projected to the illumination area where the detected object is placed through the optical system.
  • the optical components of the beam splitter constitute a coaxial illumination/imaging system, or an optical system formed by an inclination with an included angle between the imaging optical axis and the projection optical axis.
  • a camera to take pictures of the lighting area, use a computer to analyze the image, record the underexposed and overexposed areas, form a feedback matrix and feed it back to the area array light-emitting device, increase the luminous intensity of the underexposed lighting area corresponding to the light-emitting unit area and reduce the exposure
  • the transitional illumination area corresponds to the luminous intensity of the light-emitting unit area, and the surface of the detected object is photographed again by the camera to realize the analysis of the subsequent steps, such as analyzing the imaging image to realize the accurate detection of the surface defect of the detected object.
  • the above method further includes: before acquiring the characteristic data of the image grayscale distribution of the standard sample within the field of view of the camera, fixing the parameters of the camera; using the fixed camera The parameters of the standard sample are obtained to obtain the image grayscale distribution characteristic data of the standard sample within the field of view of the camera; after adjusting the luminous intensity distribution of the light source according to the image grayscale distribution characteristic data, adjust the parameters of the camera so that the brightness of the image reflected by the standard sample is adjusted to a balanced In the balanced state, the average brightness value of the image reaches the preset value and the absolute value of the brightness difference between the sub-regions of the image is less than the first preset threshold value. By adjusting one of the exposure time, aperture size and gain of the camera or If there are more than one, the average brightness value of the imaged image can reach a preset value.
  • the present invention also provides a light source, the light source is an area-array light-emitting device, and the area-array light-emitting device includes a light-emitting unit with a controllable luminous intensity,
  • the light source is used to illuminate the product to be inspected, and the luminous intensity distribution of the light source is adjusted according to the image grayscale distribution characteristic data by acquiring the image grayscale distribution characteristic data of the standard sample within the camera's field of view.
  • the realization principle and technical effect of the light source are similar to the above-mentioned light source setting method, which will not be described here.
  • the present invention also provides an optical detection system, the system comprising:
  • the parameters are adjusted so that the brightness of the image reflected by the standard sample is adjusted to a balanced state.
  • the balanced state is that the average brightness value of the image reaches the preset value and the absolute brightness difference between the sub-regions of the image The value is less than the second preset threshold.

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Abstract

一种光源及其设置方法、光学检测方法及系统，光源为面阵发光器件（1），面阵发光器件（1）包括发光强度可控的发光单元（4），获取标准样品在相机视场范围内的图像灰度分布特性数据，根据图像灰度分布特性数据调整光源的发光强度分布，利用调整后的光源对被检测产品进行照明，调整面阵照明光源的发光强度分布，将补偿后的亮度分布反馈给光源，进行补偿亮度分布的照明，避免高反射区域图像饱和，同时提高低反射区域的图像亮度，从而提高被检测物体的检测精度。

Description

一种光源及其设置方法、光学检测方法及系统 【技术领域】
本发明属于光学检测技术领域，具体涉及一种光源及其设置方法、光学检测方法及系统。
【背景技术】
产品外观缺陷检测设备的构成通常包括照明光源、光源控制器、工业相机、镜头和图像分析处理软件，其中，照明光源的作用是将产品上的缺陷显现出来，显示缺陷的基本原则是突出缺陷区域和缺陷所处产品正常区域在人眼可感知物理量方面的差别，此差别通常为光强度差异和颜色差异。
例如，目前主要用于图像显示的LCD、OLED、Mini LED、Micro LED等面阵发光器件就其自身特点来说是高度灵活、可控的光源。这些发光器件不仅在结构形式上突破了常规面光源的限制，可以实现曲面、球面或自由曲面，而且表现在发光特性数据方面，例如可以在微米级别控制发光单元的颜色和发光强度。一方面，这些特点用于显示应用时，带来的是人们视觉感官方面的友好改善，使得使用者享受高品质图像展示。另一方面，当这些特点结合光学投影设备，用于缺陷检测照明时，使得在照明空间内生成可控光强和颜色分布的光场成为可能，而且可以几乎自由地在照明空间内调整光强、颜色。这些特点无疑会给缺陷检测技术带来新的手段。
现有的缺陷检测技术，存在由于被检测目标区域不同位置反射强度差异大，超过相机响应动态范围的情况，此时，单幅图像局部区域或出现曝光不足，或出现过曝，使得图像的局部信息差异缺失。目前通常采用相机多次曝光的方法来解决，但此方法受到特定检测场合的限制，例如产品处于移动状态。一种与本发明所述技术相关的照明光源形式是在光源前面放置一块具有可变或固定图案的透射模板，模板上的图案被光源和投影光学系统照射在投影平面上，该种形式以条纹结构光为主，大多用于3D轮廓检测。另一种形式是普遍使用的投影机、投影仪，用于显示播放图像及视频，可以将丰富的图像投射在被照明平面上，但其使用目的是显示放映图像，并没有根据放映出的图像进行反馈调整功能。
【发明内容】
针对现有技术的以上缺陷或改进需求，本发明提供了一种光源及其设置方法、光学检测方法及系统，通过调整面阵照明光源的发光强度分布以提高被其照射的被检测物体的检测精度。
为实现上述目的，按照本发明的一个方面，提供了一种光源设置方法，该方法包括：
获取标准样品在相机视场范围内的图像灰度分布特性数据；
根据图像灰度分布特性数据调整光源的发光强度分布，光源为面阵发光器件，面阵发光器件包括发光强度可控的发光单元；
利用调整后的光源对被检测产品进行照明。
作为本发明的进一步改进，根据图像灰度分布特性数据调整所述光源的发光强度分布包括：
对于图像子区域的平均灰度值低于设定阈值范围，则提高与所述图像子区域对应的发光单元的光强，对于图像子区域的平均灰度值高于设定阈值范围，则降低与所述图像子区域对应的发光单元的光强。
作为本发明的进一步改进，获取标准样品在相机视场范围内的图像灰度分布特性数据包括：
设置发光单元的初始发光强度相同，面阵发光器件成像或投影至照明区域内的标准样品表面，利用相机对标准样品表面拍照以获取图像灰度分布特性数据。
作为本发明的进一步改进，根据图像灰度分布特性数据调整光源的发光强度分布包括：
获取图像各子区域与发光单元之间的对应关系；
获取图像各子区域的平均灰度值与预先设置的灰度参考值之间的偏差，根据偏差设置反馈矩阵，根据反馈矩阵调整对应发光单元的发光强度；
灰度参考值为图像处于均衡状态时的灰度值，均衡状态为图像的平均亮度值达到预设值且图像各子区域之间的亮度差值的绝对值小于第一预设阈值。
作为本发明的进一步改进，根据偏差设置反馈矩阵，具体为：
若偏差为负数且偏差的绝对值大于第二预设阈值，则根据偏差按照比例增强图像子区域对应的发光单元的发光强度；
若偏差为正数且偏差的绝对值大于第二预设阈值，则根据偏差按照比例减小图像子区域对应的发光单元的发光强度；
根据反馈矩阵调整对应发光单元的发光强度，具体为：
根据调整后的发光强度更新标准样品在相机视场范围内的图像灰度分布特性数据，以获得更新后的反馈矩阵，通过迭代，使得获得的图像为均衡状态。
作为本发明的进一步改进，获取标准样品在相机视场范围内的图像灰度分布特性数据包括：
获取预先存储的数据，预先存储的数据包括标准样品在相机视场范围内的图像灰度分布特性数据，或者，预先存储根据标准样品在相机视场范围内的图像灰度分布特性数据获得的用于对各个发光单元进行光强调节的反馈矩阵；
反馈矩阵的设置规则为，对于图像子区域的平均灰度值低于设定阈值范围，则提高与图像子区域对应的发光单元的光强，对于图像子区域的平均灰度值高于设定阈值范围，则降低与图像子区域对应的发光单元的光强。
作为本发明的进一步改进，根据图像灰度分布特性数据调整光源的发光强度分布包括：
根据预先存储的数据获取初始反馈矩阵，根据初始反馈矩阵设置光源的初始发光强度；
根据初始发光强度更新标准样品在相机视场范围内的图像灰度分布特性数据，以获得更新后的反馈矩阵；
通过迭代，使得获得的图像为均衡状态，均衡状态为图像的平均亮度值达到预设值且图像各子区域之间的亮度差值的绝对值小于第一预设阈值。
作为本发明的进一步改进，面阵发光器件发出的光线通过光学组件成像或投影到照明区域，以使得照明区域的各个子区域与面阵发光器件的各个发光单元具有光学共轭关系。
为实现上述目的，按照本发明的另一个方面，提供了一种光学检测方法，光学检测方法包括上述光源设置方法，以及
相机，用于对标准样品或者待测产品进行成像。
作为本发明的进一步改进，该方法还包括：
在获取标准样品在相机视场范围内的图像灰度分布特性数据之前，固定相机模组的可调整参数；
利用固定相机的可调整参数获取标准样品在相机视场范围内的图像灰度分布特性数据。
作为本发明的进一步改进，该方法还包括：
在根据图像灰度分布特性数据调整光源的发光强度分布之后，调整相机模组的可调整参数，使得标准样品反射的图像亮度调节到均衡状态，均衡状态为图像的平均亮度值达到预设值且图像各子区域之间的亮度差值的绝对值小于第一预设阈值。
作为本发明的进一步改进，相机模组的可调整参数包括曝光时间、光圈大小和增益中的一个或多个。
作为本发明的进一步改进，其中，
光源与相机利用包括分光镜的光学组件形成的同轴光照/成像系统，或者
光源的投影光轴与相机的成像光轴之间具有夹角，使得成像系统对被测样品的反射光成像或透射光成像。
为实现上述目的，按照本发明的另一个方面，提供了一种光源，光源为面阵发光器件，面阵发光器件包括发光强度可控的发光单元，
光源用于对被检测产品进行照明，通过根据标准样品在相机视场范围内的图像灰度分布特性数据获得的反馈矩阵调整光源的发光强度分布。
为实现上述目的，按照本发明的另一个方面，提供了一种光学检测系统，该系统包括：
上述的光源；
以及相机，用于在根据图像灰度分布特性数据调整光源的发光强度分布之后，调整相机模组的可调整参数以使得标准样品反射的图像亮度调节到均衡状态，均衡状态为图像的平均亮度值达到预设值且图像各子区域之间的亮度差值的绝对值小于第一预设阈值。
总体而言，通过本发明所构思的以上技术方案与现有技术相比，具有以下有益效果：
本发明的一种光源及其设置方法、光学检测方法及系统，其根据被检测产品在相机视场范围内的图像灰度分布，调整面阵照明光源的发光强度分布，将补偿后的亮度分布反馈给光源，进行补偿亮度分布的照明，从而使得图像达到灰度均匀状态。在此基础上，还可以通过调节相机的参数，从而调整图像的亮度。通过上述手段，避免高反射区域图像饱和，同时提高低反射区域的图像亮度，使得无论是高反射区域还是低反射区域的缺陷都可以被同时显示出来，其工作原理简单、清晰，使用的各项单元技术成熟，例如成像技术、投影技术、发光元件显示技术、图像灰度分析技术，因此便于工程实现和产品化，而且因为增加了照射光强度的差异，可以使单帧图像获得超出其自身动态范围的检测能力，不需要对反差大的被测产品进行多次曝光，节省了检测时间，从而提高检测效率、降低成本。
【附图说明】
图1为本发明技术方案的面阵发光器件与照明区域映射关系的示意图；
图2为本发明技术方案的面阵发光器件投影图案的示意图；
在所有附图中，同样的附图标记表示相同的技术特征，具体为：
1-面阵发光器件、2-成像/投影光学组件、3-照明区域、4-发光单元和5-照明子区域。
【具体实施方式】
为了使本发明的目的、技术方案及优点更加清楚明白，以下结合附图及实施例，对本发明进行进一步详细说明。应当理解，此处所描述的具体实施例仅仅用以解释本发明，并不用于限定本发明。
此外，下面所描述的本发明各个实施方式中所涉及到的技术特征只要彼此之间未构成冲突就可以相互组合。下面结合具体实施方式对本发明进一步详细说明。
本发明所涉及的技术术语解释如下：
Lcos：Liquid Crystal on Silicon，即硅基液晶。
在一个实施例中，提供了一种光源设置方法，该方法包括如下步骤：
获取标准样品在相机视场范围内的图像灰度分布特性数据；根据图像灰度分布特性数据调整光源的发光强度分布，光源为面阵发光器件，面阵发光器件包括发光强度可控的发光单元；利用调整后的光源对被检测产品进行照明。
具体地，该方法中所用到的光源为面阵发光器件，面阵发光器件包括发光强度可控的发光单元，这样不同发光单元照射至被检测产品所对应的区域不同，由于被检测产品各个区域的反射特性数据不同，通过相机拍照获取标准样品在相机视场范围内的图像灰度分布特性数据，图像灰度分布特性数据即为各个像素点对应的灰度的分布情况，分析该图像中各个像素点对应的灰度的分布情况就可以得到标准样品在相机视场范围内的图像灰度分布特性数据，通过图像灰度分布特性数据调整光源的发光强度分布，如对于图像子区域的平均灰度值低于设定阈值范围，则提高与所述图像子区域对应的发光单元的光强，对于图像子区域的平均灰度值高于设定阈值范围，则降低与所述图像子区域对应的发光单元的光强，利用调整后的光源对被检测产品进行照明，这样可以避免被检测产品的高反射区域图像过于饱和，同时提高低反射区域的图像亮度，使得无论是高反射区域还是低反射区域的缺陷都可以被同时显示出来。
图1为本发明技术方案的面阵发光器件与照明区域映射关系的示意图。如图1所示，面阵发光器件1由多个发光单元4组成，面阵发光器件的类型包括Mini LED、OLED、Micro LED、Lcos等，每个发光单元4可以是单色发光单元，也可以是多色子发光单元的组合，例如RGB单元，面阵发光器件在驱动电路的驱动下，可以按发光单元或发光子单元独立控制发光及发光强度。面阵发光器件1发出的光线经过成像/投影光学组件2成像或投影到照明区域3，照明区域的照明子区域5与发光单元4具有光学共轭关系，其上的照度由对应的发光单元的发光强度决定，将被检测物体放置于照明区域，通过相机拍照被检测物体表面的成像照片，以供后续分析。
作为一个优选的实施例，获取标准样品在相机视场范围内的图像灰度分布特性数据包括：设置发光单元的初始发光强度相同，利用相机对标准样品表面拍照以获取图像灰度分布特性数据。
具体地，标准样品在相机视场范围内的图像可以是事先拍照所得的，也可以是现场拍摄所得，其中拍摄该图像时光源中的发光单元的初始发光强度可以依据需求进行设置，例如，设置面阵发光器件为均匀发光，即设置每个发光单元强度相同，光强为其最大发光强度的一半。面阵发光器件成像或投影至照明区域内的标准样品表面，利用相机对标准样品表面拍照 就可以获取图像灰度分布特性数据。由于反射系数与波长相关，例如用同样强度的红色光照明具有红色和蓝色区域的被测品，红色区具有较高的反射，在图像中显示为高灰阶(或过曝)，蓝色区显示为低灰阶(或曝光不足)。对于彩色样品，同样可以通过提高图像低灰度区域的光照强度，降低图像近饱和或过曝区域的光照强度，从而达到平衡图像灰度，以得到后续可进行有效处理的图像。
面阵发光器件采用均匀光场照明，利用相机拍摄样品表面(产品的首件标准品)图像，将成像图像的亮区所对应的面阵发光器件的发光单元调暗，将成像图像的暗区所对应的面阵发光器件的发光单元调亮，直到成像图像的平均灰度处于预设的有效范围内(预设的有效范围即为可实现图像有效检测的范围，例如图像饱和值的50％～80％，对应举例中的灰度128～204)，由于投影光场并不均匀，其可以将反射率低的区域所对应照明区域的亮度提升，将反射率过高的区域所对应照明区域的亮度降低，以主动的形式补偿面阵发光器件的发光强度使得被检测物体表面的反射强度处于可被检测的有效范围内。
作为一个优选的实施例，根据图像灰度分布特性数据调整光源的发光强度分布包括：获取图像各子区域与发光单元之间的对应关系；获取图像各子区域的平均灰度值与预先设置的灰度参考值之间的偏差，根据偏差获取反馈矩阵，根据反馈矩阵调整对应发光单元的发光强度。灰度参考值为图像处于均衡状态时的灰度值，所均衡状态为图像的平均亮度值达到预设值且图像各子区域之间的亮度差值的绝对值小于第一预设阈值。
具体地，由于获取拍照所得的图像各个子区域与发光单元之间存在对应关系，计算图像子区域的平均灰度值与灰度参考值之间的差值的绝对值，该绝对值大于第一预设阈值范围，即图像子区域的平均灰度值过大或者过小，则根据差值按照比例调整对应的发光单元的发光强度，如若偏差为负数且偏差的绝对值大于第二预设阈值，则说明图像子区域的平均灰度值较小，需要提高对应区域的光照强度，具体地，可以按照比例增强图像子区域对应的发光单元的发光强度，从而提高被检测产品的低反射区域图像的灰度值；若偏差为正数且偏差的绝对值大于第二预设阈值，则说明图像子区域的平均灰度值较大，需要降低对应区域的光照强度，具体地，可以根据偏差按照比例减小图像子区域对应的发光单元的发光强度，从而降低被检测产品的高反射区域图像的灰度值。灰度参考值为图像处于均衡状态时的灰度值，均衡状态为图像的平均亮度值达到预设值且图像各子区域之间的亮度差值的绝对值小于第一预设阈值，作为一个示例，均衡状态下为可实现图像有效检测，例如图像饱和值的50％～80％，对应举例中的灰度128～204。
更优选的，上述调整过程可以是一个迭代过程，根据调整后的发光强度更新标准样品在相机视场范围内的图像灰度分布特性数据，以获得更新后的反馈矩阵，通过迭代，使得获得 的图像为均衡状态，均衡状态为图像的平均亮度值达到预设值且图像各子区域之间的亮度差值的绝对值小于第一预设阈值。
通过上述迭代，可以使得面阵发光器件对应的反馈矩阵的值更精确，从而使得获取的图像灰度分布特性数据更加准确，通过控制对应的迭代参量，如控制迭代次数或者两次迭代的误差在预设范围内时终止迭代，从而使得面阵发光器件对应的反馈矩阵的值更加精确，从而使得获取的图像灰度分布特性数据更加准确。例如，对于一个样品表面存在4个反射系数不同的区域，在最亮和最暗区域分别有反射系数与其所处背景相差不大的缺陷，当用均匀分布的光场照明时，可能存在亮区过曝，其他区域正常，或者暗区曝光不足而其他区域正常的情况，使用上述方法，在设定面阵发光器件为均匀发光的设置状态拍照，分析图像，将强度分布反馈矩阵传递给面阵发光器件，调整各区的照射强度(反馈补偿)，可以循环拍摄图像和调整各区的照射强度，直到各个区域的照明强度达到图像处理所需要的理想状态；此时记录反馈矩阵，并补偿给面阵发光器件，作为针对此产品、此区域检测缺陷的设置。
作为一个优选的实施例，获取标准样品在相机视场范围内的图像灰度分布特性数据还可以为：获取预先存储的数据，预先存储的数据包括标准样品在相机视场范围内的图像灰度分布特性数据，或者，预先存储根据标准样品在相机视场范围内的图像灰度分布特性数据获得的用于对各个发光单元进行光强调节的反馈矩阵；反馈矩阵的设置规则为，对于图像子区域的平均灰度值低于设定阈值范围，则提高与图像子区域对应的发光单元的光强，对于图像子区域的平均灰度值高于设定阈值范围，则降低与图像子区域对应的发光单元的光强。
具体地，若已知晓标准样品表面各个区域对光线的反射特性数据，例如已知晓标准样品表面各个区域对光线的反射系数，可以依据标准样品表面各个区域对光线的反射系数设置对应的发光单元的初始发光强度，具体地，若对应的区域反射系数较大，则较小与该区域对应的光强，若对应的区域反射系数较小，则增大与该区域对应的光强，从而使得获得的图像达到初步均衡的状态。
更优选的，上述调整过程可以是一个迭代过程，根据预先存储的数据获取初始反馈矩阵，根据初始反馈矩阵设置光源的初始发光强度；根据初始发光强度更新标准样品在相机视场范围内的图像灰度分布特性数据，以获得更新后的反馈矩阵；通过迭代，使得获得的图像为均衡状态，均衡状态为图像的平均亮度值达到预设值且图像各子区域之间的亮度差值的绝对值小于第一预设阈值。通过迭代，可以使得面阵发光器件对应的反馈矩阵的值更精确，从而使得获取的图像灰度分布特性数据更加准确，通过控制对应的迭代参量，如控制迭代次数或者两次迭代的误差在预设范围内时终止迭代，从而使得面阵发光器件对应的反馈矩阵的值更加精确，从而使得获取的图像灰度分布特性数据更加准确。
图2为本发明技术方案的面阵发光器件投影图案的示意图。如图2所示，已知灰度分布特性数据为被检测物体反射系数，被检测物体反射系数分别为a区：10、b区：128、c区：160和d区：240，其中，反射系数为0时对入射光全部吸收，没有反射；反射系数为255时，对入射光有100％的反射。设置反射系数区间为0～255也对应着相机采集图像的灰度值为0～255，图像像素灰度值超过255为饱和或过曝，低于50为曝光不足。则按照样品表面反射系数的分布情况来调整照明区域各个子区域的光照强度，例如，设置照明区域各个子区域的光照强度分别为a区：10x255、b区：255、c区：255和d区：0.5x255，则各个子区域的反射强度(相机拍摄图像对应的灰度值)分别为a区：100、b区：128、c区：160和d区：120，在各个子区域的缺陷(以反射系数减少10％为示例)对应的灰度值分别为a区：(1-10％)*100＝90、b区：(1-10％)*128＝115、c区：(1-10％)*160＝144和d区：(1-10％)*120＝108，各个子区域基底与缺陷的灰度差分别为a区：10、b区:13、c区：16和d区：12。可见，相比于各个子区域的缺陷与基底灰度差均衡到10几个灰阶，a区原来1个灰阶的差别放大到10个灰阶，有利于a区的缺陷检出，同时，d区缺陷与基底灰阶差降到12，不影响缺陷检出。
对比于现有技术中，强度为255的照明投影均匀光场照明至被测品表面时，被测品各区的反射强度(灰度值)分别为a区：10、b区：128、c区：160、d区：240，被测品存在缺陷(以缺陷反射系数与各处背景区域相差10％为示例)时，在各区的缺陷(以反射系数减少10％为示例)对应的灰度值分别为a区：(1-10％)*10＝9、b区：(1-10％)*128＝115、c区：(1-10％)*160＝144、d区：(1-10％)*240＝216，各区基底与缺陷的灰度差为：a:1，b:13，c:16，d:24。因此，对比于b、c、d区，a区的缺陷与基底灰度差小到1个灰阶，如果相机的图像噪声超过1个灰阶，则通常检测不到a区的缺陷。
与此对应的，本发明还提供了一种光学检测方法，该光学检测方法包括上述光源设置方法。作为一个优选的实施例，通过将投影图案输出给面阵发光器件，以使得面阵发光器件依据该投影图案发光，通过光学系统投射至放置有被检测物体的照明区域，光学系统可以是通过包括分光镜的光学组件构成同轴光照/成像系统，也可以是成像光轴与投影光轴有夹角的倾斜方式形成的光学系统。利用相机对照明区域拍照，利用计算机对图像进行分析，记录曝光不足和曝光过度的区域，形成反馈矩阵并反馈给面阵发光器件，增加曝光不足的照明区域对应发光单元区域的发光强度和降低曝光过渡的照明区域对应发光单元区域的发光强度，利用相机对被检测物体表面再次拍照，以实现后续步骤的分析，如分析该成像图像实现被检测物体的表面缺陷的准确检测。
由于图像亮度还跟相机的参数有关，作为另一个优选的实施例，上述方法还包括：在获取标准样品在相机视场范围内的图像灰度分布特性数据之前，固定相机的参数；利用固定相机的参数获取标准样品在相机视场范围内的图像灰度分布特性数据；在根据图像灰度分布特性数据调整光源的发光强度分布之后，调整相机的参数，使得标准样品反射的图像亮度调节到均衡状态，均衡状态为图像的平均亮度值达到预设值且图像各子区域之间的亮度差值的绝对值小于第一预设阈值，通过调整相机的曝光时间、光圈大小和增益中的一个或多个，可以使得成像图像的平均亮度值达到预设值。
与上述一种光源设置方法相对应的，本发明还提供了一种光源，该光源为面阵发光器件，面阵发光器件包括发光强度可控的发光单元，
该光源用于对被检测产品进行照明，通过获取标准样品在相机视场范围内的图像灰度分布特性数据，根据图像灰度分布特性数据调整光源的发光强度分布。该光源的实现原理、技术效果与上述光源设置方法类似，在此不做累述。
与上述一种光学检测方法相对应的，本发明还提供了一种光学检测系统，该系统包括：
上述光源；
以及相机，用于在获取标准样品在相机视场范围内的图像灰度分布特性数据之前，利用固定参数拍照以获取标准样品在相机视场范围内的图像；还用于在根据图像灰度分布特性数据调整光源的发光强度分布之后，调整参数以使得标准样品反射的图像亮度调节到均衡状态，均衡状态为图像的平均亮度值达到预设值且图像各子区域之间的亮度差值的绝对值小于第二预设阈值。该系统的实现原理、技术效果与上述光学检测方法类似，在此不做累述。
本领域的技术人员容易理解，以上所述仅为本发明的较佳实施例而已，并不用以限制本发明，凡在本发明的精神和原则之内所作的任何修改、等同替换和改进等，均应包含在本发明的保护范围之内。

Claims (15)

  1. 一种光源设置方法，其特征在于，所述方法包括：
    获取标准样品在相机视场范围内的图像灰度分布特性数据；
    根据所述图像灰度分布特性数据调整所述光源的发光强度分布，所述光源为面阵发光器件，所述面阵发光器件包括发光强度可控的发光单元；
    利用调整后的光源对被检测产品进行照明。
  2. 根据权利要求1所述的一种光源设置方法，其中，根据所述图像灰度分布特性数据调整所述光源的发光强度分布包括：
    对于图像子区域的平均灰度值低于设定阈值范围，则提高与所述图像子区域对应的发光单元的光强，对于图像子区域的平均灰度值高于设定阈值范围，则降低与所述图像子区域对应的发光单元的光强。
  3. 根据权利要求1所述的一种光源设置方法，其中，获取标准样品在相机视场范围内的图像灰度分布特性数据包括：
    设置所述发光单元的初始发光强度相同，所述面阵发光器件成像或投影至照明区域内的标准样品表面，利用相机对标准样品表面拍照以获取所述图像灰度分布特性数据。
  4. 根据权利要求3所述的一种光源设置方法，其中，根据所述图像灰度分布特性数据调整所述光源的发光强度分布包括：
    获取图像各子区域与所述发光单元之间的对应关系；
    获取所述图像各子区域的平均灰度值与预先设置的灰度参考值之间的偏差，根据所述偏差设置反馈矩阵，根据所述反馈矩阵调整对应发光单元的发光强度；
    所述灰度参考值为图像处于均衡状态时的灰度值，所述均衡状态为图像的平均亮度值达到预设值且图像各子区域之间的亮度差值的绝对值小于第一预设阈值。
  5. 根据权利要求4所述的一种光源设置方法，其中，根据所述偏差设置反馈矩阵，具体为：
    若所述偏差为负数且偏差的绝对值大于第二预设阈值，则根据所述偏差按照比例增强所述图像子区域对应的发光单元的发光强度；
    若所述偏差为正数且偏差的绝对值大于第二预设阈值，则根据所述偏差按照比例减小所述图像子区域对应的发光单元的发光强度；
    根据所述反馈矩阵调整对应发光单元的发光强度，具体为：
    根据调整后的发光强度更新所述标准样品在相机视场范围内的图像灰度分布特性数据，以获得更新后的反馈矩阵，通过迭代，使得获得的所述图像为均衡状态。
  6. 根据权利要求1所述的一种光源设置方法，其中，获取标准样品在相机视场范围内的图像灰度分布特性数据包括：
    获取预先存储的数据，所述预先存储的数据包括所述标准样品在相机视场范围内的图像灰度分布特性数据，或者，预先存储根据所述标准样品在相机视场范围内的图像灰度分布特性数据获得的用于对各个发光单元进行光强调节的反馈矩阵；
    所述反馈矩阵的设置规则为，对于图像子区域的平均灰度值低于设定阈值范围，则提高与所述图像子区域对应的发光单元的光强，对于图像子区域的平均灰度值高于设定阈值范围，则降低与所述图像子区域对应的发光单元的光强。
  7. 根据权利要求6所述的一种光源设置方法，其中，根据所述图像灰度分布特性数据调整所述光源的发光强度分布包括：
    根据所述预先存储的数据获取初始反馈矩阵，根据所述初始反馈矩阵设置所述光源的初始发光强度；
    根据所述初始发光强度更新所述标准样品在相机视场范围内的图像灰度分布特性数据，以获得更新后的反馈矩阵；
    通过迭代，使得获得的所述图像为均衡状态，所述均衡状态为图像的平均亮度值达到预设值且图像各子区域之间的亮度差值的绝对值小于第一预设阈值。
  8. 根据权利要求1所述的一种光源设置方法，其中，所述面阵发光器件发出的光线通过光学组件成像或投影到照明区域，以使得所述照明区域的各个子区域与所述面阵发光器件的各个发光单元具有光学共轭关系。
  9. 一种光学检测方法，其特征在于，所述光学检测方法包括权利要求1-8中任一项所述的光源设置方法，以及
    相机，用于对所述标准样品或者所述待测产品进行成像。
  10. 根据权利要求9所述的一种光学检测方法，其中，所述方法还包括：
    在获取标准样品在相机视场范围内的图像灰度分布特性数据之前，固定所述相机模组的可调整参数；
    利用固定所述相机的可调整参数获取标准样品在相机视场范围内的图像灰度分布特性数据。
  11. 根据权利要求9所述的一种光学检测方法，其中，所述方法还包括：
    在根据所述图像灰度分布特性数据调整所述光源的发光强度分布之后，调整所述相机模组的可调整参数，使得标准样品反射的图像亮度调节到均衡状态，所述均衡状态为图像的平均亮度值达到预设值且图像各子区域之间的亮度差值的绝对值小于第一预设阈值。
  12. 根据权利要求9所述的一种光学检测方法，其中，所述相机模组的可调整参数包括曝光时间、光圈大小和增益中的一个或多个。
  13. 根据权利要求9所述的一种光学检测方法，其中，
    所述光源与所述相机利用包括分光镜的光学组件形成的同轴光照/成像系统，或者
    所述光源的投影光轴与所述相机的成像光轴之间具有夹角，使得成像系统对被测样品的反射光成像或透射光成像。
  14. 一种光源，其特征在于，所述光源为面阵发光器件，所述面阵发光器件包括发光强度可控的发光单元，
    所述光源用于对被检测产品进行照明，通过根据标准样品在相机视场范围内的图像灰度分布特性数据获得的反馈矩阵调整所述光源的发光强度分布。
  15. 一种光学检测系统，其特征在于，所述系统包括：
    如权利要求14所述的光源；
    以及相机，用于在根据所述图像灰度分布特性数据调整所述光源的发光强度分布之后，调整所述相机模组的可调整参数以使得标准样品反射的图像亮度调节到均衡状态，所述均衡状态为图像的平均亮度值达到预设值且图像各子区域之间的亮度差值的绝对值小于第一预设阈值。
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