Calibration method of incident light angle for microscopic vision

Abstract

The present invention provides a method for calibrating the angle of incident light for microscopic vision, comprising fixing a line structured light source and a microscopic image acquisition unit, the relative positions of which are fixed; calculating the magnification of the microscopic image acquisition unit; setting a calibration block so that the line structured light emitted by the line structured light source is reflected by the calibration block and then captured by the microscopic image acquisition unit; moving the calibration block so that the line structured light is projected onto a first plane, which is then captured by the microscopic image acquisition unit after reflection, resulting in a first line structured light image on the image plane of the microscopic image acquisition unit; moving the calibration block within the same horizontal plane so that the line structured light is projected onto a second plane, which is then captured by the microscopic image acquisition unit after reflection, resulting in a second line structured light image on the image plane of the microscopic image acquisition unit; calculating the image spacing between the first and second line structured light images; and calculating the angle of incident light for microscopic vision. The present invention is simple to prepare, has a simple calibration process, and can quickly complete the calibration of the structured light incident angle.

Description

Technical Field

[0001] The invention relates to a microscopic vision incident light angle calibration method. Background Art

[0002] In existing microscopic imaging measurement systems, structured light is often projected onto the surface of spatial objects. The imaging system of the microscopic system measures the geometric features of the object by receiving reflected light from the object's surface. In microscopic imaging measurement systems using structured light, it is often necessary to calibrate the angle of incident light of the structured light before performing microscopic visual measurement. Some existing microscopic imaging measurement systems use structured light to calibrate the angle of incident light. Commonly used structured light sources in microscopic measurement systems include point structured light sources and line structured light sources. Line structured light sources are widely used in industrial microscopic measurement. However, in current systems, to calibrate the incident angle or spatial orientation of the structured light source, the commonly used method is to use a three-dimensional or two-dimensional target to calibrate the spatial position relationship between the camera coordinate system, the target coordinate system, and the structured light source, and then solve the rotation and translation matrices in each coordinate system. The projection angle and other spatial orientation parameters of the line structured light source in the microscopic spatial system are then solved using the rotation and translation matrices.

[0003] When calibrating with a three-dimensional target, the manufacturing process for a three-dimensional high-precision calibration plate is complex and costly, and it is difficult to simultaneously obtain high-quality calibration images of different spatial points on the three-dimensional calibration plate. When calibrating with a two-dimensional planar target, this method requires manual placement of the calibration plate in multiple positions during the calibration process. Due to the small depth of field of the microscope system, it is necessary to ensure that the spatial position adjustment mechanism of the planar target can achieve rotation or translation of the planar target within the depth of field. This operation is complex and difficult to implement, and the calibration results are easily affected by the placement of the calibration plate.

[0004] As can be seen, the above calibration process requires the use of a three-dimensional or two-dimensional target. At the same time, the calculation process involves solving multiple parameters such as the camera and structured light translation and rotation matrices, which makes the solution process complicated. To address the above problems, a calibration method with simple device and easy operation is urgently needed to calibrate the incident light angle of microscopic vision. Summary of the Invention

[0005] To address the above issues, this application proposes a method for calibrating the incident light angle in microscopic vision. The technical solution of this application is as follows.

[0006] A method for calibrating the angle of incident light for microscopic vision includes: fixing a line structured light source and a microscopic image acquisition unit, wherein the relative positions of the line structured light source and the microscopic image acquisition unit are fixed; calculating the magnification β1 of the microscopic image acquisition unit; setting a calibration block so that the line structured light emitted by the line structured light source can be collected by the microscopic image acquisition unit after being reflected by the calibration block, wherein the calibration block includes a first plane and a second plane parallel to each other, the first plane and the second plane forming a first step on the calibration block, and the height of the first step is H1; moving the calibration block so that the line structured light is projected onto the first plane, is collected by the microscopic image acquisition unit after being reflected by the first plane, and a first line structured light image is obtained on the image plane of the microscopic image acquisition unit; moving the calibration block within the same horizontal plane so that the line structured light is projected onto the second plane, is collected by the microscopic image acquisition unit after being reflected by the second plane, and a second line structured light image is obtained on the image plane of the microscopic image acquisition unit; calculating the image spacing δ1 between the first line structured light image and the second line structured light image; and calculating the angle of incident light θ1 for microscopic vision:

[0007]

[0008] Let θ1 be the final calibrated microscopic vision incident light angle.

[0009] Furthermore, the microscopic vision incident light angle calibration method of the present invention calculates the magnification β1 of the microscopic image acquisition unit, including: using the microscopic image acquisition unit to image the calibration picture to obtain a calibration image, wherein the calibration picture includes a characteristic pattern, the characteristic pattern includes a first characteristic point and a second characteristic point, the calibration image includes a first characteristic image point and a second characteristic image point, and the first characteristic image point and the second characteristic image point are respectively images of the first characteristic point and the second characteristic point on the image plane of the microscopic image acquisition unit; measuring the point spacing l1 between the first characteristic point and the second characteristic point and calculating the point spacing L1 between the first characteristic image point and the second characteristic image point, and calculating the magnification β1 of the microscopic image acquisition unit according to β1=L1 / l1.

[0010] Furthermore, the microscopic vision incident light angle calibration method of the present invention calculates the point spacing L1 between the first characteristic image point and the second characteristic image point, including: establishing a coordinate system on the image plane of the microscopic image acquisition unit; using an image processing algorithm to respectively extract the point coordinates of the first characteristic image point and the second characteristic image point; and calculating the point spacing L1 between the first characteristic image point and the second characteristic image point based on the coordinates.

[0011] Furthermore, the microscopic vision incident light angle calibration method of the present invention includes: the characteristic pattern includes a third characteristic point, the calibration image includes a third characteristic image point, and the third characteristic image point is the image of the third characteristic point on the image plane of the microscopic image acquisition unit; measuring the point spacing l2 between the second characteristic point and the third characteristic point and calculating the point spacing L2 between the second characteristic image point and the third characteristic image point, and calculating the magnification β2 of the microscopic image acquisition unit according to β2=L2 / l2; calculating the average value β of β1 and β2, and recording β as the final magnification of the microscopic image acquisition unit.

[0012] Furthermore, the microscopic vision incident light angle calibration method of the present invention calculates the image spacing δ1 between the first line structured light image and the second line structured light image, including: establishing a rectangular coordinate system on the image plane of the microscopic image acquisition unit; using an image processing algorithm to extract the stripe centers of the first line structured light image and the second line structured light image, respectively, to obtain the first line structured light image stripe center point set and the second line structured light image stripe center point set, respectively; using a straight line fitting algorithm to perform linear fitting on the first line structured light image stripe center point set and the second line structured light image stripe center point set, to obtain the first line structured light image stripe center line and the second line structured light image stripe center line; calculating the line spacing between the first line structured light image stripe center line and the second line structured light image stripe center line, which is the image spacing δ1 between the first line structured light image and the second line structured light image.

[0013] Furthermore, the present invention provides a microscopic vision incident light angle calibration method, comprising: a calibration block including a third plane, the third plane being parallel to the second plane, the second plane and the third plane forming a second step on the calibration block, and the height of the second step being H2; moving the calibration block within the same horizontal plane so that the line structured light is projected onto the third plane, is reflected by the third plane, and is captured by a microscopic image acquisition unit, thereby obtaining a third line structured light image on an image plane of the microscopic image acquisition unit; calculating an image spacing δ2 between the second line structured light image and the third line structured light image; and calculating the microscopic vision incident light angle θ2:

[0014]

[0015] Calculate the average value θ of θ1 and θ2, and denote θ as the final calibrated microscopic vision incident light angle.

[0016] Furthermore, the microscopic vision incident light angle calibration method of the present invention includes: setting a calibration block so that the line structured light emitted by the line structured light source is simultaneously projected onto the first plane and the second plane, and can be collected by the microscopic image acquisition unit after being reflected by the first plane and the second plane, wherein the line structured light is reflected by the first plane to obtain a first line structured light image on the image plane of the microscopic image acquisition unit, and the line structured light is reflected by the second plane to obtain a second line structured light image on the image plane of the microscopic image acquisition unit.

[0017] Furthermore, in the microscopic vision incident light angle calibration method of the present invention, optical reflective layers are provided on the surfaces of the first plane and the second plane, and the optical properties of the optical reflective layers are consistent with the optical properties of the sample being measured for microscopic vision.

[0018] Furthermore, in the microscopic vision incident light angle calibration method of the present invention, the calibration image is set on the first plane or the second plane.

[0019] Furthermore, in the microscopic vision incident light angle calibration method of the present invention, the calibration block includes a first standard gauge block and a second standard gauge block, the first standard gauge block includes a first plane, and the second standard gauge block includes a second plane.

[0020] The present invention has the following beneficial effects:

[0021] (1) The device of the present invention is easy to prepare and has a simple calibration process, which can quickly calibrate the incident angle of structured light in a microscopic vision system;

[0022] (2) Simple repetitive operation steps can improve the accuracy of structured light angle calibration in microscopic vision systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the microscopic vision incident light angle calibration principle of the present invention;

[0024] Figure 2 It is a flow chart of the microscopic vision incident light angle calibration method of the present invention;

[0025] Figure 3 is a flow chart of the magnification calculation of the microscopic image acquisition unit of the present invention;

[0026] Figure 4 is a flow chart of calculating the image distance between the first line structured light image and the second line structured light image according to the present invention;

[0027] Figure 5 is a schematic diagram of a calibration block in an embodiment of the present invention;

[0028] Figure 6 is a schematic diagram of line structured light projection in one embodiment of the present invention;

[0029] Figure 7 This is another schematic diagram of a calibration block in an embodiment of the present invention. DETAILED DESCRIPTION

[0030] In conventional 3D vision measurement, the camera's internal and external parameters, as well as the structured light plane equation, can be accurately obtained by capturing a target with checkerboard or circular markers at different positions within the field of view using an image acquisition unit. However, in microscopic 3D measurement, due to the very small depth of field of the microscopic image acquisition unit, the target can only be clearly imaged when it is approximately parallel to the CCD or at a slight angle to the CCD. Therefore, conventional line structured light locating methods are not suitable for microscopic measurement.

[0031] The present invention provides a calibration block and a calibration picture. The calibration picture is used to calibrate the magnification of a microscopic image acquisition unit, and the calibration block is used to calibrate the incident light angle of the microscopic vision.

[0032] The calibration block proposed in this application includes a first plane and a second plane that are parallel to each other. The first plane and the second plane form a first step on the calibration block. The height of the first step is H1. The calibration image includes a characteristic pattern, which includes a first characteristic point and a second characteristic point. The distance between the first characteristic point and the second characteristic point is l1.

[0033] The following is the technical principle of the present invention using the above calibration block and calibration image to calibrate the incident light angle. Figure 1 This is a schematic diagram of the microscopic vision incident light angle calibration principle of the present invention.

[0034] The incident light is projected onto the calibration block at an incident angle θ1, reaching point A on the first plane and point C on the second plane respectively. The reflected light passes through the objective lens and forms images A′ and C′ on the image plane respectively. AD is the focal plane of the microscopic image acquisition unit, and the magnification β1 of the microscopic image acquisition unit satisfies:

[0035] Right now:

[0036] According to the geometric relationship, we have:

[0037]

[0038] From this, we can get the height H1 of the first step formed by the first plane and the second plane:

[0039]

[0040] thereby:

[0041] The above formula shows that even small changes in the incident angle can cause significant errors in the measurement results. However, due to errors in the actual processing or assembly of components, the actual installed incident angle of the incident light source may deviate from the designed value. To eliminate the effects of incident angle errors and improve measurement accuracy, the incident angle of the incident light must be calibrated.

[0042] Furthermore, the incident angle θ1 can be calculated according to the height H1 of the first step:

[0043]

[0044] Based on the above theory, the present invention proposes a microscopic vision incident light angle calibration method based on triangulation. Figure 2 The specific contents of the method of the present invention are as follows.

[0045] S201 , setting a line structured light source and a microscopic image acquisition unit, wherein the line structured light source and the microscopic image acquisition unit are fixed relative to each other.

[0046] The line structured light source used in the present invention can be a line laser, or white light, red light, or other light sources, which can be selected according to different experimental scenarios. In some embodiments, the present invention often uses a line laser to complete the experimental calibration process.

[0047] The microscopic image acquisition unit used in some embodiments of the present invention is a microscopic camera. Generally, the depth of field of the objective lens of a microscopic camera is very small, and a clear image can only be formed at a position approximately parallel to the CCD. In order to ensure accurate calibration of the incident angle of the incident light, the position of the line structured light source and the microscopic camera is usually fixed relative to each other so that the line structured light emitted by the line structured light source can be reflected by the sample to be tested and then captured by the microscopic camera. The line structured light on the surface of the sample to be tested at different heights is captured by the microscopic camera and formed on the image plane of the microscopic camera. After calculation, the height of the sample to be tested can be truly reflected.

[0048] S202, calculating the magnification β1 of the microscopic image acquisition unit.

[0049] The dimensions of a sample imaged by a microscopic image acquisition unit, such as a microscopic camera, are not necessarily the same as the sample's actual dimensions. To ensure that the imaged dimensions truly reflect the sample's actual three-dimensional dimensions, the magnification of the microscopic image acquisition unit must be calculated and converted to the actual three-dimensional dimensions. Typically, the magnification of the microscopic image acquisition unit is calculated by comparing the three-dimensional dimensions of a sample of known dimensions on the image plane of the microscopic image acquisition unit with the sample's actual dimensions.

[0050] The present invention uses the microscopic image acquisition unit to image the calibration picture to calculate the magnification β1 of the microscopic image acquisition unit. Figure 3 , the specific steps are as follows:

[0051] S2021: Use a microscopic image acquisition unit to image the calibration picture to obtain a calibration image.

[0052] The calibration image of the present invention includes a characteristic pattern, the characteristic pattern includes a first characteristic point and a second characteristic point, and the calibration image includes a first characteristic image point and a second characteristic image point, and the first characteristic image point and the second characteristic image point are respectively images of the first characteristic point and the second characteristic point on the image plane of the microscopic image acquisition unit.

[0053] In some embodiments of the present invention, the characteristic pattern used is a circular spot-shaped coding point with two black dots on a white background. The centers of the two circular spots are selected as the first characteristic point and the second characteristic point respectively. At this time, the images formed on the image plane of the microscope camera correspond to the first characteristic image point and the second characteristic image point.

[0054] When using a microscope camera to image a characteristic pattern, adjust the microscope camera's working distance so that the characteristic pattern can leave a clear image on the microscope's image plane. Adjust the microscope camera's exposure time so that the characteristic pattern's image on the image plane has moderate brightness.

[0055] When the present invention uses the microscopic image acquisition unit to capture an image of a characteristic pattern, it is not necessary to capture the entire characteristic pattern, and it is only necessary to capture the first characteristic point and the second characteristic point clearly.

[0056] The characteristic pattern of the present invention may also use circular spot-shaped coding points with black dots on a white background, or other characteristic patterns of unlimited shapes, as long as the first characteristic point and the second characteristic point can be clearly marked on the characteristic pattern.

[0057] S2022 , measuring the point distance l1 between the first feature point and the second feature point and calculating the point distance L1 between the first feature image point and the second feature image point.

[0058] S2023, calculate the magnification β1 of the microscopic image acquisition unit according to β1=L1 / l1.

[0059] The point distance l1 between the first characteristic point and the second characteristic point can be directly measured using a measuring instrument with relatively high precision.

[0060] The distance L1 between the first characteristic image point and the second characteristic image point is calculated using an image processing algorithm. The calculation process of some embodiments of the present invention includes:

[0061] A coordinate system is established on the image plane of the microscopic image acquisition unit; the coordinates of the first characteristic image point and the second characteristic image point are respectively extracted using an image processing algorithm; and the distance L1 between the first characteristic image point and the second characteristic image point is calculated based on the coordinates.

[0062] More specifically, some embodiments of the present invention establish a rectangular coordinate system on the image plane of the microscopic image acquisition unit; use an image processing algorithm to extract the coordinates (x1, y1) and (x2, y2) of the first feature image point and the second feature image point respectively; The point distance L1 between the first characteristic image point and the second characteristic image point is calculated.

[0063] In some embodiments of the present invention, an edge extraction algorithm is used to determine the positions of the first and second feature points. A rectangular coordinate system is established on the image plane of the microscopic image acquisition unit to provide rectangular coordinates (x1, y1) and (x2, y2). After the coordinates of the two points are determined, the existing point distance formula is used to calculate the point spacing L1 between the first and second feature points.

[0064] The present invention only needs to determine the relative position of the first characteristic image point and the second characteristic image point, and then calculate the distance between the two points, and is not limited to the adopted coordinate system, algorithm and formula.

[0065] When calculating the magnification of a microscopic image acquisition unit, the present invention can either use the imaging module of the microscopic image acquisition unit alone for measurement or directly place an image below a fixed microscopic image acquisition unit for measurement. When using the imaging module of the microscopic image acquisition unit alone for measurement, the calibration image can be directly aligned with the imaging plane of the imaging module, which results in higher measurement accuracy.

[0066] S203 , setting a calibration block so that the line structured light emitted by the line structured light source can be collected by the microscopic image collection unit after being reflected by the calibration block.

[0067] In some embodiments of the present invention, a calibration block is placed below the line structured light source and the microscopic image acquisition unit. The line structured light emitted by the line structured light source is projected onto the calibration block and is reflected by the calibration block and then acquired by the microscopic image acquisition unit.

[0068] The line structured light source of the present invention can use line laser, white light, red light or other light sources, depending on the specific experimental conditions. It only needs to ensure that the line structured light emitted by the line structured light source can be collected by the microscopic image acquisition unit after being reflected by the calibration block.

[0069] S204 , moving the calibration block so that the line structured light is projected onto the first plane, and is captured by the microscopic image acquisition unit after being reflected by the first plane, thereby obtaining a first line structured light image on the image plane of the microscopic image acquisition unit.

[0070] In some embodiments of the present invention, after securing the line structured light source and the microscopic image acquisition unit, the camera's working distance is adjusted to ensure that the calibration block and the line structured light projected onto it are clearly imaged on the image plane of the microscopic image acquisition unit. During the imaging process, the microscopic image acquisition unit's exposure time can be adjusted to ensure that the image brightness meets the requirements for clear imaging.

[0071] S205 , moving the calibration block in the same horizontal plane so that the line structured light is projected onto the second plane, and is captured by the microscopic image acquisition unit after being reflected by the second plane, thereby obtaining a second line structured light image on the image plane of the microscopic image acquisition unit.

[0072] To ensure that the height difference between the line structured light projected onto the first and second planes is the known height H1 of the first step, the calibration block is controlled to move within the same horizontal plane as it moves within the field of view of the microscopic image acquisition unit. In some embodiments of the present invention, the calibration block is placed directly on a platform below the line structured light source and the microscopic image acquisition unit to ensure that the calibration block moves within the same horizontal plane.

[0073] S206 , calculating an image distance δ1 between the first line structured light image and the second line structured light image.

[0074] In the above steps, the first line structured light image and the second line structured light image have been obtained on the image plane of the microscopic image acquisition unit. The next step is to use the image processing algorithm to calculate the image spacing δ1 between the first line structured light image and the second line structured light image. Figure 4 , the specific steps include:

[0075] S2061: Establish a rectangular coordinate system on the image plane of the microscopic image acquisition unit.

[0076] Some embodiments of the present invention establish a rectangular coordinate system on the image plane of the microscopic image acquisition unit, but the present invention may also adopt other methods of establishing a coordinate system, such as establishing a polar coordinate system, as long as the image separation δ1 between the two structured light images can be calculated through mathematical calculation.

[0077] S2062 , using an image processing algorithm to extract fringe centers of the first line structured light image and the second line structured light image, respectively, to obtain a first line structured light image fringe center point set and a second line structured light image fringe center point set.

[0078] There are many image processing algorithms that can be used to extract the centers of stripes in line structured light images. Common methods include the grayscale centroid method and the Steger method. However, the actual processing algorithm is not limited to one of these methods.

[0079] Some embodiments of the present invention use the grayscale centroid method to extract the stripe centers of the line structured light image. The specific steps are:

[0080] The coordinates of the center point of each row of stripes in the structured light image are solved from top to bottom. For each row of points, assume that the x coordinate value of the point in the image plane coordinate system is x i , the y coordinate value is y i (All y-point coordinate values ​​in this row are y i ), the gray value of this point is p i, assuming that the number of light spots on the stripes in the row in the image coordinate system is n, then the pixel coordinate x of the center point of the stripes in the row can be expressed as:

[0081]

[0082] By using this formula to solve the coordinates of the center point of each row, we can get the center coordinates of each row of stripes. These points constitute the center point set of the first line structured light image stripes and the center point set of the second line structured light image stripes.

[0083] S2063 , performing linear fitting on the first line structured light image fringe center point set and the second line structured light image fringe center point set using a straight line fitting algorithm to obtain the first line structured light image fringe center line and the second line structured light image fringe center line.

[0084] The straight line fitting algorithm adopted in some embodiments of the present invention is the least squares method. By using the least squares method to perform straight line fitting on the above-mentioned first line structured light image stripe center point set and the second line structured light image stripe center point set, the straight line equation of the first line structured light image stripe center line and the second line structured light image stripe center line can be obtained.

[0085] S2064 , calculating the line spacing between the center lines of the first line structured light image stripes and the center lines of the second line structured light image stripes, which is the image spacing δ1 between the first line structured light image and the second line structured light image.

[0086] After solving the equations of the lines between the center line of the first structured light image stripe and the center line of the second structured light image stripe, the distance between the lines can be calculated. The distance between the lines can be calculated using the conventional straight line distance formula.

[0087] S207, calculate the microscopic vision incident light angle θ1:

[0088]

[0089] Let θ1 be the final calibrated microscopic vision incident light angle.

[0090] According to the data obtained in the above steps, the various parts are substituted into the formula to calculate the microscopic vision incident light angle θ1, which is the calibrated microscopic vision incident light angle.

[0091] The above is the microscopic incident light angle calibration method proposed by the present invention. In some embodiments of the present invention, the height H1 of the first step can be measured using a gauge block comparator. The high measurement accuracy lays the foundation for the accuracy of subsequent calculations.

[0092] In some embodiments of the present invention, the characteristic pattern further includes a third characteristic point. The image of the third characteristic point on the image plane of the microscopic image acquisition unit is the third characteristic image point. Using the same calculation method as described above, the magnification factor β2 of the microscopic image acquisition unit can be calculated based on the inter-point spacing l2 between the second and third characteristic points and the inter-point spacing L2 between the second and third characteristic image points: that is, β2 = L2 / l2. To account for errors in individual measurements, β1 and β2 are not necessarily the same. A more accurate magnification factor β can be obtained by averaging β1 and β2.

[0093] Similar to the method of using three characteristic points, the present invention can also use multiple characteristic points to calculate the magnification. When multiple different characteristic points are used for measurement, the measurement accuracy will be higher.

[0094] The multiple feature points of the present invention are not limited to their positions in the feature pattern, and only need to satisfy the above measurement steps in a single measurement.

[0095] like Figure 5 In some embodiments of the present invention, the calibration block further includes a third plane, which is parallel to the second plane. The second plane and the third plane form a second step on the calibration block. When the line structured light is projected onto the third plane, it is reflected by the third plane and captured by the microscopic image acquisition unit, resulting in a third line structured light image on the image plane of the microscopic image acquisition unit.

[0096] Following the same steps as above, measure the height H2 of the second step, calculate the image spacing δ2 between the second and third line structured light images, and calculate the microscopic vision incident light angle θ2 based on this:

[0097]

[0098] Through different measurements and calculations, different incident light angle values ​​are obtained. Calculating the average value of each value can obtain a more accurate microscopic vision incident light angle, that is, the final calibrated microscopic vision incident light angle.

[0099] The present invention can repeat the above steps to determine the microscopic vision incident light angle through different step heights, thereby improving the accuracy of microscopic vision incident light angle calibration.

[0100] like Figure 6 In one embodiment of the present invention, a calibration block is configured to allow the line structured light emitted by the line structured light source to be simultaneously projected onto a first plane and a second plane. After reflection from both planes, the light can be captured by the microscopic image acquisition unit. Two line structured light images appear directly on the image plane of the microscopic image acquisition unit. An image processing algorithm is used to calculate the line spacing between these two line structured light images. This calculation also yields the final calibrated microscopic incident light angle.

[0101] In this embodiment, line structured light images on multiple planes can be processed simultaneously, which saves calibration steps and improves the calibration speed of the microscopic vision incident light angle.

[0102] like Figure 7 In some embodiments of the present invention, the calibration block used is a combination of different standard gauge blocks. For example, in one embodiment, a first standard gauge block and a second standard gauge block are used, and the height difference between the first standard gauge block and the second standard gauge block is equivalent to the height H1 of the first step described above. Similarly, multiple standard gauge blocks of different heights can be combined, spliced, or placed separately, and multiple measurements can be performed to obtain more accurate calibration results for the microscopic visual incident light angle.

[0103] In some embodiments of the present invention, the calibration image is directly set on the first plane or the second plane, and the magnification calculation of the microscopic image acquisition unit and the image spacing between line structured light images can be performed simultaneously, thereby improving the calibration speed of the microscopic vision incident light angle.

[0104] In some embodiments of the present invention, optical reflective layers are provided on the surfaces of the first and second planes, and the optical properties of the optical reflective layers are consistent with the optical properties of the sample being measured under microscopic vision. Microscopic vision measurement is primarily used for three-dimensional detection of samples. During calibration, calibrating the incident light angle on the optical reflective layer, which has optical properties consistent with those of the sample being measured, can improve the accuracy of the three-dimensional detection results of the sample being measured.

[0105] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A microscopic vision incident light angle calibration method, characterized in that: include: A fixed line structured light source and a microscopic image acquisition unit, wherein the line structured light source and the microscopic image acquisition unit are fixed in relative position; Calculating the magnification β1 of the microscopic image acquisition unit; A calibration block is provided so that the line structured light emitted by the line structured light source can be collected by the microscopic image collection unit after being reflected by the calibration block, wherein: The calibration block includes a first plane and a second plane that are parallel to each other, the first plane and the second plane forming a first step on the calibration block, and the height of the first step is H1; Moving the calibration block so that the line structured light is projected onto a first plane, and is captured by the microscopic image acquisition unit after being reflected by the first plane, thereby obtaining a first line structured light image on an image plane of the microscopic image acquisition unit; Moving the calibration block within the same horizontal plane so that the line structured light is projected onto a second plane, and is captured by the microscopic image acquisition unit after being reflected by the second plane, thereby obtaining a second line structured light image on an image plane of the microscopic image acquisition unit; Calculating an image distance δ1 between the first line structured light image and the second line structured light image; Calculate the incident light angle θ1 for microscopic vision: Let θ1 be the final calibrated microscopic vision incident light angle.

2. The microscopic vision incident light angle calibration method according to claim 1, characterized in that: The calculating of the magnification β1 of the microscopic image acquisition unit includes: The calibration picture is imaged using the microscopic image acquisition unit to obtain a calibration image, wherein: The calibration image includes a characteristic pattern, and the characteristic pattern includes a first characteristic point and a second characteristic point. The calibration image includes a first characteristic image point and a second characteristic image point, wherein the first characteristic image point and the second characteristic image point are images formed by the first characteristic point and the second characteristic point on the image plane of the microscopic image acquisition unit respectively; The point distance l1 between the first characteristic point and the second characteristic point is measured and the point distance L1 between the first characteristic image point and the second characteristic image point is calculated. The magnification β1 of the microscopic image acquisition unit is calculated according to β1=L1 / l1.

3. The microscopic vision incident light angle calibration method according to claim 2, characterized in that: The calculating of the distance L1 between the first feature image point and the second feature image point includes: Establishing a coordinate system on the image plane of the microscopic image acquisition unit; Extracting the coordinates of the first feature image point and the second feature image point respectively using an image processing algorithm; The point distance L1 between the first characteristic image point and the second characteristic image point is calculated according to the coordinates.

4. The microscopic vision incident light angle calibration method according to claim 2, characterized in that: include: The characteristic pattern includes a third characteristic point, the calibration image includes a third characteristic image point, and the third characteristic image point is an image formed by the third characteristic point on the image plane of the microscopic image acquisition unit; Measuring the point distance l2 between the second characteristic point and the third characteristic point and calculating the point distance L2 between the second characteristic image point and the third characteristic image point, and calculating the magnification β2 of the microscopic image acquisition unit according to β2=L2 / l2; Calculate the average value β of β1 and β2, and denote β as the magnification of the final microscopic image acquisition unit.

5. The microscopic vision incident light angle calibration method according to claim 1, characterized in that: The calculating of the image distance δ1 between the first line structured light image and the second line structured light image includes: Establishing a rectangular coordinate system on the image plane of the microscopic image acquisition unit; Extracting the fringe centers of the first line structured light image and the second line structured light image respectively using an image processing algorithm to obtain a fringe center point set of the first line structured light image and a fringe center point set of the second line structured light image respectively; Performing linear fitting on the first line structured light image fringe center point set and the second line structured light image fringe center point set using a straight line fitting algorithm to obtain a first line structured light image fringe center line and a second line structured light image fringe center line; The line spacing between the center line of the first line structured light image stripes and the center line of the second line structured light image stripes is calculated, which is the image spacing δ1 between the first line structured light image and the second line structured light image.

6. The microscopic vision incident light angle calibration method according to claim 1, characterized in that: include: The calibration block includes a third plane, the third plane is parallel to the second plane, the second plane and the third plane form a second step on the calibration block, and the height of the second step is H2; Moving the calibration block within the same horizontal plane so that the line structured light is projected onto a third plane, is reflected by the third plane, and is captured by the microscopic image acquisition unit, thereby obtaining a third line structured light image on an image plane of the microscopic image acquisition unit; Calculating an image distance δ2 between the second line structured light image and the third line structured light image; Calculate the incident light angle θ2 for microscopic vision: Calculate the average value θ of θ1 and θ2, and denote θ as the final calibrated microscopic vision incident light angle.

7. The microscopic vision incident light angle calibration method according to claim 1, characterized in that: include: A calibration block is provided so that the line structured light emitted by the line structured light source is projected onto the first plane and the second plane at the same time, and can be collected by the microscopic image collection unit after being reflected by the first plane and the second plane, wherein: After the line structured light is reflected by the first plane, a first line structured light image is obtained on the image plane of the microscopic image acquisition unit. After the line structured light is reflected by the second plane, a second line structured light image is obtained on the image plane of the microscopic image acquisition unit.

8. The microscopic vision incident light angle calibration method according to claim 1, characterized in that: An optical reflective layer is provided on the surfaces of the first plane and the second plane, and the optical properties of the optical reflective layer are consistent with the optical properties of the sample to be measured under microscopic vision.

9. The microscopic vision incident light angle calibration method according to claim 2, characterized in that: The calibration image is set on the first plane or the second plane.

10. The microscopic vision incident light angle calibration method according to claim 1, characterized in that: The calibration block includes a first standard gauge block and a second standard gauge block, the first standard gauge block includes a first plane, and the second standard gauge block includes a second plane.

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