CN108765301B - Optical system and distortion correction method and system thereof - Google Patents

Optical system and distortion correction method and system thereof Download PDF

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CN108765301B
CN108765301B CN201810258291.2A CN201810258291A CN108765301B CN 108765301 B CN108765301 B CN 108765301B CN 201810258291 A CN201810258291 A CN 201810258291A CN 108765301 B CN108765301 B CN 108765301B
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determining
visible light
infrared
collimator
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景文博
刘健
王晓曼
罗秦
刘智
王春艳
刘鹏
赵海丽
姜会林
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Changchun University of Science and Technology
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    • G06T7/00—Image analysis
    • G06T7/80—Analysis of captured images to determine intrinsic or extrinsic camera parameters, i.e. camera calibration
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    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2207/00—Indexing scheme for image analysis or image enhancement
    • G06T2207/10—Image acquisition modality
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    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
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Abstract

The invention discloses an optical system and a distortion correction method and system thereof. The distortion correction method includes: acquiring the focal length of a first collimator lens when a collimator generates parallel light; determining a visible light image and a near infrared image according to the focal length of the first parallel light pipe lens; establishing an image coordinate system by taking the optical axis of incident light as a Z axis and taking a plane vertical to the optical axis as an XOY plane; acquiring the side length of a unit square in the grid plate; the grid plate comprises a plurality of unit squares; determining pixel points corresponding to the unit square according to the side length; determining a coordinate transformation matrix according to the pixel points and the image coordinate system; determining a visible light distortion-free image according to the visible light image and the transformation matrix; and determining a near-infrared undistorted image according to the near-infrared image and the transformation matrix. The optical system and the distortion correction method and system thereof can reduce the measurement error of the optical system.

Description

Optical system and distortion correction method and system thereof
Technical Field
The present invention relates to the field of optical distortion correction technologies, and in particular, to an optical system and a distortion correction method and system thereof.
Background
The laser semi-active terminal guided munition system consists of an irradiator and guided munitions, wherein the irradiator emits laser to irradiate an attacked target, and the guided munition identifies and strikes the target according to irradiation light spots; the laser irradiation performance is an important index for evaluating a weapon system, and the laser irradiation performance spatial characteristic monitoring system captures a moving diffuse reflection target plate and measures the diffuse reflection target plate through a single visible light camera. However, when a single visible light camera is degraded for use to perform measurement, because the imaging spectral response range of the visible light camera only has high quantum efficiency in the visible light range, and although the visible light camera responds to 1064nm near-infrared light, the quantum efficiency is low, when the single visible light camera simultaneously images a target plate (visible light) and a light spot (near-infrared light), the single visible light camera must have a large integration time to image, so that large background noise is introduced, the signal-to-noise ratio of the light spot image is low, and the measurement error of the optical system is large.
Disclosure of Invention
The invention aims to provide an optical system and a distortion correction method and system thereof, which aim to solve the problem of large measurement error of the optical system in the prior art.
In order to achieve the purpose, the invention provides the following scheme:
an optical system, comprising: the device comprises a light source, a collimator and a telephoto optical system, wherein the collimator and the telephoto optical system are sequentially arranged on one side of the light source, and the telephoto optical system is connected with a computer;
a grid plate is arranged in the collimator;
the bottoms of the light source, the collimator and the telephoto optical system are respectively provided with an adjusting table; the adjusting table is used for adjusting the positions of the light source, the collimator and the telephoto optical system;
the telephoto optical system comprises a Cassegrain reflection structure, a lens, a beam splitter prism, a visible light camera, an optical filter, a reflector and a near-infrared camera; the lens comprises a first lens, a second lens and a third lens; the telephoto optical system receives the light emitted by the light source, and the light is transmitted to the beam splitting prism by the Cassegrain reflecting structure through the first lens; the beam splitter prism divides the light into two paths, the first path of light is collected by the visible light camera through the second lens, and the positions of the grid plate and the telephoto optical system are adjusted to obtain a visible light image; the second path of light passes through the filter plate, passes through the third lens by the reflector and is collected by the near-infrared camera, and the positions of the grid plate and the telephoto optical system are adjusted again to obtain a near-infrared image; and converting the coordinate system of the visible light image and the near infrared image to obtain a visible light undistorted image and a near infrared undistorted image.
An optical system distortion correction method applied to an optical system of claim 1, the distortion correction method comprising:
acquiring the focal length of a first collimator lens when a collimator generates parallel light;
determining a visible light image and a near infrared image according to the focal length of the first parallel light pipe lens;
establishing an image coordinate system by taking the optical axis of incident light as a Z axis and taking a plane vertical to the optical axis as an XOY plane;
acquiring the side length of a unit square in the grid plate; the grid plate comprises a plurality of unit squares;
determining pixel points corresponding to the unit square according to the side length;
determining a coordinate transformation matrix according to the pixel points and the image coordinate system; the coordinate transformation matrix is used for transforming the distorted image to the undistorted image; the distorted images are visible light images and near infrared images; the undistorted image comprises a visible light undistorted image and a near infrared undistorted image;
determining a visible light distortion-free image according to the visible light image and the transformation matrix;
and determining a near-infrared undistorted image according to the near-infrared image and the transformation matrix.
Optionally, the determining the visible light image and the near-infrared image according to the focal length of the first collimator lens specifically includes:
determining the visible light adjusting distance of the collimator according to the focal length of the first collimator lens;
and determining a visible light image according to the visible light adjusting distance.
Optionally, the determining the visible light image and the near-infrared image according to the focal length of the first collimator lens specifically includes:
determining a second collimator lens focal length according to the first collimator lens focal length;
determining the near infrared adjusting distance of the collimator according to the focal length of the second collimator lens;
and determining a near-infrared image according to the near-infrared adjusting distance.
Optionally, the determining a pixel point corresponding to the unit square according to the side length specifically includes:
and determining pixel points corresponding to the unit square by using a small hole imaging model according to the side length.
Optionally, the determining a coordinate transformation matrix according to the pixel point and the image coordinate system specifically includes:
acquiring a world coordinate system;
determining a world-image transformation matrix according to the world coordinate system and the image coordinate system;
and determining a coordinate transformation matrix according to the pixel points and the world-image transformation matrix.
An optical system distortion correction system comprising:
the first collimator lens focal length acquisition module is used for acquiring the first collimator lens focal length when the collimator generates the parallel light;
the image determining module is used for determining a visible light image and a near infrared image according to the focal length of the first parallel light pipe lens;
the image coordinate system establishing module is used for establishing an image coordinate system by taking the optical axis of incident light as a Z axis and taking a plane vertical to the optical axis as an XOY plane;
the side length obtaining module is used for obtaining the side length of a unit square in the grid plate; the grid plate comprises a plurality of unit squares;
the pixel point determining module is used for determining pixel points corresponding to the unit square according to the side length;
the coordinate transformation matrix determining module is used for determining a coordinate transformation matrix according to the pixel points and the image coordinate system; the coordinate transformation matrix is used for transforming the distorted image to the undistorted image; the distorted images are visible light images and near infrared images; the undistorted image comprises a visible light undistorted image and a near infrared undistorted image;
the visible light undistorted image determining module is used for determining a visible light undistorted image according to the visible light image and the transformation matrix;
and the near-infrared undistorted image determining module is used for determining a near-infrared undistorted image according to the near-infrared image and the transformation matrix.
Optionally, the image determining module specifically includes:
the visible light adjusting distance determining unit is used for determining the visible light adjusting distance of the collimator according to the focal length of the first collimator lens;
and the visible light image determining unit is used for determining the visible light image according to the visible light adjusting distance.
Optionally, the image determining module specifically includes:
the second collimator lens focal length determining unit is used for determining the second collimator lens focal length according to the first collimator lens focal length;
the near-infrared adjusting distance determining unit is used for determining the near-infrared adjusting distance of the collimator according to the focal length of the second collimator lens;
and the near-infrared image determining unit is used for determining a near-infrared image according to the near-infrared adjusting distance.
Optionally, the pixel point determining module specifically includes:
and the pixel point determining unit is used for determining the pixel points corresponding to the unit square by using a small-hole imaging model according to the side length.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects: the invention provides an optical system and a distortion correction method and system thereof. The optical system is provided with the visible light camera and the near infrared camera, corrected undistorted images are obtained by correcting images acquired by the two cameras, and compared with an imaging technology of a single visible light camera in the prior art, the imaging time can be greatly shortened, and the measurement error of the optical system is reduced.
According to the distortion correction method and system of the optical system, the coordinate transformation matrix is determined according to the unit square in the grid plate, so that a visible light image obtained by the visible light camera is transformed into a visible light distortion-free image, a near infrared image obtained by the near infrared camera is transformed into a near infrared distortion-free image, and the measurement error of the optical system is reduced.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
FIG. 1 is a diagram of the structure of an optical system provided by the present invention;
FIG. 2 is a first calibration image provided by the present invention;
FIG. 3 is a block diagram of a telephoto optical system according to the present invention;
FIG. 4 is a flowchart of a method for correcting optical distortion according to the present invention;
FIG. 5 is a diagram of a coordinate system transformation provided by the present invention;
FIG. 6 is a schematic diagram of a first captured image provided by the present invention;
FIG. 7 is a schematic diagram of the first captured image of FIG. 6 after distortion correction according to the present invention;
FIG. 8 is a plot of a coordinate point to be collected for marking the first collected image of FIG. 6 in accordance with the present invention;
FIG. 9 is a schematic diagram of a near infrared image provided by the present invention;
FIG. 10 is a schematic diagram of the near-infrared image of FIG. 9 after distortion correction according to the present invention;
FIG. 11 is a plot of a coordinate point to be collected for marking the near-infrared image of FIG. 9 according to the present invention
Fig. 12 is a structural diagram of a distortion correction system of an optical system according to the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention aims to provide an optical system and a distortion correction method and system thereof, so as to reduce the measurement error of the optical system.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
Fig. 1 is a structural diagram of an optical system according to the present invention, and as shown in fig. 1, the optical system includes: the device comprises a light source 1, a collimator 2 and a telephoto optical system 3 which are sequentially arranged on one side of the light source 1, wherein the telephoto optical system 3 is connected with a computer 4; a grid plate 5 is arranged in the collimator 2; the bottoms of the light source 1, the collimator 2 and the telephoto optical system 3 are respectively provided with an adjusting table; the adjusting table is used for adjusting the positions of the light source 1, the collimator 2 and the telephoto optical system 3; the adjusting stages include a first adjusting stage 6, a second adjusting stage 7, and a third adjusting stage 8, wherein the first adjusting stage 6, the second adjusting stage 7, and the third adjusting stage 8 correspond to the light source 1, the collimator 2, and the telephoto optical system 3 one to one, as shown in fig. 1. Before acquiring the image, the positions of the devices in the optical system are first adjusted so that the center point of the grid plate 5 is imaged in the center of the visible light image, as shown in fig. 2.
FIG. 3 is a structural diagram of a telephoto optical system according to the present invention, and as shown in FIG. 3, the telephoto optical system includes a Cassegrain reflection structure 3-1, a lens, a beam splitter prism 3-2, a visible light camera 3-3, a filter 3-4, a reflector 3-5, and a near infrared camera 3-6; the lens comprises a first lens, a second lens and a third lens; the telephoto optical system receives the light emitted by the light source 1, and the light is transmitted to the beam splitter prism 3-2 by the Cassegrain reflecting structure 3-1 through the first lens 3-7; the beam splitter prism 3-2 splits the light into two paths, the first path of light is collected by the visible light camera 3-3 through the second lens 3-8, and the positions of the grid plate 5 and the telephoto optical system are adjusted to obtain a visible light image; the second path of light passes through the optical filter 3-4 and the reflector 3-5, the second path of light passes through the third lens 3-9 through the reflector 3-5 and is collected by the near-infrared camera 3-6, and the positions of the grid plate 5 and the telephoto optical system are adjusted again to obtain a near-infrared image; and converting the coordinate system of the visible light image and the near infrared image to obtain a visible light undistorted image and a near infrared undistorted image.
The optical system provided by the invention can shorten the imaging time, reduce the background noise and improve the signal-to-noise ratio of the facula image, thereby reducing the measurement error of the optical system and improving the measurement precision of the optical system.
According to the optical system provided by the invention, the light source at the equivalent distance L of the collimator is adopted, and the adjustment positions of the two cameras corresponding to the grid plate 5 of the equivalent L light source are calculated as follows:
wherein, the collimator is a collimator with adjustable visibility, the focal length is f' when generating the collimator, and the scale of the collimator fine tuning scale is r.
Fig. 4 is a flowchart of an optical distortion correction method provided by the present invention, and as shown in fig. 4, the optical distortion correction method includes:
step 401: and acquiring the focal length of the first collimator lens when the collimator generates the parallel light.
The relationship between the focal length and the refractive index of the first collimator lens is known as
Figure BDA0001609556580000071
Wherein k is a proportionality constant coefficient, n is a refractive index in air, and n' is a refractive index of the visible light camera lens.
Step 402: and determining a visible light image and a near infrared image according to the focal length of the first parallel light pipe lens.
From the known parameters, f ', n, n', of step 401, we can derive:
Figure BDA0001609556580000072
calculating a second collimator lens focal length, at which the refractive index n in air, the lens refractive index n 'in the near infrared spectral range'IRK is known, can be obtained
Figure BDA0001609556580000073
Wherein f'IRAnd when the near-infrared parallel light equivalent target source is generated, the focal length of the second parallel light pipe lens is adjusted by the parallel light pipe.
Imaging formula:
Figure BDA0001609556580000074
the equivalent v-L grid plate is spaced from the collimator by a distance of
Figure BDA0001609556580000075
Where f is the focal length, v is the image distance (i.e., the equivalent distance L), u is the object distance,which is the distance of the grid plate from the collimator lens.
Calculating the distance between the grid plate and the collimator lens when visible light is obtained by an imaging formula
Figure BDA0001609556580000076
Distance between the grid plate and the collimator lens in the near infrared light
Figure BDA0001609556580000077
Therefore, the relative position is adjusted relative to the focal length of the collimator:
under visible light: Δ uVis＝uVis-f'；
In the near infrared light: Δ uIR＝uIR-f'。
The corresponding collimator micro-adjustment scale is as follows:
under visible light: r isVis＝r+ΔuVis；
In the near infrared light: r isIR＝r+ΔuIR。
Adjusting the position of the grid plate to rVisThe visible light camera can clearly image and collect the visible light image; readjusting the position of the grid plate to rIRThe near-infrared camera can clearly image and collect near-infrared images.
The rotating telephoto optical system has the image central axis unchanged in each rotation process, and takes the condition that the central image of the grid plate is imaged in the field-of-view center of the two-camera, and the angles of the grid lines and the horizontal line are gradually increased as the adjustment basis.
And circularly adjusting the position of the grid plate, adjusting a telephoto optical system, enabling the visible light camera and the near-infrared camera to obtain images with different shooting angles, and re-collecting a plurality of pairs of visible light images and near-infrared images with different angles, wherein the number of circulation times N is more than or equal to 14 (the number of circulation times is determined according to the number of finally required unknowns and the number of equations which can be listed in each image, and the number of reprojection errors is calculated).
Step 403: an image coordinate system is established by taking the optical axis of incident light as a Z axis and taking a plane vertical to the optical axis as an XOY plane.
As shown in fig. 5, an incident light coordinate system O-XCYCZC is established with an optical axis of incident light as a Z-axis and a plane perpendicular to the optical axis as an XOY plane; establishing a visible light camera coordinate system OC1-XC1YC1ZC1 by taking the optical axis of the visible light camera as a Z axis and taking the optical axis vertical to the incident optical axis of visible light as an XOY plane; establishing a near-infrared camera coordinate system OC2-XC2YC2ZC2 by taking the optical axis of the near-infrared camera as a Z axis and taking the optical axis vertical to the near-infrared incident optical axis as an XOY plane; image pixel coordinate system: establishing an image pixel coordinate system by taking the upper left corner of the two-dimensional image as a coordinate origin, the horizontal axis as a u axis and the vertical axis as a v axis; image physical coordinate system: the image center point is taken as the origin, the horizontal axis is taken as the x axis, and the vertical axis is taken as the y axis. World coordinate system O-XWYWZWAnd the coordinate system of incident light O-XCYCZCIs a rotation and translation relationship and requires 6 parameters; p is the world coordinate system O-XWYWZWAt any point, through the incident light coordinate system O-XCYCZCThe visible light is transmitted to a coordinate system OC1-XC1YC1ZC1And a near infrared camera coordinate system OC2-XC2YC2ZC2In connection, 12 parameters are needed, wherein the three-dimensional coordinate system is transformed into a rotation and translation relation, and the rotation and translation are respectively 3 parameters, which are 6 parameters in total; thus, the incident light coordinate system O-XCYCZCCoordinate system O with visible light cameraC1-XC1YC1ZC1The relation between rotation and translation is formed, and the total number of the parameters is 6; analogously, the incident light coordinate system O-XCYCZCAnd a near infrared camera coordinate system OC2-XC2YC2ZC26 parameters are also needed; as shown in FIG. 5, the coaxial portion is the incident optical axis, which is the incident optical coordinate system O-XCYCZCZ of (A)CA shaft. The light reaching the two cameras, which is the same light before the beam splitting prism, is linked by this coaxial part.
The relation between a visible light camera coordinate system OC1-XC1YC1ZC1 and a visible light image pixel coordinate system u1ov1 is that the camera intrinsic parameters are 4 parameters, and similarly, the near infrared camera also has 4 intrinsic parameters, so that the relation between the visible light image pixel coordinate system u1ov1 and the near infrared image pixel coordinate system u2ov2 is determined. A total of 26 parameters need to be solved for 6+12+4+ 4. It should be noted that one camera needs to solve 16 parameters, and if two cameras are not related, 32 parameters need to be solved, where the two cameras have coaxial portions, so that one rigid body transformation can be done less.
It can be seen that the conventional single-camera optical correction needs to solve for 16 parameters, and two cameras need 32 parameters. According to the optical correction method, the two cameras need 26 parameters, and the distortion correction method provided by the invention can reduce the calculation amount of parameter solution.
For a planar image, 8 variances can be provided, that is, mapping a square to a quadrangle can be described by 4 (x, y), and for four fields of view, 8 × 4 × 32 × 4 × 6+4+4, that is, solving all parameters requires at least four fields of view, that is, four fields of view are required for the visible light camera and the near infrared camera, and thus 4 images (two visible light images and two near infrared images) are required. In order to improve the accuracy and reduce the random error, the number of images N is more than or equal to 14, the reprojection error is less than 0.5 pixel in a plurality of tests, the table 1 is a reprojection error statistical table, as shown in the table 1,
TABLE 1
Number of images 10 14 16 18
Reprojection error (pixel) 0.550324 0.451422 0.440131 0.380354
As can be seen from table 1, the larger the number of images acquired, the lower the reprojection error.
Step 404: acquiring the side length of a unit square in the grid plate; the grid plate includes a plurality of unit squares.
Step 405: and determining the pixel points corresponding to the unit square according to the side length.
Step 406: determining a coordinate transformation matrix according to the pixel points and the image coordinate system; the coordinate transformation matrix is used for transforming the distorted image to the undistorted image; the distorted images are visible light images and near infrared images; the undistorted image includes a visible light undistorted image and a near infrared undistorted image.
Step 407: and determining a visible light distortion-free image according to the visible light image and the transformation matrix.
Step 408: and determining a near-infrared undistorted image according to the near-infrared image and the transformation matrix.
And (3) extracting distortion coordinates, acquiring an image as shown in fig. 6 and 9, selecting grid corner points with the size of a matrix of 9 × 9 at the center of the image, namely an image formed by grid points of 9 × 9 in a dashed frame in fig. 2, and extracting the coordinates of the grid corner points. Extracting coordinates of grid points marked in the coordinates of FIG. 8 and FIG. 11, wherein FIG. 8 is the grid point of the visible light image mark, and FIG. 11 is the grid point of the near infrared image mark; wherein the marked grid point coordinates are bright dots.
Calculating a calibration model of the dual camera, as shown in fig. 5, a physical coordinate system X1oy1 of the visible light image, a physical coordinate system X2oy2 of the near infrared image, a pixel coordinate system u1ov1 of the visible light image, a pixel coordinate system u2ov2 of the near infrared image, and a world coordinate system O-XWYWZWIncident light is perpendicular to the optical axis with the optical axis as the Z axisEstablishing a coordinate system (incident light coordinate system) O-X for the XOY planeCYCZCVisible light camera coordinate system OC1-XC1YC1ZC1Near infrared camera coordinate system OC2-XC2YC2ZC2. Matrix T from world coordinate system to image pixel coordinate systemmAnd (4) showing. For example, in the grid plate in fig. 2, each cell is a square with a side length of d, the pixel size dpix corresponding to the side length d on the ideal image can be calculated through a small-hole imaging model, the grid point coordinate relation on the ideal undistorted image is determined according to the dpix, and the matrix T is combinedmObtaining ideal undistorted image coordinate CdTherefore, the distortion coordinates extracted before are denoted as C, CdThe relation between C is as follows: cdWhere T is a coordinate transformation matrix from a distorted image to an undistorted image.
And setting the image after optical correction as I', the image with optical distortion as I, and obtaining the relationship of the three according to the matrix T: i' ═ I.T
Collecting images, performing matrix transformation to obtain visible light and near infrared undistorted images, performing matrix T transformation to obtain visible light undistorted images such as shown in FIG. 6 and near infrared images such as shown in FIG. 9, and performing matrix T transformation to obtain visible light undistorted images such as shown in FIG. 7 and near infrared undistorted images such as shown in FIG. 10.
The distortion correction method provided by the invention is applied to the practice, the collimator equivalent 1Km light source is adopted in the invention, and the adjustment positions of the two cameras corresponding to the grid plate equivalent 1Km light source are calculated as follows:
when the collimator generates parallel light, f 'is 1604.07mm, r is 97.2mm, f' is 1604.07mm, n is 1, n is 1.5194725831,
Figure BDA0001609556580000101
thus, n is 1, n' is 1.516960102, k is 0.0012000907;
Figure BDA0001609556580000102
i.e. producing equivalent 1Km near infrared light, the focal length of the collimator is f'IR1611.87 mm; in parallelThe scale of the light pipe fine adjustment scale is r equal to 105 mm.
From the imaging formula:
Figure BDA0001609556580000103
equivalent v is 1000000mm grid plate placing position
Figure BDA0001609556580000104
Calculated to obtain uVis＝1606.64717mm，uIR1614.47232mm, the relative position is adjusted by Delaut relative to the focal length of the collimatorVis＝uVis-f 1606.64717-1604.07-2.57717 mm and Δ uIR＝uIR-f 1614.47232-1604.07-10.40232 mm; the scale of the corresponding collimator micro-adjustment scale is rVis＝r+ΔuVis99.77717mm and rIR＝r+ΔuIR＝107.60232mm；
Adjusting the position of the grid plate to rVisThe visible light camera can clearly image and collect the visible light image; readjusting the position of the grid plate to rIRThe near-infrared camera can clearly image and acquire a near-infrared image; the rotating telephoto optical system has the image central axis unchanged in each rotation process, and takes the condition that the central image of the grid plate is imaged in the field-of-view center of the two-camera, and the angles of the grid lines and the horizontal line are gradually increased as the adjustment basis.
And (4) circulating the adjusting step for a number of times N which is more than or equal to 14 (the number of times is determined according to the number of finally required unknowns and the number of equations which can be listed in each image, and calculating the reprojection error).
As shown in fig. 5, a coordinate transformation matrix T is determined.
Restoration correction, in the test process, images are collected, after A/D conversion, the images are processed by a system level matrix T, and visible light and near infrared distortion-free images are obtained, as shown in FIGS. 6-11.
Fig. 12 is a structural diagram of a distortion correction system of an optical system according to the present invention, and as shown in fig. 12, the distortion correction system of the optical system includes:
the first collimator lens focal length acquiring module 1201 is configured to acquire a first collimator lens focal length when the collimator generates the collimated light.
And an image determining module 1202, configured to determine the visible light image and the near-infrared image according to the focal length of the first collimator lens.
The image determining module 1202 specifically includes: the visible light adjusting distance determining unit is used for determining the visible light adjusting distance of the collimator according to the focal length of the first collimator lens; and the visible light image determining unit is used for determining the visible light image according to the visible light adjusting distance.
The image determining module 1202 specifically includes: the second collimator lens focal length determining unit is used for determining the second collimator lens focal length according to the first collimator lens focal length; the near-infrared adjusting distance determining unit is used for determining the near-infrared adjusting distance of the collimator according to the focal length of the second collimator lens; and the near-infrared image determining unit is used for determining a near-infrared image according to the near-infrared adjusting distance.
The image coordinate system establishing module 1203 is configured to establish an image coordinate system by taking an optical axis of incident light as a Z-axis and a plane perpendicular to the optical axis as an XOY plane.
A side length obtaining module 1204, configured to obtain a side length of a unit square in the grid plate; the grid plate includes a plurality of unit squares.
And a pixel point determining module 1205, configured to determine a pixel point corresponding to the unit square according to the side length.
The pixel point determining module 1205 specifically includes: and the pixel point determining unit is used for determining the pixel points corresponding to the unit square by using a small-hole imaging model according to the side length.
A coordinate transformation matrix determining module 1206, configured to determine a coordinate transformation matrix according to the pixel point and the image coordinate system; the coordinate transformation matrix is used for transforming the distorted image to the undistorted image; the distorted images are visible light images and near infrared images; the undistorted image includes a visible light undistorted image and a near infrared undistorted image.
A visible light undistorted image determining module 1207, configured to determine a visible light undistorted image according to the visible light image and the transformation matrix.
And a near-infrared undistorted image determining module 1208, configured to determine a near-infrared undistorted image according to the near-infrared image and the transformation matrix.
The optical system distortion correction method and system provided by the invention can improve the measurement precision of the optical system and reduce the measurement error.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the system disclosed by the embodiment, the description is relatively simple because the system corresponds to the method disclosed by the embodiment, and the relevant points can be referred to the method part for description.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.

Claims (10)

1. An optical system, comprising: the device comprises a light source, a collimator and a telephoto optical system, wherein the collimator and the telephoto optical system are sequentially arranged on one side of the light source, and the telephoto optical system is connected with a computer;
a grid plate is arranged in the collimator;
the bottoms of the light source, the collimator and the telephoto optical system are respectively provided with an adjusting table; the adjusting table is used for adjusting the positions of the light source, the collimator and the telephoto optical system; the adjusting table comprises a first adjusting table, a second adjusting table and a third adjusting table, wherein the first adjusting table, the second adjusting table and the third adjusting table correspond to the light source, the collimator and the telephoto optical system one by one; before the image is acquired, firstly, adjusting the position of each device in the optical system to enable the central point of the grid plate to be imaged in the center of the visible light image;
the telephoto optical system comprises a Cassegrain reflection structure, a lens, a beam splitter prism, a visible light camera, an optical filter, a reflector and a near-infrared camera; the lens comprises a first lens, a second lens and a third lens; the telephoto optical system receives the light emitted by the light source, and the light is transmitted to the beam splitting prism by the Cassegrain reflecting structure through the first lens; the beam splitter prism divides the light into two paths, the first path of light is collected by the visible light camera through the second lens, and the positions of the grid plate and the telephoto optical system are adjusted to obtain a visible light image; the second path of light passes through the optical filter, passes through the third lens by the reflector and is collected by the near-infrared camera, and the positions of the grid plate and the telephoto optical system are adjusted again to obtain a near-infrared image; and converting the coordinate system of the visible light image and the near infrared image to obtain a visible light undistorted image and a near infrared undistorted image.
2. An optical system distortion correction method applied to an optical system of claim 1, the distortion correction method comprising:
acquiring the focal length of a first collimator lens when a collimator generates parallel light;
determining a visible light image and a near infrared image according to the focal length of the first parallel light pipe lens;
establishing an image coordinate system by taking the optical axis of incident light as a Z axis and taking a plane vertical to the optical axis as an XOY plane;
acquiring the side length of a unit square in the grid plate; the grid plate comprises a plurality of unit squares;
determining pixel points corresponding to the unit square according to the side length;
determining a coordinate transformation matrix according to the pixel points and the image coordinate system; the coordinate transformation matrix is used for transforming the distorted image to the undistorted image; the distorted images are visible light images and near infrared images; the undistorted image comprises a visible light undistorted image and a near infrared undistorted image;
determining a visible light distortion-free image according to the visible light image and the transformation matrix;
and determining a near-infrared undistorted image according to the near-infrared image and the transformation matrix.
3. The distortion correction method of claim 2, wherein the determining the visible light image and the near infrared image according to the first collimator lens focal length specifically comprises:
determining the visible light adjusting distance of the collimator according to the focal length of the first collimator lens;
and determining a visible light image according to the visible light adjusting distance.
4. The distortion correction method of claim 3, wherein the determining the visible light image and the near infrared image according to the first collimator lens focal length specifically comprises:
determining a second collimator lens focal length according to the first collimator lens focal length;
determining the near infrared adjusting distance of the collimator according to the focal length of the second collimator lens;
and determining a near-infrared image according to the near-infrared adjusting distance.
5. The distortion correction method of claim 2, wherein the determining the pixel corresponding to the unit square according to the side length specifically comprises:
and determining pixel points corresponding to the unit square by using a small hole imaging model according to the side length.
6. The distortion correction method of claim 2, wherein the determining a coordinate transformation matrix according to the pixel points and the image coordinate system specifically comprises:
acquiring a world coordinate system;
determining a world-image transformation matrix according to the world coordinate system and the image coordinate system;
and determining a coordinate transformation matrix according to the pixel points and the world-image transformation matrix.
7. An optical system distortion correction system applied to an optical system of claim 1, comprising:
the first collimator lens focal length acquisition module is used for acquiring the first collimator lens focal length when the collimator generates the parallel light;
the image determining module is used for determining a visible light image and a near infrared image according to the focal length of the first parallel light pipe lens;
the image coordinate system establishing module is used for establishing an image coordinate system by taking the optical axis of incident light as a Z axis and taking a plane vertical to the optical axis as an XOY plane;
the side length obtaining module is used for obtaining the side length of a unit square in the grid plate; the grid plate comprises a plurality of unit squares;
the pixel point determining module is used for determining pixel points corresponding to the unit square according to the side length;
the coordinate transformation matrix determining module is used for determining a coordinate transformation matrix according to the pixel points and the image coordinate system; the coordinate transformation matrix is used for transforming the distorted image to the undistorted image; the distorted images are visible light images and near infrared images; the undistorted image comprises a visible light undistorted image and a near infrared undistorted image;
the visible light undistorted image determining module is used for determining a visible light undistorted image according to the visible light image and the transformation matrix;
and the near-infrared undistorted image determining module is used for determining a near-infrared undistorted image according to the near-infrared image and the transformation matrix.
8. A distortion correction system as set forth in claim 7, wherein the image determination module specifically comprises:
the visible light adjusting distance determining unit is used for determining the visible light adjusting distance of the collimator according to the focal length of the first collimator lens;
and the visible light image determining unit is used for determining the visible light image according to the visible light adjusting distance.
9. A distortion correction system as set forth in claim 8, wherein the image determination module specifically comprises:
the second collimator lens focal length determining unit is used for determining the second collimator lens focal length according to the first collimator lens focal length;
the near-infrared adjusting distance determining unit is used for determining the near-infrared adjusting distance of the collimator according to the focal length of the second collimator lens;
and the near-infrared image determining unit is used for determining a near-infrared image according to the near-infrared adjusting distance.
10. The distortion correction system of claim 7, wherein the pixel determination module specifically comprises:
and the pixel point determining unit is used for determining the pixel points corresponding to the unit square by using a small-hole imaging model according to the side length.
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