Method for optical decentering correction of multi-channel imaging

Abstract

The application provides a multi-channel imaging optical eccentricity correction method applied to a multi-channel camera, and the optical eccentricity correction method comprises the following steps: real-time shooting of the inside of an integrating sphere by the multi-channel camera; adjusting the position of each lens relative to the lens chip to make the brightness of the four corners of the video display page of the multi-channel camera consistent; simultaneously shooting an infinite faraway same point light source by N lenses of the multi-channel camera, so that the video display page of the multi-channel camera simultaneously displays N shooting pictures, and the point light source is displayed on each shooting picture; and taking the image plane position of the point light source in one of the shooting pictures as a reference, adjusting the image plane positions of the point light sources in other shooting pictures to be the same as the reference. The multi-channel imaging optical eccentricity correction method can reduce the relative eccentricity degree of the lens and the chip, improve the common field of view of the multi-channel camera, and improve the shooting efficiency.

Description

Technical Field

[0001] This invention relates to the field of multi-channel spectral imaging technology, and in particular to an optical eccentricity correction method for multi-channel imaging. Background Technology

[0002] Currently, multi-channel cameras are commonly used in 3D vision and multispectral imaging applications. Each camera in each channel images the same area to obtain the corresponding image. By processing and analyzing the images, damage or material detection can be performed, etc.

[0003] Typically, a camera lens and its lens mount are connected and fixed with screws via a base. Due to manufacturing tolerances and assembly errors, the optical axis of the lens and the center vertical line of the lens mount may not coincide, a phenomenon known as lens eccentricity. This eccentricity affects not only the camera's relative illumination but also the size of the common field of view. The impact of lens eccentricity on relative illumination: Based on the imaging characteristics of lenses, the larger the image height, the smaller the light transmission. The light transmission at the center is greater than at other image heights. Therefore, once lens eccentricity occurs, it increases the distance of the lens mount from the lens center, resulting in lower relative illumination. This has a very significant impact on short-focal-length lenses.

[0004] However, existing technologies typically use positioning posts on the base combined with positioning holes on the chip board for eccentricity correction. However, since this is a mechanical structure method, it cannot be verified and corrected through imaging effects. As a result, the processing deviation will seriously affect the relative eccentricity between the lens and the chip. Eccentricity will affect the common field of view of multi-camera systems, usually making the field of view smaller and affecting shooting efficiency. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the present invention proposes an optical eccentricity correction method for multi-channel imaging that reduces the relative eccentricity between the lens and the chip, improves the common field of view of multi-channel cameras, and enhances shooting efficiency, so as to solve the above-mentioned technical problems.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] This invention provides an optical eccentricity correction method for multi-channel imaging, applicable to a multi-channel camera. The multi-channel camera includes N lenses and a lens chip matched with each lens, where N is an integer greater than or equal to 2. The optical eccentricity correction method includes the following steps:

[0008] The multi-channel camera is positioned directly inside the integrating sphere to capture real-time images;

[0009] Adjust the position of each lens relative to the lens chip to make the brightness of the four corners of the video display page of the multi-channel camera uniform;

[0010] The N lenses of the multi-channel camera simultaneously capture images of the same point light source at infinity, so that the video display page of the multi-channel camera simultaneously displays N captured images, and the point light source is displayed on each captured image.

[0011] Using the image plane position of a point light source in one of the captured images as a reference, the image plane positions of point light sources in the other captured images are adjusted to be the same as the reference.

[0012] Preferably, in the step of adjusting the position of each lens relative to the lens chip to make the brightness of the four corners of the video display page of the multi-channel camera uniform, the position adjustment of the lens is achieved by adjusting the base of the lens.

[0013] Preferably, in the step of simultaneously capturing the same point light source at infinity with N lenses of the multi-channel camera, so that the video display page of the multi-channel camera simultaneously displays N captured images, and the point light source is displayed on each captured image, the lower limit of infinity is defined as L, which satisfies the following formula (1).

[0014] L=EFL*H / 2h (1)

[0015] Wherein, EFL represents the focal length of the lens, H represents the distance between two adjacent lenses in the multi-channel camera, and h represents the pixel width of the lens chip.

[0016] Preferably, the EFL is 5mm, the h is 0.00345mm, the H is 30mm, and the infinity L is 21.7m.

[0017] Preferably, the step of adjusting the image plane position of the point light source in one of the captured images to the same position as the reference is achieved by adjusting the base of the lens corresponding to each captured image.

[0018] Preferably, in the optical eccentricity correction method,

[0019] After adjusting the image plane position of the point light source in the other captured images to be the same as the reference, the method further includes: applying adhesive to the lens.

[0020] Preferably, the image plane position is a two-dimensional coordinate system position.

[0021] Preferably, N is 2≤N≤8.

[0022] Compared with related technologies, in the embodiments of the present invention, a multi-channel camera is used to capture real-time images of the interior of an integrating sphere. The position of each lens relative to the lens chip is adjusted to ensure consistent brightness at the four corners of the video display page of the multi-channel camera. Preliminary correction of eccentricity is achieved through the relative illumination principle of the lens's own imaging and the uniform light intensity at various angles of the integrating sphere. The N lenses of the multi-channel camera simultaneously capture images of the same point light source at infinity, resulting in N simultaneous images displayed on the video display page of the multi-channel camera, each image showing the point light source. Using the image plane position of the point light source in one of the images as a reference, the image plane positions of the point light sources in the other images are adjusted to match the reference. This further eccentricity correction minimizes the eccentricity between the lenses and their corresponding chips in the multi-camera system, ensuring consistent eccentricity across different cameras. It reduces the relative eccentricity between the lenses and the chip, improves the common field of view of the multi-channel camera, and increases shooting efficiency. Attached Figure Description

[0023] The present invention will now be described in detail with reference to the accompanying drawings. The above and other aspects of the present invention will become clearer and more readily understood through the detailed description following the accompanying drawings. In the drawings:

[0024] Figure 1 This is a flowchart of the optical eccentricity correction method for multi-channel imaging in an embodiment of the present invention;

[0025] Figure 2 This is a schematic diagram of the common field of view of a dual-channel camera without eccentricity in an embodiment of the present invention;

[0026] Figure 3 This is a schematic diagram showing the left-side camera lens of the dual-channel camera in an embodiment of the present invention being tilted to the left;

[0027] Figure 4 This is a schematic diagram showing the left camera lens of the dual-channel camera in an embodiment of the present invention tilted to the right;

[0028] Figure 5 This is an image of the integrating sphere before correction in an embodiment of the present invention;

[0029] Figure 6 This is an image of the integrating sphere after correction in an embodiment of the present invention;

[0030] Figure 7 In this embodiment of the invention, the dual-channel camera is used to image the same infinitely distant point light source before eccentricity correction.

[0031] Figure 8 In this embodiment of the invention, the dual-channel camera, after eccentricity correction, images relative to the same infinitely distant point light source.

[0032] Figure 9A scene image captured simultaneously by a dual-channel camera (450nm and 850nm) without eccentricity correction in an embodiment of the present invention.

[0033] Figure 10 A scene image captured simultaneously by a 450nm and 850nm dual-channel camera after eccentricity correction in an embodiment of the present invention. Detailed Implementation

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing drawings of this application, are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or foregoing drawings of this application are used to distinguish different objects, not to describe a particular order.

[0035] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] Please refer to Figure 1 As shown, Figure 1 This is a flowchart of an optical eccentricity correction method for multi-channel imaging according to an embodiment of the present invention. The present invention provides an optical eccentricity correction method for multi-channel imaging, applied to a multi-channel camera. The multi-channel camera includes N lenses and a lens chip matched to each lens, where N is an integer greater than or equal to 2. The optical eccentricity correction method includes the following steps:

[0038] S1. Position the multi-channel camera directly inside the integrating sphere for real-time shooting.

[0039] During the shooting process, the integrating sphere is in normal working condition and can capture images, video data, etc.

[0040] Each lens is an imaging channel.

[0041] S2. Adjust the position of each lens relative to the lens chip so that the brightness of the four corners of the video display page of the multi-channel camera is consistent.

[0042] The lens exhibits relative illumination characteristics, meaning that the light transmission is greatest when incident perpendicularly, and decreases as the angle of incidence increases. This manifests on the image plane as a greater image height resulting in lower brightness. The lens chip is a photosensitive chip used to detect the light source.

[0043] The integrating sphere has the characteristic of uniform light intensity at different angles, meaning that each point inside the integrating sphere is equivalent to a Lambertian light source with uniform light intensity at all angles.

[0044] The four corners of the page can be the four corner positions of an image frame.

[0045] Taking a dual-channel camera as an example, the impact of lens offset on the common field of view is as follows: When the lens is not offset relative to the lens chip, the common field of view of a multi-channel camera is as follows: Figure 2 As shown, discarding the field of view means keeping the camera spacing constant. The camera spacing is the spacing between multiple lenses, which are arranged at equal intervals. When the lens is offset to the left, as... Figure 3 The field of vision decreased by 7.45 / 52.15 = 14.3%. For example... Figure 4 When the lens is offset to the right by 0.5mm, although the field of view increases by 6mm, the field of view will still decrease relative to the unoffset field of view as the object distance increases. This means that after adjacent field of view lines intersect, the non-common field of view will continue to increase as the object distance increases, while it remains unchanged when there is no offset.

[0046] Of course, multi-channel cameras can also be 3-channel, 4-channel, 5-channel, etc., and their working principle is the same as that of dual-channel cameras, which will not be described in detail here.

[0047] Specifically, such as Figure 5 As shown, the brightness of the four corners of the integrating sphere is inconsistent before correction. Figure 6 As shown, the brightness at all four corners is consistent after the integrating sphere is corrected. This initial correction of the eccentricity is achieved by utilizing the relative illumination principle of the lens's own imaging and the uniform light intensity of the integrating sphere at all angles.

[0048] S3. Simultaneously capture images of the same point light source at infinity using N lenses of the multi-channel camera, so that the video display page of the multi-channel camera simultaneously displays N captured images, with the point light source displayed on each captured image.

[0049] S4. Using the image plane position of the point light source in one of the captured images as a reference, adjust the image plane positions of the point light sources in the other captured images to be the same as the reference.

[0050] Specifically, when the multi-channel camera images the point light source at the same relative position on the lens chip, the lens of the second channel is adjusted to the same image plane position based on the point light source acquired by the first channel. This ensures that the relative eccentricity of the lenses of different channels to the lens chip is consistent, thereby maximizing the field of view. The reason for using a point light source is that the camera's exposure time can be set very short, preventing other objects from entering the camera and affecting the determination of relative position.

[0051] Specifically, the process involves using a multi-channel camera to capture real-time images of the integrating sphere; adjusting the position of each lens relative to the lens chip to ensure consistent brightness at the four corners of the video display screen; initially correcting eccentricity by utilizing the relative illumination principle of the lens's own imaging and the uniform light intensity at all angles of the integrating sphere; acquiring a point light source at infinity; obtaining the image plane position of the point light source in each channel; and using the image plane position of the point light source in one channel as a reference to adjust the point light sources in other channels to the same image plane position; further eccentricity correction minimizes the eccentricity between the lenses and their corresponding lens chips in the multi-camera system, achieving a consistent eccentricity across different cameras; reducing the relative eccentricity between the lenses and lens chips, improving the common field of view of the multi-channel cameras, and increasing shooting efficiency.

[0052] In this embodiment, in step S2, the position of the lens is adjusted by adjusting the base of the lens.

[0053] Specifically, the position of the lens relative to the lens chip is adjusted, and the brightness of the four corners of the multi-channel camera video page is observed. When the brightness of the lens chip is consistent, the optical axis of the lens coincides with the central vertical line of the lens chip, thus completing the initial correction of the eccentricity.

[0054] Specifically, when the lens captures the interior of the illuminated integrating sphere, the incident light intensity is consistent at all angles of the lens. The brightness is greatest at the center of the lens image on the lens chip, and gradually decreases as the image height increases. When the brightness of the four corners of the lens chip is consistent, the optical axis of the lens coincides with the vertical line of the center of the lens chip. However, due to the certain tolerance of the lens and the certain error in the light sensitivity of the lens chip, this adjustment is only used as a preliminary correction of the eccentricity.

[0055] In this embodiment, in step S3, the lower limit of infinity is defined as L, which satisfies the following formula (1);

[0056] L=EFL*H / 2h (1)

[0057] Wherein, EFL represents the focal length of the lens, H represents the distance between two adjacent lenses in the multi-channel camera, and h represents the pixel width of the lens chip.

[0058] When a multi-channel camera captures a point light source at the same distance, the height difference of the point light source is equal to the distance H between the two channels. h represents the width or length of the lens chip. Optionally, the lens chip has a rectangular structure.

[0059] Preferably, when the infinity object distance satisfies the expression (1), the image height converted from the infinity object distance is less than 2 pixels. If the lens is not eccentric relative to the lens chip, the image point of the point light source imaged by the multi-channel camera is at the same relative position on the lens chip. Using one multi-channel camera as a reference, other multi-channel lenses can be adjusted so that the point light source is imaged at the same image plane position on different channels. This ensures that the relative eccentricity between the lenses and the lens chip in different channels is consistent, thereby maximizing the field of view.

[0060] In this embodiment, the EFL is 5mm, the h is 0.00345mm, the H is 30mm, and according to the expression (1), the infinity L = 21.7m.

[0061] In this embodiment, step S4 is achieved by adjusting the base of the lens corresponding to each captured image.

[0062] Specifically, the lens is moved so that the lens imaging the point light source and the lens chip are in the same relative position.

[0063] In this embodiment, the optical eccentricity correction method, after adjusting the image plane position of the point light sources in the other captured images to be the same as the reference, further includes: applying adhesive to the lens. This achieves installation and fixation, facilitating lens assembly.

[0064] In this embodiment, the image plane position is a two-dimensional coordinate system position. The two-dimensional coordinate system includes an X-axis and a Y-axis. For example, using the display screen corresponding to one channel as a reference, the lenses of other channels are adjusted so that the light source points in the display screen corresponding to the adjusted lens are also adjusted to the X-axis and Y-axis coordinates.

[0065] Among them, the dual-channel camera simultaneously captures point light sources at a distance. Taking the image plane position of the point light source in one channel as a reference, the point light sources in other channels are adjusted to the same image plane position. The adjustment method is to move the relative position of the lens and the lens chip. After the movement is completed, adhesive dispensing is required.

[0066] In this embodiment, multi-channel imaging is illustrated using a dual-channel example, where each channel is equipped with two lenses. Optionally, the first channel of the dual-channel system uses a 450nm wavelength, and the second channel uses an 850nm wavelength. Of course, other wavelengths can also be used, depending on the actual number of channels, which will not be described in detail here.

[0067] Specifically, a comparison of the point light source positions before and after correcting the lens's eccentricity relative to the lens chip, such as... Figure 7 and Figure 8 .in, Figure 7 (a) A shot taken when shooting a point light source at infinity from the first lens or the first channel in front of the first lens or the first channel; Figure 7 (b) A shot taken when shooting a point light source at infinity in front of the second lens or second channel.

[0068] After correction via step S2 Figure 8 (a) A shot taken when the first lens or first channel is offset to capture a point light source at infinity; Figure 8 (b) The shot taken when the second lens or second channel is offset to capture a point light source at infinity.

[0069] Visual field effects before and after correction Figure 9 and Figure 10 As shown. Among them, Figure 9 (a) Scene taken before the first channel was eccentric; Figure 9 (b) Scene taken before the second channel was eccentric.

[0070] After correction via step S4 Figure 10 (a) Scene image taken after the first channel was eccentric; Figure 10 (b) Scene image captured after the second channel is eccentric. The captured image has a wider field of view and higher clarity. This makes integrating sphere correction easier and results in better image capture.

[0071] In this embodiment, N is 2≤N≤8.

[0072] It should be noted that the various embodiments described above with reference to the accompanying drawings are merely illustrative of the present invention and not intended to limit its scope. Those skilled in the art should understand that any modifications or equivalent substitutions made to the present invention without departing from its spirit and scope should be included within the scope of the present invention. Furthermore, unless the context otherwise requires, words appearing in the singular include those in the plural, and vice versa. Additionally, unless specifically stated otherwise, all or part of any embodiment may be used in conjunction with all or part of any other embodiment.

Claims

1. An optical eccentricity correction method for multi-channel imaging, applied to a multi-channel camera, wherein the multi-channel camera includes N lenses and a lens chip matched with each of the lenses, where N is an integer greater than or equal to 2, characterized in that, The optical eccentricity correction method includes the following steps: The multi-channel camera is positioned directly inside the integrating sphere to capture real-time images; Adjust the position of each lens relative to the lens chip to make the brightness of the four corners of the video display page of the multi-channel camera uniform; The N lenses of the multi-channel camera simultaneously capture images of the same point light source at infinity, so that the video display page of the multi-channel camera simultaneously displays N captured images, and the point light source is displayed on each captured image. Using the image plane position of a point light source in one of the captured images as a reference, the image plane positions of point light sources in the other captured images are adjusted to be the same as the reference.

2. The optical eccentricity correction method for multi-channel imaging according to claim 1, characterized in that, In the step of adjusting the position of each lens relative to the lens chip to make the brightness of the four corners of the video display page of the multi-channel camera uniform, the position adjustment of the lens is achieved by adjusting the base of the lens.

3. The optical eccentricity correction method for multi-channel imaging according to claim 1, characterized in that, In the step of simultaneously capturing the same point light source at infinity using N lenses of the multi-channel camera, so that the video display page of the multi-channel camera simultaneously displays N captured images, and the point light source is displayed on each captured image, the lower limit of infinity is defined as L, which satisfies the following formula (1). L=EFL*H / 2h (1) Wherein, EFL represents the focal length of the lens, H represents the distance between two adjacent lenses in the multi-channel camera, and h represents the pixel width of the lens chip.

4. The optical eccentricity correction method for multi-channel imaging according to claim 3, characterized in that, The EFL is 5mm, the h is 0.00345mm, the H is 30mm, and the infinity L is 21.7m.

5. The optical eccentricity correction method for multi-channel imaging according to claim 1, characterized in that, The step of adjusting the image plane position of the point light source in one of the captured images to the same position as the reference is achieved by adjusting the base of the lens corresponding to each captured image.

6. The optical eccentricity correction method for multi-channel imaging according to claim 5, characterized in that, In the optical eccentricity correction method described above After adjusting the image plane position of the point light source in the other captured images to be the same as the reference, the method further includes: applying adhesive to the lens.

7. The optical eccentricity correction method for multi-channel imaging according to claim 1, characterized in that, The image plane position is a two-dimensional coordinate system position.

8. The optical eccentricity correction method for multi-channel imaging according to claim 1, characterized in that, The value of N is 2 ≤ N ≤ 8.

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