A multi-band high-speed visible imaging system and method

Abstract

The present invention discloses a multi-band high-speed visible imaging system and method, and relates to the technical field of high-speed image collaborative acquisition. It includes an aspheric reflector, a plane reflector, a collimating lens, a vacuum window glass, a dichroic mirror, and a camera placed in sequence along the optical path; the aspheric reflector and the plane reflector constitute a front-end reflection system for deflecting the incident light into a first light beam; the collimating lens is used to collimate the first light beam into parallel light; the dichroic mirror is used to split the parallel light into three bands of B, G, and R; the camera is used to independently image the three bands of B, G, and R to achieve synchronous image acquisition. The present invention can simultaneously achieve large-field-of-view, multi-band visible light image acquisition, and complete high-speed true-color image acquisition.

Description

Technical Field

[0001] The present invention relates to the technical field of high-speed image collaborative acquisition, and more specifically, to a multi-band high-speed visible imaging system and method. Background Art

[0002] In the prior art, there is only one camera interface in the large field-of-view optical path, and one camera is connected for high-speed image acquisition. Usually, a color camera is actually a pseudo-color camera, and it is difficult to be compatible with resolution and sensitivity. True color cameras (3CCD or 3CMOS cameras) have emerged in the market, but it is difficult to break through the 100fps level in terms of speed. Therefore, for those skilled in the art, how to achieve high-resolution acquisition of large field-of-view and multi-band visible light images is an urgent problem to be solved. Summary of the Invention

[0003] In view of this, the present invention provides a multi-band high-speed visible imaging system and method to solve the problems raised in the background art.

[0004] To achieve the above object, the present invention adopts the following technical solutions: A multi-band high-speed visible imaging system includes an aspherical mirror, a plane mirror, a collimating lens, a vacuum isolation window glass, a dichroic mirror, and a camera, which are sequentially arranged along the optical path;

[0005] The aspherical mirror and the plane mirror form a front-end reflection system for deflecting incident light into a first light beam;

[0006] The collimating lens is used to collimate the first light beam into parallel light;

[0007] The vacuum isolation window glass is used to isolate the atmospheric environment and protect the vacuum environment of the system;

[0008] The dichroic mirror is used to split the parallel light into three bands: B, G, and R;

[0009] The camera is used to independently image the three bands of B, G, and R to achieve synchronous image acquisition.

[0010] Optionally, the folding angle of the plane mirror is determined according to the installation position and observation position of the camera.

[0011] Optionally, it further includes a filter, which is installed on the filter interface reserved on the optical path interface and is used to monitor the distribution of different impurities in the light source in space.

[0012] Optionally, the plane mirror is provided with pores.

[0013] Optionally, the aspherical mirror and the plane mirror are spaced at a fixed distance.

[0014] Optionally, the dichroic mirror and the vacuum isolation window glass are made of fused quartz material.

[0015] On the other hand, a multi-band high-speed visible imaging method is provided, which uses the multi-band high-speed visible imaging system described above for high-speed visible imaging. The specific steps are as follows:

[0016] The optical axis of the incident light rotates by a fixed degree after passing through the aspherical mirror and the plane mirror, obtaining a second optical path;

[0017] The second optical path becomes a third optical path after passing through the collimating lens;

[0018] The third optical path passes through the vacuum isolation window glass and is divided into different bands by the dichroic mirror;

[0019] A camera is connected to the end of each optical path channel after splitting, and independent imaging of the object to be measured in the same field of view is performed in different bands.

[0020] Optionally, image processing is also included for the imaging in different bands, and then synthesized into a true color image.

[0021] Optionally, the incident light enters the optical system through the pores on the plane mirror, first hits the aspherical mirror, and after being reflected by the aspherical mirror, it is deflected to the plane mirror, and then deflected into the barrel at the rear end of the optical path.

[0022] Optionally, the process of obtaining the true color image is as follows: the cameras connected to the ends of each optical path channel acquire the three-color channel images of the object to be photographed in the same field of view area at the same moment, obtain the relative intensity coefficients of each channel through color calibration, and then synthesize the color channels corresponding to each pixel to obtain a true color image.

[0023] It can be seen from the above technical solutions that compared with the prior art, the present invention discloses a multi-band high-speed visible imaging system and method, which has the following beneficial technical effects:

[0024] (1) The visible light is divided into three bands: blue light band (380 - 500nm), green light band (500 - 580nm), and red light band (580 - 750nm) by the dichroic mirror, so as to realize independent imaging of the object to be measured in the same field of view in three different visible light bands, and at the same time realize large field of view and multi-band visible light image acquisition;

[0025] (2) The present invention can be used to simultaneously obtain images of multiple spectral bands of the object to be photographed, so as to analyze relevant physical phenomena from different aspects;

[0026] (3) Perform image processing on multi - band visible light imaging to synthesize a true - color image, enabling a true - color camera with a frame rate exceeding 100,000 fps, while also taking into account high resolution, high sensitivity, and ultra - high frame rate performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings described below are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the provided drawings.

[0028] Figure 1 It is the system structure diagram of the present invention;

[0029] Figure 2 It is the front - end optical path structure diagram of the present invention;

[0030] Figure 3 It is the B - band optical path structure diagram of the present invention;

[0031] Figure 4 It is the G - band optical path structure diagram of the present invention;

[0032] Figure 5 It is the R - band optical path structure diagram of the present invention;

[0033] Figure 6 It is the optical path head structure and the optical path principle diagram;

[0034] Among them, 1 is an aspherical mirror, 2 is a plane mirror, 3 is a collimating lens, 4 is a vacuum - isolating window glass, 5 is a first dichroic mirror, 6 is a second dichroic mirror, 7 is a second dichroic mirror, 8 is a first camera, 9 is a second camera, and 10 is a third camera. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0036] The embodiments of the present invention disclose a multi - band high - speed visible light imaging system, as Figure 1 shown, including an aspherical mirror 1, a plane mirror 2, a collimating lens 3, a vacuum - isolating window glass 4, a dichroic mirror, and a camera arranged in sequence along the optical path;

[0037] The aspherical mirror 1 and the plane mirror 2 form a front-end reflection system for deflecting the incident light into a first light beam;

[0038] The collimating lens 3 is used to collimate the first light beam into parallel light;

[0039] The dichroic mirror is used to split the parallel light into three bands: B, G, and R;

[0040] The camera is used to independently image the three bands of B, G, and R to achieve synchronous image acquisition.

[0041] The dichroic mirror includes a first dichroic mirror 5, a second dichroic mirror 6, and a second dichroic mirror 7; the splitting wavelength bands are: B blue light region (380 - 500 nm), G green light region (500 - 580 nm), and R red light region (580 - 750 nm).

[0042] Cameras are connected to the end of each optical path channel, namely the first camera 8, the second camera 9, and the third camera 10 respectively.

[0043] Specifically, in this embodiment, under the conditions of ensuring the outer dimensions, field of view angle, and relative aperture, the system focal length is maintained at 16 mm, and the clear aperture is maintained at 4 mm. Within the designed field of view angle, the coverage range on the image plane is smaller than the target surface size of the camera, which is 28.16×19.712 mm. At the current field of view angle, the occupied target surface size is 18.36×13 mm.

[0044] In this embodiment, the aspherical mirror 1 is a parabolic mirror, R = -133.533 mm, k = -1; the clear aperture is: 86×64 mm, and the off-axis amount is: 20.1406 mm;

[0045] The clear aperture of the plane mirror 2 is: 82×68 mm;

[0046] A small hole is opened on the plane mirror 2. Since the system clear aperture is 4 mm and the plane mirror is installed at an inclination of 32.5°, the diameter of the small hole opening is: 4 / cos(32.5°) = 4.743 mm. To ensure a margin, it is recommended that the size of the small hole be φ 5.2 mm; calculated according to the small hole size of φ 5.2 mm, the blind spot occupies approximately 4.3° of the field of view;

[0047] The folding angle of the plane mirror 2 should be determined according to the installation position of the camera lens and the observation position. In this embodiment, the folding angle of the plane mirror is 32.5°, and the included angle between the object-side optical axis and the lens barrel is 115°.

[0048] In the front-end reflection system, the distance between the aspherical mirror 1 and the plane mirror 2 is: 70 mm; the front-end optical path structure is as Figure 2 shown.

[0049] Distance between the plane mirror 2 and the collimating lens 3: 1277.238 mm; Clear aperture of the collimating lens 3: 83.5 mm;

[0050] The light beam becomes parallel light after passing through the collimating lens 3;

[0051] The plane mirror 2 is 1664.351 mm away from the vacuum isolation window glass 4; The diameter of the vacuum isolation window glass 4 is 72.5 mm, the thickness is 12 mm, and the material is fused quartz;

[0052] 9) After the vacuum isolation window glass 4, after being split by the dichroic mirror, it is an imaging lens group for three bands of B, G, and R. The optical structures of the three lens groups are the same. The length of the camera lens barrel (from the front lens to the rear lens) is 617.801 mm; The focal length is about 182.99 mm. The optical path structures of the three bands of B, G, and R are as Figures 3 - 5 shown.

[0053] On the other hand, a multi-band high-speed visible imaging method is provided, which uses a multi-band high-speed visible imaging system for high-speed visible imaging. The specific steps are as follows:

[0054] S1. After the incident light passes through the aspherical mirror 1 and the plane mirror 2, the optical axis rotates by a fixed degree to obtain the second optical path;

[0055] S2. The second optical path becomes the third optical path after passing through the collimating lens 3;

[0056] S3. The third optical path passes through the vacuum isolation window glass 4 and is split into different bands by the dichroic mirror;

[0057] S4. Cameras are connected to the ends of each optical path channel after splitting. Independent imaging of the measured object in the same field of view is performed in different bands.

[0058] Furthermore, it also includes image processing of the imaging in different bands, and then synthesizing it into a true color image, so as to realize the function of high-speed true color image acquisition. The image acquisition frame rate can reach more than 100 kfps, while the frame rate of the existing true color camera can only reach about 100 fps. The former is more than 1000 times that of the latter. In addition to being able to more accurately restore the color information of the photographed object, the true color camera can also obtain higher spatial resolution compared with the pseudo-color camera. Even further, the process of obtaining the true color image is as follows: The cameras connected to the ends of each optical path channel acquire the three color channel images of the photographed object in the same field of view area at the same moment. The relative intensity coefficients of each channel are obtained through color calibration, and then the color channels corresponding to each pixel are synthesized to obtain the true color image.

[0059] Through the filter interface reserved on the optical path interface, different narrow-band filters can also be installed for each channel, so as to monitor the distribution of different impurities in the space of light sources such as plasma and their evolution process over time, which is of great significance for the application of Tokamak plasma.

[0060] Another core structure of the optical system is Figure 6 The optical path of the optical head is shown. It consists of a plane mirror 2 with a small hole and an aspherical mirror 1. The incident light enters the optical system through the small hole, first hits the aspherical mirror 1, is reflected by the aspherical mirror 1 and then turns to the plane mirror, and then is turned into the lens barrel at the rear end of the optical path. Such a design is to achieve the periscope function of the optical path, that is, there can be a certain angle between the incident light and the lens barrel, which is very effective for applications that need to install the optical path along a certain fixed direction but there is an angle between the observation direction and the optical path. In addition, the small hole can effectively block a large amount of pollutants from entering the optical path and avoid the lenses being contaminated with coatings.

[0061] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the description of the method part.

[0062] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A multi-band high-speed visible imaging system, characterized in that: It includes an aspheric reflector, a plane reflector, a collimating lens, a vacuum window glass, a dichroic mirror, and a camera which are sequentially placed along the optical path; The aspherical reflector and the plane reflector constitute a front-end reflective system for deflecting the incident light into a first light beam; The collimating lens is used to collimate the first light beam into parallel light; The vacuum-isolating window glass is used to isolate the atmospheric environment and protect the vacuum environment of the system; The dichroic mirror is used to split the parallel light into three bands: B, G, and R; The cameras include a first camera, a second camera, and a third camera, which are respectively arranged at the ends of corresponding optical paths and are used to independently image the three bands of B, G, and R to achieve synchronous image acquisition.

2. A multi-band high-speed visible imaging system according to claim 1, characterized in that: The turning angle of the plane reflector is determined according to the installation position and observation position of the camera.

3. The multi-band high-speed visible imaging system according to claim 1, characterized in that: It also includes a filter, which is installed on a filter interface reserved on the optical path interface and is used to monitor the distribution of different impurities in the light source in space.

4. The multi-band high-speed visible imaging system according to claim 1, characterized in that: The plane reflecting mirror is provided with holes.

5. The multi-band high-speed visible imaging system according to claim 1, characterized in that: The aspherical reflector is spaced a fixed distance from the plane reflector.

6. The multi-band high-speed visible imaging system according to claim 1, characterized in that: The dichroic mirror and the vacuum window glass are made of fused quartz material.

7. A multi-band high-speed visible imaging method, characterized in that: High-speed visible imaging is performed using a multi-band high-speed visible imaging system as described in any one of claims 1 to 6, and the specific steps include the following: After the incident light passes through the aspherical reflector and the plane reflector, the optical axis rotates a fixed degree to obtain a second optical path; The second light path is transformed into a third light path through a collimating lens; The third light path passes through the vacuum window glass and is divided into different wavelength bands by the dichroic mirror; After the splitting, each end of the optical path channel is connected to a camera to independently image the object under test in the same field of view in different bands.

8. The multi-band high-speed visible imaging method according to claim 7, characterized in that: It also includes image processing of imaging in different bands and then synthesizing them into true color images.

9. The multi-band high-speed visible imaging method according to claim 7, characterized in that: The incident light enters the optical system through the aperture on the plane reflector, first hits the aspheric reflector, is reflected by the aspheric reflector, and then is folded to the plane reflector, and then is folded into the lens barrel at the rear end of the optical path.

10. The multi-band high-speed visible imaging method according to claim 8, characterized in that: The process of obtaining the true color image is as follows: the camera connected to the end of each optical path channel obtains three color channel images of the photographed object in the same field of view at the same time, obtains the relative intensity coefficient of each channel through color calibration, and then synthesizes the color channel corresponding to each pixel to obtain a true color image.

Images