阅读说明：本技术 一种红外连续变焦面阵扫描光学系统及像移补偿方法 (Infrared continuous zooming area array scanning optical system and image motion compensation method ) 是由 丁学专 黄姜卿 李范鸣 李争 孙夏杰 于洋 于 2019-11-11 设计创作，主要内容包括：本发明公开了一种红外连续变焦面阵扫描光学系统及像移补偿方法,从物面到像面依次包括：前固定组、补偿组、变倍组、后固定组、扫描振镜、二次会聚组、转折反射镜、三次成像组、光学窗口、孔径光阑。扫描振镜处于锁紧状态时,光学系统可工作于凝视跟踪模式,变焦倍率可达6倍,各焦距畸变小于0.5％。扫描振镜在一定角度范围内往返扫描时,光学系统可工作于面阵周扫搜索模式,系统可在多档焦距之间变焦,扫描过程不产生离焦,成像清晰。系统变焦及扫描形式简洁、通过两组光学元件的移动以及中间平行光路引入扫描镜、使系统具有扫描镜尺寸小、扫描过程无离焦、多档面阵周扫、超低光学畸变、凝视连续变焦的特点,可实用于搜索与跟踪一体的红外系统中。(The invention discloses an infrared continuous zooming area array scanning optical system and an image motion compensation method, which sequentially comprise the following steps from an object plane to an image plane: the device comprises a front fixed group, a compensation group, a zoom group, a rear fixed group, a scanning galvanometer, a secondary convergence group, a turning reflector, a tertiary imaging group, an optical window and an aperture diaphragm. When the scanning galvanometer is in a locked state, the optical system can work in a staring tracking mode, the zoom magnification can reach 6 times, and the distortion of each focal length is less than 0.5 percent. When the scanning galvanometer scans back and forth within a certain angle range, the optical system can work in an area array circumferential scanning search mode, the system can zoom among multiple focal lengths, defocusing is not generated in the scanning process, and imaging is clear. The system has simple zooming and scanning forms, introduces the scanning mirror through the movement of the two groups of optical elements and the middle parallel light path, has the characteristics of small size of the scanning mirror, no defocusing in the scanning process, multi-level array circumferential scanning, ultralow optical distortion and staring continuous zooming, and can be practically used in an infrared system integrating searching and tracking.)

1. The utility model provides an infrared continuous zoom area array scanning optical system, includes preceding fixed group (1), compensation group (2), zoom group (3), back fixed group (4), scanning galvanometer (5), secondary convergence group (6), turn speculum (7), cubic imaging group (8), optical window (9), aperture diaphragm (10), image plane (11), its characterized in that:

imaging light beams from an object space sequentially pass through a front fixing group (1), a compensation group (2), a zoom group (3) and a rear fixing group (4) and then are changed into parallel light beams, and after the parallel light beams are bent by a scanning galvanometer (5), the parallel light beams pass through a secondary convergence group (6), a bending reflector (7), a tertiary imaging group (8), an optical window (9) and an aperture diaphragm (10), and then are imaged on an image surface; magnification ratio Γ of optical system: 1< gamma is less than or equal to 6; f number of optical system: f is more than or equal to 4.0 and less than or equal to 5.5;

the zoom group (3) moves towards the object space, and the focal length is shortened; the zoom group (3) moves to the image side, and the focal length is lengthened. In the moving process of the zoom group (3), the compensation group (2) correspondingly moves to compensate the image surface movement in the zooming process, so that continuous zooming is realized;

the compensation group (2) moves along the optical axis direction, and has the functions of zooming image plane drift, image plane drift at different working temperatures and imaging image plane drift compensation at different object distances;

a telescopic system is composed of a front fixed group (1), a compensation group (2), a zoom group (3) and a rear fixed group (4), rays from infinity pass through the front four groups and then become parallel rays to be emitted, and the exit pupil of the parallel rays is positioned at the position of a scanning galvanometer (5); the position of the entrance pupil of the optical system is positioned on the front surface of the front fixed first lens (1-1) in the longest focal state; the aperture diaphragm (10) is superposed with the cold diaphragm in the infrared detector matched with the system, and the apertures are the same; the angle between the turning reflector (7) and the light path is 45 degrees, and the light path is turned by 90 degrees.

2. The infrared continuous-zoom-area-array scanning optical system according to claim 1, characterized in that: the front fixed group (1) consists of a front fixed first lens (1-1) and a front fixed second lens (1-2); the front fixed first lens (1-1) is a meniscus silicon lens with positive focal power bent to the image side; the front fixed second lenses (1-2) are meniscus aspheric germanium lenses with negative focal power and bending towards the image.

3. The infrared continuous-zoom-area-array scanning optical system according to claim 1, characterized in that: the compensation group (2) is a meniscus type aspheric germanium lens with negative focal power and bent to the image side.

4. The infrared continuous-zoom-area-array scanning optical system according to claim 1, characterized in that: the zoom group (3) is an aspheric zinc selenide lens with double convex positive focal power.

5. The infrared continuous-zoom-area-array scanning optical system according to claim 1, characterized in that: the rear fixed group (4) consists of a rear fixed first lens (4-1) and a rear fixed second lens (4-2); the rear fixed first lens (4-1) is a meniscus spherical germanium lens with negative focal power and bent towards an object, and the rear fixed second lens (4-2) is a meniscus aspheric diffractive germanium lens with positive focal power and bent towards the object.

6. The infrared continuous-zoom-area-array scanning optical system according to claim 1, characterized in that: the secondary convergence group (6) consists of a secondary convergence first lens (6-1) and a secondary convergence second lens (6-2); the second-time convergence first lens (6-1) is a negative-focal-power spherical calcium fluoride lens which is bent to the scanning galvanometer (5); the second secondary converging lens (6-2) is a positive power aspheric AMTIR1 lens bent towards the turning reflector (7).

7. The infrared continuous-zoom-area-array scanning optical system according to claim 1, characterized in that: the cubic imaging group (8) consists of a cubic imaging first lens (8-1) and a cubic imaging second lens (8-2); the third imaging first lens (8-1) is a meniscus spherical silicon lens with positive focal power and bent towards the turning reflector (7); the third imaging second lens (8-2) is a meniscus type aspheric silicon lens with positive focal power and bent to the image side.

8. An image motion compensation method of an infrared continuous zooming area array scanning optical system based on claim 1 is characterized by comprising the following steps:

the optical system has two working modes, when the scanning galvanometer (5) is in a locking state, the scanning galvanometer is placed at an angle of 45 degrees with an optical axis of the telescope, a light path is turned by 90 degrees, the system works in a staring tracking mode, the maximum zooming magnification can reach 6 times, the distortion in the zooming process is less than 0.5%, when the scanning galvanometer (5) is in a back-and-forth retrace state, the optical system works in an area array circumferential scanning search mode, the system can zoom among multiple focal lengths, the defocusing is not generated in the scanning process, the imaging is clear, the optical system can be applied to the scanning mode under the state of the multiple focal lengths, α is an effective backswing scanning angle of the scanning galvanometer (5), β is an amplification magnification of the telescope system consisting of a front fixed group (1), a compensation group (2), a zoom group (3) and a rear fixed group (4) under the short-focus state, the circumferential scanning rotation speed of the optical system is omega, the area array detector integration time is tau, and when the infrared optical system performs image shift compensation:

Technical Field

The present invention relates to infrared detection optical systems, and in particular, to an infrared optical system for continuous zoom area array scanning and an image motion compensation method.

Background

The infrared searching and tracking utilizes the infrared characteristic of the target to detect and track the target, can provide panoramic monitoring capability, can search the target at night or under the condition of poor visibility, improves the perception capability of the system on the threatening target in the air, the ground and the sea surface, and becomes one of the modern important weaponry. The infrared search tracking system has two functions of target search and target tracking. Firstly, the infrared system platform performs scanning imaging in 360 degrees of azimuth or in an angle range of a key area at a certain rotating speed. After the target is found, the system switches to tracking mode. The infrared search tracking system has the advantages of good concealment, wide detection range, high positioning accuracy, strong identification camouflage capability, electromagnetic interference resistance and the like, and has been widely concerned and applied.

The infrared alarm system adopting the infrared line detector can carry out imaging in the range of 360 degrees in azimuth through platform scanning. After the target is found, the target cannot be tracked. With the application requirement of integration of search and tracking, a continuous scanning type surface array detector imaging system is developed. Scanning of a continuous scan type linear array imaging system during the integration time results in relative motion between the focal plane and the scene, causing smearing and blurring of the image. By the backswing compensation technology, the area array scanning infrared system with the functions of infrared periphery scanning search and gaze tracking can be realized.

The relevant application research of the scanning type infrared search tracking system based on the area array detector is carried out abroad. The French HGH infrared system company develops a high-fraction wide-area monitoring system Spynel-X8000 in 2014, and the system can complete 360-degree azimuth scanning and 5-degree elevation field scanning at a search rate of 2 seconds/turn. The system adopts a reverse scanning compensation type image motion compensation scheme and adopts a refrigeration type medium wave infrared area array detector.

The research is carried out in 2012 of the university of the Western-Ann industry for a photoelectric early warning detection system, a medium wave 3.7-4.8 um area array detector is adopted, and the resolution is 320 multiplied by 256. The frame frequency of an output image is 50Hz, the focal length of the system is 90mm, and the F number of the optical system is 2. In the mode of reverse scanning compensation, a limited-angle direct-current torque motor is used for driving a reflector to realize the staring compensation function of the system for focusing the planar thermal imager, and the phenomenon of image trailing of an area array device in the panoramic search process is eliminated. (white wave, research on key technology of an infrared search and tracking system adopting a focal plane detector, and research on key technology of an infrared search and tracking system adopting a focal plane detector [ D ]. university of Sigan industry).

In 2014, CN 104539829 a disclosed an optical-mechanical structure based on scanning imaging of an infrared area array detector, which realizes 360-degree omni-directional scanning imaging of a single infrared area array detector, ensures that no blurring effect is generated due to rotation of a platform during infrared image acquisition, and can fully exert the characteristics of long integration time and high sensitivity of the area array infrared focal plane detector.

In 2016, an area array detector continuous scanning imaging optical system is designed by Shanghai technical and physical research institute of Chinese academy of sciences, wherein the focal length of the system is 73mm, F/2, and the system is matched with a detector of 320 multiplied by 256. (in ocean, Wang Shi Yong, et al. area array detector continuous scanning imaging optical system, infrared and laser engineering, 2016, 45(1): 0118002-1-0118002-5).

In 2019, in invention CN110119022A, a two-stage zoom area array scanning optical system is disclosed, which can switch the large and small fields of view and perform area array return imaging in two states.

Therefore, currently reported infrared area array scanning optical systems are all designed with fixed focal length or two-gear zooming, and do not have the functions of multi-gear area array scanning and gaze tracking continuous zooming. During 360-degree circumferential scanning search and gaze tracking, the resolution of the target cannot be continuously changed, and the functions of large-field search and small-field continuous tracking cannot be considered.

Disclosure of Invention

Based on the problems, the invention provides an infrared continuous zooming area array scanning optical system. The purpose of the invention is: the infrared continuous zooming area array scanning optical system can realize multi-stage zooming area array scanning, continuous zooming and staring tracking, maximum optical zooming multiplying power reaching 6 times, distortion less than 0.5% in the zooming process, working temperature compensation between minus 30 ℃ and plus 60 ℃ and focusing of imaging at different distances by moving the zooming group and the compensation group.

The technical problem to be solved by the invention is as follows: firstly, under the multi-gear focal length state, off-axis aberration caused by the back swing of the scanning galvanometer is corrected, and the scanning galvanometer can be ensured to be imaged clearly in the whole scanning process; and secondly, under the multi-gear focal length state, the distortion caused by the swinging of the galvanometer is reduced, and the registration of the image in the full view field range is ensured in the swinging process, so that the image is kept stable. Thirdly, a solution is provided, and simultaneously, the ultra-low distortion multi-gear zooming area array scanning, the gaze tracking with the maximum magnification reaching 6 times of continuous zooming, the compensation of the working temperature of-30 ℃ to +60 ℃ and the focusing of the imaging at different distances are realized. And fourthly, the galvanometer is introduced by adopting an intermediate light path to perform the motion of the inverse scanning compensation platform, so that the problem of light path design of the scanning of the small-size galvanometer of the intermediate light path is solved.

The system adopts a refrigeration type infrared detector to realize better detection performance. To suppress background radiation, the aperture stop of the optical system is 100% matched to the cold stop of the detector. Meanwhile, in order to reduce the volume of the optical system, the aperture of the first lens is reduced, so that the entrance pupil is designed on the front end surface of the first lens. Further, in order to reduce the size of the galvanometer, the exit pupil of the telescopic system is designed to be at the galvanometer position.

The technical scheme for solving the problems is shown in figure 1, and the invention is realized by the following technical scheme: the optical system for infrared imaging sequentially comprises a front fixed group 1, a compensation group 2, a zoom group 3, a rear fixed group 4, a scanning galvanometer 5, a secondary convergence group 6, a turning reflector 7, a tertiary imaging group 8, an optical window 9, an aperture diaphragm 10 and an image plane 11 from an object space to an image space. The imaging light beam from the object space sequentially passes through the front fixed group 1, the compensation group 2, the zoom group 3 and the rear fixed group 4 to be changed into parallel light beams, and after the parallel light beams are bent by the scanning galvanometer 5, the parallel light beams pass through the secondary convergence group 6, the bending reflector 7, the tertiary imaging group 8, the optical window 9 and the aperture diaphragm 10 to be imaged on the image surface.

The working wave band of the system is 3-5 μm; short focal length of f₁Focal length of tele is f₂The zoom ratio of the system is as follows: f ═ f₂/f₁(ii) a The zoom ratio of the system is 1<Gamma is less than or equal to 6; the F number of the infrared system ranges from: f/#ismore than or equal to 4.0 and less than or equal to 5.5;

the zoom group 3 moves towards the object space, and the focal length is shortened; the zoom group 3 moves toward the image side, and the focal length becomes longer. In the moving process of the zoom group 3, the compensation group 2 correspondingly moves to compensate the image plane movement in the zooming process, so as to realize continuous zooming.

The compensation group 2 moves along the optical axis direction, and has the functions of zooming image plane drift, image plane drift at different working temperatures and imaging image plane drift compensation at different object distances. The continuous zooming, the working temperature in the range of-30 ℃ to +60 ℃, the imaging object distance range of 10 m to infinity and the like can be realized, the image quality is good, and the focal plane position is unchanged.

A telescopic system is composed of a front fixed group 1, a compensation group 2, a zoom group 3 and a rear fixed group 4, rays from infinity pass through the front four groups and become parallel rays to be emitted, and the exit pupil of the parallel rays is positioned at the position of a scanning galvanometer 5. The optical system entrance pupil position in the longest focus state is located on the front surface of the front fixed first lens 1-1. The aperture diaphragm 10 is superposed with the cold diaphragm in the infrared detector matched with the system, and the apertures are the same. The angle between the turning reflector 7 and the light path is 45 degrees, and the light path is turned by 90 degrees.

The scanning galvanometer 5 is positioned in a parallel light path; has two working states: a locking state and a scanning state; when the scanning galvanometer 5 is in a locking state, the scanning galvanometer is placed at an angle of 45 degrees with the optical axis of the telescope, and the light path is turned by 90 degrees. Scanning galvanometerα is effective backswing scanning half angle of the scanning galvanometer 5, β is magnification of a telescopic system consisting of a front fixed group 1, a compensation group 2, a variable magnification group 3 and a rear fixed group 4 in a short focus state, the periodic scanning rotating speed of the optical system is omega, the integration time of an area array detector is tau, and when the infrared optical system carries out image shift compensation of the periodic scanning of the area array, the galvanometer compensation angle α meets the following requirements:

the front fixed group 1 consists of a front fixed first lens 1-1 and a front fixed second lens 1-2. The front fixed first lens 1-1 is a meniscus silicon lens of positive power curved toward the image side. The front fixed second lenses 1-2 are meniscus aspheric germanium lenses with negative focal power and bending towards the image.

The compensation group 2 is a meniscus type aspheric germanium lens with negative focal power and bent to the image side.

The zoom group 3 is an aspheric zinc selenide lens with biconvex positive focal power.

The rear fixed group 4 consists of a rear fixed first lens 4-1 and a rear fixed second lens 4-2; the rear fixed first lens 4-1 is a meniscus spherical germanium lens with negative focal power and bent towards the object space, and the rear fixed second lens 4-2 is a meniscus aspheric diffractive germanium lens with positive focal power and bent towards the object space.

The secondary convergence group 6 consists of a secondary convergence first lens 6-1 and a secondary convergence second lens 6-2; the second-time convergence first lens 6-1 is a negative focal power spherical calcium fluoride lens which is bent to the scanning galvanometer 5; the second-time converging second lens 6-2 is a positive-power aspheric AMTIR1 lens of the bending turning reflector 7;

the three-time imaging group 8 consists of a three-time imaging first lens 8-1 and a three-time imaging second lens 8-2. The first lens 8-1 for tertiary imaging is a meniscus spherical silicon lens with positive focal power and bent toward the turning reflector 7. The third imaging second lens 8-2 is a meniscus aspherical silicon lens with positive power bent to the image side.

The infrared continuous zooming area array scanning optical system has the following maximum characteristics: by moving the zoom group and the compensation group and the back and forth retrace of the scanning galvanometer, multi-stage focal length area array scanning and continuous zooming and staring tracking are realized; and the accurate registration of images in the full field of view in the multi-focus state scanning process is ensured, and the definition and stability of imaging are ensured. The distance of the compensation group is finely adjusted front and back, and the working temperature compensation between minus 30 ℃ and plus 60 ℃ and the focusing of the imaging at different distances are realized simultaneously. The optical system has the advantages of search, tracking, continuous zooming, wide working temperature range and clear imaging distance range. The method is mainly applied to an infrared search and tracking integrated system.

Drawings

FIG. 1 is an optical layout of an infrared continuous zoom area array scanning short-focus 60 mm; wherein 1 is a front fixed group, 2 is a compensation group, 3 is a zoom group, 4 is a rear fixed group, 5 is a scanning galvanometer, 6 is a secondary convergence group, 7 is a turning reflector, 8 is a tertiary imaging group, 9 is an optical window, 10 is an aperture diaphragm, and 11 is an image surface;

FIG. 2 is an optical layout of a 180mm mid-focus in an infrared continuous zoom area array scan;

FIG. 3 is an optical layout of an infrared continuous zoom area array scanning tele 360 mm;

FIG. 4 is a diagram of the short focus 60mm optical modulation transfer function;

FIG. 5 is a diagram of the optical modulation transfer function for a short-focus 60mm galvanometer with an included angle of 44.35 degrees;

FIG. 6 is a diagram of the optical modulation transfer function of a short-focus 60mm galvanometer with an included angle of 45.65 degrees;

FIG. 7 is a short focus 60mm optical distortion plot;

FIG. 8 is a plot of the 180mm mid focus optical modulation transfer function;

FIG. 9 is a diagram of the optical modulation transfer function at an included angle of 44.35 ° for a 180mm galvanometer at mid focus;

FIG. 10 is a diagram of the optical modulation transfer function at an included angle of 45.65 ° for a 180mm galvanometer with a middle focus;

FIG. 11 is a 180mm optical distortion plot for mid focus;

FIG. 12 is a plot of the tele 360mm optical modulation transfer function;

FIG. 13 is a diagram of the optical modulation transfer function for a tele 360mm galvanometer with an included angle of 44.35;

FIG. 14 is a diagram of the optical modulation transfer function at a telephoto 360mm galvanometer included angle of 45.65 degrees;

FIG. 15 is a tele 360mm optical distortion diagram.

Detailed Description

The invention will now be further described with reference to the following examples and drawings:

as shown in fig. 1, 2 and 3, the infrared continuous zoom area array scanning optical system of the present invention sequentially includes a front fixed group 1, a compensation group 2, a zoom group 3, a rear fixed group 4, a scanning galvanometer 5, a secondary convergence group 6, a turning mirror 7, a tertiary imaging group 8, an optical window 9 and an aperture stop 10 from an object space to an image space.

An infrared continuous zoom area array scanning optical system having a focal length variable range of 60mm to 360mm will be described as an example. The optical system is a six-time continuous zooming area array scanning optical system, and the working waveband is 3.0-5.0 mu m; the F number of the infrared system is F/4; the infrared two-gear zoom area array scanning optical system is matched with a refrigeration type infrared detector, and the detector array is 640 multiplied by 512; the pixel size is 15 μm;

short focal length of the focal length system is f₁60mm long focal length f₂The zoom ratio of the system is 360 mm: f ═ f₂/f₁6; the corresponding optical field coverage is from 1.53 ° × 1.22 ° to 9.15 ° × 7.33 °, and the F-number is constant at 4 throughout the zoom range. The optical system adopts a structural form of refraction-diffraction mixed transmission type three-time imaging and has 100% cold diaphragm efficiency. Fig. 1, fig. 2 and fig. 3 are schematic diagrams of the positions of the large visual field of 60mm, the middle visual field of 180mm and the small visual field of 360mm respectively.

At the position of 60mm short focus, the compensation group 2 is 5.14mm apart relative to the center of the back surface of the front fixed second lens 1-2; the distance from the center of the front surface of the first lens 4-1 fixed relatively backward of the variable power group 3 is 58.58 mm; the center of the back surface of the compensation group 2 is 57.25mm away from the center of the front surface of the zoom group;

at the 180mm position of the middle focus, the center of the rear surface of the compensation group 2 relative to the front fixed second lens 1-2 is 23.67 mm; the distance from the center of the front surface of the first lens 4-1 fixed relatively to the back of the variable power group 3 is 36.75 mm; the center of the back surface of the compensation group 2 is 60.55mm away from the center of the front surface of the variable-magnification group;

at the position of 360mm long focus, the compensation group 2 is 5.88mm apart relative to the center of the back surface of the front fixed second lens 1-2; the distance from the center of the front surface of the first lens 4-1 fixed relatively to the back of the zoom group 3 is 15.19 mm; the center of the back surface of the compensation group 2 is 99.9mm away from the center of the front surface of the zoom group;

the optical system can perform area array scanning work in a three-gear focal length state. When the focal length is 360mm, the searching speed of the platform is 60 degrees/s; when the focal length is 180 mm; the adaptive platform searching speed is 120 degrees/s; when the focal length is 60mm, the adaptive platform searching speed is 360 degrees/s.

Furthermore, in order to correct chromatic aberration and large field aberration, the invention adopts a mode of an aspheric surface or an aspheric surface plus a diffraction surface on part of the lens surface so as to improve the image quality and reduce the number of lenses and the volume of the lens.

Furthermore, in order to correct the aberration of the system under multiple states, the system adds a diffraction surface in the rear fixed second lens 4-2, which can effectively eliminate chromatic aberration and cancel the residual aberration of the front lens group.

Furthermore, in order to improve the energy utilization efficiency, the front and back surfaces of all the lenses are plated with high-quality antireflection films so as to improve the response sensitivity and the detection distance of the system.

The remarkable effect of the infrared continuous zooming area array scanning optical system is shown in the attached drawing, wherein in the attached drawing, FIG. 4 is a short-focus 60mm optical modulation transfer function graph; FIG. 5 is a diagram of the optical modulation transfer function for a short-focus 60mm galvanometer with an included angle of 44.35 degrees; FIG. 6 is a diagram of the optical modulation transfer function of a short-focus 60mm galvanometer with an included angle of 45.65 degrees; FIG. 7 is a short focus 60mm optical distortion plot; FIG. 8 is a plot of the 180mm mid focus optical modulation transfer function; FIG. 10 is a diagram of the optical modulation transfer function at an included angle of 45.65 ° for a 180mm galvanometer with a middle focus; FIG. 11 is a 180mm optical distortion plot for mid focus; FIG. 12 is a plot of the tele 360mm optical modulation transfer function; FIG. 13 is a diagram of the optical modulation transfer function for a tele 360mm galvanometer with an included angle of 44.35; FIG. 14 is a diagram of the optical modulation transfer function at a telephoto 360mm galvanometer included angle of 45.65 degrees; FIG. 15 is a tele 360mm optical distortion diagram;

technical features of the present invention which are not described may be implemented by the prior art, and will not be described herein. The above description is only an embodiment of the present invention, and is not intended to limit the present invention, and the present invention is not limited to the above examples, and variations, modifications, additions or substitutions, such as a corresponding change in lens material or an increase in the number of lenses in a lens set, which are made by those skilled in the art within the spirit of the present invention, should also fall within the protection scope of the present invention.