A baffle and optical path based on scene temperature non-uniformity correction

Abstract

The present invention relates to a baffle and an optical path based on scene temperature non-uniform correction. Based on the principles of diffraction optics and geometric optics, a parallel plate diffraction optical element with optical focal length is used as a non-uniform correction baffle of an infrared system. When the parallel plate diffraction optical element with optical focal length is used to perform non-uniform correction of the infrared system, the parallel plate diffraction optical element with optical focal length can change the object distance position of the infrared lens, and transform the infrared lens at an infinite object distance of normal imaging into an air layer at a limited distance under the non-uniform correction state. The air layer is imaged onto the focal plane of the infrared detector through the parallel plate diffraction optical element with optical focal length and the infrared lens, and then non-uniform correction is performed. The temperature of the air layer represents the actual temperature of the exterior scene, and non-uniform correction based on the scene temperature is realized.

Description

Technical Field

[0001] The invention belongs to the field of optical technology and relates to a baffle based on scene temperature non-uniform correction and a light path used therein. Background Art

[0002] Infrared detection technology is a thermal detection technology that works in the infrared band (medium wave: 3-5μm, long wave: 8-12μm) and uses the differences in radiation temperature of different objects in the scene. It can work during the day and at night and in adverse weather conditions such as fog, haze, smoke, and dust, and can greatly expand the visual performance of the human eye.

[0003] The core of infrared detection technology is various infrared detectors that convert received scene thermal radiation into electrical signals. Although the photosensitive elements on the same infrared detector focal plane array are made of the same material, there are generally differences between the detection units due to the non-uniformity of the production materials and the different manufacturing processes. Therefore, when receiving the same uniform radiation, the response output of different detection units is different. This is the fundamental reason for the non-uniformity of the infrared detector focal plane array. Non-uniformity is a ubiquitous noise that is superimposed on the image in the form of fixed pattern noise. This noise is the non-uniformity of the infrared focal plane array. It seriously affects the imaging quality of the infrared system, making it difficult to distinguish the target image from the background, which limits the performance of the infrared focal plane array and its military and civilian applications.

[0004] At present, the most common method to solve this problem is to add a baffle correction mechanism to the design of the infrared system, use the baffle as a reference radiation source to correct the image non-uniformity, solidify the image non-uniformity correction coefficient, and thus improve the imaging quality of the infrared system. The base of the baffle in this baffle correction mechanism is usually made of metal or composite materials, and then a matte material is sprayed on its surface to form a diffuse reflection coating on its surface, and the surface temperature of the diffuse reflection coating is as uniform as possible.

[0005] The disadvantage of this correction method is that when the infrared system works in an environment with large temperature changes, the temperature of the baffle itself is uneven and has a large temperature difference with the external scene, resulting in large image noise in the picture after non-uniformity correction, which seriously affects the image quality. Summary of the invention

[0006] Technical issues to be solved

[0007] In order to avoid the shortcomings of the prior art, the present invention proposes a baffle and optical path based on scene temperature non-uniform correction, and adopts a parallel plate diffraction optical element with optical focal length as the design of an infrared non-uniform correction baffle, thereby realizing non-uniform correction based on scene temperature, solving the problems of uneven temperature of the baffle itself and large difference between the correction temperature and the scene temperature, and improving the image quality of the infrared system.

[0008] Technical Solution

[0009] A baffle based on scene temperature non-uniform correction, comprising a non-uniform correction area 1 and a support handle 2; characterized in that it also includes a support tube 3; the outer ring of the non-uniform correction area 1 is the support tube 3; the non-uniform correction area 1 adopts a parallel plate diffraction optical element with optical focal length; the support tube 3 adopts metal or composite material.

[0010] The material of the parallel plate diffractive optical element includes, but is not limited to: single crystal silicon, single crystal germanium, zinc selenide or zinc sulfide infrared transparent optical material.

[0011] The applicable wavelength of the material of the parallel plate diffractive optical element is 3 μm to 5 μm and 8 μm to 12 μm.

[0012] The applicable infrared lens aperture range is: φ8mm~φ35mm.

[0013] An optical path using the baffle based on scene temperature non-uniformity correction, characterized in that: the optical path is in order: object plane 4, non-uniformity correction baffle 7, infrared lens 5 and image plane 6;

[0014] Optical parameter table, unit: mm

[0015]

[0016]

[0017] Beneficial Effects

[0018] The present invention proposes a baffle and optical path based on scene temperature non-uniform correction, based on the principles of diffraction optics and geometric optics, using a parallel plate diffraction optical element with optical focal length as a non-uniform correction baffle for an infrared system. When using the parallel plate diffraction optical element with optical focal length to perform non-uniform correction of the infrared system, the parallel plate diffraction optical element with optical focal length can change the object distance position of the infrared lens, and transform the infrared lens at an infinite object distance of normal imaging into an air layer at a finite distance under the non-uniform correction state. The air layer is imaged onto the focal plane of the infrared detector through the parallel plate diffraction optical element with optical focal length and the infrared lens, and then non-uniform correction is performed. The temperature of the air layer represents the actual temperature of the exterior scene, and non-uniform correction based on the scene temperature is achieved.

[0019] The technical effects of the present invention are:

[0020] 1 Based on scene temperature correction

[0021] When a parallel plate diffractive optical element with optical focal length is used to perform non-uniform correction of an infrared system, the parallel plate diffractive optical element with optical focal length can change the object distance position of the infrared lens, and transform the infrared lens with normal imaging at an infinite object distance into an air layer with a finite distance under a non-uniform correction state. The air layer is imaged onto the focal plane of the infrared detector via the parallel plate diffractive optical element with optical focal length and the infrared lens, and then non-uniform correction is performed. The temperature of the air layer represents the actual temperature of the outdoor scene, thereby realizing infrared non-uniform correction based on the scene temperature.

[0022] 2. Compact structure

[0023] The light beam converging effect is achieved by using a parallel plate diffractive optical element with optical focal length. Compared with a conventional spherical lens for achieving the light beam converging effect, the light beam converging effect occupies a smaller volume and is lighter in weight.

[0024] 3. Uniform temperature field

[0025] Since the non-uniform correction is to image the air layer at a finite distance, the air layer at a finite distance is used as a reference radiation source and has nothing to do with the temperature of the correction baffle itself, thereby improving the uniformity of the temperature field during correction. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of a baffle in the prior art;

[0027] a: front view, b: side view

[0028] 1-Non-uniform correction area: diffuse coating, 2-Support handle: metal or composite material

[0029] Figure 2 Schematic diagram of the baffle of the present invention

[0030] a: front view, b: side view

[0031] 1-Non-uniform correction area: parallel plate diffractive optical element with optical power, 2-Support handle: metal or composite material, 3-Support tube: metal or composite material

[0032] Figure 3 Schematic diagram of the imaging optical path of an infrared lens with infinite object distance

[0033] 4—object plane: infinite scene, 5—infrared lens, 6—image plane: detector focal plane

[0034] Figure 4Schematic diagram of the optical path of the existing baffle

[0035] 4—object plane: infinite scene, 5—infrared lens, 6—image plane: detector focal plane. 7—non-uniform correction support mechanism

[0036] Figure 5 Schematic diagram of the optical path of the baffle of the present invention

[0037] 2—Non-uniform correction support mechanism, 4—Object plane: infinite scene, 5—Infrared lens: including lens 5-1, lens 5-2, lens 5-3, lens 5-4, 6—Image plane: detector focal plane. 7—Non-uniform correction support mechanism DETAILED DESCRIPTION

[0038] The present invention will now be further described with reference to the embodiments and the accompanying drawings:

[0039] When the present invention uses a parallel plate diffractive optical element with optical focal length to perform non-uniform correction of an infrared system, the parallel plate diffractive optical element with optical focal length can change the object distance position of an infrared lens, and transform the infrared lens with normal imaging at an infinite object distance into an air layer with a finite distance under a non-uniform correction state. The air layer is imaged onto a focal plane of an infrared detector via the parallel plate diffractive optical element with optical focal length and the infrared lens, and then non-uniform correction is performed. The temperature of the air layer represents the actual temperature of an exterior scene, thereby realizing infrared non-uniform correction based on the scene temperature.

[0040] The present invention is further described in detail by specific embodiments: Figures 1 to 5 The present invention discloses a baffle design based on scene temperature non-uniform correction, which comprises, according to the direction of the light path: an object plane 1 (an air layer at a finite distance), a non-uniform correction baffle 2 (a parallel flat plate diffraction optical element with optical power), an infrared lens 3, an image plane 4 (a detector focal plane), and a non-uniform correction support mechanism 8.

[0041] The optical path diagram Figure 5 Based on the principles of diffraction optics and geometric optics, a parallel plate diffraction optical element with optical focal length is used as a non-uniform correction baffle of an infrared system to realize a baffle design based on scene temperature non-uniform correction.

[0042] According to the direction of the optical path, it includes: an object plane 4 (air layer at a limited distance), a non-uniform correction baffle 8 (a parallel flat plate diffraction optical element with optical power), an infrared lens 5, an image plane 6 (detector focal plane) and a non-uniform correction support mechanism 2. Detailed optical parameters are shown in the table below.

[0043] Optical parameter table (unit: mm)

[0044]

[0045]

[0046] Aspheric equations:

[0047]

[0048] Where: r – distance from the optical axis;

[0049] R——the radius of curvature at the vertex of the aspherical surface;

[0050] K——conic constant;

[0051] A, B, C, D – aspheric coefficients.

[0052] The diffraction surface equation is:

[0053]

[0054] Where: r – distance from the optical axis;

[0055] R——the radius of curvature at the vertex of the aspherical surface;

[0056] K——conic constant;

[0057] HOR – diffraction order;

[0058] c1, c2——diffraction surface coefficients;

[0059] n——refractive index of base material;

[0060] n0——refractive index of air;

[0061] λ0——center wavelength.

Claims

1. A baffle based on scene temperature non-uniformity correction, comprising a non-uniformity correction area (1) and a support handle (2); characterized in that It also includes a support tube (3); the outer ring of the non-uniform correction area (1) is the support tube (3); the non-uniform correction area (1) uses a parallel plate diffractive optical element with optical focal length; the support tube (3) uses metal or composite materials; wherein, when the parallel plate diffractive optical element with optical focal length is used to perform non-uniform correction of the infrared system, the parallel plate diffractive optical element with optical focal length can change the object distance position of the infrared lens, and transform the infrared lens at an infinite object distance of normal imaging into an air layer at a finite distance under the non-uniform correction state; the air layer is imaged onto the focal plane of the infrared detector through the parallel plate diffractive optical element with optical focal length and the infrared lens (5), and then non-uniform correction is performed; the temperature of the air layer represents the actual temperature of the outdoor scene, thereby realizing infrared non-uniform correction based on the scene temperature.

2. The baffle based on scene temperature non-uniformity correction according to claim 1, characterized in that: The material of the parallel plate diffractive optical element includes, but is not limited to: single crystal silicon, single crystal germanium, zinc selenide or zinc sulfide infrared transparent optical material.

3. The baffle based on scene temperature non-uniformity correction according to claim 1 or 2, characterized in that: The applicable wavelength of the material of the parallel plate diffractive optical element is 3 μm to 5 μm and 8 μm to 12 μm.

4. An optical path using the baffle based on scene temperature non-uniformity correction according to claim 1 or 2, characterized in that: The optical paths are: an object plane (4), a non-uniform correction baffle (7), an infrared lens (5), and an image plane (6).

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