Refrigeration type laser three-dimensional imaging optical system based on avalanche detector

Abstract

The invention provides a refrigeration type laser three-dimensional imaging optical system based on an avalanche detector. The refrigeration type laser three-dimensional imaging optical system comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens which are sequentially arranged in the light path direction. The invention aims to improve the signal-to-noise ratio of a laser three-dimensional imaging system and suppress stray light interference outside a field of view; a high-sensitivity refrigeration type avalanche detector is used as a core detection element, so that the response to weak laser echo signals can be remarkably enhanced; the optical system adopts a refrigeration design, an entrance pupil is matched with a cold diaphragm of the detector, and thermal noise can be effectively inhibited by matching with a refrigeration technology of the detector; the avalanche detector responds to stray light noise very sensitively, an optical system is designed to be a secondary imaging system, and a diaphragm can be arranged at the position of a middle image plane to intercept stray light outside a view field and prevent the stray light from reaching the detector to form stray light noise.

Description

Technical Field

[0001] This application relates to the field of optical equipment technology, specifically to a cooled laser three-dimensional imaging optical system based on an avalanche detector. Background Technology

[0002] Laser 3D imaging is a cutting-edge technology with a wide range of applications. Compared with passive optoelectronic imaging systems, it has the advantage of being able to acquire accurate 3D images of targets instead of 2D images. It is not affected by lighting conditions and the contrast characteristics of the target background. It can be applied to military and civilian fields such as intelligence reconnaissance, precision guidance, navigation and obstacle avoidance, target identification, disaster assessment and security monitoring.

[0003] The optical system required for laser 3D imaging equipment is an important component that receives the laser echo reflected from the target and images it onto the avalanche detector. Existing optical systems suffer from stray light interference and noise interference, which can affect the imaging of the avalanche detector. Therefore, these problems urgently need to be solved. Summary of the Invention

[0004] In view of the above-mentioned defects or deficiencies in the prior art, it is desirable to provide a cooled laser three-dimensional imaging optical system based on an avalanche detector.

[0005] This application provides a cooled laser three-dimensional imaging optical system based on an avalanche detector, including a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged sequentially along the optical path. The front surface of the first lens is spherical, and the rear surface is planar; The front surface and the rear surface of the second lens are both spherical. The front surface and the rear surface of the third lens are both spherical. The front surface and the rear surface of the fourth lens are both spherical. The front surface and the rear surface of the fifth lens are both spherical. The front surface and the rear surface of the sixth lens are both spherical. The front surface of the seventh lens is aspherical, and the rear surface is spherical.

[0006] Furthermore, The first lens, The optical material is H-ZF7LA; The radius of curvature of the front surface is 76.752 mm, and the light transmission aperture ranges from φ64 mm to φ65 mm. The aperture range of the rear surface is φ62mm~φ63mm; The thickness ranges from 11.5mm to 11.7mm.

[0007] Furthermore, The second lens, The optical material is H-ZF7LA; The radius of curvature of the front surface is 38.7 mm, and the aperture range is φ55 mm~φ56 mm; The radius of curvature of the rear surface is 66.6 mm, and the aperture range is φ50 mm~φ51 mm; The thickness ranges from 11.8 mm to 12 mm.

[0008] Furthermore, The third lens The optical material is H-ZF62; The radius of curvature of the front surface is 28.14 mm, and the aperture range is φ41 mm to φ42 mm. The radius of curvature of the rear surface is 26.5 mm, and the aperture range is φ28 mm~φ29 mm; The thickness ranges from 12.9 mm to 13.1 mm.

[0009] Furthermore, The fourth lens, The optical material is ZnS; The radius of curvature of the front surface is 47.25 mm, and the aperture of the light transmission is φ24 mm; The radius of curvature of the rear surface is 11.04 mm, and the aperture diameter is φ14 mm. The thickness is 8.38mm.

[0010] Furthermore, The fifth lens, The optical material is H-ZF62; The radius of curvature of the front surface is 22.612 mm, and the light transmission aperture ranges from φ21 mm to φ23 mm. The radius of curvature of the rear surface is 17.529 mm, and the aperture range is φ27 mm~φ28 mm; The thickness ranges from 7.4 mm to 7.6 mm.

[0011] Furthermore, The sixth lens, The optical material is H-ZF7LA; The radius of curvature of the front surface is 120.57 mm, and the light transmission aperture ranges from φ34 mm to φ35 mm. The radius of curvature of the rear surface is 65.12 mm, and the aperture range is φ35 mm~φ36 mm; The thickness ranges from 8.5mm to 8.7mm.

[0012] Furthermore, The seventh lens The optical material is arsenic selenium germanium; The vertex curvature radius of the front surface is 33.66 mm, the fourth-order aspherical coefficient is -4.04×10-6, the sixth-order aspherical coefficient is -9.62×10-10, the eighth-order aspherical coefficient is 3.38×10-14, the tenth-order aspherical coefficient is -2.11×10-15, and the light transmission aperture range is φ39 mm~φ41 mm; The radius of curvature of the rear surface is 92.2 mm, and the aperture range is φ37 mm~φ39 mm; The thickness ranges from 8.1 mm to 8.3 mm.

[0013] Furthermore, The distance between the first lens and the second lens varies from 0.1 mm to 0.3 mm. The distance between the second lens and the third lens varies from 1mm to 2mm; The distance between the third lens and the fourth lens varies from 4.6 mm to 4.8 mm. The distance between the fourth and fifth lenses varies from 13.8 mm to 14 mm. The distance between the fifth lens and the sixth lens varies from 0.1 mm to 0.3 mm. The distance between the sixth and seventh lenses varies from 21.7 mm to 21.9 mm.

[0014] The advantages and positive effects of this application are: This technical solution aims to improve the signal-to-noise ratio of the laser 3D imaging system and suppress stray light interference outside the field of view. It employs a highly sensitive cooled avalanche detector as the core detection element, which significantly enhances the response to weak laser echo signals. The optical system adopts a cooled design, with the entrance pupil matched to the detector's cooling aperture. Combined with the detector's cooling technology, this effectively suppresses thermal noise. Because the avalanche detector is highly sensitive to stray light noise, the optical system is designed as a secondary imaging system. An aperture can be placed at the intermediate image plane to intercept stray light outside the field of view, preventing it from reaching the detector and causing stray light noise. Attached Figure Description

[0015] Figure 1 A schematic diagram of the structure of a cooled laser three-dimensional imaging optical system based on an avalanche detector provided in an embodiment of this application; Figure 2 The optical transfer function of the cooled laser three-dimensional imaging optical system based on an avalanche detector provided in this application embodiment at 20°C; Figure 3 The optical transfer function diagram of the cooled laser three-dimensional imaging optical system based on an avalanche detector provided in the embodiments of this application at -40°C; Figure 4 The optical transfer function of the cooled laser three-dimensional imaging optical system based on an avalanche detector provided in this application embodiment is plotted at 60°C.

[0016] The text labels in the diagram represent: 100 - first lens; 200 - second lens; 300 - third lens; 400 - fourth lens; 500 - fifth lens; 600 - sixth lens; 700 - seventh lens. Detailed Implementation

[0017] To enable those skilled in the art to better understand the technical solution of this application, the application will be described in detail below with reference to the accompanying drawings. The description in this section is only exemplary and explanatory, and should not be used to limit the scope of protection of this application.

[0018] Please refer to Figure 1 This embodiment provides a cooled laser three-dimensional imaging optical system based on an avalanche detector, including a first lens 100, a second lens 200, a third lens 300, a fourth lens 400, a fifth lens 500, a sixth lens 600, and a seventh lens 700 arranged sequentially along the optical path. The front surface of the first lens 100 is spherical, and the rear surface is planar. The front surface and rear surface of the second lens 200 are both spherical. The front surface and rear surface of the third lens 300 are both spherical. The front surface and rear surface of the fourth lens 400 are both spherical. The front surface and rear surface of the fifth lens 500 are both spherical. The front surface and rear surface of the sixth lens 600 are both spherical. The front surface of the seventh lens 700 is aspherical, and the rear surface is spherical.

[0019] In this embodiment, based on the direction of the light path, the left surface of all optical elements in the figure is defined as the front surface, and the right surface as the rear surface.

[0020] In this embodiment, the technical performance achievable by the present invention is as follows: Operating wavelength: 1.064μm; Field of view: 9° (pitch) × 7.2° (heading); Effective receiver diameter: φ61mm; F-number: 2.0; Optical distortion: less than 3%; Total detector pixel size: 19.2mm × 15.36mm; The anechoic temperature range is -40℃ to 60℃.

[0021] In this embodiment, the optical material of the first lens 100 is H-ZF7LA, the front surface is spherical with a radius of curvature of 76.752mm and a light-transmitting aperture of φ64.6mm; the rear surface is flat with a light-transmitting aperture of φ63mm; and the thickness is 11.59mm.

[0022] In this embodiment, the optical material of the second lens 200 is H-ZF7LA, the front surface is spherical with a radius of curvature of 38.7mm and a light-transmitting aperture of φ55.6mm; the rear surface is spherical with a radius of curvature of 66.6mm and a light-transmitting aperture of φ50mm; and the thickness is 11.91mm.

[0023] In this embodiment, the optical material of the third lens 300 is H-ZF62, the front surface is spherical with a radius of curvature of 28.14 mm and a light-transmitting aperture of φ41.7 mm; the rear surface is spherical with a radius of curvature of 26.5 mm and a light-transmitting aperture of φ28.4 mm; and the thickness is 12.99 mm.

[0024] In this embodiment, the optical material of the fourth lens 400 is ZnS, the front surface is spherical with a radius of curvature of 47.25 mm and a light-transmitting aperture of φ24 mm; the rear surface is spherical with a radius of curvature of 11.04 mm and a light-transmitting aperture of φ14 mm; and the thickness is 8.38 mm.

[0025] In this embodiment, the optical material of the fifth lens 500 is H-ZF62, the front surface is spherical with a radius of curvature of 22.612mm and a light-transmitting aperture of φ21.8mm; the rear surface is spherical with a radius of curvature of 17.529mm and a light-transmitting aperture of φ27.4mm; and the thickness is 7.5mm.

[0026] In this embodiment, the optical material of the sixth lens 600 is H-ZF7LA, the front surface is spherical with a radius of curvature of 120.57mm and a light-transmitting aperture of φ34.4mm; the rear surface is spherical with a radius of curvature of 65.12mm and a light-transmitting aperture of φ36mm; and the thickness is 8.54mm.

[0027] In this embodiment, the optical material of the seventh lens 700 is arsenic selenium germanium. The front surface is aspherical with a vertex radius of curvature of 33.66 mm, a fourth-order aspherical coefficient of -4.04 × 10⁻⁶, a sixth-order aspherical coefficient of -9.62 × 10⁻¹⁰, an eighth-order aspherical coefficient of 3.38 × 10⁻¹⁴, a tenth-order aspherical coefficient of -2.11 × 10⁻¹⁵, and a light-transmitting aperture of φ39.8 mm. The rear surface is spherical with a radius of curvature of 92.2 mm and a light-transmitting aperture of φ37 mm. The thickness is 8.2 mm.

[0028] In this embodiment, the distance between the first lens 100 and the second lens 200 is 0.21 mm; the distance between the second lens 200 and the third lens 300 is 1.42 mm; the distance between the third lens 300 and the fourth lens 400 is 4.69 mm; the distance between the fourth lens 400 and the fifth lens 500 is 13.83 mm; the distance between the fifth lens 500 and the sixth lens 600 is 0.22 mm; and the distance between the sixth lens 600 and the seventh lens 700 is 21.82 mm.

[0029] Please refer to further information. Figure 2-4 The system utilizes CodeV optical design software to generate the optical transfer function (MTF) values ​​of the best-in-class embodiment. The design input is a wavelength of 1.064 μm, with half-fields of view of 0°, 1.4°, 2.8°, 4°, 4.7°, 5.8°, and -5.8°, and an F-number of 2.0. The horizontal axis of the figure represents spatial frequency, and the vertical axis represents the optical transfer function value. It can be seen that the optical system has a high MTF under high temperature, normal temperature, and low temperature conditions, and the consistency of each field of view is good.

[0030] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. The above descriptions are only preferred embodiments of this application. It should be noted that due to the limitations of textual expression, while there are objectively infinite specific structures, those skilled in the art can make several improvements, modifications, or changes without departing from the principles of this invention, and can also combine the above technical features in an appropriate manner. These improvements, modifications, changes, or combinations, or the direct application of the inventive concept and technical solution to other situations without modification, should all be considered within the scope of protection of this application.

Claims

1. A cooled laser three-dimensional imaging optical system based on an avalanche detector, characterized in that, It includes a first lens (100), a second lens (200), a third lens (300), a fourth lens (400), a fifth lens (500), a sixth lens (600), and a seventh lens (700) arranged sequentially along the optical path. The front surface of the first lens (100) is spherical, and the rear surface is planar; The front surface and the rear surface of the second lens (200) are spherical; The front surface and the rear surface of the third lens (300) are spherical; The front surface and the rear surface of the fourth lens (400) are spherical; The front surface and the rear surface of the fifth lens (500) are spherical; The front surface and the rear surface of the sixth lens (600) are spherical; The front surface of the seventh lens (700) is aspherical, and the rear surface is spherical.

2. The cooled laser three-dimensional imaging optical system based on an avalanche detector according to claim 1, characterized in that, The first lens (100). The optical material is H-ZF7LA; The radius of curvature of the front surface is 76.752 mm, and the light transmission aperture ranges from φ64 mm to φ65 mm. The aperture range of the rear surface is φ62mm~φ63mm; The thickness ranges from 11.5mm to 11.7mm.

3. The cooled laser three-dimensional imaging optical system based on an avalanche detector according to claim 1, characterized in that, The second lens (200) The optical material is H-ZF7LA; The radius of curvature of the front surface is 38.7 mm, and the light transmission aperture ranges from φ55 mm to φ56 mm. The radius of curvature of the rear surface is 66.6 mm, and the aperture range is φ50 mm~φ51 mm; The thickness ranges from 11.8 mm to 12 mm.

4. The cooled laser three-dimensional imaging optical system based on an avalanche detector according to claim 1, characterized in that, The third lens (300). The optical material is H-ZF62; The radius of curvature of the front surface is 28.14 mm, and the aperture range is φ41 mm to φ42 mm. The radius of curvature of the rear surface is 26.5 mm, and the aperture range is φ28 mm~φ29 mm; The thickness ranges from 12.9 mm to 13.1 mm.

5. The cooled laser three-dimensional imaging optical system based on an avalanche detector according to claim 1, characterized in that, The fourth lens (400). The optical material is ZnS; The radius of curvature of the front surface is 47.25 mm, and the light transmission aperture is φ24 mm; The radius of curvature of the rear surface is 11.04 mm, and the aperture diameter is φ14 mm. The thickness is 8.38mm.

6. The cooled laser three-dimensional imaging optical system based on an avalanche detector according to claim 1, characterized in that, The fifth lens (500). The optical material is H-ZF62; The radius of curvature of the front surface is 22.612 mm, and the light transmission aperture ranges from φ21 mm to φ23 mm. The radius of curvature of the rear surface is 17.529 mm, and the aperture range is φ27 mm~φ28 mm; The thickness ranges from 7.4 mm to 7.6 mm.

7. The cooled laser three-dimensional imaging optical system based on an avalanche detector according to claim 1, characterized in that, The sixth lens (600). The optical material is H-ZF7LA; The radius of curvature of the front surface is 120.57 mm, and the light transmission aperture ranges from φ34 mm to φ35 mm. The radius of curvature of the rear surface is 65.12 mm, and the aperture range is φ35 mm~φ36 mm; The thickness ranges from 8.5mm to 8.7mm.

8. The cooled laser three-dimensional imaging optical system based on an avalanche detector according to claim 1, characterized in that, The seventh lens (700). The optical material is arsenic selenium germanium; The vertex curvature radius of the front surface is 33.66 mm, the fourth-order aspherical coefficient is -4.04×10-6, the sixth-order aspherical coefficient is -9.62×10-10, the eighth-order aspherical coefficient is 3.38×10-14, the tenth-order aspherical coefficient is -2.11×10-15, and the light transmission aperture range is φ39 mm~φ41 mm; The radius of curvature of the rear surface is 92.2 mm, and the aperture range is φ37 mm~φ39 mm; The thickness ranges from 8.1 mm to 8.3 mm.

9. The cooled laser three-dimensional imaging optical system based on an avalanche detector according to claim 1, characterized in that, The distance between the first lens (100) and the second lens (200) varies from 0.1 mm to 0.3 mm. The distance between the second lens (200) and the third lens (300) varies from 1 mm to 2 mm; The distance between the third lens (300) and the fourth lens (400) varies from 4.6 mm to 4.8 mm. The distance between the fourth lens (400) and the fifth lens (500) varies from 13.8 mm to 14 mm. The distance between the fifth lens (500) and the sixth lens (600) varies from 0.1 mm to 0.3 mm. The distance between the sixth lens (600) and the seventh lens (700) varies from 21.7 mm to 21.9 mm.

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