Long focal length large field of view object side scanning optical system based on single point source detector

Abstract

The application relates to a long-focus large-view-field object scanning optical system based on a single point source detector, and belongs to the optical field.The application comprises a scanning mirror group, a turning mirror, a filter, a field stop and a point source detector; the scanning mirror group comprises a main mirror, a secondary mirror and a small mirror; light of a detected target is irradiated onto the main mirror, is reflected and converged by the main mirror, is reflected by the secondary mirror, is reflected by the small mirror, is reflected and converged by the turning mirror, is transmitted through the filter and the field stop, and is irradiated onto a target surface of the point source detector; and the scanning mode of the scanning mirror group is swing scanning or 360-degree full-view field scanning at high speed.The application improves the farthest detectable distance of the system and the working efficiency of the system, improves the scanning speed and stability of the system, has simple system structure, small volume, good stability, low cost, high detection sensitivity, high reflectivity, a wide spectral band, multi-spectral detection capability and improved contrast of a detection signal.

Description

Technical Field

[0001] This invention relates to the field of optical technology, and more specifically to a long focal length, large field-of-view object scanning optical system based on a single point source detector. Background Technology

[0002] Given a chosen detector type, a staring infrared search and track system faces an irreconcilable trade-off between system resolution and field of view when aiming for rapid, wide-area searching of small targets. In contrast, a scanning infrared search and track system can achieve rapid detection and tracking of small targets within a large field of view without sacrificing system resolution.

[0003] Traditional object-space scanning optical systems have large apertures, requiring the scanning mirror—the main optical component—to be positioned at the very front of the system. To accommodate the large aperture and wide field of view of these systems, the size of the scanning mirror needs to be increased, resulting in an excessively large actual manufacturing size. Furthermore, the larger the aperture and field of view of the object-space scanning optical system, the larger the scanning mirror becomes, directly reducing the system's scanning speed and increasing its overall size. Since the scanning mirror rotates 360°, the detector spends a significant portion of its time in an idle state without receiving a signal. As the integration time for receiving signals decreases, the system's efficiency is significantly reduced. In addition, in object-space scanning optical systems, the scanning mirror is typically externally mounted. This means that after prolonged operation, the mirror's reflective surface may become contaminated with dust, mud, dew, and corrosion, affecting reflectivity, reducing the system's detection range, and significantly decreasing its reliability, ultimately impacting its lifespan and practical application performance. Summary of the Invention

[0004] To address the problems of slow scanning speed, large size, short detector integration time, low efficiency, and short detection distance in existing object-space scanning optical systems, this invention provides a long focal length, large field-of-view object-space scanning optical system based on a single point source detector.

[0005] The technical solution adopted by this invention to solve the technical problem is as follows:

[0006] The present invention relates to a long focal length, large field-of-view object scanning optical system based on a single point source detector, comprising: a scanning mirror group, a deflector mirror, a filter, a field stop, and a point source detector; the scanning mirror group includes a primary mirror, a secondary mirror, and a small mirror; the light from the target being detected is irradiated onto the primary mirror, and is subsequently reflected and converged by the primary mirror, the secondary mirror, the small mirror, and the deflector mirror, and then transmitted through the filter and the field stop before irradiating the target surface of the point source detector; the scanning mode of the scanning mirror group is either swing scanning or 360° full-field panoramic high-speed scanning.

[0007] Furthermore, it also includes a filter switcher installed at the front end of the point source detector, which switches between different spectral filters to achieve multispectral detection.

[0008] Furthermore, the front surface of the primary reflector is aspherical with a radius of curvature of -128 mm and K = -0.7609; the thickness of the primary reflector is 6.8 mm; the aperture of the primary reflector is 62 mm; the diameter of the primary reflector is 63 mm; the material of the primary reflector is H-K9; the distance between the primary reflector and the secondary reflector is 49 mm; and the surface of the primary reflector is coated with a high-reflectivity film.

[0009] Furthermore, the secondary mirror has a reflective surface curvature radius of -32.46 mm; a thickness of 6 mm; a light-transmitting aperture of 14 mm; a diameter of 15 mm; is made of H-K9 material; has a distance of 39.5 mm between it and the small reflector; and is coated with a high-reflectivity film.

[0010] Furthermore, the small reflector has a light-transmitting aperture of 11mm; the small reflector has a diameter of 12mm; the small reflector is made of H-K9 material; the distance between the small reflector and the folding reflector is 48mm; and the surface of the small reflector is coated with a high-reflectivity film.

[0011] Furthermore, the aperture of the deflector is 6.3 mm; the diameter of the deflector is 8 mm; the material of the deflector is H-K9; the distance between the deflector and the point source detector is 50 mm; the distance between the deflector and the filter is 35 mm; and the surface of the deflector is coated with a high-reflectivity film.

[0012] Furthermore, the filter has a thickness of 2 mm; a light-transmitting aperture of 5.8 mm; a diameter of 8 mm; a material of ZnSe; and a distance of 8 mm between the filter and the field stop.

[0013] Furthermore, when the scanning field of view is small, the distance between the field stop and the point source detector is 5 mm.

[0014] Furthermore, the point source detector is a four-stage cooled point source detector, with a three-stage semiconductor cooling chip added to the point source detector for cooling.

[0015] Furthermore, the oscillation angle of the scanning mirror assembly during oscillation scanning is ±30°.

[0016] The beneficial effects of this invention are:

[0017] (1) Improved the maximum detectable distance of the system and the working efficiency of the system;

[0018] This invention employs a large-aperture, wide-field-of-view reflective long-focal-length object-side scanning optical system. The entrance pupil diameter at the system's incident end reaches 62mm, significantly increasing the system's detectable distance. To accommodate the field of view of visible light lenses, the maximum field of view at the system's incident end is ±11°, enabling simultaneous wide-field imaging of observation areas such as forests, thereby improving the system's working efficiency.

[0019] (2) Improved the scanning speed and stability of the system;

[0020] During target detection, the scanning mirror assembly can achieve a high rotation speed based on the highest sampling frequency of the point source detector, enabling swing scanning or 360° panoramic high-speed scanning across the entire field of view. This allows for rapid acquisition of information about the detected target. Furthermore, it enables the point source detector to receive target signals at all times. Since the system can achieve uninterrupted scanning across the entire field of view, it improves the system's integration time and scanning efficiency, significantly enhancing the utilization of light energy and the target detection capability, thus achieving high-resolution, rapid target search and tracking.

[0021] (3) The system has a simple structure, small size and good stability;

[0022] This invention utilizes the optical components necessary for forming a reflective optical path to form a scanning mirror assembly, saving the reflective mirrors in the optical path of traditional optical systems. It can perform both swing scanning and 360° full-field panoramic high-speed scanning, simplifying the optical path, reducing size, lowering costs, improving system scanning efficiency and system stability, and greatly enhancing the system's adaptability to the environment.

[0023] Compared to traditional telescope optical systems and scanning optical systems, this invention allows for a larger aperture and field of view, as well as a longer focal length, within the same space. It also eliminates the need for bulky reflectors, greatly increasing the detectability of the optical system.

[0024] (4) Low cost and high detection sensitivity;

[0025] In this invention, the detector is a cooled point source detector, which is much cheaper than a cooled area array infrared detector. In order to ensure the reliable operation of the point source detector, a three-stage semiconductor cooling chip is added to the point source detector for cooling. Therefore, the system has high detection sensitivity and is stable and reliable.

[0026] (5) It has a wide spectral band with high reflectivity;

[0027] In this invention, the optical element is a metal-coated mirror, which gives the system a relatively wide high reflectivity, a wide spectral band, low light energy loss, and improves the system's transmittance and detectability.

[0028] (6) It has multispectral detection capability;

[0029] A set of filter switching components is placed in front of the point source detector. By switching filters of different spectral bands, the multispectral image of the target is acquired. After completing one scan of the entire field of view, the filter spectral band is switched to another spectral band, and the spectral data of the next spectral band is collected to achieve multispectral detection.

[0030] (7) Improved the contrast of the detection signal;

[0031] When the scanning field of view is small, a one-way wide-slit field stop is added in front of the point source detector to improve the resolution of the detected target and the signal contrast, thereby improving the detectability and stability of the system. Attached Figure Description

[0032] Figure 1 This is a schematic diagram (front view) of the optical path of a long focal length, large field-of-view object-side scanning optical system based on a single point source detector according to the present invention.

[0033] Figure 2 This is a schematic diagram (top view) of the optical path of a long focal length, large field-of-view object-side scanning optical system based on a single point source detector according to the present invention.

[0034] In the diagram, 1 is the primary mirror, 2 is the secondary mirror, 3 is the small mirror, 4 is the folding mirror, 5 is the filter, 6 is the field stop, and 7 is the point source detector. Detailed Implementation

[0035] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0036] like Figure 1 and Figure 2 As shown, the present invention provides a long focal length, large field of view object-side scanning optical system based on a single point source detector. This is a novel object-side scanning optical system, which mainly includes: a primary mirror 1, a secondary mirror 2, a small mirror 3, a deflecting mirror 4, a filter 5, a field stop 6, a point source detector 7, and a filter switcher.

[0037] The light from the distant target is reflected onto the primary reflector 1, then converged by the primary reflector 1 and onto the secondary reflector 2. After being reflected by the secondary reflector 2, it is reflected onto the small reflector 3. After being reflected by the small reflector 3, it is reflected onto the deflector 4. After being reflected and converged by the deflector 4, it is transmitted through the filter 5 and the field stop 6 in sequence and then onto the target surface of the point source detector 7.

[0038] The scanning mirror assembly consists of a primary reflector 1, a secondary reflector 2, and a small reflector 3. The scanning mirror assembly can achieve scanning at different angles based on the mechanical transmission method; for example, the scanning mirror assembly can rotate... Figure 2 The AA-axis swing scanning in the image can achieve an angle of ±30° during swing scanning; the scanning mirror assembly can also rotate... Figure 1 The CC axis features 360° full-field panoramic high-speed scanning. By changing the angle of the scanning lens group, high-resolution target search and tracking can be achieved.

[0039] This invention discloses a long focal length, large field-of-view object-side scanning optical system based on a single point source detector. It utilizes the components of the optical system itself to form a scanning mirror group, enabling swing scanning or 360° full-field panoramic high-speed scanning. This invention fully leverages the high transmittance, long focal length, and large field of view characteristics of reflective optical systems to achieve high sampling ratios, wide spectral bands, and multispectral detection.

[0040] This invention discloses a long focal length, large field-of-view object-side scanning optical system based on a single point source detector. The field of view is determined by the minimum resolution of the point source detector 7 and the target being detected. The angle at which the scanning mirror assembly swings during each scan determines the width of the observation field of view, and the system's displacement determines the bandwidth of the observation strip.

[0041] During target detection, the scanning mirror group adopts swing scanning or 360° full-field panoramic high-speed scanning, which can achieve a high rotation speed according to the highest sampling frequency of the point source detector 7. Since the scanning mirror group can scan the full field of view continuously, the point source detector 7 can receive target signals at all times, thus improving the system's integration time and scanning efficiency. This allows for the rapid acquisition of information about the target to be detected, greatly improving the utilization rate of light energy and the target detection capability.

[0042] A filter switcher can be set in front of the point source detector 7. Depending on the characteristics of the target being detected, by switching between filters 5 of different spectral bands and selecting point source detectors 7 of different bands, categories, and characteristics, a wider spectral band in mid-wave infrared and long-wave infrared can be arbitrarily selected without changing the optical system to obtain a multispectral image of the target. After completing one scan of the entire field of view, the filter 5 is switched to another spectral band to continue collecting spectral data of the next spectral band, thus realizing multispectral detection.

[0043] The front surface of the primary reflector 1 is aspherical with a radius of curvature of -128 mm and K = -0.7609; the thickness of the primary reflector 1 is 6.8 mm; the aperture of the primary reflector 1 is 62 mm; the diameter of the primary reflector 1 is 63 mm; the material of the primary reflector 1 is H-K9; the distance between the primary reflector 1 and the secondary reflector 2 is 49 mm; and the surface of the primary reflector 1 is coated with a high-reflectivity film.

[0044] Among them, the radius of curvature of the reflective surface of the secondary mirror 2 is -32.46mm; the thickness of the secondary mirror 2 is 6mm; the light transmission aperture of the secondary mirror 2 is 14mm; the diameter of the secondary mirror 2 is 15mm; the material of the secondary mirror 2 is H-K9; the distance between the secondary mirror 2 and the small reflector 3 is 39.5mm; and the surface of the secondary mirror 2 is coated with a high-reflection film.

[0045] Among them, the light-transmitting aperture of the small reflector 3 is 11mm; the diameter of the small reflector 3 is 12mm; the material of the small reflector 3 is H-K9; the distance between the small reflector 3 and the folding reflector 4 is 48mm; and the surface of the small reflector 3 is coated with a high-reflection film.

[0046] The light-transmitting aperture of the deflector 4 is 6.3 mm; the diameter of the deflector 4 is 8 mm; the material of the deflector 4 is H-K9; the distance between the deflector 4 and the point source detector 7 is 50 mm; the distance between the deflector 4 and the filter 5 is 35 mm; and the surface of the deflector 4 is coated with a high-reflectivity film.

[0047] In this design, both the filter 5 and the field stop 6 are positioned near the point source detector 7; the filter 5 is used to achieve multispectral detection; the filter 5 has a thickness of 2 mm; the aperture of the filter 5 is 5.8 mm; the diameter of the filter 5 is 8 mm; the material of the filter 5 is ZnSe; and the distance between the filter 5 and the field stop 6 is 8 mm.

[0048] In the case of a smaller scanning field of view, a unidirectional wide-slit field stop 6 is added in front of the point source detector 7 to improve the resolution of the detected target and the signal contrast. The distance between the field stop 6 and the point source detector 7 is 5 mm.

[0049] In the point source detector 7, the distance between the protective glass and the receiving target surface is 2mm.

[0050] Among them, the point source detector 7 adopts a 4-stage cooled point source detector. In order to adapt to the working environment of the system, a 3-stage semiconductor cooling chip can be added to the point source detector 7 for cooling.

[0051] The present invention discloses a long focal length, large field-of-view object scanning optical system based on a single point source detector, the parameters of each component of which are shown in the table below.

[0052]

[0053]

[0054] The present invention discloses a long focal length, large field-of-view object-side scanning optical system based on a single point source detector, the specifications of which are as follows:

[0055] Aperture diameter: 62mm;

[0056] Focal length: 600mm;

[0057] Optical field of view: 0.095°;

[0058] Operating wavelength: 3μm-12μm.

[0059] This invention discloses a long-focal-length, wide-field-of-view object-scanning optical system based on a single point source detector, applicable to forest fire prevention, wildlife monitoring, and border surveillance within a monitored area. It monitors targets containing mid-wave infrared and long-wave infrared wavelengths, enabling multi-spectral detection of open flames, smoldering fires, and high-temperature gases in forest fires, thus achieving rapid alarm for forest fires and other emergencies.

[0060] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only used to facilitate the description of this invention and to simplify the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this invention.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. However, these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A long focal length, large field-of-view object-side scanning optical system based on a single point source detector, characterized in that, include: The system comprises a scanning mirror assembly, a deflector, a filter, a field stop, and a point source detector. The scanning mirror assembly includes a primary mirror, a secondary mirror, and a small mirror. Light from the target object illuminates the primary mirror, and is subsequently reflected and converged by the primary mirror, the secondary mirror, the small mirror, and the deflector, before being transmitted through the filter and the field stop to the target surface of the point source detector. The scanning method of the scanning mirror assembly is either swing scanning or 360° full-field panoramic high-speed scanning. It also includes a filter switcher disposed in front of the point source detector, which switches between different spectral filters to achieve multispectral detection; The front surface of the primary reflector is aspherical with a radius of curvature of -128 mm and K = -0.7609; the thickness of the primary reflector is 6.8 mm; the aperture of the primary reflector is 62 mm; the diameter of the primary reflector is 63 mm; the material of the primary reflector is H-K9; the distance between the primary reflector and the secondary reflector is 49 mm; and the surface of the primary reflector is coated with a high-reflectivity film. The secondary mirror has a reflective surface curvature radius of -32.46 mm; a thickness of 6 mm; a light-transmitting aperture of 14 mm; a diameter of 15 mm; is made of H-K9 material; has a spacing of 39.5 mm between it and the small reflector; and is coated with a high-reflectivity film. The small reflector has a light-transmitting aperture of 11mm; the small reflector has a diameter of 12mm; the small reflector is made of H-K9 material; the distance between the small reflector and the folding reflector is 48mm; and the surface of the small reflector is coated with a high-reflectivity film. The aperture of the reflex mirror is 6.3 mm; the diameter of the reflex mirror is 8 mm; the material of the reflex mirror is H-K9; the distance between the reflex mirror and the point source detector is 50 mm; the distance between the reflex mirror and the filter is 35 mm; and the surface of the reflex mirror is coated with a high-reflectivity film. The filter has a thickness of 2 mm; a light-transmitting aperture of 5.8 mm; a diameter of 8 mm; a material of ZnSe; and a distance of 8 mm between the filter and the field stop. When the scanning field of view is small, the distance between the field stop and the point source detector is 5 mm; The point source detector is a 4-stage cooled point source detector, and a 3-stage semiconductor cooling chip is added to the point source detector for cooling. When the scanning mirror assembly performs a swing scan, the swing angle is ±30°.

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