A mid-wave refrigerated infrared microscope optical system

Abstract

This invention discloses a mid-wave cooled infrared microscopic optical system. The system includes a Dewar flask, a cold stop, a lens group, and an image plane. The Dewar flask has a housing and a window disposed on the housing. The cold stop, lens group, and image plane are disposed within the housing. The window, cold stop, lens group, and image plane are sequentially arranged along the incident light direction on the optical axis of the optical system. The lens group is installed in the optical path between the cold stop and the image plane, close to the cold stop. The lens group is used to process the incident light so that the diameter of the processed beam matches the aperture of the cold stop. The lens group is also used to further refract and focus the light passing through the cold stop, thus imageing the object onto the image plane. This invention significantly shortens the system's back intercept and overall length, achieving miniaturization and weight reduction of the system structure, while maintaining excellent cold stop matching characteristics and imaging performance, making it particularly suitable for mid-wave cooled infrared detectors.

Description

Technical Field

[0001] This utility model relates to the field of infrared optical equipment technology, and more specifically, to a compact mid-wave cooled infrared microscopic optical system. Background Technology

[0002] In cooled infrared detector optical systems, especially in the mid-infrared band, the positioning of the aperture is crucial to system performance. To fully leverage the performance advantages of cooled detectors, the optical system needs to achieve precise matching with the detector's internal cold stop to suppress stray radiation and improve the signal-to-noise ratio. However, in traditional designs, to achieve cold stop matching and maintain a certain back focal distance, optical lenses are often placed outside the cold stop, resulting in problems such as excessively long back cutoff and increased lens aperture. This design not only increases the overall system size and weight but also increases the projection height of edge field rays onto the lens surface, further amplifying the lens aperture requirements and exacerbating optical processing difficulties and manufacturing costs.

[0003] A 1x microscopic imaging system, as an optical system achieving ±1x magnification, holds particular value in the aforementioned mid-wave cooled detector applications. This system enables a strict 1:1 image transfer between the object and image sides, effectively avoiding dimensional distortion caused by magnification deviations and ensuring the accuracy and reliability of imaging information. Crucially, such 1:1 imaging systems often serve as core relay modules, forming a complete secondary imaging system together with the front objective lens group; within this architecture, its performance directly determines the final imaging quality, cold-aperture matching efficiency, and structural compactness of the entire system.

[0004] The aforementioned issues collectively restrict the application of detector systems in space-constrained platforms (such as UAV-borne optoelectronic systems and portable monitoring equipment). Therefore, effectively reducing the axial dimensions and weight of the system while ensuring imaging quality and cold-aperture matching efficiency has become a critical technical bottleneck that urgently needs to be overcome in this field. Utility Model Content

[0005] To address the aforementioned deficiencies or improvement needs of existing technologies, this utility model provides a compact mid-wave cooled infrared microscopic optical system. By embedding all rear-group optical lenses within the narrow space between the cold stop and the image plane, the system's back intercept and overall length are significantly shortened, achieving miniaturization and weight reduction of the system structure. At the same time, it maintains excellent cold stop matching characteristics and imaging performance, making it particularly suitable for mid-wave cooled infrared detectors.

[0006] To achieve the above objectives, this utility model provides a mid-wave cooled infrared microscopic optical system, including a Dewar flask, a cold stop, a lens group, and an image plane; the Dewar flask has a housing and a window disposed on the housing, and the cold stop, lens group, and image plane are disposed inside the housing; the window, cold stop, lens group, and image plane are sequentially arranged on the optical axis of the optical system along the incident direction of light; the lens group is installed in the optical path between the cold stop and the image plane, close to the cold stop; the lens group is used to process the incident light so that the diameter of the processed beam matches the aperture of the cold stop; the lens group is also used to further refract and focus the light passing through the cold stop to image the object on the image plane.

[0007] In some embodiments, the lens group consists of multiple lens groups; wherein, some lens groups are negative power lens groups, used to compress the edge ray angle of the optical system and reduce the aperture of the lens group; and some lens groups are positive power lens groups, used to shorten the back intercept of the optical system.

[0008] In some implementations, the lens group is a negative power lens group, used to compress the edge light angle and reduce the lens group aperture.

[0009] In some implementations, the lens group is a positive power lens group, used to shorten the back intercept of the optical system.

[0010] In some embodiments, the lens group includes a first optical lens and a second optical lens; the first optical lens is used to converge the incident light into parallel light or converging light, so that the diameter of the converged beam matches the aperture of the cold stop; the second optical lens is used to further compress the beam converged by the first optical lens and image the object onto the image plane.

[0011] In some implementations, the lens group is also used to suppress stray light and reduce noise interference.

[0012] In some implementations, the lens group is also used to correct chromatic aberration and geometric phase aberration of the incident light.

[0013] In some embodiments, the first optical lens is an aspherical lens or a spherical lens, used to correct spherical aberration; the second optical lens is an aspherical lens or a spherical lens, used to correct coma.

[0014] In some embodiments, the first optical lens and the second optical lens are made of infrared materials with different dispersion characteristics.

[0015] In some embodiments, the first optical lens is made of germanium and the second optical lens is made of silicon.

[0016] In summary, the technical solutions conceived by this utility model have the following beneficial effects compared with the prior art: (1) The lens group is integrated between the cold stop and the detector image plane inside the Dewar bottle, which fundamentally eliminates the axial space occupied by the lens group extending forward in the traditional structure (the lens group is distributed outside the cold stop of the Dewar bottle), effectively shortening the total length of the system. (2) Embedding the lens group in the optical path between the detector cold stop and the image plane means that they can be integrated into a compact lens tube and integrated with the detector components. This simplifies the mechanical structure, reduces the complexity of assembly and adjustment, and improves the stability and reliability of the system. (3) The compact structure allows the lens group to be closer to the cooled detector, enabling more efficient temperature management of the entire rear optical cavity in extreme environments where active temperature control is required, thereby reducing thermal aberrations caused by lens temperature gradients. (4) By carefully designing the optical power distribution, surface shape (usually using high-order aspherical or diffractive surfaces) and material combination of the lens group, while achieving extreme compactness, it can still correct aberrations (especially field curvature and distortion) well, ensure high-quality imaging effect, and achieve 100% matching with the detector cold stop, effectively suppressing stray light. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of a compact mid-wave cooled infrared microscopy optical system according to an embodiment of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of this application. Therefore, the drawings and description are considered exemplary in nature and not restrictive.

[0019] like Figure 1 As shown, the compact mid-wave cooled infrared microscopic optical system of this embodiment includes a Dewar flask, an aperture 2, a lens group, and an image plane 6. The Dewar flask has a housing 5 and a window 1 disposed on the housing 5. The aperture 2, lens group, and image plane 6 are disposed inside the housing 5. The window 1, aperture 2, lens group, and image plane 6 are sequentially arranged on the optical axis of the optical system along the incident direction of light. The aperture 2 is fixedly installed at a predetermined position inside the housing 5, the image plane 6 is disposed at an imaging position inside the housing 5, and the lens group is installed in the optical path between the aperture 2 and the image plane 6, close to the aperture 2. The lens group is stably installed inside the housing 5 by a fixing bracket.

[0020] The lens group is used to process the incident light from object plane 7, ensuring that the diameter of the processed beam precisely matches the aperture of the cold stop 2. The lens group also suppresses stray light and reduces noise interference. Furthermore, the lens group performs chromatic aberration correction and geometric phase aberration correction on the incident light. The incident light enters the Dewar flask from window 1, passes through the cold stop 2, and is further refracted and focused by the lens group, accurately forming an image on image plane 6.

[0021] In some embodiments, the lens group comprises one or more lens groups. In some embodiments, the lens group is a single lens group, specifically a negative power lens group, used to compress the edge ray angle and reduce the lens group aperture. In some embodiments, the lens group is a single lens group, specifically a positive power lens group, used to shorten the back intercept of the optical system. In some embodiments, the lens group comprises multiple lens groups, with some lens groups being negative power lens groups to compress the edge ray angle of the optical system and reduce the lens group aperture; and some lens groups being positive power lens groups to shorten the back intercept of the optical system.

[0022] The aperture of the lens assembly is matched with the size of the cold stop to ensure 100% cold stop efficiency. The lens assembly is made of materials suitable for the mid-infrared band, and its radius of curvature and thickness are precisely calculated and processed according to the design requirements of the optical system.

[0023] like Figure 1 As shown, in some embodiments, the lens group is a set of lenses, including a first optical lens 3 and a second optical lens 4. In some embodiments, the first optical lens 3 is used to initially converge the incident light into parallel or converging light, so that the diameter of the converged beam precisely matches the aperture of the cold stop 2. The second optical lens 4 is used to further compress the beam converged by the first optical lens 3, accurately imaging it onto the image plane 6. In some embodiments, the first optical lens 3 and the second optical lens 4 are made of infrared materials with different dispersion characteristics; for example, the material of the first optical lens 3 is germanium, and the material of the second optical lens 4 is silicon. Furthermore, the first optical lens 3 is an aspherical lens or a spherical lens for correcting spherical aberration, and the second optical lens 4 is an aspherical lens or a spherical lens for correcting coma.

[0024] After actual testing, the improved structure of this embodiment shows that the optical system of the compact mid-wave cooled infrared microscopy system has reduced the system length by 50% compared with the prior art while ensuring imaging quality, thus meeting the requirements of drones, handheld devices and other related application scenarios for detector miniaturization and high performance.

[0025] This invention embeds an optical lens group in the optical path between the detector's cold stop and the image plane. The lens group is located inside the Dewar flask and close to the cold stop, fundamentally solving the problem of excessive system axial length caused by placing the lens group outside the Dewar flask in traditional structures. The structure is simple and compact, with high stability and reliability. Furthermore, when the lens group is a negative power lens group, it is used to compress the edge ray angle of the lens group and reduce the lens group aperture; when the lens group is a positive power lens group, it is used to shorten the back intercept of the optical system, thereby shortening the overall length of the optical system. Through careful design of the lens group's power distribution, surface shape (usually using high-order aspherical or diffractive surfaces), and material combination, while achieving extreme compactness, it can still effectively correct aberrations (especially field curvature and distortion), ensuring high-quality imaging effects and achieving 100% matching with the detector's cold stop, effectively suppressing stray light.

[0026] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of those different embodiments or examples.

[0027] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0028] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more (two or more) executable instructions for implementing a particular logical function or process. Furthermore, the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functionality involved.

[0029] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various variations or substitutions within the technical scope disclosed in this application, and these should all be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A mid-wave cooled infrared microscopy optical system, characterized in that, The system includes a Dewar flask, a cold stop, a lens group, and an image plane; the Dewar flask has a housing and a window disposed on the housing, and the cold stop, the lens group, and the image plane are disposed inside the housing; the window, the cold stop, the lens group, and the image plane are sequentially arranged on the optical axis of the optical system along the incident direction of light; The lens group is installed in the optical path between the cold stop and the image plane, close to the cold stop; the lens group is used to process the incident light so that the diameter of the processed beam matches the aperture of the cold stop; the lens group is also used to further refract and focus the light passing through the cold stop to image the object on the image plane.

2. The mid-wave cooled infrared microscopy optical system as described in claim 1, characterized in that, The lens group consists of multiple lens groups; some of these lens groups are negative power lens groups, used to compress the edge ray angle of the optical system and reduce the lens group aperture; and some of these lens groups are positive power lens groups, used to shorten the back intercept of the optical system.

3. The mid-wave cooled infrared microscopy optical system as described in claim 1, characterized in that, The lens group is a negative power lens group, used to compress the edge light angle and reduce the lens group aperture.

4. The mid-wave cooled infrared microscopy optical system as described in claim 1, characterized in that, The lens group is a positive power lens group, used to shorten the back intercept of the optical system.

5. The mid-wave cooled infrared microscopy optical system as described in claim 3 or 4, characterized in that, The lens group includes a first optical lens and a second optical lens; the first optical lens is used to converge the incident light into parallel light or converging light, so that the diameter of the converged beam matches the aperture of the cold stop; the second optical lens is used to further compress the beam converged by the first optical lens and image the object on the image plane.

6. The mid-wave cooled infrared microscopy optical system as described in claim 5, characterized in that, The lens group is also used to suppress stray light and reduce noise interference.

7. The mid-wave cooled infrared microscopy optical system as described in claim 5, characterized in that, The lens group is also used to correct chromatic aberration and geometric phase aberration of the incident light.

8. The mid-wave cooled infrared microscopy optical system as described in claim 7, characterized in that, The first optical lens is an aspherical lens or a spherical lens, used to correct spherical aberration; the second optical lens is an aspherical lens or a spherical lens, used to correct coma.

9. The mid-wave cooled infrared microscopy optical system as described in claim 5, characterized in that, The first optical lens and the second optical lens are made of infrared materials with different dispersion characteristics.

10. The mid-wave cooled infrared microscopy optical system as described in claim 9, characterized in that, The first optical lens is made of germanium, and the second optical lens is made of silicon.

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