A compact cat-eye reverse modulation device with large field of view and close to diffraction limit

Abstract

The present application relates to free space laser communication technical field, specifically, a kind of small large field of view cat-eye reverse modulation device close to diffraction limit, comprising: first lens, seventh lens, fourth lens, second lens, third lens, fifth lens, sixth lens and diaphragm, first lens, second lens, fourth lens, sixth lens and seventh lens are set to positive crescent lens;Third lens is set to double-concave lens;Fifth lens is set to flat convex lens;Diaphragm is arranged between third lens and fourth lens;First lens, second lens, third lens, fourth lens, fifth lens, sixth lens and seventh lens are sequentially arranged along optical axis from object plane to image plane, and its focal length is positive, positive, negative, positive, positive, positive, positive respectively.The present application can be widely used in small platform cat-eye reverse modulation laser communication field, with small size, strong applicability, low cost.

Description

Technical Field

[0001] This invention relates to the field of free-space laser communication technology, and more specifically, to a small, large field-of-view cat's-eye inverse modulation device that is close to the diffraction limit. Background Technology

[0002] Cat's eye reverse modulation laser communication technology establishes a communication link by reflecting the incident beam along the original path and modulating the beam during the reflection process. Through the cat's eye effect, it eliminates the need for a laser and a capture and tracking aiming system at the reverse terminal in the laser communication link. This is of great significance for laser communication applications on small platforms. The miniaturized antenna effectively reduces the size and weight of the terminal. The large field of view ensures that the cat's eye reverse modulator has good modulation effect in a large spatial range, and the near diffraction limit ensures that the optical antenna of the cat's eye reverse modulator has high transmission gain.

[0003] Existing devices have a certain field of view and a small aperture, but the optical lenses used are all aspherical structures, which are difficult to process, complex to design, and expensive, making them unsuitable for widespread use. Furthermore, they are limited in their compatibility with small-aperture spatial light modulators and their application on small platforms. Therefore, a small cat's eye inverse modulation device with a large field of view that is close to the diffraction limit is needed. Summary of the Invention

[0004] The purpose of this invention is to provide a small, large-field-of-view cat's-eye inverse modulation device that approaches the diffraction limit, thereby improving the aforementioned problems. To achieve this objective, the technical solution adopted by this invention is as follows:

[0005] This application provides a small, large field-of-view cat's-eye inverse modulation device approaching the diffraction limit, comprising: a first lens, a seventh lens, a fourth lens, a second lens, a third lens, a fifth lens, a sixth lens, and an aperture stop. The first lens is configured as a positive meniscus lens; the seventh lens is configured as a positive meniscus lens and is disposed on one side of the first lens; the fourth lens is configured as a positive meniscus lens and is disposed between the first lens and the seventh lens; the second lens is configured as a positive meniscus lens and is disposed between the first lens and the fourth lens; the third lens is configured as a biconcave lens and is disposed between the second lens and the fourth lens; the fifth lens is configured as a plano-convex lens and is disposed between the fourth lens and the seventh lens; the sixth lens is configured as a positive meniscus lens and is disposed between the fifth lens and the seventh lens; the aperture stop is disposed between the third lens and the fourth lens; the focal lengths of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens are positive, positive, negative, positive, positive, positive, and positive, respectively.

[0006] Optionally, the field of view of the cat-eye reverse modulation device is at least 18°, the F number is less than or equal to 0.9, the focal plane is less than or equal to 3mm, and the length of the cat-eye reverse modulation device is less than or equal to 46mm.

[0007] Optionally, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens are all made of H-ZF13.

[0008] Optionally, the ratio of the front and rear radii of curvature of the first lens is greater than or equal to 0.24.

[0009] Optionally, the ratio of the front and rear radii of curvature of the second lens is greater than or equal to 0.33.

[0010] Optionally, the ratio of the front and rear radii of curvature of the third lens is greater than or equal to -28.6.

[0011] Optionally, the ratio of the front and rear radii of curvature of the fourth lens is greater than or equal to 0.84.

[0012] Optionally, the ratio of the front and rear radii of curvature of the fifth lens is greater than or equal to -24.

[0013] Optionally, the ratio of the front and rear radii of curvature of the sixth lens is greater than or equal to 0.28.

[0014] Optionally, the ratio of the front and rear radii of curvature of the seventh lens is greater than or equal to 0.6.

[0015] The beneficial effects of this invention are as follows:

[0016] This invention utilizes a simple and easily fabricated structure of seven spherical mirrors and one aperture. Through parameter optimization design based on specific requirements, a small, large-field-of-view, near-diffraction-limited cat's-eye inverse modulator optical antenna can be obtained, ensuring good modulation effect for beams incident at large field-of-view angles. Simultaneously, the near-diffraction limit ensures high transmit gain for the antenna. Furthermore, the system's low F-number allows for better matching with small-sized spatial light modulators, guaranteeing good gain and stability for the cat's-eye inverse modulation terminal. Additionally, this system features low wavefront distortion and good energy concentration, making it widely applicable in the field of small-platform cat's-eye inverse modulation laser communication. It is characterized by its small size, strong applicability, and low cost.

[0017] The small, large field-of-view, near-diffraction-limited cat's-eye inverse modulator optical antenna of the present invention has a planar focal plane with a small focal plane size, which can be matched with small-aperture planar spatial light modulators such as micromechanical system spatial light modulators and electro-optic modulator spatial light modulators.

[0018] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing embodiments of the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description, claims, and drawings. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the small, large field-of-view cat's-eye inverse modulation device with near-diffraction limit as described in an embodiment of the present invention.

[0021] Figure 2 This is a schematic diagram of ray tracing for the small, large field-of-view cat's-eye inverse modulation device near the diffraction limit described in an embodiment of the present invention.

[0022] Figure 3 The MTF diagram of the small, large field-of-view, near-diffraction-limited cat's-eye inverse modulation device described in this embodiment of the invention is shown below.

[0023] Figure 4 This is a dot diagram of the small, large field-of-view cat's-eye inverse modulation device near the diffraction limit described in the embodiments of the present invention.

[0024] The markings in the diagram are: 1. First lens; 2. Second lens; 3. Third lens; 4. Fourth lens; 5. Fifth lens; 6. Sixth lens; 7. Seventh lens; 8. Focal plane; 9. Aperture stop. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0026] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this invention, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0027] Example 1

[0028] like Figure 1 and Figure 2 As shown, this embodiment provides a small, large field-of-view cat's-eye reverse modulation device approaching the diffraction limit, including: a first lens 1, a seventh lens 7, a fourth lens 4, a second lens 2, a third lens 3, a fifth lens 5, a sixth lens 6, and an aperture 9. The first lens 1 is configured as a positive meniscus lens; the seventh lens 7 is configured as a positive meniscus lens and is disposed on one side of the first lens 1; the fourth lens 4 is configured as a positive meniscus lens and is disposed between the first lens 1 and the seventh lens 7; the second lens 2 is configured as a positive meniscus lens and is disposed between the first lens 1 and the fourth lens 4; the third lens 5 is configured as a positive meniscus lens and is disposed between the first lens 1 and the fourth lens 4; the third lens 6 is configured as a positive meniscus lens; the fourth lens 7 is configured as a positive meniscus lens; the fifth lens 6 is configured as a positive meniscus lens; the sixth lens 6 is configured as a positive meniscus lens; the sixth lens 9 is configured as a positive meniscus lens; the seventh lens 7 ... Lens 3 is configured as a biconcave lens, and the third lens 3 is positioned between the second lens 2 and the fourth lens 4; the fifth lens 5 is configured as a plano-convex lens, and the fifth lens 5 is positioned between the fourth lens 4 and the seventh lens 7; the sixth lens 6 is configured as a positive meniscus lens, and the sixth lens 6 is positioned between the fifth lens 5 and the seventh lens 7; the aperture stop 9 is positioned between the third lens 3 and the fourth lens 4; the focal lengths of the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6, and the seventh lens 7 are positive, positive, negative, positive, positive, positive, and positive, respectively.

[0029] In this invention, the first lens 1 has a convex object plane and a concave image plane, with a front-to-back radius of curvature ratio of 0.236; the second lens 2 has a convex object plane and a concave image plane, with a front-to-back radius of curvature ratio of 0.343; the third lens 3 is a biconcave lens with a front-to-back radius of curvature ratio of 0.343; the fourth lens 4 has a concave object plane and a convex image plane, with a front-to-back radius of curvature ratio of 0.84; the fifth lens 5 has a flat object plane and a convex image plane, with a back radius of curvature of -24.25; and the sixth lens 6 has a convex object plane and a concave image plane. The front and rear radii of curvature of the seventh lens 7 are convex on the object side and concave on the image side, with a front and rear radii of curvature ratio of 0.604. Through parameter optimization design based on specific requirements, a small, large field-of-view, near-diffraction-limited cat's-eye reverse modulator optical antenna can be obtained, ensuring good modulation effect for beams incident at a large field of view. At the same time, it can approach the diffraction limit, ensuring that the antenna has a high transmission gain. In addition, the system has a small F-number, which can be well matched with a small-sized spatial light modulator, ensuring that the cat's-eye reverse modulation terminal has good gain and stability.

[0030] like Figure 1 and Figure 2 As shown, the field of view of the cat-eye reverse modulation device is at least 18 degrees, the F-number is less than or equal to 0.9, the focal plane is less than or equal to 3 mm, and the length of the cat-eye reverse modulation device is less than or equal to 46 mm.

[0031] This invention can optimize the parameters of a specific optical system according to specific needs to achieve a large field of view and approach the diffraction limit; ultimately enabling the cat's eye optical system to achieve a field of view better than 18°, an F number of 0.9, and all lenses to be spherical mirrors.

[0032] like Figure 1 and Figure 2 As shown, the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6, and the seventh lens 7 are all made of H-ZF13.

[0033] The ratio of the front and rear radii of curvature of the first lens 1 is greater than or equal to 0.24.

[0034] The ratio of the front and rear radii of curvature of the second lens 2 is greater than or equal to 0.33.

[0035] The ratio of the front and rear radii of curvature of the third lens 3 is greater than or equal to -28.6.

[0036] The ratio of the front and rear radii of curvature of the fourth lens 4 is greater than or equal to 0.84.

[0037] The ratio of the front and rear radii of curvature of the fifth lens 5 is greater than or equal to -24.

[0038] The ratio of the front and rear radii of curvature of the sixth lens 6 is greater than or equal to 0.28.

[0039] The ratio of the front and rear radii of curvature of the seventh lens 7 is greater than or equal to 0.6.

[0040] The small, wide-field-of-view, near-diffraction-limited cat's-eye inverse modulator optical antenna of this invention achieves a full field of view of 18° while maintaining good retroreflection characteristics across the entire field of view, all within a 25mm aperture and meeting design gain requirements. At a wavelength of 1550nm, the system uses H-ZF13 lenses, has a focal length of 9.2mm, an entrance pupil diameter of 10mm, an F-number of 0.9, a focal plane diameter of 2.96mm, and a total length of less than 46mm. The system exhibits a spot size of less than 2.3μm at normal incidence and less than 5μm at the maximum incidence angle. The system comprises 7 lenses with 14 surfaces, each coated with a 1550nm anti-reflection coating, achieving a two-way transmittance better than 93.5%.

[0041] The following are the structural parameters of this optical system embodiment.

[0042] Table 1

[0043]

[0044]

[0045] This invention employs a 7-piece compact standard spherical mirror design, achieving a large field of view, near-diffraction limit, and small size structure while maintaining low system cost. This is beneficial for cat's eye reverse modulation laser communication applications on small platforms.

[0046] The cat-eye inverse modulator optical antenna of the present invention is close to the diffraction limit. While meeting the gain requirements, it achieves a full field of view of 18°, a system entrance pupil diameter better than 10mm, an F number of 0.9, a focal plane diameter of 2.96mm, a total length of less than 46mm, and maintains good retroreflection characteristics throughout the entire field of view.

[0047] like Figure 3 The MTF curve of the present invention shown shows that the transfer function curves of the system in different fields of view are basically close to the diffraction limit. At the maximum incident angle, the optical transfer function value is 0.3, the number of line pairs per millimeter is better than 200, and the resolution is better than 5μm.

[0048] like Figure 4 The system dot diagram of the present invention shown indicates that the radius of the diffuse spot within the maximum field of view is within 2.3 μm, demonstrating good energy focusing performance.

[0049] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0050] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A small, large field-of-view cat's-eye inverse modulation device approaching the diffraction limit, characterized in that, include: The first lens (1) is configured as a positive meniscus lens; The seventh lens (7) is configured as a positive meniscus lens and is disposed on one side of the first lens (1); The fourth lens (4) is configured as a positive meniscus lens and is disposed between the first lens (1) and the seventh lens (7); The second lens (2) is configured as a positive meniscus lens and is disposed between the first lens (1) and the fourth lens (4); The third lens (3) is configured as a double concave lens and is disposed between the second lens (2) and the fourth lens (4); The fifth lens (5) is configured as a plano-convex lens and is disposed between the fourth lens (4) and the seventh lens (7); The sixth lens (6) is configured as a positive meniscus lens and is disposed between the fifth lens (5) and the seventh lens (7); An aperture stop (9) is disposed between the third lens (3) and the fourth lens (4); The focal lengths of the first lens (1), the second lens (2), the third lens (3), the fourth lens (4), the fifth lens (5), the sixth lens (6), and the seventh lens (7) are positive, positive, negative, positive, positive, positive, positive, positive, respectively; The field of view of the cat-eye reverse modulation device is at least 18°, the F number is less than or equal to 0.9, the focal plane (8) is less than or equal to 3mm, and the length of the cat-eye reverse modulation device is less than or equal to 46mm. The first lens (1), the second lens (2), the third lens (3), the fourth lens (4), the fifth lens (5), the sixth lens (6), and the seventh lens (7) are all made of H-ZF13.

2. The small, large field-of-view, near-diffraction-limited cat's-eye inverse modulation device according to claim 1, characterized in that: The ratio of the front and rear radii of curvature of the first lens (1) is greater than or equal to 0.

24.

3. The small, large field-of-view, near-diffraction-limited cat's-eye inverse modulation device according to claim 1, characterized in that: The ratio of the front and rear radii of curvature of the second lens (2) is greater than or equal to 0.

33.

4. The small, large field-of-view, near-diffraction-limited cat's-eye inverse modulation device according to claim 1, characterized in that: The ratio of the front and rear radii of curvature of the third lens (3) is greater than or equal to -28.

6.

5. The small, large field-of-view, near-diffraction-limited cat's-eye inverse modulation device according to claim 1, characterized in that: The ratio of the front and rear radii of curvature of the fourth lens (4) is greater than or equal to 0.

84.

6. The small, large field-of-view, near-diffraction-limited cat's-eye inverse modulation device according to claim 1, characterized in that: The ratio of the front and rear radii of curvature of the fifth lens (5) is greater than or equal to -24.

7. The small, large field-of-view, near-diffraction-limited cat's-eye inverse modulation device according to claim 1, characterized in that: The ratio of the front and rear radii of curvature of the sixth lens (6) is greater than or equal to 0.

28.

8. The small, large field-of-view, near-diffraction-limited cat's-eye inverse modulation device according to claim 1, characterized in that: The ratio of the front and rear radii of curvature of the seventh lens (7) is greater than or equal to 0.6.

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