An optical system of an astronomical telescope objective with an ultra-long working distance

Abstract

The application belongs to the technical field of telescope manufacturing, and discloses an astronomical telescope objective lens optical system with an ultra-long working distance, which is characterized in that: an objective lens first lens, an objective lens second lens, an objective lens third lens, an objective lens fourth lens and an objective lens fifth lens are sequentially arranged along the optical axis direction from the object side to the image side; the focal length of the optical system is 450.175 mm, the entrance pupil diameter is 90 mm, the field of view is 3.488°, the F number is 5, the total length of the optical system is 428.58 mm, and the working distance is 224.38 mm.

Description

Technical Field

[0001] This invention relates to the field of telescope manufacturing technology, specifically to an astronomical telescope objective optical system with an ultra-long back working distance. Background Technology

[0002] The design of astronomical telescopes typically involves designing the objective lens group and the eyepiece group. When designing the objective lens group, the back working distance must be considered. The same objective lens structure will produce different images when adapted to different eyepiece structures. This needs to be considered comprehensively during the design process. Currently, the back working distance of most astronomical telescope objectives is less than 200mm. Summary of the Invention

[0003] The purpose of this invention is to provide an astronomical telescope objective optical system with an ultra-long back working distance to solve the problems mentioned in the background art.

[0004] To solve the above-mentioned technical problems, the present invention provides the following technical solution: an astronomical telescope objective lens optical system with an ultra-long back working distance, comprising, along the optical axis from the object side to the image side, a first objective lens, a second objective lens, a third objective lens, a fourth objective lens, and a fifth objective lens arranged sequentially.

[0005] The first objective lens is a biconvex lens, the second objective lens is a biconcave lens, the third objective lens is a plano-convex lens with the plane facing the object side, the fourth objective lens is a concave-convex lens with the concave surface facing the object side, and the fifth objective lens is a concave-convex lens with the convex surface facing the object side. Only these five lenses in the optical system have optical power.

[0006] As a preferred technical solution, the first objective lens has an object-side radius of curvature of 144.88 mm, an image-side radius of curvature of -122.18 mm, a center thickness of 21 mm, is made of HCD100 glass, and has an overall diameter of 96 mm; the second objective lens has an object-side radius of curvature of -122.18 mm, an image-side radius of curvature of 1169.50 mm, a center thickness of 7.7 mm, is made of H-TF3 glass, and has an overall diameter of 96 mm; the third objective lens has a flat object side and an image-side radius of curvature of -197.70 mm. The objective lens has a center thickness of 10.6 mm, is made of H-ZLAF56B glass, and has an outer diameter of 96 mm. The fourth objective lens has an object-side radius of curvature of -116.68 mm, an image-side radius of curvature of -381.90 mm, a center thickness of 8.8 mm, is made of H-ZF2 glass, and has an outer diameter of 70 mm. The fifth objective lens has an object-side radius of curvature of 92.26 mm, an image-side radius of curvature of 7.7 mm, a center thickness of 15.85 mm, is made of H-ZF7L glass, and has an outer diameter of 70 mm.

[0007] As a preferred technical solution, the distance between the first objective lens and the second objective lens along the optical axis is 0.6 mm, the distance between the second objective lens and the third objective lens is 79.46 mm, the distance between the third objective lens and the fourth objective lens is 59.09 mm, and the distance between the fourth objective lens and the fifth objective lens is 1.10 mm.

[0008] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0009] The optical system of this application has a focal length of 450.175mm, an entrance pupil diameter of 90mm, a field of view of 3.488°, an F number of 5, a total length of 428.58mm, and a back working distance of 224.38mm. Attached Figure Description

[0010] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0011] Figure 1 This is a schematic diagram of the optical system of the present invention;

[0012] Figure 2 This is a dot diagram of the present invention;

[0013] Figure 3 This is the MTF plot of the transfer function of this invention;

[0014] Figure 4 This is the field distortion diagram of the present invention;

[0015] Figure 5 This is the color difference curve diagram of the present invention. Detailed Implementation

[0016] 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 embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] As attached Figure 1-5 As shown, an astronomical telescope objective lens optical system with an ultra-long back working distance includes, sequentially arranged along the optical axis from the object side to the image side, an objective lens 1, an objective lens 2, an objective lens 3, an objective lens 4, and an objective lens 5.

[0018] The first objective lens 1 is a biconvex lens, the second objective lens 2 is a biconcave lens, the third objective lens 3 is a plano-convex lens with the plane facing the object side, the fourth objective lens 4 is a concave-convex lens with the concave surface facing the object side, and the fifth objective lens 5 is a concave-convex lens with the convex surface facing the object side. Only the above 5 lenses in the optical system have optical power.

[0019] The first objective lens 1 has an object-side radius of curvature of 144.88 mm, an image-side radius of curvature of -122.18 mm, a center thickness of 21 mm, is made of HCD100 glass, and has an outer diameter of 96 mm. The second objective lens 2 has an object-side radius of curvature of -122.18 mm, an image-side radius of curvature of 1169.50 mm, a center thickness of 7.7 mm, is made of H-TF3 glass, and has an outer diameter of 96 mm. The third objective lens 3 has a flat object side, an image-side radius of curvature of -197.70 mm, and a center thickness of 21 mm. The objective lens has an object-side radius of curvature of 10.6 mm, is made of H-ZLAF56B glass, and has an outer diameter of 96 mm. The fourth objective lens 4 has an object-side radius of curvature of -116.68 mm, an image-side radius of curvature of -381.90 mm, a center thickness of 8.8 mm, is made of H-ZF2 glass, and has an outer diameter of 70 mm. The fifth objective lens 5 has an object-side radius of curvature of 92.26 mm, an image-side radius of curvature of 7.7 mm, a center thickness of 15.85 mm, is made of H-ZF7L glass, and has an outer diameter of 70 mm.

[0020] Along the optical axis, the distance between the first objective lens 1 and the second objective lens 2 is 0.6 mm, the distance between the second objective lens 2 and the third objective lens 3 is 79.46 mm, the distance between the third objective lens 3 and the fourth objective lens 4 is 59.09 mm, and the distance between the fourth objective lens 4 and the fifth objective lens 5 is 1.10 mm.

[0021] The optical system of this application has a focal length of 450.175mm, an entrance pupil diameter of 90mm, a field of view of 3.488°, an F number of 5, a total length of 428.58mm, and a back working distance of 224.38mm.

[0022] Appendix Figure 2 This is a dot plot of the present application. The distribution of points in the dot plot should be uniform and dense, with no obvious outliers or isolated points. The average data distribution indicates stable imaging quality, relatively concentrated energy, and relatively clear imaging. At the maximum field of view of 27.5mm, the dot distribution slightly diffuses, indicating a slight decrease in imaging quality, but the degree of decrease is very small.

[0023] Appendix Figure 3The MTF plot of this invention shows that the MTF curves of different fields of view are relatively close, indicating good image quality uniformity; the high degree of overlap between the meridian and the sagittal line indicates that astigmatism and coma are small; the overall MTF decreases slowly, indicating that high-frequency details are well preserved.

[0024] Appendix Figure 4 This is the field curvature distortion diagram of the present invention. The meridional field curvature and sagittal field curvature at the maximum field of view are both close to 0.1 mm, indicating that the field curvature is very small. The distortion at the maximum field of view is only 0.2377%, and the distortion curves of different bands highly overlap, indicating that the distortion is very small.

[0025] Appendix Figure 5 This is the color difference curve of the present invention. The axial aberration of light rays at different pupil heights is less than 0.1mm, indicating that the system has a small color difference.

[0026] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. An astronomical telescope objective optical system with an ultra-long back working distance, characterized in that: Along the optical axis, from the object side to the image side, there are a first objective lens (1), a second objective lens (2), a third objective lens (3), a fourth objective lens (4), and a fifth objective lens (5). The first objective lens (1) is a biconvex lens, the second objective lens (2) is a biconcave lens, the third objective lens (3) is a plano-convex lens with its plane facing the object side, the fourth objective lens (4) is a concave-convex lens with its concave surface facing the object side, and the fifth objective lens (5) is a concave-convex lens with its convex surface facing the object side. Only the above 5 lenses have optical power in the optical system. The first objective lens (1) has an object-side radius of curvature of 144.88 mm, an image-side radius of curvature of -122.18 mm, a center thickness of 21 mm, is made of HCD100 glass, and has an outer diameter of 96 mm; the second objective lens (2) has an object-side radius of curvature of 122.18 mm, an image-side radius of curvature of 1169.50 mm, a center thickness of 7.7 mm, is made of H-TF3 glass, and has an outer diameter of 96 mm; the third objective lens (3) has a plane object side, an image-side radius of curvature of -197.70 mm, and a center thickness of 21 mm. The thickness is 10.6mm, the material is glass H-ZLAF56B, and the outer diameter is 96mm; the fourth objective lens (4) has an object-side radius of curvature of -116.68mm, an image-side radius of curvature of -381.90mm, a center thickness of 8.8mm, and is made of glass H-ZF2 with an outer diameter of 70mm; the fifth objective lens (5) has an object-side radius of curvature of 92.26mm, an image-side radius of curvature of 7.7mm, a center thickness of 15.85mm, and is made of glass H-ZF7L with an outer diameter of 70mm. Along the optical axis, the distance between the first objective lens (1) and the second objective lens (2) is 0.6 mm, the distance between the second objective lens (2) and the third objective lens (3) is 79.46 mm, the distance between the third objective lens (3) and the fourth objective lens (4) is 59.09 mm, and the distance between the fourth objective lens (4) and the fifth objective lens (5) is 1.10 mm.

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