Fixed-focus infrared lens

Abstract

The invention relates to the technical field of infrared lens production, and provides a fixed-focus infrared lens which is characterized in that an objective lens first lens, an objective lens second lens and an objective lens third lens are sequentially arranged from the object side to the image side in the optical axis direction, the objective lens first lens is a meniscus lens, the convex face faces the object side, the objective lens second lens is a meniscus lens, and the convex face faces the image side. The convex surface faces the object side, the third lens of the objective lens is a biconvex lens, and the lens only comprises the three lenses with focal power, so that the lens is an excellent prime lens with the focal length of 50mm.

Description

Technical Field

[0001] The invention relates to the technical field of infrared lens production, and in particular to a fixed-focus infrared lens. Background Art

[0002] Fixed-focus infrared lens is an optical lens specially designed for infrared imaging. It has a fixed focal length and is suitable for infrared light of a specific wavelength. It has a simple structure and stable imaging. The materials mainly use infrared light-transmitting materials such as germanium and zinc selenide. It can effectively reduce light loss, adapt to temperature changes, and avoid thermal expansion and contraction affecting imaging. High-resolution lenses provide clearer details. At present, the mid-band fixed-focus infrared lens has a complex structure, a long optical system, and a large volume. Summary of the invention

[0003] The object of the present invention is to provide a fixed-focus infrared lens to solve the problems mentioned in the background technology.

[0004] To achieve the above object, the technical solution adopted by the present invention is: a fixed-focus infrared lens, characterized in that: an objective lens first lens, an objective lens second lens, and an objective lens third lens are sequentially arranged from the object side to the image side along the optical axis direction; The first lens of the objective lens is a meniscus lens with a convex surface facing the object side, the second lens of the objective lens is a meniscus lens with a convex surface facing the object side, and the third lens of the objective lens is a double convex lens. Only the above three lenses of the lens have optical power.

[0005] As a further improvement of the present invention, the object side curvature radius of the first lens of the objective lens is 48.31 mm, the image side curvature radius is 88.51 mm, the center thickness is 5.8 mm, and the material is silicon lens; the object side curvature radius of the second lens of the objective lens is 91.366 mm, the image side curvature radius is 54.7 mm, the center thickness is 2.5 mm, and the material is germanium lens; the object side curvature radius of the third lens of the objective lens is 248.9 mm, the image side curvature radius is -248.9 mm, the center thickness is 3 mm, and the material is silicon lens.

[0006] As a further improvement of the present invention, along the optical axis direction, the distance between the first lens of the objective lens and the second lens of the objective lens is 1.44 mm, and the distance between the second lens of the objective lens and the third lens of the objective lens is 26.308 mm.

[0007] As a further improvement of the present invention, the diameter of the first lens of the objective lens is 46 mm, the diameter of the second lens of the objective lens is 42 mm, and the diameter of the third lens of the objective lens is 27 mm.

[0008] As a further improvement of the present invention, the object side of the first lens of the objective lens is coated with an AR film.

[0009] The beneficial effects of the present invention are mainly embodied in: Through reasonable optical system design, the focal length of the lens is 50mm, the F number is 2.0, the working wavelength is 3-5um, the FOV is 11°*8.8°, and the weight is 102g. It is an excellent fixed-focus optical athermal lens. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a schematic diagram of the optical system structure of the present invention; Figure 2 It is the MTF diagram of the present invention at -40°C; Figure 3 is the MTF diagram of the present invention at 20°C; Figure 4 is the MTF diagram of the present invention at 60°C; Figure 5 It is a distortion diagram of the present invention. DETAILED DESCRIPTION

[0011] The present invention will be further described below in conjunction with the accompanying drawings. Figure 1-5 As shown, a fixed-focus infrared lens is characterized in that: a first lens 1, a second lens 2, and a third lens 3 are arranged in sequence from the object side to the image side along the optical axis direction, the first lens 1 is a meniscus lens with a convex surface facing the object side, the second lens 2 is a meniscus lens with a convex surface facing the object side, and the third lens 3 is a double convex lens. Only the above three lenses of the lens have optical power. The object side curvature radius of the first lens 1 is 48.31mm, the image side curvature radius is 88.51mm, the center thickness is 5.8m, and the material is a silicon lens. The object side curvature radius of the second lens 2 is 91.366mm, the image side curvature radius is 54.7mm, the center thickness is 2.5mm, and the material is a germanium lens. The object side curvature radius of the third lens 3 is 91.366mm, the image side curvature radius is 54.7mm, the center thickness is 2.5mm, and the material is a germanium lens. The curvature radius is 248.9mm, the image side curvature radius is -248.9mm, the center thickness is 3mm, and the material is silicon lens. Along the optical axis, the distance between the first lens 1 and the second lens 2 of the objective lens is 1.44mm, and the distance between the second lens 2 and the third lens 3 of the objective lens is 26.308mm. The diameter of the first lens 1 of the objective lens is 46mm, the diameter of the second lens 2 of the objective lens is 42mm, and the diameter of the third lens 3 of the objective lens is 27mm. The object side of the first lens 1 of the objective lens is coated with AR film. Through reasonable optical system design, the focal length of the lens is 50mm, the F number is 2.0, the working wavelength is 3-5um, the FOV is 11°*8.8°, and the weight is 102g. It is an excellent fixed-focus optical athermal lens.

[0012] Figures 2 to 4It is the MTF diagram of the optical system of this application under different temperature conditions of -40℃, 20℃ and 60℃, and is the modulation transfer function diagram of the optical system. From the diagram we can see that the lens transmits a large amount of information, has good imaging quality, and a relatively clear image, and the MTF performance of the lens at different temperatures is stable.

[0013] Figure 5 is the field curvature distortion diagram of this application, from Figure 5 We can see that the distortion of this application is very small, less than 0.2%, and there is almost no deformation at the edge of the image. In simple terms, the edge of the image surface is not deformed after imaging.

Claims

1. A fixed-focus infrared lens, characterized in that: An objective lens first lens (1), an objective lens second lens (2), and an objective lens third lens (3) are arranged in sequence from the object side to the image side along the optical axis; The first lens (1) of the objective lens is a meniscus lens with a convex surface facing the object side, the second lens (2) of the objective lens is a meniscus lens with a convex surface facing the object side, and the third lens (3) of the objective lens is a double convex lens. Only the above three lenses have optical power.

2. The fixed-focus infrared lens according to claim 1, characterized in that: The first lens (1) of the objective lens has an object side curvature radius of 48.31 mm, an image side curvature radius of 88.51 mm, a center thickness of 5.8 mm, and is made of a silicon lens. The second lens (2) of the objective lens has an object side curvature radius of 91.366 mm, an image side curvature radius of 54.7 mm, a center thickness of 2.5 mm, and is made of a germanium lens. The third lens (3) of the objective lens has an object side curvature radius of 248.9 mm, an image side curvature radius of -248.9 mm, a center thickness of 3 mm, and is made of a silicon lens.

3. The fixed-focus infrared lens according to claim 1, characterized in that: Along the optical axis direction, the distance between the first lens (1) of the objective lens and the second lens (2) of the objective lens is 1.44 mm, and the distance between the second lens (2) of the objective lens and the third lens (3) of the objective lens is 26.308 mm.

4. The fixed-focus infrared lens according to claim 1, characterized in that: The diameter of the first lens (1) of the objective lens is 46 mm, the diameter of the second lens (2) of the objective lens is 42 mm, and the diameter of the third lens (3) of the objective lens is 27 mm.

5. The fixed-focus infrared lens according to claim 1, characterized in that: The object side of the first lens (1) of the objective lens is coated with an AR film.

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