A short focal length optical passive thermal ablation uncooled long-wave infrared optical system

Abstract

This invention discloses a short-focal-length passive pyrometric uncooled long-wave infrared optical system, comprising, from the object side to the image side and along the optical axis, a first lens, a second lens, a third lens, and an uncooled long-wave infrared detector protection window. The first lens has positive optical power, with a spherical front surface and a binary diffraction surface with an even-order aspherical substrate on the rear surface. The second lens has negative optical power, with a spherical front surface and an even-order aspherical rear surface. The third lens has positive optical power, with an even-order aspherical front surface and a spherical rear surface. This optical system has an effective focal length of 37mm, a total optical length of 37mm, an F-number of 1.277, a linear field of view of 9.84mm, and a maximum distortion of 0.52%. The aperture stop is selected on the front surface of the first lens. The focal length to total optical length ratio of this optical system is 1:1, achieving the design requirements of miniaturization and lightweight design.

Description

Technical Field

[0001] This invention belongs to the field of optical design technology and relates to a short focal length optical passive pyrolysis uncooled long-wave infrared optical system, and more particularly to an optical passive pyrolysis uncooled long-wave infrared optical system with a focal length to total optical length ratio of 1:1. Background Technology

[0002] Current search and tracking optoelectronic devices not only require long search and tracking distances but also small size and light weight. A common method to reduce size and weight is to employ passive pyroelectric optical design technology in the optical system, eliminating the corresponding temperature compensation servo mechanism. Typically, the focal length of a passive pyroelectric optical system is longer than its total optical length, with a focal length to total optical length ratio of approximately 1:1.25 or greater, making further reduction in size and weight difficult. Therefore, to further reduce the size and weight of optoelectronic devices, a focal length to total optical length ratio approaching or equal to 1:1 in the passive pyroelectric optical system becomes a pressing need. Summary of the Invention

[0003] The purpose of this invention is to overcome the above-mentioned shortcomings, and the technical problem to be solved is to provide an optical passive thermal differential uncooled long-wave infrared optical system with a focal length to total optical length ratio of 1:1.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] According to an embodiment of an optical passive pyrometric noncooled long-wave infrared optical system with a focal length to total optical length ratio of 1:1, the system includes a first lens, a second lens, a third lens, and a noncooled long-wave infrared detector protection window, arranged sequentially from the object side to the image side along the optical axis.

[0006] According to an embodiment of the present invention, an uncooled long-wave infrared optical system with a focal length to total optical length ratio of 1:1 is provided, wherein the infrared optical system is adapted to an uncooled long-wave infrared detector with a resolution of 640×512 and a pixel pitch of 12 micrometers.

[0007] According to an embodiment of the present invention, an optical passive pyrometric noncooled long-wave infrared optical system with a focal length to total optical length ratio of 1:1 is provided, wherein the effective focal length is 37 mm, the total optical length is 37 mm, the F number is 1.277, the linear field of view is 9.84 mm, the maximum distortion is 0.52%, and the aperture stop is selected on the front surface of the first lens.

[0008] According to an embodiment of the present invention, a passively calorimetric, non-cooled long-wave infrared optical system with a focal length to total optical length ratio of 1:1 is provided, wherein the operating wavelength is 8μm to 10μm (center wavelength) to 12μm.

[0009] According to an embodiment of the optical passive pyrometric differential uncooled long-wave infrared optical system with a focal length to total optical length ratio of 1:1, the first lens, the second lens and the third lens are respectively made of IRG206, ZnSe and IRG206 materials.

[0010] According to an embodiment of the present invention, a passively pyrometric, uncooled long-wave infrared optical system with a focal length to total optical length ratio of 1:1, wherein the first lens has positive optical power, its front surface is spherical, and its rear surface is a binary diffraction surface with an even-order aspherical substrate; the second lens has negative optical power, its front surface is spherical, and its rear surface is an even-order aspherical substrate; and the third lens has positive optical power, its front surface is an even-order aspherical substrate, and its rear surface is spherical.

[0011] According to an embodiment of the present invention, an optical passive thermal ablation uncooled long-wave infrared optical system with a focal length to total optical length ratio of 1:1 is provided, wherein the protective window of the uncooled long-wave infrared detector is a flat glass plate made of germanium material, and the radii of the front and rear surfaces are infinite.

[0012] According to an embodiment of the present invention, an optical passive pyrometric differential uncooled long-wave infrared optical system with a focal length to total optical length ratio of 1:1 is provided, wherein the optical system housing material is selected from aluminum alloy.

[0013] According to an embodiment of the present invention, an optical passive pyrolysis uncooled long-wave infrared optical system with a focal length to total optical length ratio of 1:1 is provided, wherein the optical passive pyrolysis system is formed by combining the selected lens surface type, lens material and housing aluminum alloy material.

[0014] According to an embodiment of the present invention, an optical passive pyrometric adiabatic uncooled long-wave infrared optical system with a focal length to total optical length ratio of 1:1 is provided, wherein the even-order aspherical surface used in the lens satisfies the following expression:

[0015]

[0016] Where z represents the position of the even-order aspherical surface along the optical axis at a height of r, from the vertex of the aspherical surface; c represents the curvature of the vertex; k represents the conic coefficients; and α4, α6, α8, α... 10 This represents the higher-order aspheric coefficients.

[0017] According to an embodiment of the optical passive pyrometric differential uncooled long-wave infrared optical system with a focal length to total optical length ratio of 1:1, the binary diffraction surface of the lens satisfies the following expression.

[0018] φ=A1ρ 2 +A2ρ 4

[0019] Where Φ is the phase of the diffraction plane, and ρ = r / r n ,r n A1 and A2 are the planned radius of the diffraction surface and the phase coefficients of the diffraction surface.

[0020] The beneficial effects of this invention are:

[0021] This invention discloses an uncooled long-wave infrared optical system with a focal length-to-total optical length ratio of 1:1, characterized by passive pyrolysis and a 1:1 focal length-to-total optical length ratio. This optical system has an effective focal length of 37mm, a total optical length of 37mm, an F-number of 1.277, a linear field of view of 9.84mm, a maximum distortion of 0.52%, and the aperture stop is selected on the front surface of the first lens. Specifically, this invention has the following advantages:

[0022] 1) This optical system adopts a passive optical thermal ablation design technology;

[0023] 2) The ratio of focal length to total optical length of this optical system is 1:1;

[0024] 3) This optical system can meet the design requirements of miniaturization and lightweighting. Attached Figure Description

[0025] Figure 1 : An optical layout diagram of the present invention.

[0026] Figure 2 MTF curve of the optical system at 20℃.

[0027] Figure 3 : Graph of optical system at 20℃.

[0028] Figure 4 Distortion curve of optical system at 20℃.

[0029] Figure 5 MTF curve of the optical system at -45℃.

[0030] Figure 6 : Optical system at -45℃ (point-by-point diagram).

[0031] Figure 7 Distortion curve of optical system at -45℃.

[0032] Figure 8 MTF curve of the optical system at 70℃.

[0033] Figure 9 : Graph of optical system at 70℃.

[0034] Figure 10 Distortion curve of optical system at 70℃. Detailed Implementation

[0035] To make the objectives, contents, and advantages of the present invention clearer, the specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples.

[0036] See Figure 1 As shown, a thermally neutralized, uncooled long-wave infrared optical system with a focal length to total optical length ratio of 1:1 includes a first lens 1, a second lens 2, a third lens 3, and an uncooled long-wave infrared detector protection window 4, arranged sequentially from the object side to the image side along the optical axis.

[0037] The optical system is adapted to an uncooled long-wave infrared detector 4, which has a resolution of 640×512 and a pixel pitch of 12 micrometers.

[0038] The optical system has an effective focal length of 37mm, a total optical length of 37mm, an F-number of 1.277, a linear field of view of 9.84mm, a maximum distortion of 0.52%, and the aperture stop is selected on the front surface S11 of the first lens 1.

[0039] The optical system operates in the wavelength range of 8μm to 10μm (center wavelength) to 12μm.

[0040] The first lens 1 of the optical system is made of IRG206 material from Xinhua Optoelectronics.

[0041] The second lens 2 of the optical system is made of ZnSe material.

[0042] The third lens 3 of the optical system is made of IRG206 material from Xinhua Optoelectronics.

[0043] The first lens 1 has positive optical power, its front surface S11 is a spherical surface, and its rear surface S12 is a binary diffraction surface with an even-order aspherical substrate.

[0044] The second lens 2 has negative optical power, with its front surface S21 being spherical and its rear surface S22 being an even-order aspherical surface.

[0045] The third lens 3 has positive optical power, its front surface S31 is an even-order aspherical surface, and its rear surface S32 is a spherical surface.

[0046] The uncooled long-wave infrared detector protection window 4 is a flat glass plate made of germanium, with infinite radii for the front surface S41 and the rear surface S42.

[0047] The housing material of the optical system is aluminum alloy.

[0048] The optical system is a passive optical thermal differential protection system composed of the selected lens surface type, lens material, and housing aluminum alloy material.

[0049] All surfaces of the optical system need to be coated with an anti-reflective coating.

[0050] Table 1 shows the optical structure parameters of the optical system of the present invention.

[0051] Table 1

[0052] surface radius of curvature thickness Material Half-caliber S11 23.11 5.1 IRG206 14.1 S12 46.54 3.1 13.2 S21 24.86 2.4 ZnSe 11.3 S22 14.54 10.1 9.8 S31 38.92 2.4 IRG206 7.5 S32 44.34 11.6 7.2 S41 Infinity 1 GERMANIUM 5.2 S42 Infinity 1.3 5.2 Image Infinity 0 4.9

[0053] The even-order aspherical surface types involved in surfaces S12, S22, and S31 satisfy the following expression.

[0054]

[0055] Where z represents the position of the even-order aspherical surface along the optical axis at a height of r, from the vertex of the aspherical surface; c represents the curvature of the vertex; k represents the conic coefficients; and α4, α6, α8, α... 10 This represents the higher-order aspheric coefficients.

[0056] Table 2 shows the even-order aspherical parameters of surfaces S12, S22, and S31.

[0057] Table 2

[0058] surface k <![CDATA[α4]]> <![CDATA[α6]]> <![CDATA[α8]]> <![CDATA[α 10 ]]> S12 0 9.646134E-06 1.096119E-08 -8.613575E-11 2.417645E-13 S22 0 -2.083819E-05 -3.862437E-07 2.038281E-09 -1.348471E-11 S31 0 2.489757E-05 -2.458134E-06 3.879116E-08 -2.868725E-10

[0059] The binary diffraction surface involved in the S21 surface satisfies the following expression.

[0060] φ=A1ρ 2 +A2ρ 4

[0061] Where Φ is the phase of the diffraction plane, and ρ = r / r n ,r n A1 and A2 are the planned radius of the diffraction surface and the phase coefficients of the diffraction surface.

[0062] Table 3 shows the diffraction parameters of the S12 surface.

[0063] Table 3

[0064] surface <![CDATA[r n ]]> <![CDATA[H1]]> <![CDATA[H2]]> <![CDATA[H3]]> <![CDATA[H4]]> S21 13.2 -0.230182 -20.067675 22.455542 -10.791307

[0065] Figures 2 to 10 The optical transfer function (42 lp / mm), dot plot, field curvature, and distortion curves for the optical system at 20℃, -45℃, and 70℃ are shown. From the figures, it can be determined that the seven aberrations related to the large and small fields of view and the field of view and aperture—axial spherical aberration, transverse spherical aberration, axial chromatic aberration, transverse chromatic aberration, coma, field curvature, and distortion—as well as their corresponding higher-order aberrations, are well corrected, resulting in clear imaging without significant distortion.

[0066] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. 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.

Claims

1. A short-focal-length, passively thermally ablated, uncooled long-wavelength infrared optical system, characterized in that, From the object side to the image side, along the optical axis, it includes, in order: a first lens, a second lens, a third lens, and an uncooled long-wave infrared detector protection window; The first lens has positive optical power, its front surface is spherical, and its rear surface is a binary diffraction surface with an even-order aspherical substrate; the second lens has negative optical power, its front surface is spherical, and its rear surface is an even-order aspherical substrate; the third lens has positive optical power, its front surface is an even-order aspherical substrate, and its rear surface is spherical. The even-order aspherical surfaces used in the first lens, second lens, and third lens satisfy the following expression: ； In the formula: z represents the position of the even-order aspherical surface along the optical axis at a height of r, which is the sag of the aspherical surface vertex; c represents the curvature of the surface vertex; k represents the conic coefficients; α4, α6, α8, α... 10 Represents higher-order aspheric coefficients; The binary diffraction surfaces used in the first lens, second lens, and third lens satisfy the following expression: ； In the formula: Φ represents the phase of the diffraction plane. ,r n A1 and A2 are the planned radius of the diffraction surface and the phase coefficients of the diffraction surface. The optical system has an effective focal length of 37mm, a total optical length of 37mm, an F-number of 1.277, a linear field of view of 9.84mm, a maximum distortion of 0.52%, and a focal length to total optical length ratio of 1:

1.

2. The short focal length optical passive thermal ablation uncooled long-wave infrared optical system according to claim 1, characterized in that: The first lens, the second lens, and the third lens are made of IRG206, ZnSe, and IRG206 materials, respectively.

3. The short focal length optical passive thermal ablation uncooled long-wave infrared optical system according to claim 1, characterized in that: The housing material of the optical system is aluminum alloy.

4. The short focal length optical passive thermal ablation uncooled long-wave infrared optical system according to claim 1, characterized in that: The surface shape, lens material, and housing aluminum alloy material of the first lens, second lens, and third lens are combined to form an optical passive thermal ablation system.

5. The short focal length optical passive thermal ablation uncooled long-wave infrared optical system according to claim 1, characterized in that: The aperture plane of the optical system is selected on the front surface of the first lens.

6. The short focal length optical passive pyrolysis uncooled long-wave infrared optical system according to claim 1, characterized in that: The infrared optical system is adapted to an uncooled long-wave infrared detector with a resolution of 640×512 and a pixel pitch of 12 micrometers.

7. The short focal length optical passive pyrometric differential uncooled long-wave infrared optical system according to any one of claims 1-6, characterized in that: The optical system operates in the 8μm to 12μm band, with a center wavelength of 10μm.

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