CN216248544U

CN216248544U - Infrared wide spectrum optical system

Info

Publication number: CN216248544U
Application number: CN202123124773.5U
Authority: CN
Inventors: 孙浩; 邓岩; 于兴
Original assignee: Beijing North China Rhine Photoelectric Technology Co ltd
Current assignee: Beijing North China Rhine Photoelectric Technology Co ltd
Priority date: 2021-12-13
Filing date: 2021-12-13
Publication date: 2022-04-08
Anticipated expiration: 2031-12-13

Abstract

The utility model discloses an infrared broad spectrum optical system, which comprises a transmission lens group, wherein the transmission lens group comprises a first lens, a second lens, a third lens, a fourth lens and a fifth lens; the first lens, the second lens, the third lens, the fourth lens and the fifth lens are coaxially arranged and are sequentially arranged from front to back; a detector window is arranged behind the fifth lens, and the detector window and the focal plane array are coaxially arranged and are sequentially arranged from front to back; the position of the front end surface of the fourth lens is an aperture diaphragm of the optical system; the wide infrared spectrum optical system is suitable for the application fields of infrared spectrum analysis, infrared alarm, Volatile Organic Compounds (VOCs) detection and the like of a target, can realize imaging of wide infrared spectrum with medium wave (3-5 mu m) and long infrared wave (8-12 mu m), and has the advantages of large relative aperture, compact structure, long back intercept and the like.

Description

Infrared wide spectrum optical system

Technical Field

The utility model relates to an optical system, in particular to an infrared wide spectrum optical system.

Background

In the field of infrared imaging, 3-5 μm and 8-12 μm are wide-application atmospheric window wave bands which are respectively characterized; in a hot and humid atmosphere, medium wave transmittance is high, and long waves are suitable for a land area. For different targets, according to the blackbody radiation law, the emission peak of the high-temperature target deflects to medium waves, and the emission peak of the low-temperature target deflects to long waves. For some detection of air mass, the molecular absorption spectrum is in long wave band, and some are in medium wave band, so that the medium wave and the long wave have specific application directions. With the development of detector technology, the use of bicolor or multicolor imaging becomes more and more extensive, the utility model provides an optical system of a non-refrigeration type infrared detector based on the response wave band of 3-5 μm and 8-12 μm, the array scale of 640 multiplied by 480 and the pixel size of 17 μm, and the optical system is suitable for the application fields of infrared spectroscopy, infrared alarm, organic volatile gas (VOCs) detection and the like.

SUMMERY OF THE UTILITY MODEL

In order to solve the defects of the technology, the utility model provides an infrared wide spectrum optical system.

In order to solve the technical problems, the utility model adopts the technical scheme that: an infrared wide-spectrum optical system comprises a transmission lens group, wherein the transmission lens group comprises a first lens, a second lens, a third lens, a fourth lens and a fifth lens; the first lens, the second lens, the third lens, the fourth lens and the fifth lens are coaxially arranged and are sequentially arranged from front to back; a detector window is arranged behind the fifth lens, and the detector window and the focal plane array are coaxially arranged and are sequentially arranged from front to back; the position of the front end surface of the fourth lens is an aperture diaphragm of the optical system;

the focal length of the optical system is f, and the focal length corresponding to the transmission lens group is f_1-5The focal length of the first lens is f₁Focal length of the second lens is f₂The focal length of the third lens is f₃The focal length of the fourth lens is f₄The focal length of the fifth lens is f₅The value ranges of the focal length values are as follows in sequence:

0.4<f₁/|f₂|<0.6，1.5<|f_1-5|/f<2.5，2<|f₁|/f<3，1.5<|f₂|/f<1，

1.5<|f₃|/f<1，0.6<|f₄|/f<1，4<|f₅|/f<5。

furthermore, the front end surface of the first lens is a spherical surface; the front end surface and the rear end surface of the second lens are spherical surfaces; the rear end surface of the third lens is a spherical surface; the front end surface of the fourth lens is a spherical surface; the front end surface and the rear end surface of the fifth lens are spherical surfaces.

Furthermore, the materials of the first lens, the second lens and the fourth lens are all zinc selenide.

Further, the material of the third lens is germanium.

Further, the material of the fifth lens is barium fluoride.

The wide infrared spectrum optical system is suitable for the application fields of infrared spectrum analysis, infrared alarm, Volatile Organic Compounds (VOCs) detection and the like of a target, can realize imaging of wide infrared spectrum with medium wave (3-5 mu m) and long infrared wave (8-12 mu m), and has the advantages of large relative aperture, compact structure, long back intercept and the like.

Drawings

FIG. 1 is a schematic structural diagram of the present invention.

FIG. 2 is a graph of MTF resolution in different fields according to one embodiment.

Fig. 3 is a graph of field curvature and optical distortion of the first embodiment.

In the figure: 1. a first lens; 2. a second lens; 3. a third lens; 4. a fourth lens; 5. a fifth lens; 6. a detector window; 7. a focal plane array.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

As shown in fig. 1, an infrared broad spectrum optical system includes a transmission lens group, which includes a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, and a fifth lens 5; the first lens 1, the second lens 2, the third lens 3, the fourth lens 4 and the fifth lens 5 are coaxially arranged and are sequentially arranged from front to back; a detector window 6 is arranged behind the fifth lens 5, and the detector window 6 and the focal plane array 7 are coaxially arranged and are sequentially arranged from front to back; the position of the front end surface of the fourth lens 4 is an aperture stop of the optical system.

The front end surface of the first lens 1 is a spherical surface; the front end surface and the rear end surface of the second lens 2 are spherical surfaces; the rear end surface of the third lens 3 is a spherical surface; the front end surface of the fourth lens 4 is a spherical surface; the front end surface and the rear end surface of the fifth lens 5 are spherical surfaces.

The focal length of the whole optical system is f, and the focal length corresponding to the transmission lens group is f_1-5The focal length of the first lens 1 is f₁The focal length of the second lens 2 is f₂The focal length of the third lens 3 is f₃The focal length of the fourth lens 4 is f₄The focal length of the fifth lens 5 is f₅The value ranges of the focal length values are as follows in sequence:

0.4<f₁/|f₂|<0.6，1.5<|f_1-5|/f<2.5，2<|f₁|/f<3，1.5<|f₂|/f<1，

1.5<|f₃|/f<1，0.6<|f₄|/f<1，4<|f₅|/f<5。

the materials of the first lens 1, the second lens 2 and the fourth lens 4 of the optical system are all zinc selenide. The material of the third lens 3 is germanium. The material of the fifth lens 5 is barium fluoride.

The optical performance of the optical system of the present invention is further illustrated in detail by a specific embodiment.

The first embodiment,

Front end of first lens 1 of optical System of the present invention the front end and rear end surfaces of first lens 1 of the optical System of the present invention are first surfaces S₁A second surface S₂The front and rear surfaces of the second lens element 2 are the third surfaces S₃A fourth surface S₄The front and rear surfaces of the third lens element 3 are the fifth surfaces S₅A sixth surface S₆The front and rear surfaces of the fourth lens element 4 are the seventh surfaces S₇The eighth surface S₈The front and rear end surfaces of the fifth lens element 5 are the ninth surface S₉The tenth surface S₁₀And the S7 position is an aperture stop of the optical system. Specific optical parameters of the optical system are shown in tables 1 and 2:

TABLE 1 optical System parameters

Name (R)	Parameter(s)
		Focal length	25mm
F#	1.2
		Operating band	3～5μm；8～12μm
Adaptive detector	640×480 17μm
		Angle of view	24.5°×18.5°
Total optical length	≤105mm

TABLE 2 optical System data

The surface type expression of the aspheric surface of the optical system of the utility model satisfies the formula I:

wherein: z is rise and is in mm; r is the lens half diameter in mm; r is the vertex radius of the lens and the unit is mm; k is a conic coefficient; a. the₂Is a quadratic coefficient; a. the₄Is a quartic coefficient; a. the₆Coefficient of the sixth order term; a. the₈Coefficient of eight degree terms; a. the₁₀Ten-degree term coefficients; aspheric coefficients see table 3:

TABLE 3 aspherical coefficients

Surface of	Conic	A4	A6	A8	A10
						First surface	0	0	0	0	0
Third surface	0	3.379E-6	2.75E-9	2.22E-11	0
						The sixth surface	0	7.147E-6	3.673E-9	5.215E-13	0
The ninth surface	0	1.133E-5	-9.263E-9	6.238E-12	0

The imaging evaluation of the optical system of the present invention is as follows: the MTF (modulation Transfer Function) curves of different fields are shown in fig. 2, where TS diffraction limit represents the diffraction limit of the system, TS0.0000 represents the MTF of the central field, TS6.8000 represents the edge field, the horizontal axis represents the corresponding line logarithm per mm, and the vertical axis represents the normalized OTF coefficient, where the OTF is fully called: optical transfer function, i.e. the optical transfer function. The central field-of-view transfer function in the figure is more than or equal to 0.7@20lp/mm and is close to the diffraction limit, and the marginal field-of-view transfer function is more than or equal to 0.5@20 lp/mm.

The distortion of the optical system is expressed by an f-Tan theta distortion graph, and the f-Tan theta distortion is expressed by the height H of principal rays of different view fields on an image surface_{Practice of}And f tan theta image height H_f-tanθDifference of (a) to (b) of_f-tanθThus obtaining the product. FIG. 3 is the distortion diagram of the field curvature after the optical system of the present invention is designed, and the f-theta distortion is less than-3% in the full field of view.

The optical system of the present invention is suitable for array scale: the pixel size of 640 multiplied by 480 is 17 mu m, the pixel size of 1280 multiplied by 1024 is 12 mu m, and the working wave band: 3-5 μm, 8-12 μm.

The above embodiments are not intended to limit the present invention, and the present invention is not limited to the above examples, and those skilled in the art may make variations, modifications, additions or substitutions within the technical scope of the present invention.

Claims

1. An infrared broad spectrum optical system characterized by: the lens comprises a transmission lens group, wherein the transmission lens group comprises a first lens (1), a second lens (2), a third lens (3), a fourth lens (4) and a fifth lens (5); the first lens (1), the second lens (2), the third lens (3), the fourth lens (4) and the fifth lens (5) are coaxially arranged and are sequentially arranged from front to back; a detector window (6) is arranged behind the fifth lens (5), and the detector window (6) and the focal plane array (7) are coaxially arranged and are sequentially arranged from front to back; the position of the front end surface of the fourth lens (4) is an aperture diaphragm of an optical system;

the focal length of the optical system is f, and the focal length corresponding to the transmission lens group is f_1-5The focal length of the first lens (1) is f₁The focal length of the second lens (2) is f₂The focal length of the third lens (3) is f₃The focal length of the fourth lens (4) is f₄The focal length of the fifth lens (5) is f₅The value ranges of the focal length values are as follows in sequence:

0.4<f₁/|f₂|<0.6，1.5<|f_1-5|/f<2.5，2<|f₁|/f<3，1.5<|f₂|/f<1，

1.5<|f₃|/f<1，0.6<|f₄|/f<1，4<|f₅|/f<5。

2. the infrared broad spectrum optical system of claim 1, wherein: the front end surface of the first lens (1) is a spherical surface; the front end surface and the rear end surface of the second lens (2) are spherical surfaces; the rear end surface of the third lens (3) is a spherical surface; the front end surface of the fourth lens (4) is a spherical surface; the front end surface and the rear end surface of the fifth lens (5) are both spherical surfaces.

3. The infrared broad spectrum optical system of claim 1, wherein: the first lens (1), the second lens (2) and the fourth lens (4) are all made of zinc selenide.

4. The infrared broad spectrum optical system of claim 1, wherein: the material of the third lens (3) is germanium.

5. The infrared broad spectrum optical system of claim 1, wherein: the material of the fifth lens (5) is barium fluoride.