CN207586516U - A kind of two-piece type LONG WAVE INFRARED tight shot - Google Patents

Abstract

The utility model provides a kind of two-piece type LONG WAVE INFRARED tight shot, two groups of lens are disposed with along optical axis from object space to image space, first lens are meniscus shaped lens with positive light coke of the convex surface towards object side, and the second lens are meniscus shaped lens with negative power of the concave surface towards image side；Positive lens uses the chalcogenide glass material of lower temperature specific refractivity before the utility model, negative lens uses the germanite glass material of focal power coefficient maximum and dispersion minimum afterwards, by adding aspherical design using diffraction surfaces to the first lens, and to the simple mechanical structure of movement, it can ensure image quality while number of lenses is reduced；The reduction of number of lenses also effectively increases light-transmissive rate, improves detection, the discrimination of infrared system.

Description

A kind of two-piece type LONG WAVE INFRARED tight shot

Technical field

The utility model belongs to optical lens technical field, and in particular to a kind of two-piece type LONG WAVE INFRARED tight shot.

Background technology

With the maturation of uncooled detector technology, LWIR Uncooled Optical System obtains in dual-use field Extensive use is arrived.Since the thermal refractive index coefficient of infrared optical material is larger, the acute variation of operating temperature can be to infrared Optical system has serious and influences, cause system focal length variation, image planes drift, image quality decline the problems such as.For these Special application field and infrared optical system must carry out athermal design, design when consider temperature change to system The influence of image quality so that infrared optical system is respectively provided with good image quality within the scope of a larger temperature.

Comprehensive research report both domestic and external, the method for carrying out athermalizing infrared optical systems generally have following three kinds: Optical passive mode, mechanical active type and mechanical passive type.Optical passive mode method is not additional any focus adjusting mechanism, relies only on light Itself image-forming principle of system and optical material realize infrared optical system without thermalization and mechanical structure using simple and mechanical structure The thermal characteristics of material matches to realize no thermalized design.Although this method makes system have light weight and spy simple in structure Point, but domestic available infrared optical material is very little, and it is matched cannot to meet this method needs at least three kinds or more optical materials It is required that.It is external that it is set as a kind of optical material in no thermalization since binary optical elements are with no heat differential, Negative Dispersion Properties It is used in meter, but domestic binary optical processing technology is still immature, and binary knot can only be processed in the planar substrates of finite size Structure, so optical passive mode method is difficult to be widely used at this stage.Mechanical active type method, i.e. look-up table are in optical system The big optical element of heat sensitivity (generally object lens) nearby adds temp measuring system, according to existing focusing data, passes through mechanical machine Structure is realized without thermalization.This method technology maturation at present, the country use more, but the volume of this system and complexity are all very big, can Decline by property.Mechanical passive type method, i.e., using simple and mechanical structure, the system bulk designed is smaller, and domestic machinery adds Tooling can meet performance and the required precision of system with level completely, so mechanical passive type method has the latent of popularization and application Power.

Utility model content

In view of this, the purpose of this utility model is to provide a kind of two-piece type LONG WAVE INFRARED tight shot, mechanical structure letter Single, it is at low cost to reduce manufacture, light-weight, transmissivity is high, can be applied to the fields such as safety monitoring, aircraft pod.

A kind of infrared tight shot includes the first lens and the second lens successively along optical axis from object space to image space, and first thoroughly Mirror is meniscus shaped lens with positive light coke of the convex surface towards object side, and the second lens have negative power for concave surface towards image side Meniscus shaped lens；The material of first lens uses chalcogenide glass, and second lens material uses germanium.

Further, the camera lens diaphragm for being placed on the first lens front surface is further included.

Preferably, the focal length f=90mm of the camera lens, F-number FNO=1；The focal length f1=of first lens 112.8495mm the focal length f2=160.3181mm of the second lens.

The utility model has the advantages that：

The utility model provides a kind of two-piece type LONG WAVE INFRARED tight shot, is set gradually along optical axis from object space to image space There are two groups of lens, the first lens are meniscus shaped lens with positive light coke of the convex surface towards object side, and the second lens are concave surface direction The meniscus shaped lens with negative power of image side；Positive lens uses the sulphur system of lower temperature specific refractivity before the utility model Glass material, rear negative lens uses focal power coefficient maximum and the germanite glass material of dispersion minimum, by using the first lens Diffraction surfaces add aspherical design and to the simple mechanical structures of movement, can ensure into while number of lenses is reduced Image quality amount.The reduction of number of lenses also effectively increases light-transmissive rate, improves detection, the discrimination of infrared system.

Description of the drawings

Fig. 1 is the structure diagram of the specific embodiment of two-piece type LONG WAVE INFRARED tight shot described in the utility model；

Fig. 2 is the point range figure of specific embodiment；

Fig. 3 is the astigmatism curve graph of specific embodiment；

Fig. 4 is the distortion curve figure of specific embodiment；

Fig. 5 is the MTF curve figure of specific embodiment.

Specific embodiment

With reference to the accompanying drawings and examples, the utility model is described in detail.

The utility model provides a kind of two-piece type LONG WAVE INFRARED tight shot, is set gradually along optical axis from object space to image space First lens, the second lens, the first lens are meniscus shaped lens with positive light coke of the convex surface towards object side, and the second lens are recessed Facing towards the meniscus shaped lens with negative power of image side, preceding positive lens spreads out hybrid lens using lower temperature refractive index for folding The chalcogenide glass of coefficient, using most of aberration of diffraction surfaces compensating material and fraction heat differential, residual achromatic aberration and heat differential are by rear Negative lens balances.

To solve the above problems, the utility model writes formula under meeting：

The distribution of athermal imaging optical system focal power needs to meet following three equations：Focal power equation, achromatism side Journey and athermal equation.

In formulaFor focal power, φ_sFor total focal power, V is Abbe constant, and T is normalization light focal power temperature coefficient.

The focal power distribution equations group of two-piece type athermal structure is：

In formulaFor positive focal power,For negative focal power,The focal power of diffraction surfaces, visual field top edge centered on h Normalization height of incidence of the light at rear group.

(2) formula of analysis is due to the high h ＜ 1 of rear group of light then h²＜ ＜ 1, cause it is rear group smaller to the contribution coefficient of heat differential, so Preceding group of positive lens should select focal power temperature coefficient material as small as possible, and group is to the contribution coefficient of heat differential after negative lens choosing Smaller, focal power temperature coefficient material as small as possible should be selected and negative lens selection focal power temperature by organizing positive lens in the past Coefficient material as big as possible.

The characteristic of the diffraction surfaces of preceding group of lens is that dispersion can mutually balance greatly with the aberration of positive lens very much, is organized later negative Lens should select the small material of dispersion, and rational material selection can reduce the front and rear respective focal power of group, be conducive to system Senior aberration reduces.

The utility model is eliminated except through infrared optical system outside most of heat differential, also to add a simple machinery knot Structure, it is main to change optical system rear cut-off distance, i.e., the machine core housing of camera lens in a cask, cask is connect with camera lens, On cask plus a linear small machine, driving cask are moved forward and backward so that movement can move 0.1mm or 6 picture Plain size can just recover remaining heat differential and aberration.

This optical system is in design, to reach movement resolution ratio 640*512, the high-resolution image quality of 17 microns of pixel size It is required that camera lens diaphragm is placed in the front surface of the first lens.

In the present embodiment, the focal length f=90mm of the optical system, F-number FNO=1.The focal length f1=of first lens 112.8495mm the focal length f2=160.3181mm of the second lens.

The utility model optical system parameter refers to table one, table two, table three.

It is described aspherical to meet following expression formula：

In formula, Z be it is aspherical along optical axis direction when being highly the position of Y, away from aspheric vertex of surface apart from rise Sag, R Represent the paraxial curvature radius of minute surface, K is circular cone coefficient conic, and A, B, C, D are high order aspheric surface coefficient.

Two aspherical surface data of table

The diffraction surfaces meet following expression formula：

Three diffraction face data of table

It should be noted that the design parameter in above table was merely an illustrative, the parameters of each lens be not limited to by Value shown by above-mentioned each numerical example, may be used other values, can reach similar technique effect.

In conclusion the above is only the preferred embodiments of the present utility model only, it is not intended to limit the utility model Protection domain.Within the spirit and principle of the utility model, any modification, equivalent replacement, improvement and so on should all wrap Containing being within the protection scope of the utility model.

Claims (6)

1. a kind of infrared tight shot, which is characterized in that include the first lens and second successively thoroughly from object space to image space along optical axis Mirror, the first lens are meniscus shaped lens with positive light coke of the convex surface towards object side, and the second lens are tool of the concave surface towards image side There is the meniscus shaped lens of negative power；The material of first lens uses chalcogenide glass, and second lens material uses germanium.

2. a kind of infrared tight shot as described in claim 1, which is characterized in that further include and be placed on the first lens front surface Camera lens diaphragm.

3. a kind of infrared tight shot as described in claim 1, which is characterized in that the focal length f=90mm of the camera lens, aperture Number FNO=1；The focal length f1=112.8495mm of first lens, the focal length f2=160.3181mm of the second lens.

A kind of 4. infrared tight shot as described in claim 1, which is characterized in that the systematic parameter of camera lens such as following table：

5. a kind of infrared tight shot as claimed in claim 4, which is characterized in that in first lens and the second lens It is aspherical to meet following expression formula：

In formula, Z be it is aspherical along optical axis direction when being highly the position of Y, away from aspheric vertex of surface apart from rise；R represents mirror The paraxial curvature radius in face, K are circular cone coefficient conic, and A, B, C, D are asphericity coefficient；Then two aspherical equation coefficients It is as follows：

6. a kind of infrared tight shot as claimed in claim 5, which is characterized in that the curved surface 2 of the first lens is diffraction surfaces, Parameter such as following table：