Athermal Design of Infrared Telephoto Used in Joint Transform Correlator

On the basis of optical correlation detection, joint transform correlator(JTC) is widely used in military, aviation and intelligentization and so on. It has the advantages of great flexibility and high precision of recognition. The optical system is applied to receive the infrared radiation of the target. Athermalization is the key to stabilizing the optical performance with respect to off-design temperature. Therefore, the image quality of optical system in different temperatures plays an important role in JTC. In order to improve the environmental adaptability of JTC, the infrared telephoto system with high image quality and high performance-price ratio is designed for wavelength 8μm～12μm to detect target in a large range of temperature. This telephoto lens is composed of four refractive lenses. Three materials, zinc selenide, germanium and zinc sulfide are used to compensate for the temperature. The focal length is 200 mm, the relative aperture is 1:3, and the field of view is 6.4°. This system has the characteristics of small volume and compact structure. The optical system image quality is evaluated with ZEMAX optical design software. The results have shown that MTFs in the range of -40°C to +60°C are all closed to the diffraction limited curve. The spot diagram RMS radius of each field is closed to the Airy disk radius. The system meets the requirements of technical specification and improves the ability of JTC in target tracking and recognition.

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Infrared Telephoto Design Used in Joint Transform Correlator

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.552.21 ◽

2013 ◽

Vol 552 ◽

pp. 21-26

Author(s):

Chun Yun Xu ◽

Jia Ning Dong ◽

Su Zhang ◽

Wen Sheng Wang

Keyword(s):

Image Quality ◽

Target Detection ◽

Optical System ◽

Spherical Surface ◽

Focal Length ◽

Optical Design ◽

System Structure ◽

Initial Structure ◽

Price Ratio ◽

Joint Transform Correlator

In order to meet the requirement of tank sight and improve the ability of Joint Transform Correlator(JTC) in target detection and recognition, the infrared telephoto system with high image quality and high performance-price ratio is designed for wavelength 8μm～12μm. Initial structure is composed of four refractive lenses. The focal length is 200 mm, the relative aperture is 1:2.6 and image field of view is 1 inch (CCD). Considering the fabrication process, production cost and other factors, the system structure is further improved. First the telephoto which is composed of four lenses is designed with normal spherical surface. Then on the basis of the original spherical structure, an aspheric surface is introduced. The optical system can be reduced into three lenses. The image quality of the whole system becomes much better. The optical system image quality is evaluated with ZEMAX optical design software. The result shows that MTF of each field is close to the diffraction-limited curve at the cut-off frequency 17lp/mm. The spot diagram RMS radiuses are smaller than the radius of Airy disk 25.35μm. The wave front aberrations for all the fields are less than 0.25λ. The telephoto can meet the requirement of target detection. Combining JTC with this infrared telephoto lens, the infrared target at longer distance can be detected and recognized.

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The Design of a Hybrid Diffractive-Refractive Wide-Angle Eyepiece with a Large Exit Pupil Distance

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.710.469 ◽

2013 ◽

Vol 710 ◽

pp. 469-473

Author(s):

Feng Wang ◽

Jian Zhong Cao ◽

En Shi Qu ◽

Deng Qun Yu ◽

A Qi Yan ◽

...

Keyword(s):

Image Quality ◽

Optical System ◽

Focal Length ◽

Optical Design ◽

Random Phase ◽

Optical Element ◽

Wide Angle ◽

Optical Elements ◽

Exit Pupil ◽

Design Software

The diffractive optical elements, with the negative dispersive characteristic and the random phase distributing to realize random phase modulation for wave-front, are not only helpful to simplify the optical system, but also improve the image quality, while putting it into the optical system. It can decrease the element numbers of the system and obtain a compact configuration that introducing diffractive optical element into the design of eyepiece. A hybrid diffractive-refractive wide-angle eyepiece, with a big exit pupil distance, is designed by using the Code V Optical Design Software. The features of the wide-angle eyepiece are 30mm effective focal length, 60°whole field-of-view (FOV), 30mm exit pupil distance and 6mm exit pupil diameter, and which consists of four lens and two diffractive elements. From the result of design, the MTF in the center field of the wide-angle eyepiece is over 0.55at 60lp/mm, at the same time, the MTFs in all fields are over 0.3 at 50lp/mm, which show that this wide-angle eyepiece has a great image quality.

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Optical Design of a Shortwave Infrared Dual Camera CASSI Based on Improved Offner-Wynne Imaging Spectrometer

Journal of Physics Conference Series ◽

10.1088/1742-6596/2112/1/012021 ◽

2021 ◽

Vol 2112 (1) ◽

pp. 012021

Author(s):

Chong Song ◽

Lipeng Huo ◽

Yong Huang ◽

Yangdong Yan ◽

Gang Wang ◽

...

Keyword(s):

Optical System ◽

Imaging System ◽

Optical Measurement ◽

Focal Length ◽

Optical Design ◽

Optical Transmittance ◽

Coded Aperture ◽

Visual Axis ◽

Imaging Spectrometer ◽

Shortwave Infrared

Abstract Based on the optical system characteristics of coded aperture snapshot spectral imager (CASSI), an optimized optical system of shortwave infrared dual camera CASSI was designed based on improved Offner-Wynne imaging spectrometer. The operating wavelength of the optical system ranges from 900nm to 1700nm, and the focal length is 1200mm. It consists of two parts: the two dimensional imaging system and the multispectral CASSI imaging system. The key technical parameters of the two parts are the same and there is no visual axis difference. Therefore, the optimized optical system can effectively improve real-time performance, optical transmittance and compactness of the dual camera shortwave infrared CASSI, which is conducive to the application in optical measurement scenes in the shooting range.

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Design of Athermalized Infrared Telephoto Lens

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.552.8 ◽

2013 ◽

Vol 552 ◽

pp. 8-13

Author(s):

Yu Zhang ◽

Ji Yang Shang ◽

Yue Xu ◽

Wen Sheng Wang

Keyword(s):

Image Quality ◽

Optical System ◽

Power Distribution ◽

Focal Length ◽

Diffraction Limit ◽

Field Of View ◽

Optical Systems ◽

Modulation Transfer ◽

Full Field ◽

Telephoto Lens

IR optical system is much more appropriate to be applied in cluttered and formidable conditions. The change of temperature could degrade image quality of the infrared optical system. So the athermalization becomes the difficult part and key factor in the designing of MWIR optical systems for working under temperature range of -40°C~60°C. In this paper, the infrared telephoto lens is designed; it meets the designing requirements and has good image quality. The effective focal length is 240mm and the F-number is 2.The full field of view is 3.2°. In order to balance the chromatic aberration, an aspherical surface is used in the athermalized infrared optical system. Through carefully selected optical material and reasonable optical power distribution, passive optical athermalization can be realized. The curve of MTF is close to diffraction limit. Within the working temperature, the value of MTF at 30cy/mm is always large than 0.6. The results show that the modulation transfer function (MTF) of optical system in all field of view approaches the diffraction limit at different temperature, and 80% energy concentrates in 1 pixel.

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Study on the Optical Properties of the Point-Focus Fresnel System

Sustainability ◽

10.3390/su131810367 ◽

2021 ◽

Vol 13 (18) ◽

pp. 10367

Author(s):

Fei Shen ◽

Weidong Huang

Keyword(s):

Density Distribution ◽

Flux Density ◽

Optical System ◽

Focal Length ◽

Optical Design ◽

Solar Flux ◽

Characteristic Analysis ◽

Design And Optimization ◽

Receiver Plane ◽

Flux Density Distribution

The characteristic analysis of the flux formed by the heliostat in the optical system is the basis in design and optimization of the whole system. In this paper, our research subject is a pilot installation of the point-focus Fresnel system, which is a new optical design between the tower system and the dish system. For the optical system, it is very important to accurately calculate the solar flux density distribution on the receiver plane. Aiming at the case that the focal length of the heliostat is not equal to the distance from the center of the heliostat to the center of the receiver plane, based on the projection, an approximate calculation method is proposed. Using the method to calculate the solar flux density distribution of the point-focus Fresnel system, and the results are compared with that calculated by SolTrace code, it is found that the solar flux density distribution of both is relatively consistent in shape and numerical value, which verifies the accuracy of the method and it can be used for design and optimization of the point-focus Fresnel system.

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Design of Reflective/Diffractive Objective Optical System for Handed Low-Light Night Vision Google

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.597.439 ◽

2014 ◽

Vol 597 ◽

pp. 439-443

Author(s):

Ning Li ◽

Rui Lan Zhang

Keyword(s):

Image Quality ◽

Optical System ◽

Focal Length ◽

Optical Element ◽

Night Vision ◽

Field Of View ◽

Improved Method ◽

Low Light ◽

High Image Quality ◽

Aberration Theory

For the design direction of low-light night vision goggle become more and more miniaturization and high image quality [1], this artical design a reflective/diffractive objective optical system with optical software ZEMAX. It combines diffractive elements with reflective elements to design a reflective/diffractive objective with a 14.5° field of view and a 1.0/1.2 relative aperture and a 95mm focal length , and it introduces an improved method based on primary aberration theory in reflective/diffractive hybrid optical system. Etching diffractive optical element on the mirror can be usful for correcting aberration and improving the image quality.

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Use of the Magnetostatic Analogue In Electromagnetic Lens Engineering

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100068795 ◽

1970 ◽

Vol 28 ◽

pp. 360-361

Author(s):

John W. Coleman

Keyword(s):

Boundary Conditions ◽

High Performance ◽

Force Fields ◽

Optical Design ◽

Direct Conversion ◽

Design Engineering ◽

Design Data ◽

Scalar Potentials ◽

Geometric Elements ◽

At Will

In the design engineering of high performance electromagnetic lenses, the direct conversion of electron optical design data into drawings for reliable hardware is oftentimes difficult, especially in terms of how to mount parts to each other, how to tolerance dimensions, and how to specify finishes. An answer to this is in the use of magnetostatic analytics, corresponding to boundary conditions for the optical design. With such models, the magnetostatic force on a test pole along the axis may be examined, and in this way one may obtain priority listings for holding dimensions, relieving stresses, etc..The development of magnetostatic models most easily proceeds from the derivation of scalar potentials of separate geometric elements. These potentials can then be conbined at will because of the superposition characteristic of conservative force fields.

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High-Performance Ultra-Thin Spectrometer Optical Design Based on Coddington’s Equations

Sensors ◽

10.3390/s21020323 ◽

2021 ◽

Vol 21 (2) ◽

pp. 323

Author(s):

Zhiwei Feng ◽

Guo Xia ◽

Rongsheng Lu ◽

Xiaobo Cai ◽

Hao Cui ◽

...

Keyword(s):

High Resolution ◽

Spectral Resolution ◽

High Performance ◽

Optical Design ◽

Pixel Size ◽

Simulation Design ◽

Central Wavelength ◽

Spot Radius ◽

Unique Method ◽

Almost All

A unique method to design a high-throughput and high-resolution ultrathin Czerny–Turner (UTCT) spectrometer is proposed. This paper reveals an infrequent design process of spectrometers based on Coddington’s equations, which will lead us to develop a high-performance spectrometer from scratch. The spectrometer is composed of cylindrical elements except a planar grating. In the simulation design, spot radius is sub-pixel size, which means that almost all of the energy is collected by the detector. The spectral resolution is 0.4 nm at central wavelength and 0.75 nm at edge wavelength when the width of slit is chosen to be 25 μm and the groove density is 900 lines/mm.

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