With the increasing demand of the high-resolution remote sensing images by military and civilians, Countries around the world are optimistic about the prospect of higher resolution remote sensing images. Moreover, design a visible/infrared integrative optic system has important value in earth observation. Because visible system can’t identify camouflage and recon at night, so we should associate visible camera with infrared camera. An earth observation optical system with dual spectral and high resolution is designed. The paper mainly researches on the integrative design of visible and infrared optic system, which makes the system lighter and smaller, and achieves one satellite with two uses. The working waveband of the system covers visible, middle infrared (3-5um). Dual waveband clear imaging is achieved with dispersive RC system. The focal length of visible system is 3056mm, F/# is 10.91. And the focal length of middle infrared system is 1120mm, F/# is 4. In order to suppress the middle infrared thermal radiation and stray light, the second imaging system is achieved and the narcissus phenomenon is analyzed. The system characteristic is that the structure is simple. And the especial requirements of the Modulation Transfer Function (MTF), spot, energy concentration, and distortion etc. are all satisfied.
In order to achieve the multi-band and multi-field of view imaging for target and to meet the needs of target detection for large amount of information, a common-aperture visible light/long-wave infrared(VIS/LWIR) imaging optical system with muti-field of view was designed. In this paper, the aperture is 400mm, the working wavelength is 500～700nm and 7.5～10μm, the temperature range is -15℃～+50℃, this system can realize 1500mm and 3000mm dual focal length(VIS), the full field of view of short focal length is 1.16° and long focal length is 0.58° respectively, and realize 1400mm focal length(LWIR) and the full field of view of 0.54°, satisfy 100% cold shield efficiency. A re-imaging system was adopted in this designed optical system consists of main optics, VIS projection components and LMIR projection components. First of all, the structural selection and the initial parameter calculation were introduced in detail. Secondly, to improve image quality and environment adaptability, the analysis of temperature change was described particularly and the structural design requirements were put forward according to the analysis of the data. The design results proved that at the spatial frequency of 50 lp/mm, the axis MTF of the VIS system is greater than 0.48, the MTF of the LWIR system approaches the diffraction limit, the system can offer a high resolution and excellent images in whole range of the focal length, and it has the advantages of good adaptability, compact structure and small size, the results satisfy the design requirement.
Wavefront coding is a technology which combination of the optical design and digital image processing. By inserting a phase mask closed to the pupil plane of the optical system，the wavefront of the system is re-modulated. And the depth of focus is extended consequently. In reality the idea is same as the athermalization theory of infrared optical system. In this paper, an uncooled infrared dual field optical system with effective focal as 38mm/19mm, F number as 1.2 of both focal length, operating wavelength varying from 8μm to 12μm was designed. A cubic phase mask was used at the pupil plane to re-modulate the wavefront. Then the performance of the infrared system was simulated with CODEV as the environment temperature varying from -40℃ to 60℃. MTF curve of the optical system with phase mask are compared with the outcome before using phase mask. The result show that wavefront coding technology can make the system not sensitive to thermal defocus, and then realize the athermal design of the infrared optical system.
Binary optics can be used to increase optical performances, decrease size and weight, and decrease systems costs in numerous applications. By means of hybrid diffractive-refractive, a switch-zoom optical system of catadioptric large aperture ground-based photoelectric detection is designed. The characteristic of the system is that it is a compact optical system without moving parts which can get two focal lengths. And the quality of image approaches the diffraction limited. Ritchey-Chrétien (R-C) mirror and a field lens are common for long-focus system and short-focus system. Two refract groups transmitting optical system are used for zooming. In order to satisfy the demand of energy regulation, it is designed afocal beam between field lens and later refract optical system. Filter and variable density plate are placed in it to guarantee the imaging quality. The focal length is 3750mm and F number is 7.5 for the long-focus system, and the focal length is 1850mm and F number is 3.75 for the short-focus system. Former part and later lens of the system are both perfect imaging. They can be fabricated and detected independently. So the design demand can be satisfied better and the imaging quality can be improved.
According to the large aperture, long focal length zoom system design, the structure of the optical system based on the modular concept is proposed. The structure is constituted of an afocal compression telescope and a zoom system. The parts of each other are individually designed. The aberrations of them are independently. Because of this, the alignment of the system and the difficulty of test are greatly reduced. It is easily replaced by changing the zoom system parts, which can achieve other different focal length and ratio. Using afocal compression telescope greatly reduces the radial aperture of the zoom group, simplifies the system structure and reduces the cost. Meanwhile, the variable stop is placed in the vicinity of the primary mirror. It is instead of the zoom system used in floating variable stop. In addition, the problem about large aperture zoom system pupil matching is solved perfectly. In this article, four methods of pupil matching are given and the advantages and disadvantages of them are analyzed. Using this optical structure, a zoom system is designed, which is working in the visible wavelength band with variable focal length between 900mm and 4500mm, 500mm maximum aperture. The axial dimension of the system is less than 650mm. The maximum diameter of zoom system parts is less than 40 mm. Moreover, the distances of the zoom group and compensating group are all less than 60 mm. Besides, the motion curves of each other are given in the article. The Modulation Transfer Function (MTF) values of the system are greater than 0.3 at 48lp/mm across different focal length and field pointing on the axis. The design results show that the imaging quality is excellent, the structure is compact, and the alignment and test are easy. The imaging requirements of zoom system are all satisfied.
A kind of space target acquisition optical system with small F-number was designed. The system had a working wavelength range of 0.45~0.85μm, an effective focal length of 240 mm, a field of view is 2ω=3°, and an F-Number of F/2. The system characteristic is that the structure is simple. And the especial requirements of the spot, energy concentration, distortion and lateral color etc. are all satisfied. The primary and secondary mirrors are all spheres, so the difficulty and cost of machining are reduced. Moreover, the temperature characteristic of the system is analyzed. The temperature request is satisfied.
In order to effectively improve the target detection and recognition ability of IR imagers, based on a 320×256 cooled staring focal plane array(FPA) detector, pixel size 30μm×30μm, a mid-wavelength infrared dual field of view zoom system was designed. In this paper, the working wavelength is 3μm～5μm, the temperature range is -40°C~+50°C, this system can realize 200mm and 400mm dual focal length, the F-number is 2, the full field of view of short focal length is 3.44° and long focal length is 1.72° respectively, satisfy 100% cold shield efficiency. A re-imaging refractive system was adopted in this designed optical system consists of main optics and projection components. First of all, the structural selection and the initial parameter calculation were introduced in detail. Secondly, on the basis of variety of the distance and temperature, a focusing lens was presented in this system to adjust to produce a clear image. Last but not the least, to improve image quality and environment adaptability, the analysis of temperature change and narcissus effect were described particularly. The design results prove that at the spatial frequency of 17 lp/mm, the MTF of the optical system is greater than 0.5(the axis MTF of the optical is greater than 0.6), the system can offer a high resolution and excellent images in whole range of the focal length, and it has the advantages of good adaptability, compact structure, high optical transmission and small size.
As a high-resolution imaging instrument, angular resolution is the most important index of Lyman-α ultraviolet telescope. In this paper a new allocation and budget method is introduced. An resolution error allocation of surface roughness, figure error and alignment error was developed early in the program. And the allocation was used to guide the design. Though testing the surface roughness and figure error in visible light, the variation of diffraction encircled energy can be obtained by non-sequence model and Zernike coefficients brought into optical design software. The numerical results show that the effective RMS surface roughness of primary and secondary mirrors are 0.49nm and 0.40nm in the spatial frequency from 1/D (D is the diameter of the mirror) to 1/λ (λ is an incident wavelength). And the effects of the surface roughness are both less than 0.1″. The figure error of the primary and secondary mirrors are 0.009λ and 0.007λ (Λλ=632.8nm). The resolution errors which were brought by the figure error are 0.33″ and 0.16″. Then the effect of alignment error on angular resolution was gotten by testing visual resolution. Finally the angular resolution in ultraviolet band can be calculated. The focal length of Lyman-α ultraviolet telescope is 2000mm and the pixel size of detector is 14μm. So the pixel resolution is 1.4″. Experimental results show that the angular resolution of Lyman-α ultraviolet telescope is 0.59″, which is approached to the estimate and meet the requirement.
Near-space platform has a high signal contrast and a long detection time. In order to realize effective detection of low altitude penetration target, a middle wave infrared (MWIR) optical system used in near space detection with high optical performance is given. First, the optical system scheme was described. Then on the basis of instrument and system consideration, the optical design parameters were distributed reasonably. The system had an effective focal length of 600 mm, an F-Number of F/4, a field of view of 2ω=1.16°, spatial resolution of 18 lp/mm and a working wavelength range of 3～5μm. The system structure is simple. And the requirements of the spot, energy concentration, distortion are all satisfied. Because the change of environment temperature will deeply influence image quality of MWIR optical system, the temperature characteristic of the system is analyzed. Moreover, first -order ghost and narcissus effect of the system are all analyzed in CODEV software. The analysis results show that temperature, first-order ghost and narcissus effect requests are all satisfied.
A design of a laser communications optical system with high transmitting and receiving performance is given. The traditional on-axis Cassegrain optical antenna has the default that the transmitting and receiving power decreased greatly because of the obscuration of the secondary mirror. Considering that the eccentric-pupil Cassegrain optical antenna is designed. The optical antenna system in transceiver has been designed by means of CODEV software. It improves the efficiency of transmitting and receiving power effectively. Its properties have been analyzed, such as gain, image quality, and transmission efficiency. Meanwhile, the materials of optical elements have been analyzed. The power decline curve has been obtained by means of the detailed analysis of antenna system in partial axis situation. The system includes transmitter channel, receiving channel and experiment channel. It can realize the functions of transmitter-receiver isolation and multi-light ways using dichroic mirrors and beam splitting prisms. The system volume and weight are reduced greatly. The complexity of conventional laser communication system is reduced enormously at the same time. It has important reference significance and application value.
Based on the princip le of the intersection measurement, the mathematical model of measuring the position and dimension of the moving ships was established, and the formu la of the metrical accuracy was deduced. The Matlab software was utilized to simu late and emulate the metrical accuracy, and analysed the primary errors of the system measurement accuracy; the measurement model is validated, co mbined with the examination. The result indicated that the method is feasible which utilized the measurement principle to measure the position and dimension of the moving ships, and establish the basical for further project application.