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101.
102.
非球面光学系统设计、加工及检验的综合考虑 总被引:3,自引:0,他引:3
某研究所要求研制一台夜间红外观测系统 ,观测波段为 3~ 5 μm ,焦距 f =90 0mm ,相对口径为 1∶4,视场角 2ω =0 8°。红外焦平面是已有的 ,其冷屏直径为Φ5mm ,冷屏至焦面的距离为 2 0mm。由于从设计开始 ,要求完成的时限很短 ,因此必须将缩短加工周期的问题作为重要因素来考虑。工作在 3~ 5 μm波段 ,首选的必然是非球面反射系统 ,而非球面的加工与检验的难易直接和其参数有关。因此在评价设计结果时 ,不能仅从像质好坏来看 ,还要看其需要的加工周期长短。接受到任务之后 ,首先找到了可行的方案 ,然后设计了几个具体的系统 ,在比较了两个最可行的设计结果之后 ,选择了其中之一。 相似文献
103.
This paper describes an optical system for high temperature creep strain measurement using quartz optical fiber, super long working distance microscope and digital image processing techniques. In this system one end of the quartz optical fibers is arrayed in a small area on the specimen surface and the other end is illuminated by a laser beam. The fiber ends on the specimen surface form the spot array. The small optical spots on the specimen are tracked by a CCD camera and the images are processed by digital image processing software. The diameter of each quartz fiber is 100 μm and the fibers can be arrayed in a small area. The local strains are determined by measuring the variety of relative distance between two spots. Experimental results of local creep strain on the welding joints of 15CrMo and HK40 at 850°C are obtained. 相似文献
104.
介绍一种4.3m红外望远镜。它与2.16m望远镜用真空管道联机用于CCD照相和光干涉测量,可使集光能力达4.8m口径,分辨率达101m口径。 相似文献
105.
Youbao Wan Junhao Chu Shaoling Guo Lingxian Bo Tianyan Yu Bingkun Yu 《International Journal of Infrared and Millimeter Waves》2001,22(1):197-205
The potassium lithium niobate crystals have been grown up. The shapes of solid-melt interfaces which maintaining the steady growth of the potassium lithium niobate crystals have been described. The optical transmission spectrum of the crystal has been surveyed. The perfected crystals showed good Second Harmonic Generation properties. 相似文献
106.
Anisotropic (elliptically polarized) photoinduced second harmonic generation (PISHG) in SiNxOy/Si1 1 1 films was proposed for contact-less monitoring of specimens with different nitrogen to oxygen (N/O) ratios. As a source for the photoinducing light, we used a nitrogen Q-switched pulse laser at wavelengths of 315, 337 and 354 nm as well as doubled frequency YAG–Nd laser wavelength (λ=530 nm). The YAG : Nd pulse laser (λ=1.06 μm; W=30 MW; τ=10–50 ps) was used to measure the PISHG. All measurements were done in a reflected light regime. We found that the output PISHG signal was sensitive to the N/O ratio and the film thickness. Measurements of the PISHG versus pumping wavelengths, powers, incident angles as well as independent measurements of the DC-electric field induced second harmonic generation indicate the major role played in this process by axially symmetric photoexcited electron–phonon states. The SiNxOy films were synthesized using a technique of chemical evaporation at low pressures. Films with thickness varying between 10 and 30 nm and with an N/O ratio between 0 and 1 were obtained. Electrostatic potential distribution at the Si1 1 1–SiNxOy interfaces was calculated. Comparison of the experimentally obtained and quantum chemically calculated PISHG data are presented. High sensitivity of anisotropic PISHG to the N/O ratio and film thickness is revealed. The role of the electron–phonon interactions in the dependencies observed is discussed. We have shown that the PISHG method has higher sensitivity than the traditional extended X-ray absorption fine structure spectroscopic and linear optical method for films with the N/O ratio higher than 0.50. 相似文献
107.
Direct Monitoring of Thickness and Refractive Index of Optical Thin Film Deposited on Fiber End-face
We propose a system for depositing thin films on waveguides which enables low-temperature deposition and precise control of the refractive index and film thickness. It is composed of a conventional ion-beam sputtering (IBS) system and a new system for directly monitoring film characteristics during deposition. We controlled refractive indices over a wide range from 1.52 to 1.97 by moving the sputtering targets (SiO2 and Si3N4) in the IBS system. The refractive index or film thickness was in-situ monitored by observing the optical power reflected from the end-face of a monitoring fiber set in the deposition chamber. Antireflection coating films were successfully deposited on a fiber end-face and a laser diode chip facet with low reflectivity from 0.05 to 0.07%. This deposition system is attractive for constructing highly functional optical devices for future photonic networks. 相似文献
108.
109.
M. Grifoni E. Paladino U. Weiss 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,10(4):719-729
The dynamics of the reduced density matrix of the driven dissipative two-state system is studied for a general diagonal/off-diagonal
initial state. We derive exact formal series expressions for the populations and coherences and show that they can be cast
into the form of coupled nonconvolutive exact master equations and integral relations. We show that neither the asymptotic
distributions, nor the transition temperature between coherent and incoherent motion, nor the dephasing rate and relaxation
rate towards the equilibrium state depend on the particular initial state chosen. However, in the underdamped regime, effects
of the particular initial preparation, e.g. in an off-diagonal state of the density matrix, strongly affect the transient dynamics. We find that an appropriately tuned external ac-field
can slow down decoherence and thus allow preparation effects to persist for longer times than in the absence of driving.
Received 23 October 1998 and Received in final form 26 February 1999 相似文献
110.
We developed a system to measure disk noise as a function of both radial and angular position. In order to obtain an accurate disk noise measurement, crosstalk and intersymbol interference were avoided by recording regularly repeating pit patterns and the influence of electronic and laser noise was removed by averaging techniques. We found the system’s mapping ability and its high sensitivity to be very useful in investigating disk noise phenomena in the mastering process. We used the system to assess the accuracy and reproducibility of the photopolymerization replication and Al vapor deposition processes. Also, we investigated the choice of photoresist and found that photoresists with the combination of the narrowest molecular weight distribution and the highest photo-active compound content resulted in the lowest disk noise levels. Our system can, in principle, be adapted to evaluate magneto-optical and phase change disks. 相似文献