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Issue 4 ， 2004
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Radiation exchange and temperature response function of the absolute radiometer with wide field of view mounted on the satellite
Abstract：The change of the sun incidence power with time during the sun flies over the view field of the absolute radiometer mounted on spacecraft, and the temperature response function under the change were given. While the view field is 10?, the solar irradiance is invariable, and the temperature response of the cavity of absolute radiometer reaches balance. And the solar irradiance value can be observed by closing the shutter at the balance point and electric calibrating. The solar irradiance was measured in this way by the solar constant monitor mounted on Shenzhou-3 spacecraft, which is consisted of three Solar Irradiance Absolute Radiometers(SIARs)with 15? view field. The result is: the data correspond well with that measured on other satellite in the same term. And the result also indicates that the method is feasible.Keywords：absolute radiometer;solar irradiance;temperature response of cavity;Shenzhou-3 spacecraft- 54
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Published：2020-08-12 -
Development of return signal simulator for chinese satellite altimeter prelaunch performance assessment
Abstract：An ocean Return Signal Simulator(RSS)and the principles of the RSS with its means of testing and calibrating for a satellite altimeter were given. By using the chirp regeneration technique, full de-ramp technique, ocean return spectrum digitally synthesizing technique and high speed DSP technique, a full signal RSS was successfully developed for a Chinese satellite altimeter test and calibration, full range of time delay and full sea state simulation were achieved. Time delay precision is(0.2)ns, significant wave height(SWH)simulation precision 0.5 m and backscattered coefficient precision 1 dB. By using the RSS, the full system testing and calibrating experiment to the Chinese satellite altimeter were implemented. The results show the dynamic performance of the RSS and the altimeter are validated.Keywords：Radar;Altimeter;RSS;Microwave remote sensing- 57
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Published：2020-08-12 -
Design of microscopic hyperspectral imaging system
Abstract：A novel microscopic hyperspectral imaging system was presented,and its operating principle,structure,hardware and software design were discussed.The system was designed based on the principle of pushbroom hyperspectral imager,direct vision dispersing prism-grating-prism component was used as spectrum-dividing component,and PCI bus was used as computer interface of high-speed imaging spectral data acquiring subsystem. The whole system was composed of a microscope,a spectrometer,an area CCD camera,an automatic stage and data acquisition and control subsystem. Comparing to other spectrum-dividing technologies,the prism-grating-prism has advantages such as direct vision,high spectral resolution,compact structure and low cost. The system is capable of performing spectral imaging inplenty of spectral bands and micro-spectroscopy in any image pixel,in the spectral range 400 through 800 nm.The spectral resolution is less than 5 nm,and the spatial resolution is about one imicrometre. The system can be applied to a lot of fields,such as clinic medicine,biology,material science,microelectronics. The analysis results show that it can be successfully to apply hyperspectral imaging technique to microscopic fields by combining spectral imaging with microscopic imaging technique.- 80
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Published：2020-08-12 -
Comparisons between radiometric scales on UV-VUV radiant standard light sources
Abstract：A high precision spectroradiometric system was established, and the comparisons between three spectral radiant standard sources-deuterium lamps in the range of 164～300nm were given. The three transfer standard deuterium lamps are calibrated based on: BESSYⅡ Synchrotron Radiation of German National Institute of Science and Technology for Metrology(PTB), Daresburg Synchrotron Radiation of National Physical Laboratory(NPL)in UK, and Synchrotron radiation of HeFei National Laboratory of Synchrotron Radiation in China, respectively as primary standard sources. A series of methods, such as alternative sequence of comparison, computer controlled time consuming, and polishing the window of the deuterium lamp, was adopted to eliminate the systemic error efficiently. And the experimental result data were analyzed. It shows that the relative spectral radiant distributions of the lamps are consistent within the uncertainties designated respectively. It also shows that the consistency between UV-VUV radiometric standards established by different countries is confirmed. The error arising from the comparison is estimated at 1.7%. Meanwhile the spectral radiation characteristics of deuterium lamps are demonstrated.Keywords：UV-VUV spectral radiometric standard;deuterium lamp;synchrotron radiation;spectral radiance- 41
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Published：2020-08-12 -
Roughness effects on the reflectance in the design of a soft X-ray multi-layer mirror
Abstract：In the design of a multi-layer mirror at λ=1.03 nm in soft X-ray regin, a modified method is presented, in which the effects of root-mean-square(rms)roughness of the substrate and interfaces between these films on the reflectance are considered and discussed. Then, the mathematical model for rough interfaces is given based on the scattering theory presented by D. G. Stearns. The design result shows that the substrate roughness(rms)should be smaller than 0.6 nm in order to fabricate a multi-layer mirror whose reflectance is greater than 10%. A few super-polished fused quartz substrates with 0.5 nm(rms)roughness are chosen in coating experiments. The measured reflectance is about 10% at λ=1.03 nm,which is consistent with the result acquired by the modified design method. The multi-layer mirror has been applied in a X-ray spectrograph for diagnosis of inertial confinement fusion(ICF).Keywords：roughness;Reflectance;multi-layer mirror- 36
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Published：2020-08-12 -
Electro-optic modulators with self-assembled superlattice waveguides
Abstract：This paper reports a new waveguide electro-optic(EO)modulator with self-assembled superlattice(SAS)electro-optic films. This work focuses on the measurement for the EO coefficient of SAS films and the optimization for the devices structure. In order to have a precise and effective design, we test the angle-dependence of the second harmonic generation of incident laser beam to determine the effective EO coefficient. We study he absorptive loss of electrodes of devices with the optical propagation theory of multi-layered films and optimize the devices structure to obtain the lowest drive voltage. The paper gives the structure of experimental samples and the scanned electronic microscopy(SEM)pictures of our fabricated devices. Finally, 1.0 dB/cm optical propagation loss of the EO modulators is achieved, which agrees with the experimental results.Keywords：electrooptic modulator;self-assembled superlattice;waveguide;optical propagation loss;propagation matrix- 56
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Published：2020-08-12 -
Influences of stress changes on transmission characteristics of multilayer thin-film narrow bandpass filters
Abstract：On the base of film stress formula and micro-bending principle of elasticity, the relation between multilayer film strain and film thickness was analyzed. A mathematic model was established, and a new theory that thickness of multilayer film changes disuniform was brought forward. By using this model, the spectrum of 100 GHz filter with 138 layers and 4 cavities was simulated when the stress decreased by 200 MPa. Compared with the designed value, it was found that central wavelength increased by 0.562 nm, bandwidth decreased by 0.124 nm at 0.5 dB and 0.01 nm at 25 dB, rectangular spectrum deformed, and insert loss increased apparently. These demonstrated that uneven film thickness caused by stress change was the main reason that caused spectrum of narrow-band interference filter to degrade. Experimental results were that central wavelength of 100 GHz narrow-band filter increased by 0.325 nm after heat treatment, bandwidth decreased by 0.01 nm at 0.5 dB and 0.014 nm at 20 dB, insert loss increased, spectrum of pass band deformed badly, and ripple enlarged. The experimental result conforms to the theory analysis.- 58
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Published：2020-08-12 -
Support technique of a deployable unit mirror
Abstract：Based on the deployable structure of a mirror and the operation principle,the finite element method was used to analyze the unit naked mirror and some different mirror support schemes. The principal aim of the naked mirror analysis is to get the numbers of the support points and the ways of the support. There are three schemes including 12-6-1,12-8-1 and 16-8-1 models. Deformation of the deadweight is calculated under the three conditions. The way of 16-8-1 is more suitable than the designs of other two. The optimum design of the support structure is based on the surface figure error and the structure rigidity. Support subassembly is amended to meet with the mirror surface RMS in the range of 30 μm.Deformation of the mirror with support structure has been calculated. The result is 16.52 nm,lower than a quarter of the wavelength,which indicates the feasibility of the support scheme applied to unit mirror.Keywords：deployable mirror;unit mirror;surface figure accuracy;support structure- 42
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Published：2020-08-12 -
Manufacturing of a big aperture lightweight mirror
Abstract：The mechanical light-weighting technique to manufacture a big aperture lightweight mirror was given. Based on CAD(computer aided design),the technique searches the zone of the lightweight process and marking it, then chooses the radii of the diamond tool, and describing the tool path in the lightweight process zone. If the area of the tool path covers the lightweight process zone, it will write down the tool path datum for the editing CNC program. The CNC program is made up of TPH documents and program language that follow definite regulations of frame, syntax, and format. The CNC program can control system functions such as principal axis rotating speed, tool moving speed, cooling form of mirror, workbench travel path.Meantime the chemical etching is used to eliminate the stress and minute cracks induced in the manufacturing process, which can affect the quality of the mirror and reduce its working life,and even more lead to the serious sequent of mirror breaking. Using the technique,a big aperture lightweight mirror was achieved. The results show that the big aperture lightweight mirror has met the requested specifications,with the lightweight rate of more than 65%,the precision of the aspheric surface is 0.029 λ(rms,λ=633 nm).The mirror is steady in both its testing and working status.Keywords：lightweight mirror;mechanical method;lightweighting;CNC- 63
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Published：2020-08-12 -
Blend zone model for excimer laser refractive surgery
Abstract：A blend zone model for excimer laser refractive surgery is presented. Firstly, a blend function is designed. Then, an expand ablation depth in the blend zone is constructed using the ablation depth on the edge of the optical zone. Finally, the model is developed by multiplying the blend function and the expand ablation depth. The simulation of the model on computer and results of clinical practice have been studied. Sixteen eyes with myopic astigmatism underwent LASIK using the blend zone model. One day postoperatively, mean uncorrected visual acuity was 1.06?0.24 compared to 0.09?0.04 preoperatively. One month after surgery, mean uncorrected visual acuity was 1.42?0.36. All eyes reached uncorrected visual acuity of 1.0 or better. The computer simulation and especially LASIK results show that the model gradually smoothes out the connection of the optical zone and untreated zone. The model has two parameters that make it very useful in adjusting the diameter of the optical zone and changing the width of the blend zone. The ablation depth in the optical zone does not increase when the width of the blend zone is changed. The model not only can be applied to the correction of refractive errors such as myopia and astigmatism, but also can be used in wavefront guided laser refractive surgery. Visual acuity after excimer laser refractive surgery has been remarkably improved using this model.Keywords：blend zone;optical zone;mathematical model;wavefront aberration;LASIK- 49
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Published：2020-08-12 -
Magnetic force coupling in maglev feeding mechanism
Abstract：The magnetic coupling force existing when a magnetic levitation(maglev)feeding mechanism moves was analyzed. With a V-shaped guide rail in its maglev system and a balance point automatically regressed, the maglev feeding mechanism has a high guiding accuracy, and can be applied to IT manufacturing devices such as laser lithography tools to meet the needs of the super-clean condition and the precision positioning. Then the distribution of the magnetic forces in the maglev system was analyzed, and a set of formulas of the coupling was derived. The results show that the magnetic force coupling exists in the maglev system's controlling process. When the feeding mechanism moves its offset along the y-axis, the magnetic forces of the two magnets along the y-axis and the z-axis must couple each other; but when the feeding mechanism moves its offset along the z-axis, there will be no magnetic force coupling between the two magnets along the y-axis and the z-axis. The magnetic force coupling can be reduced or even be eliminated after a decoupling control with compensation added into the maglev controlling system.Keywords：magnetic levitation(maglev);feeding mechanism;eddy sensor;magnetic force coupling- 55
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Published：2020-08-12 -
Experimentation of the X-ray elliptical crystal spectrograph
Abstract：Based on the theory that is ray emitted from a focus(front)of an ellipse will converge on the other focus(back)by the reflection on the elliptical surface, the Elliptical Crystal Spectrograph(ECS)in the X-ray region of 620～6200 eV was designed. The principle of the system was analyzed,and the design and manufacture were accomplished. KAP,LiF,PET and MiCa are used as dispersive elements covering Bragg angle from 30°to 67.5°. The crystal sizes are 120×8×0.2 mm with the curved analyzer substrate of eccentricity ε=0.9586, focal distance of 1350 mm,and optical path length of 1456 mm. The analyzer of the elliptical profiles was machined into a suitable substrate material using a Computer-Controlled milling machine. The Elliptical Crystal Spectrograph was experimented on Shanghai "Shenzhou Ⅱ" with laser energy of 150 J,laser wavelength of 0.35 μm,and chamber vacuum level 3×13-3 Pa. To achieve optical alignment with a small point source,an aligned telescope was precisely fitted to the elliptical analyzer block. The result shows that spectra of Au target can be measured in 0.63～0.709 nm with a resolution of 1/486(△λ/λ). It is found that the resolution of the spectrograph depends on the rocking curve and the thickness of the crystal and the laser spot diameter. In addition,ECS is simpler and easier to use,with a higher collecting efficiency and a better resolution. It can effectively obtain abundant information of the laser-plasma emission spectra in an inertial confinement fusion.Keywords：crystal spectrograph;Laser plasma;X-ray spectrum;spectral analysis- 46
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Published：2020-08-12 -
Design of weld inspection system for intersected pipe based on redundant manipulator
Abstract：A robotic system was designed for the pipe intersected weld inspection. The manipulator can be hung on a branch pipe and rotates 360° according to a split pipe clamp device. The required inspection trajectory of the inspection probe on the manipulator's end-detector is finalized by using the redundancy joints. The robotic system has two inspection modes. One is the 360° circumferential inspection with different scanning radii. The other is the 'Z' shape inspection along the radial direction. The robotic system can perform intersected weld inspection when the radius range of the branch pipe and the inspected pipe are 100～400 mm and 600～1 000 mm,respectively. The results of the analysis of the designed system architecture and the operation under control algorithm show that the inspection accuracy of the robotic system can be: circumferential stepping accuracy≤0.2 mm/m, radial stepping accuracy≤0.5 mm/m, and axial stepping accuracy≤1 mm/mm.Keywords：intersection weld;weld inspection;robotic system- 56
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Published：2020-08-12 -
Image edge-enhanced technique for X-ray lithography alignment
Abstract：The image edge-enhanced technique was proposed to improve the automatic aligning efficiency and aligning accuracy in the X-ray lithography aligning system, and the numerical analysis was given. After analyzing individuals, and the whole view of the image edge-enhanced techniques was given, the novel method were presented. The image obtained from the CCD image system is processed with three image edge-enhanced methods, which are SOBEL operator, LAPLAC operator and convolution. Then the processed results of the novel methods were compared with each other. The conclusion is that the best method is LAPLAC operator and convolution work together, first convolution, then using LAPLAC operator. With this method automatic aligning efficiency can be improved by about 50% in aligning system. Comparing with 20 minutes for the original method, the automatic aligning time only needs 10 minutes or so with novel method, and the aligning accuracy can be improved from 0.10 microns to 0.08 microns.Keywords：XRL;alignment system;LAPLAC operator;SOBEL operator- 91
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Published：2020-08-12 -
Influence of refractive index mismatch on data bit in two-photon three-dimensional data storage
Abstract：Based on Torok's theory, the profile of IPSF was simulated under the condition of refractive index mismatch. Under the condition of refractive index 1.48 and several kinds of objective lens such as NA=0.25,0.45,0.65, 0.85, the variation trends of the axial bit size and readout signal intensity were analyzed. Selecting appropriate optical parameter(such as NA=0.45, refractive index 1.48), at the depth of less than 200 μm, the variation of the axial bit size is less than 10%, the max variation of readout signal intensity is less than 30%, so the effect of recording is improved. By analyzing the variation trends of data bit under the condition of several kinds of NA and refractive index, it indicates that refractive index mismatch makes lateral bit size little change but axial bit size and readout signal intensity greater change. The change degree is closely related with NA, refractive index and recording depth. Adopting the same optical parameter with simulating, three-dimensional data was recorded in photochromic material by two-photon excitation. By observing the scanning image of data bit in axial and lateral direction and readout signal intensity, this variation trend was testified.Keywords：refractive index mismatch;two-photon;three-dimensional optical data storage- 43
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Published：2020-08-12 -
Approach of automatically identifying valid measure-area by using modulation segmentation for 3D profilometry
Abstract：An approach to identify the valid measure-area automatically by using threshold segmentation with respect to the modulation for 3D profilometry was provided. The existing fringe projection technique cannot effectively deal with the invalid measure-area due to local shadows,irregular reflectivity,fringe discontinuities,unlighted background,under-sampling,etc. The phase data from the invalid areas will have no effect on the data from the valid areas by using temporal phase unwrapping. The modulation from the invalid area is significantly lower than that from the valid measure-area. Deriving from the image segmentation concept,the method can calculate iteratively the optimal threshold of the segmentation for automatically identifying the valid measure-area by analyxing the modulation histogram. Thus it makes a single-view measurement procedure automatic. The resulting phase of a 3D shape of an automobile headlamp reflector is also presented to verify the advantages and the reliability of the method.Keywords：3D shape measurement;Phase unwrapping;modulation;automatic segmentation- 51
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Published：2020-08-12 -
Variable precision camera calibration using neural network
Abstract：A method is proposed to improve the precision of camera calibration. Based on the radial distortion model of a camera, the approach is presented, in which the partition number of distortion region can be adjusted automatically. In a region far from the image center, where distortion is high, the number of partition is big. While in the region near the image center, where the distortion is low, the number is small. Through the partition of the camera distortion regions and processing pixels in the corresponding regions, the neural network can be built. Then, the calibration result can be obtained. The processed results of the novel method were compared with different partitions. The conclusion is that the number of partition is bigger and the calibration precision is higher. The precision can reach 99.45% at the maximal partitions.Keywords：camera calibration;neural network;variable precision- 58
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Published：2020-08-12
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