Testing of the large-aperture convex aspheric mirror is a very difficult task in the aspherical testing. The null lens compensator is one of the efficient methods for testing the large-aperture convex aspheric mirrors...
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Testing of the large-aperture convex aspheric mirror is a very difficult task in the aspherical testing. The null lens compensator is one of the efficient methods for testing the large-aperture convex aspheric mirrors. However, with the aperture increasing, some unavoidable errors are induced in the fabrication and adjustment of the compensator. In this paper, a method using a standard sphere mirror is proposed to calibrate the error of the compensator. The system error in the compensator is tested and calibrated. The calibrated compensator is used to measure the large-aperture aspheric mirror. The calibration error is also analyzed. The root-mean-square (RMS) error before calibration is 0.097 λ (wavelength λ=632.8 nm), which significantly deteriorates the testing accuracy in the null lens testing. The final testing RMS error after calibration is smaller than 0.0046 λ, which satisfies the designed precision requirement of the large-aperture convex aspheric mirror.
The fabrication, optical processing and surface modification of Ø1.45 m SiC mirror were researched. The blank for a 1.45 m SiC mirror was fabricated by using Gel-casting combined with the reaction bonding technol...
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The fabrication, optical processing and surface modification of Ø1.45 m SiC mirror were researched. The blank for a 1.45 m SiC mirror was fabricated by using Gel-casting combined with the reaction bonding technology and a larger size and lightweight SiC mirror was obtained. Then, the optical surface processing of the SiC mirror was introduced. A metallographic microscope and the X-ray diffractemoter were used to analyze the microstructure of the SiC mirror and the ZYGO interferometer and a WYKO roughmeter were taken to test the surface profile. Obtained results show that the Ø1.45 m lightweight SiC mirror is 156 kg with density of 3.0 g/cm3, and its lightweight rate and the reflectivity are more than 70% and 96%, respectively. Moreover, the SiC mirror offers its surface roughness less than 3 nm and profile precision RMS less than λ/50(λ=632.8 nm). The mechanical and optical properties of the SiC mirror designed satisfy the opticaldesign requirement and can provide the foundation for development of more large size SiC mirrors.
As the control of off-axis in the off-axis asphere manufacture is a key of the opticaldesign, this paper proposes a testing method for the off-axis using a portable and precise laser tracker in the null compensating ...
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As the control of off-axis in the off-axis asphere manufacture is a key of the opticaldesign, this paper proposes a testing method for the off-axis using a portable and precise laser tracker in the null compensating interferometry. Firstly, the optical path of the null testing and compensating was adjusted according to the aberration theory. Then, the reference surface on the compensator and the off-axis asphere was tested with the laser tracker. Finally, the collected data from reference surface was processed, constructed, coordinated and calculated, and the off-axis of the asphere was obtained directly by comparing the central point of asphere and the tested optical axis position. The measurement precision was analyzed in detail, and the off-axis testing experiment was performed with a rectangular off-axis asphere. The test result shows that the testing precision can achieve 0.042 mm. The method is also can be used in measuring the offsets of a coaxial asphere element and a spherical element.
To test convex freeform surface mirrors precisely, a Computer Generated Hologram (CGH) compensator with functions of high-precision surface measurement, optical paths alignment and the freeform mirror location was des...
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To test convex freeform surface mirrors precisely, a Computer Generated Hologram (CGH) compensator with functions of high-precision surface measurement, optical paths alignment and the freeform mirror location was designed based on the CGH software developed by ourselves. The testing principles, design method and the area function of a diffraction pattern for the CGH were introduced. A CGH diffraction pattern with an auxiliary area was designed for convex freeform surface mirrors. The main error source effecting on CGH detecting accuracy was analyzed and the method to improve the detection accuracy was proposed. Finally, the CGH compensator was used to test convex freeform surface mirrors. The obtained results show that the surface accuracy is less than λ/4 (λ=632.8 nm) in PV and the testing precision is λ/40 (λ=632.8 nm) in RMS by using the CGH compensator.
In order to manufacture off-axis aspheric silicon carbide (SiC) mirror with high quality optical surface, a perfect process specification for fabricating off-axis aspheric SiC mirror, including milling, grinding, roug...
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In order to manufacture off-axis aspheric silicon carbide (SiC) mirror with high quality optical surface, a perfect process specification for fabricating off-axis aspheric SiC mirror, including milling, grinding, rough polishing, surface modification and precise polishing, is presented. Ultrasonic 100-5 computer-controlled machine is put to use for milling Φ600 mm SiC mirror to off-axis aspheric surface directly. After milling, peak valley (PV) value of the figure accuracy of the mirror is 17.17 μm. The off-axis aspheric SiC mirror is grinded and rough polished by computer-controlled optical surfacing (CCOS), and root mean square value of the figure accuracy of off-axis aspheric SiC mirror is 0.102λ (λ=0.6328 μm). A silicon modification layer with thickness of about 10 μm is coated on off-axis aspheric SiC mirror by ion beam assisted deposition (IBAD), and the surface modified off-axis aspheric SiC mirror is precisely polished by advanced ion beam figuring (IBF). At last, root mean square values of the figure accuracy and roughness of off-axis aspheric SiC mirror are 0.018λ and 0.6968 nm, respectively. Experimental results indicate that the process specification is suit for fabricating off-axis aspheric SiC mirror.
For the purpose of overcoming the difficulty of testing figure error of large mirror, the method of subaperture stitching interferometry(SSI) and collimator is introduced. The basic principle and flow chart of SSI are...
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For the purpose of overcoming the difficulty of testing figure error of large mirror, the method of subaperture stitching interferometry(SSI) and collimator is introduced. The basic principle and flow chart of SSI are analyzed. The synthetical optimization stitching mode and effective stitching algorithm are established based on triangulation algorithm and least-squares fitting. Combining examples, a large mirror with the aperture of 2 m is tested by SSI and 1-m collimator with 9 subapertures in simulation. This method decreases the error cumulation and the number of subaperture, so it provides an accurate and swift method for measurement of large mirror.
Polymer photovoltaic(PV)cells based on UV-ozone(UVO)-treated indium vanadium oxide(IVO)anodes are *** performance of cells with UVO-treated IVO film anodes without interfacial layers was significantly improved compare...
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Polymer photovoltaic(PV)cells based on UV-ozone(UVO)-treated indium vanadium oxide(IVO)anodes are *** performance of cells with UVO-treated IVO film anodes without interfacial layers was significantly improved compared with those containing untreated IVO *** origin of the enhancement is investigated by atomic force microscopy and photoelectron spectroscopy *** results demonstrate that UVO treatment can smooth the IVO surface,and increase the work function of IVO films due to the removal of carbon contamination and a dipole resulting from a surface rich in negatively charged ***-treated IVO films are potential electrode materials for polymer PV cells.
The test of a large diameter aspheric surface needs a 4D interferometer insensitive to working environments, therefore, this paper proposes a calibration method for the errors of the interferometer. The principles of ...
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The test of a large diameter aspheric surface needs a 4D interferometer insensitive to working environments, therefore, this paper proposes a calibration method for the errors of the interferometer. The principles of the interferometer were mentioned, and by theory analysis, computer simulation and optical testing experiments, random errors (vibration, light source instability, environmental disturbance) and system errors (retrace error, shearing effect, imaging distortion) of the interferometer were analyzed. Experimental results show that the error (RMS) of the 4D interferometer is 8.9 nm and the geometric error (RMS) is 4.4 nm. Furthermore, the relationship between the averaged times and the random errors was discussed. It indicates that the more of averaged times, the less the residual errors;when the times exceed a certain number, the decrease of random errors will be slowed down. The results of the experiment show that when the averaged times exceed 30, the random errors less than 1 nm and the geometric error (RMS) 4.4 nm. The results are in agreetment with the test by a reflect mirror with RMS better than λ/100, which prove the feasibility that the random ball can calibrate the error of interferometer.
In order to optimize the optical performance of silicon carbide (SiC) mirror so as to meet the application requirement of space used optical elements, optical performance and surface roughness of surface modification ...
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In order to optimize the optical performance of silicon carbide (SiC) mirror so as to meet the application requirement of space used optical elements, optical performance and surface roughness of surface modification SiC mirror are researched. Firstly, optical performance and surface roughness of SiC mirror surface are analysed. The necessity of surface modification on SiC mirror and the choice of modification materials are investigated. Then, optical performance and surface roughness of SiC mirror are optimized after surface modification. Finally, the film adsorption power and temperature experiment are made. Experimental results indicate that: after surface modification, the scattering coefficient is reduced from more than 9.3% to less than 0.5% and the reflecting coefficient is increased from less than 88.5% to 98%. The optical performance of surface modification SiC mirror is optimized substantially, thus it can meet the application requirement of high quality space used opticalsystem.
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