High-precision measurement technique of isoplanatic angle
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摘要: 等晕角是重要大气光学参数之一,对天文光学站址选择、大气湍流效应自适应光学校正效果评价等有着重要的意义。分析了国内外等晕角测量技术,介绍了等晕角测量的基本原理,设计了三环变迹镜并开展了数值验证,分析并提出了高精度等晕角测量仪的主要技术指标,研制了一套高精度等晕角测量仪,结果表明,该仪器能够满足全天时的等晕角测量。Abstract: Isoplanatic angle is an important parameter in atmospheric optics field, and it is important for astronomical site optics selection, and evaluation of adaptive compensation for effects of atmospheric turbulence. Past measurement techniques of isoplanatic angle in the world is analyzed, and fundamental measurement principle of isoplanatic angle is introduced. A three annuli mirror was designed and its usability and precision has been verified. Primary specifications was put forward and a prototype has been developed for high precision measurement of isoplanatic angles. The results show that the prototype an measure isoplanatic angle day and night.
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表 1 变迹镜结构尺寸
Table 1. Size of tri-annuli apodizing mask
type of apodizing mask radius /mm center block 35.560 telescope 101.60 inside/outside radius of inner transmittance ring 37.3888/43.8404 inside/outside radius of middle transmittance ring 62.8904/69.2404 inside/outside radius of outer transmittance ring 81.9404/101.6000 表 2 变迹镜结构尺寸
Table 2. The size of apodizing mask
design procedures of
apodizing maskfit coefficient c of
weighting functiontransmittance area A
of the ring /m2inside/outside radius of middle
transmittance ring/mmsingle aperture 1.209×10−16 0.0095 radius 55.00 dual ring 1.551×10−16 0.0205 inside/outside radius of inner transmittance ring 37.50/50.00 inside/outside radius of outer transmittance ring 70.00/101.6 表 3 高精度等晕角测量仪的主要技术指标
Table 3. Key specifications of the high-precision isoplanometer
key specifications design value dynamic range 3~30 μrad(λ=500 nm) wave length 600~1000 nm sample frequency ≥300 Hz single sample size ≥600 sampling precision 12 bit variation range of zenith angle 5°~45° variation range of azimuth 0°~360° -
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