Polarization properties of a grating spectrograph.
Polarization properties of a grating spectrograph.
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DOI：
10.1364/ao.10.000286
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发表时间：
1971-02
期刊：
影响因子：
1.9
通讯作者：
J. B. Breckinridge
中科院分区：
文献类型：
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作者：
J. B. Breckinridge
麦克马斯太阳望远镜的 13.7 米车尔尼-特纳摄谱仪的偏振特性进行了评估。让我 || = 光谱仪对于平行于入口狭缝线性偏振的入射光的透射率，I 垂直 = 垂直于入口狭缝偏振的光的透射率。作为六个衍射级波长的函数，以光电方式测量 I||/I 垂直 的比率。该比率的值从 0.3 到 20 不等。结果表明，光谱仪透射率作为偏振的函数可能会导致较大的光度和辐射误差。这一事实并非该特定仪器所独有。似乎有两种机制对光栅的偏振有贡献。它们是：(1) 瑞利或伍德异常，其中出现偏振最大值和最小值；(2) 由于凹槽尺寸几乎与波长相同而引入矢量波相互作用。对于 lambda > 凹槽深度，我们发现峰值偏振率 (lambda(p)) 的波长由 lambda(p) = 0.7d cotheta 给出，其中 d 是主间距，theta 是光栅角。对几个伍德异常区域进行了太阳光谱的光电扫描，以获得它们的轮廓。
The 13.7-m Czerny-Turner spectrograph at the McMath solar telescope is evaluated with regard to polarization properties. Let I || = the transmissivity of the spectrograph for incident light linear polarized parallel to the entrance slit and I perpendicular = transmissivity for light polarized perpendicular to the entrance slit. The ratio I ||/I perpendicular was measured photoelectrically as a function of wavelength in six diffraction orders. Values of this ratio vary from 0.3 to 20. It is shown that spectrograph transmission as a function of polarization may cause large photometric and radiometric errors. This fact is not unique to this particular instrument. Two mechanisms appear to contribute to the polarizance of the grating. These are: (1) the Rayleigh or Wood's anomalies in which polarizance maxima and minima occur and (2) a vector wave interaction introduced because groove dimension is nearly the same as the wavelength. For lambda > groove depth it is found that the wavelength of a peak polarizance (lambda(p)) is given by lambda(p) = 0.7d costheta, where d is the ruling separation and theta is the grating angle. Photoelectric scans of the solar spectrum were made across several of the Wood's anomalies to obtain their profiles.