Common-Path Spectropolarimetric Differential Imager Using Variable Channeled Spectrum
Common-Path Spectropolarimetric Differential Imager Using Variable Channeled Spectrum
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DOI：
10.1086/513865
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发表时间：
2007-05
期刊：
影响因子：
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通讯作者：
N. Murakami;L. Abe;Motohide Tamura;N. Baba
中科院分区：
文献类型：
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作者：
N. Murakami;L. Abe;Motohide Tamura;N. Baba
我们提出了一种差分成像仪，利用可变通道光谱的方法。通道光谱是相对于波长的振荡光谱，由两个偏振器产生，在它们之间具有延迟器。在这些偏振器之间插入一个可变的延迟器，调制通道光谱。通过用带通滤波器限制光谱带，整个光学系统充当具有两个特定中心波长的共路可变带通滤波器。只要通道光谱的时间调制与相位像差的演变相比足够快，就可以获得不含非共路像差的光谱差分图像。此外，通过在该光学系统前面插入另一个可变延迟器，也可以获得偏振差分图像。因此，可以获得共路光谱和偏振差分图像。我们建议使用液晶可变延迟器，这已被成功地证明在偏振差分成像仪配备了四象限偏振掩模电晕。为了达到更高的系统吞吐量，我们建议使用Wollaston棱镜代替偏振器。在本文中，我们描述了这种技术的原理。给出了初步的实验室实验结果和光谱差分成像仪的数值模拟。
We propose a method for a differential imager that makes use of a variable channeled spectrum. The channeled spectrum is an oscillating spectrum with respect to wavelength, generated by two polarizers with a retarder between them. A variable retarder, inserted between these polarizers, modulates the channeled spectrum. By restricting a spectral band with a bandpass filter, the whole optical system acts as a common-path variable bandpass filter with two specific central wavelengths. Provided that the temporal modulation of the channeled spectrum is fast enough compared to that of the evolution of phase aberrations, it is possible to obtain spectral differential images free from non-common-path aberrations. Furthermore, polarization differential images are also available by inserting another variable retarder in front of this optical system. Thus, both common-path spectral and polarization differential images can be obtained. We propose using a liquid-crystal variable retarder, which has been successfully demonstrated in a polarization differential imager equipped with a four-quadrant polarization mask coronagraph. In order to achieve a higher system throughput, we suggest using Wollaston prisms instead of polarizers. In this paper, we describe the principle of this technique. Results of a preliminary laboratory experiment and a numerical simulation of the spectral differential imager are also given.