Diffraction-grating photopolarimeters and spectrophotopolarimeters

摘要

A division-of-amplitude photopolarimeter based on conical grating diffraction includes a diffraction grating and at least four photodetectors. An incident light beam is directed at the grating at an oblique incidence angle PHI and the grating grooves are inclined at an arbitrary angle alpha with respect to the plane of incidence. Each of the photodetectors is positioned to intercept one of the diffracted orders and may be an area array detector if spectropolarimetry use is desired. Polarizing means may be inserted in the paths of one or more of the diffracted orders. A division-of-amplitude photopolarimeter based on planar grating diffraction includes a diffraction grating and at least four photodetectors; the grating is placed in the conventional spectrometer orientation with its grating grooves perpendicular to the plane of incidence. Each of the photodetectors is positioned to intercept one of the diffracted orders, all of which lie in the plane of incidence and may be a linear array detector if spectropolarimetry use is desired. Polarizers are inserted in the paths of at least two of the diffracted orders between the grating and the detectors.