[Integration design and diffraction characteristics analysis of prism-grating-prism].

Prism-grating-prism (PGP) module is the important dispersing component in the hyper spectral imager. In order to effectively predict the distribution of diffraction efficiency of the whole PGP component and its diffraction characteristics before fabrication, a method of the PGP integration design is proposed. From the point of view of the volume phase holographic grating (VPHG) design, combined with the restrictive correlation between the various parameters of prisms and grating, we compiled the analysis software for calculating the whole PGP's diffraction efficiency. Furthermore, the effects of the structure parameters of prisms and grating on the PGP's diffraction characteristics were researched in detail. In particular we discussed the Bragg wavelength shift behaviour of the grating and a broadband PGP spectral component with high diffraction efficiency was designed for the imaging spectrometers. The result of simulation indicated that the spectral bandwidth of the PGP becomes narrower with the dispersion coefficient of prism 1 material decreasing; Bragg wavelength shift characteristics broaden the bandwidth of VPHG both spectrally and angularly, higher angular selectivity is desirable for selection requirements of the prism 1 material, and it can be easily tuned to achieve spectral bandwidth suitable for imaging PGP spectrograph; the vertex angle of prism 1, the film thickness and relative permittivity modulation of the grating have a significant impact on the distribution of PGP's diffraction efficiency, so precision control is necessary when fabrication. The diffraction efficiency of the whole PGP component designed by this method is no less than 50% in the wavelength range from 400 to 1000 nm, the specific design parameters have been given in this paper that have a certain reference value for PGP fabrication.