Research On Gratings Used In Imaging Spectrometer

The diffraction grating is the core component of the imaging spectrometer. Grooveshape determines the wavelength range and diffraction efficiency. Optimization of thegroove structure of the grating can obtain high diffraction efficiency in a wide waveband.In this paper, groove parameters of five gratings used in imaging spectrometer are designed.Effect of fabrication errors on the diffraction efficiency is analyzed.Method to designdual-blazing grating and immersion grating are proposed. Groove parameters of UV, NIR,short-wave infrared dual-blazed grating and immersion grating are optimized. The topicincludes the following aspects:Two basic theories to calculate the diffraction efficiency are summarized. Gratingpolarization properties are analyzed.Groove parameters of UV grating, NIR grating, short-wave infrared grating andlong-wave infrared grating are designed for the specific requirements of the spectrometer.The diffraction efficiency curves are calculated. Fabrication errors in holographic ion-beametching and single point diamond turning (SPDT) technology and effect of these errors ondiffraction efficiency are analyzed.Basic theory of the two dual blazed grating (dual-angle blazing grating and dualblazing grating) is introduced. Diffraction properties of dual-angle blazing grating areanalyzed. Basic idea to design dual blazed grating based on GSolver is given out. Grooveparameters of UV, NIR and short-wave infrared dual blazed grating are optimized. Thediffraction efficiency is calculated.Diffraction properties of the immersion grating are analyzed. It is founded thatadjusting the thickness of the dielectric layer makes the diffraction efficiency curveemerged several peaks and troughs. When the crest number is two, the diffractionefficiency can reach80%in two octaves. Groove structures of UV, NIR and short-wave infrared sawtooth and rectangular immersion grating are optimized. The diffractionefficiency is calculated.