Echelle gratings tiling method based on lateral shearing interferometry

A method for echelle gratings tiling based on lateral shearing interferometry is proposed. Fringe patterns of the grating assembly are generated by a wedge plate. Mosaic errors can be calculated and corrected by observing the working order and its adjacent order. An experimental mosaic of two 50 mm x 50 mm, 79 grooves/mm echelles is aligned to verify the theory. The rms wavefront is better than 0.04 wavelength. Angular and translation sensitivities of less than 1 arcsec and 10 nm are achieved respectively.

Automated summary

A method for tiling echelle gratings based on lateral shearing interferometry is proposed, with mosaic errors being calculated and corrected by observing adjacent orders. An experimental verification with two 50 mm x 50 mm, 79 grooves/mm echelles showed rms wavefront better than 0.04 wavelength, with angular and translation sensitivities achieved below 1 arcsec and 10 nm, respectively.