Monochromators with single grating rotation and holographic gratings on toroidal blanks for vacuum ultraviolet

Design of Holographic Gratings

“…A wavefront of the diffracted wave is constructed from the waves diffracted from the local elementary gratings . Our method is different from the conventional ones [1][2][3][4] that use Fermat's principle . By assuming blanks to be toric, the expression of the focal curves is represented by the loci of centres of principal curvature .…”

“…(4) The difference between the optical paths P O P 1 (n) and P O P 1 (n+ 1) is m2 . Therefore, the wavefront of the diffracted light passing through the vertex 0 of the grating can be written as where X=x+pQ', p=OP o -P 1 Po -nm2, and the number attached to the groove passing through the vertex 0 of the grating is taken to be zero .…”

“…This amounts to selecting a particular design of holographic gratings, a problem that has been discussed by Noda et al . [1,2], Pouey [3], Lepere [4] and others, who applied Fermat's principle to the light path function . However no systematic approach to designing gratings seem to have been established .…”