Patent ID: 8257885

Claim:
A method for apodizing a recorded large-sized reflection diffraction grating in a photosensitive stationary target having a first side and a second side opposite the first side, the second side being substantially parallel to the first side, the method comprising: splitting a light beam having a substantially planar wavefront using a beam splitter into a first beam and a second beam; directing the first beam along a first path incident through the first side of the target while maintaining the substantially planar wavefront to influence a first change in a refractive index of the target along the first path; directing the second beam along a second path incident through the second side of the target while maintaining the substantially planar wavefront to influence a second change in the refractive index of the target along the second path, the second beam interfering with the first beam in an interference region in the target; and scanning the light beam across the beam splitter to scan the interference region in the stationary target along a scan line bisecting an angle between the first path and the second path at the interference region in the target, the scanning of the light beam progressing such that the portions of the photosensitive stationary target near the first and second sides of the of the target are exposed to more non-interfering radiation and less interfering radiation than at the center of the target, wherein a thickness of the target along a first direction substantially perpendicular to each of the first side and the second side is comparable to a width of the first beam along the first direction and a width of the second beam along the first direction.