Method for fabricating the holographic grating

A method for fabricating a holographic grating, forming a interference recording field from two coherent beams, where one is a parallel beam and the other is a beam whose wave-front can be controlled, recording the holographic field on the substrate with aberrations, fabricating the holographic grating with low diffractive wave aberrations, by setting a deformable mirror into one of the coherent recording beams, so as to form a beam with a controllable wave-front, detecting the shape of said deformable mirror with a interferometer, controlling and adjusting the shape of said deformable mirror with the controller, so as to control the wave-front of the recording beam, obtaining a controllable interference recording field,

• said method comprising,
• (1) detecting a surface shape of a substrate of the holographic grating with a interferometer, to obtain data of aberration distribution of the substrate;
• coating a photoresist on the substrate and a recording plate to record the holographic grating;
• (2) according to the data of aberration distribution of the substrate, deducing a required wave-front of an interference recording field when the diffractive wave aberration of the grating is null, and deducing the corresponding wave-front of the recording beam and the data of surface shape of the deformable mirror;
• (3) detecting the surface shape of the deformable minor with a interferometer, so as to obtain data of said surface shape, and adjusting a controller of the deformable minor until the surface shape of the deformable minor is equal to the target wave-front;
• said deformable mirror, said controller of the deformable mirror and said interferometer forming a closed-loop system which can implement control and measurement of the interference recording field;
• and
• (4) after finishing adjustment of the deformable mirror, obtain a required interference recording field that contains a certain aberration that can compensate the aberration of the substrate, exposing the recording plate under said interference recording field obtained by adjusting said deformable minor in step (3), recording the holographic grating, after developing, to achieve the holographic grating with low diffractive wave aberrations.