New method for the fabrication of pulse compression grating

Large size pulse compression grating (PCG) with needs high adjusting precision in the light path of PCG fabrication. Note that the longitudinal error is the most error source of diffraction wavefront aberration of grating. It is difficult from conventional light path regulation to obtain such small longitudinal regulative error. A simple and practical method for regulating light path of PCG with big size is introduced. Rotate the grating fabricated by conventional light path adjustment and place it on the original recorded plane. The real grating and the imaginary one produced by two constructive beams interference overlap to produce the moire fringe pattern. Generally speaking, conventional regulation generates longitudinal error that results in cirques. Regulating the pinhole till Moire fringes become parallel and straight, and then backtrack with half of the regulating quantity, which is called Moire fringe method (MFM). With that, the problem that longitudinal precision of conventional light path adjustment is low is solved. To begin with the imaging formula of holographic lens, the principle of MFM is deduced theoretically. From results generated by ZEMAX software, the diffraction wavefront aberration of grating can be reduced to the least by MFM effectively. Proceeding with the relationship between optical system of holographic grating and the diffraction wavefront aberration of grating, the aberration of moire fringes obtained by analyzing the deviation of the fringes from parallel straight lines is about twice as the diffraction wavefront aberration of grating by reference to primary aberration theory.