Optimization and Analysis of Diffraction Spectrum of Holographic Variable Line Space Plane Grating

Holographic variable line space grating has the advantage of self focusing and aberration-reduced. They have been used in a wide variety of spectrograph and synchrotron radiation facilities. In recent years, a new fiber optic position sensor based on holographic variable line space plane grating is developed. In this paper, we briefly describe the theoretical background to the position sensor. In order to improve the performance of the position sensor, it´s necessary to study the diffraction spectrum of the variable line space grating. Based on the Fraunhofer formula for light wave scalar diffraction theory, the diffraction spectrum of the variable line space grating thus obtained is very different from that of the classical grating. The genetic algorithm is introduced to the period distribution optimization of variable line space grating. In consideration of the computational efficiency and complexity, we assume that the single wavelength incident in parallel and uniform, and use serial discrete diffraction areas in our study. The results obtained reveals that the diffraction spectrum of the variable line space grating has a relatively strong dependency upon the grating period distribution expression, the wavelength and the incident light spot size.