The transmission volume-phase holographic grating recorded on dichromated gelatin film used in Raman spectrometer

Abstract

With the intrinsic advantages of high diffraction efficiency, signal to noise ratio, wavelength and angular selectivity, and low scattering and absorption, volume phase holographic grating (VPHG) has been widely used for spectroscopy, telecommunications, astronomy and ultra-fast laser sciences. The transmission VPHG combined with on-axis imaging lenses can be used in the Raman spectroscopic imaging, which enables a spectrometer to work at high resolution over a wide field of view, and compresses the configuration to achieve very little vignetting. The subject of this paper is to design a kind of transmission VPHG used in Raman Spectrometer with high diffraction efficiency theoretically. According to the Bragg condition and the coupled wave theory, the diffraction efficiency of transmission VPHG recorded on dichromated gelatin (DCG) has been optimized by using G-solver software, which is applicable to the visible waveband ranging from 0.46μm to 0.70μm. The effects of the recording and reconstruction setup parameters, the amplitude of the index modulation (Δn) and the thickness of the gelatin layer (d), and the polarization state of reconstruction beams on the diffraction efficiency properties of the gratings are analyzed at the same time.