Purely spectrometric method to measure the bias refractive index including its dispersion and the swelling or shrinking of holographic materials

Abstract

A novel method to determine the application relevant parameters of holographic film materials is presented. The procedure is capable of measuring the refractive index n 0 of the unrecorded material at the recording wavelength λ 0 , the bias refractive index n ( λ ) of the recorded medium including its dispersion, and the shrinkage parameter S . Measurements rely on spectrometer data only, i.e., there is no necessity for Bragg angle determination. Experimental data for the holographic film material HX 200 from Covestro are presented. Theoretical analysis suggests that the method is equally well suited to determine the relevant temperature dependencies, too.