Design of compact optical setup for hologram multiplexing with a straight arrangement of two prisms

Abstract

We propose a narrowly-shaped setup containing two prisms symmetrically placed along a straight line. This method features (1) an easy alignment, (2) the capability of hologram multiplexing using array light sources. In the proposed optical systemm, prisms' apex angles are limited for two waves interference because of the total reflection at prism's boundary. Therefore, we should take this obstacle into consideration to design the setup. As a simplified calculation model, we assume that the wavelength of the light source is 780 nm, the refractive index of the prism is 1.51, and the focal length of the collimating lens is 10 mm, the apex angle of the first prism is 120 degrees, and that of the second prism is 90 degrees. If the largest oblique incident angle of the first prism is 10 degrees, the distance from light sources to a recording media becomes 45mm. The validity of our optical setup is confirmed experimentally by writing some holograms.