New application of photo-thermo-refractive glass (PTR) named “holographic prism” is presented. In the holographic prism angles between directions are set by the holograms which create “fan” of signal beams. This kind of prism creates several signal beams which are equal to the reflections from facets of the conventional silica prism. Implementation of PTR glass as a holographic medium for this device brought us several advantages and new features. First it leads to decrease in overall size of the prism that positively affects the identification process of the beam's crosspoint. Thus, it increases sensitivity and accuracy of the measure. Second, greater value of the refractive index change in PTR glass in comparison with calcium fluoride crystal allows us to increase quantity of the recorded reference beams for the measure which leads to sensitivity increase. During this work, we established recording schedule for the PTR glass in case of the superimposed gratings recording. Was found that exposure for each grating should be equal to the 1/N fraction of the optimal exposure where N is the number of multiplexed gratings. We proved that in this case the total value of the refractive index modulation amplitude is equal to that for the single grating with optimal exposure. Considering obtained data we successfully performed recording of the holographic prism of the second modification with 14 channels.

Date Published: 26 June 2017
PDF: 9 pages
Proc. SPIE 10329, Optical Measurement Systems for Industrial Inspection X, 103292Z (26 June 2017); doi: 10.1117/12.2270186

Published in SPIE Proceedings Vol. 10329:
Optical Measurement Systems for Industrial Inspection X
Peter Lehmann; Wolfgang Osten; Armando Albertazzi Gonçalves Jr., Editor(s)