Analysis and elimination of boundary reflections in transmission holograms

Elimination of reflections which occur at the glass-air interface of hologr aphic plates is an important factor to be taken into account when recording transmission holograms. If these reflections are not eliminated, unwanted secondary gratings are stored due to interference of the object and referen ce beams with the beams reflected at the interface. This not only gives ris e to an anti-aesthetic effect, but also produces a reduction in diffraction efficiency and an increase in noise. We present the results obtained using a method which eliminates these unwanted reflections. This method, instead of using liquids, makes use of a black self-adhesive PVC masking tape stuc k on the glass side of the holographic plate. We carried out a qualitative analysis of the different results obtained for plates with and without blac k PVC tape and also quantitatively analyzed the effect of the tape on the r eflectivity of the plates as well as the density of holographic gratings. T he results obtained confirm the applicability of the method described for a ntihalation reduction and elimination of unwanted reflections that cause in terference affecting the quality of the holographic image. (C) 1999 Elsevie r Science Ltd. All rights reserved.