Abstract

The physical principles underlying local deformation of thermocapillary films (TF) by heating with a Gaussian laser beam are studied in Refs. 1 and 2. Applications of TFs as real-time erasable photographic receivers are discussed in Refs. 3 and 4. In this paper we describe use of TFs to introduce and erase data in real time at the input plane of an optical data processor, Two examples are discussed: (1) real-time generation and coherent Fourier transformation of a 2-D object formed by a discrete point distribution; (2) real-time generation and transmission of a 1-D object coded in white-light spectrum. The TFs used in these experiments are thin films of heavy hydrocarbons. In the first example (Fig. 1) N pits are formed in two dimensions at given points of the TFs sequentially heated with a focused laser beam L₁. The heating time necessary to dig each pit is T_h ≃ 1 sec in our actual setup, and the lifetime of each pit after heating suppression is T₁ ≃ 15 min. This enables us to draw complex 2-D objects (Fig. 2). The spatial resolving power of the film coincides with the diameter of a single pit, namely, d ≃ 0.1 mm. The resulting set of pits is illuminated by an expanded laser beam L₂, whose diffraction pattern after reflection is observed on the screen S.

© 1983 Optical Society of America