Photosensitive deformable films

The history of deformation due to electrostatic forces, from the first experimental observation of the phenomenon to the latest materials and processes for recording optical images, is briefly outlined. The newer light sensitive systems are described in some detail This background is followed by a section on theory which covers electrical fields in nonhomogeneous media, critical electrical field for deformation, effect of photoresponse on electrostatic pressure, deformation rate, photon efficiency, spectral response, and resolution. Thereafter, an experimental method of generating the analog of -log curves for sensitometric measurements is presented and the effects of recording and medium variables on these sensitometric curves are discussed. Excellent agreement between theory and experiment is shown for the effect of initial surface potential and photoresponse on photographic speed. Experimentally measured spectral response and resolution are also included. The photographic properties of "photovoltaic" films are treated separately from the photoconductive ones because behavior is somewhat different and experimental work has been much more limited. Finally, current and potential applications are described in terms of the advantages and disadvantages which accompany photosensitive deformable films and recording processes.