A number of recent applications of lasers to the solution of photo-optical instrumentation problems are described. These include analytical and experimental studies performed to evaluate the use of both pulsed solid-state and CIV gas lasers as light sources for schlieren and interferometer systems, the application of a iCW gas laser and a high-speed camera to investigate dynamic acoustic pressure waves and the investigation of a laser source for a backscattering photometer for measuring light transmission through the atmosphere. Each application described serves to illustrate one or more of the laser's unique properties in meeting a particular photo-optical instrumentation requirement.
A brief review from a physical point of view of coherence theory and linear systems analysis as applied to optical systems used under coherent and incoherent conditions of illumination will be given. Image processing will then be looked upon as a problem of achieving a prespecified optical transfer function for both cases of illumination separately. A conceptual solution to this problem is given followed by simple illustrative examples.
The sensitivity of differing space photographic imaging concepts is compared in terms of the photo-electron population of the discrete picture element. The velocity of the scanning beam is included for storage surfaces. The photon population has been photometrically established for black-body temperatures of interest. The method is illustrated for a slow-scan vidicon for which the quantum efficiency is shown to be n = 0.4.
The utility and elegance of the Modulation Transfer Function (MTF) in photo-optical system design is well known. The difficulties involved in the measurement of this performance criteria, however, have restricted its practical application. The relationship between MTF and several of the more easily measured and specified resolution criteria, such as point and line spread functions, knife edge response, and encircled energy, is developed. A method of specifying resolution criteria determined by MTF analysis for the optical designer and the evaluation laboratory, is presented. The practicality of the method is enhanced by introducing certain simplifications to reduce the time required for computation.