Abstract: A method of processing a photosensitive glass includes exposing. Photosensitive glass by radiation from a laser whose oscillation wavelength lies within the range of wavelengths of exposing light to which the glass responds. Then, the exposed portions 1c are thermally developed and etched. Since a laser beam propagates with a high rectilinearity, the front and rear surfaces of thick photosensitive glass can be exposed without producing dimensional errors. Therefore, the etching accuracy is improved. Especially, where the front and rear surfaces of photosensitive glass are etched, both surfaces can be processed so as to form the same shape in them accurately. In addition, because almost all the energy of the laser radiation is used for exposure of the photosensitive glass, the energy is not wasted and so the efficiency is high.

Abstract: A photographic camera has a rectilinear approximate operation circuit for calculating characteristic correction data for correcting errors in the operational characteristics of the camera. Predetermined theoretical characteristic data dependent on operational characteristics of the camera are stored. Measured data corresponding to predetermined measured values are stored as individually measured characteristic data in a nonvolatile EEPROM so that the stored measured data can be easily changed by rewriting the EEPROM. An object signal is generated depending on an object to be photographed. The rectilinear approximate operational circuit calculates characteristic correction data from the object signal, the theoretical characteristic data and the measured characteristic data, which is then used for correcting errors in the operation characteristics of the camera.