Abstract: A hand held microfilm reader wherein the film is maintained within the reader housing and the controls for positioning the film are easily manipulated by one hand. An optical system provides an intense automatically focused image projected onto a screen for viewing by the user. The light source is a conventional lens end bulb that has been rendered uniformly directional by its having been mounted in pre-aligned relationship with respect to a clip which is configured to be precisely registered with remaining portions of the optical system.

Abstract: A purging system is provided for reducing and substantially eliminating contaminants, moisture, residual gas and the like from a work station such as, for example, a developer station in which ammonia gas is used for development of diazo type films. The system includes a check valve connected between one end of the developer station and a supply of compressed air, and a 3-way valve connected between the other end of the developer station and a supply of ammonia gas and an ammonia exhaust container. During development, the ammonia is passed into the developer station under a relatively high pressure and the flow of the ammonia is stopped by the check valve. After development, the pressure in the developer station is lowered thereby opening the check valve and causing flow of air from the supply of compressed air through the developer station, the 3-way valve, and into the exhaust container to thereby purge the entire system of contaminants, moisture and residual ammonia gas.