Film reader for data storage film - with dynamic reference signal obtained without disturbing light flow

摘要

The film reader is designed esp. for data storage film. A dynamic reference signal is produced proportional to the intensity of the light radiated from a source (12) to the film (10) through an optical system (13) with no other interruption or blocking. A collector (23, 24) collects the peripheral radiation directly from the area around the path between source and optical system at points equally spaced around this path. The collected radiation is transmitted to a photometer and then integrated and converted (27, 30) into an electrical signal. The collector pref. contains optical fibres with their ends arranged in a circle around the optical path.