Optical Recorder

An optical recorder is the machine used to photographically expose a sound track onto negative optical film. The machine converts an analog audio signal into a picture of the sound wave and exposes that picture onto optical film stock. Digital audio tracks (SDDS and Dolby® SR-D) are also printed optically. In the case of DTS, the audio resides on a separate element, but a proprietary DTS time code reference is recorded optically onto the film.

Film threaded through an optical recorder.