startrekfan237

The videodisc you are now watching began with the production of a glass photoresist master. Chosen because of its uniformity and freedom from blemishes, the plate glass is ground and reground with extremely fine abrasive, to remove all pits, then optically polished and carefully cleaned. Finally, a thin, uniform layer of positive photoresist is applied to the glass in preparation for mastering. Either videotape or film can be used as program source material, and all master recording is done in real time. Here we see the actual recording of an optical videodisc master. The program material is being supplied by a helical scan videotape machine