Electronic Color Separation with Laser Light Sources

Improvements in electronic color scanners appear possible by replacing current light sources with coherent radiation from lasers with much higher radiance. This allows higher speeds of operation (subject to mechanical constraints), greater enlargement capability, and the use of lower sensitivity recording films, or other media. These possibilities were verified experimentally by replacing the reading light source in an RCA color scanner by a combination of argon-ion and He-Ne lasers and the writing light source with an argon-ion laser. The light intensity of the writing light source was modulated by an electrooptic modulator driven from the signal output of the color-correction computer. When this signal was pulsed electronically, it was further possible to directly generate a screened halftone image on the scanner. This is due to the fact that a laser can be operated with a Gaussian spatial energy density distribution. When such a distribution is focused onto a high gamma film, dots are produced whose size is related uniquely to the intensity of the light pulse.