Deposition monitor

Deposition monitor

A simplified monitor for deposition of thin films features a diode-laser light source and two phototransistors connected to measure the ratio of the incident beam and the reflected beam. A similar monitor is also available that uses an incandescent bulb and interference filters to provide quasimonochromatic light. The monitor is about the size and shape of a laser pointer and looks into the deposition chamber through a sapphire window. The electronics are housed in a 4 ¥ 4-in. aluminum box, and the output is fed to a stripchart recorder.

John Brown Associates, Stirling, NJ