PURPOSE: To ensure easy measurement, by providing an introducing optical system, wherein light from an external light source is introduced into the inside of a container and projected to the surface of an inner wall, thereby obtaining the transmitted light through the surface photoelectric plane, which is in an evaporating process.
CONSTITUTION: Modulated light, which is emitted from an LED10, is introduced into a light pipe 1 and projected on a surface plate 8. An interference filter 12, which has a transmitting wavelength that is the same as the wavelength of the light emitted from the LED10, is overlapped on a silicon photodiode 13 of a light receiving device and they are closely contacted with the outer surface of the surface plate 8. The current, which is outputted from the silicon photodiode 13 based on the modulated light transmitted through an evaporated film on the surface plate 8, is amplified by an AC amplifier 14. A rectified peak value is obtained by a peak rectifier 15 based on the output of the amplifier and added to a recorder 16. In this way, the thickness of the film corresponding to the change in transmittance of the evaporated film is determined, and the evaporation can be controlled with the evaporating state being monitored.
SHIRATA YOUSUKE
KITAHARA TADASHI
| JP58074338B | ||||
| JPS5331157A | 1978-03-24 |