| 摘要 |
PURPOSE:To realize an exact film thickness measurement which has eliminated an influence caused by an output variation, etc., of a light source, by bringing reference light and measuring light to a scan and a photometry with a shift of a minute time, and measuring the film thickness, based on its difference. CONSTITUTION:First of all, the reference light from a light source 2 for reference, and subsequently, the measuring light from a light source 1 for measurement, which has been delayed by a minute time are reflected by a rotary polygonal mirror of an optical scanner 3 and scan on the surface of a film to be measured 10, respectively. In this case, the reference light and the measuring light are detected successively by a pyrodetector 5 for power monitor, and its difference is derived. Subsequently, the reference light and the measuring light which have passed through the film 10 are detected successively with a shift of a minute time, respectively, by each detecting device 6a-6c..., and a difference of the photometric values is derived in the same way. Next, based on each data of a difference of measured values of two light beams of the reference light and the measuring light, thickness by each data can be measured by using an analytical curve which has been derived from an output value after transmission of a film of the same material whose thickness has been measured in advance, and its thickness.
|
