Proceedings Article | 3 October 2008
Proc. SPIE. 7155, Ninth International Symposium on Laser Metrology
KEYWORDS: Signal to noise ratio, Thin films, Light sources, Calibration, Spectroscopy, Image resolution, Spectral resolution, Charge-coupled devices, Optics manufacturing, Thin film manufacturing
The correct monitoring of thin-film thickness is one of the main problems during the course of optical thin-film
component manufacture, in recent years, the method which is spectrum intensity measurement of thin-film component
for controlling thin-film thickness has been one of the most effective methods. When this method is used Chow
spectrum intensity is real-time, correctly measured is critical. Compared with the conventional method which is
mechanical scanning by stepper motor driving the grating of monochromator and receiving by photoelectrical multiplier
tube, in structure, the author combines the grating spectrometer with the linear CCD, which makes the problem of
spectrum intensity real-time measurement better solved, the result is satisfied. In this paper, the structure of system
affecting the spectrum intensity measurement accuracy is analyzed, By experiment, the relative parameters are
determined, the spectrum wavelength is calibrated, root-mean-square error is 0.234nm, which is up to the requirement of
monitoring wavelength resolution in the course of thin-film deposition; The algorithm is used for the real-time
compensation of spectrum intensity measurement data, which make the effect of CCD photoelectrical response
non-uniformity and nonlinear less; By changing the integral time magnitude, the rate of signal to noise of the spectrum
signal is improved, it satisfies the requirement of real-time thin film thickness control.
