| 摘要 |
PURPOSE:To make it possible to measure the thickness of a thin film in running with high precision by measuring the spectrum of transmitted light obtained by irradiating a transparent film with a parallel white light beam. CONSTITUTION:Through lens 2, light from white light source 1 is made into a parallel light beam and after it is transmitted in transparent film 3, the luminous flux has the width widened via lens systems 4 and 5 and is passed through the prism (or diffraction grating 6) to measure the spectrum through lens 7 and photodetector 8. Since the wavelength of interference light due to film 3 can be found from the maximum or minimum position of the spectrum, the thickness of the film can accurately be calculated. The parallel luminous flux is divided by half-mirror 12 and then separated by the prism (or diffraction grating) 9 into spectral component, and the spectrum of the light source is measured by prism 10 and photodetector 11 to monitor the fluctuations of the light source. Thus, the thickness of a thin film in running can be measured with precision. |
