- METHOD MEASURING THICKNESS AND REFRACTIVE INDEX OF PLANAR SAMPLES BASED ON FABRY-PEROT INTERFEROMETER

摘要

The present invention relates to a method for measuring the thickness and refractive index of a flat panel based on a Fabry-Perot interferometer, which is able to measure the thickness and refractive index of a flat panel sample with transparency and a phase refractive index value in accordance with a wavelength, send a beam from a light source emitting a light with a broad wavelength through an optical fiber, connect a green lens to an optical fiber on an output end on the opposite side of an optical fiber coupler connected to the optical fiber, make the beam outputted from the optical fiber a parallel light and transmit the beam, place a transparent window and a mirror, which are parallel to an output cross-section of the green lens, make a Fabry-Perot interferometer, form an interference pattern, allow the beam reflected from the mirror to pass through the green lens and the optical fiber coupler and to be outputted to another optical fiber path on the side of an input end of the optical fiber coupler, connect an end of the optical fiber output end to an optical spectrum analyzer, analyze an optical spectrum, insert the flat panel sample into a part between the transparent window and the mirror to be vertical to the beam path, measure the outputted interference pattern spectrum by the optical spectrum analyzer, perform a Fourier transform of the interference pattern spectrums of the two cases, obtain a frequency distribution, obtain a thickness and a group refractive index of the sample from the frequency relationship coming under the interference pattern between the surfaces, perform a Fourier filtering only on the frequency coming under the interference pattern by both surfaces of the flat panel sample, extract only the interference pattern spectrum by both surfaces of the flat panel, and simply and precisely obtain a phase refractive index of the flat panel sample in accordance with a wavelength based on the Fabry-Perot interference theory formula by a non-contact method.