An improved system for the separate measurement of the refractive index and the geometrical thickness that constitutes a hybrid configuration of a confocal microscope and a wavelength-scanning heterodyne interferometer with a laser diode is presented. The optical path difference can be measured in less than 1 s, which is 10 times quicker than with the low-coherence interferometry previously used, and with a resolution of 10 μm with a fixed reference mirror. Separate measurement of the refractive index and the geometrical thickness of glass plates was demonstrated by use of the arrangement in place of the low-coherence interferometer used previously.
© 1999 Optical Society of America
(040.2840) Detectors : Heterodyne
(120.3180) Instrumentation, measurement, and metrology : Interferometry
(120.4630) Instrumentation, measurement, and metrology : Optical inspection
(170.6960) Medical optics and biotechnology : Tomography
(180.1790) Microscopy : Confocal microscopy
Takashi Fukano and Ichirou Yamaguchi, "Separation of Measurement of the Refractive Index and the Geometrical Thickness by Use Of A Wavelength-Scanning Interferometer with A Confocal Microscope," Appl. Opt. 38, 4065-4073 (1999)