Abstract

The maximum measurable range of a spectral interference microscope depends on the coherence length of the light transmitted by its tunable spectral filter. To achieve a large range in step-height measurement we have developed a new tunable spectral filter that uses tandem liquid-crystal Fabry-Perot interferometers (LC-FPIs), which can simultaneously attain both a high spectral resolution and a large tuning range. Fringe visibility measurements were carried out, and it was found that the coherence length of the light transmitted through tandem LC-FPIs is two times larger than that transmitted through a single LC-FPI. Using this novel tunable spectral filter, we developed a new spectral interference microscope for the measurement of three-dimensional shapes of discontinuous objects. Experimental results of step-height measurements both with a single LC-FPI and with tandem LC-FPIs are presented for a combination of standard steel gauge block sets with 1-, 99-, and 100-µm steps. A large range (1–100 µm) of measurement with submicrometer resolution was achieved with tandem LC-FPIs that was not possible with our previous system in which a single LC-FPI was used.

© 2003 Optical Society of America

Simultaneous three-dimensional step-height measurement and high-resolution tomographic imaging with a spectral interferometric microscope

Dalip Singh Mehta, Masaya Sugai, Hideki Hinosugi, Shohei Saito, Mitsuo Takeda, Takashi Kurokawa, Hideki Takahashi, Masahito Ando, Masataka Shishido, and Tetsuo Yoshizawa
Appl. Opt. 41(19) 3874-3885 (2002)

Spectral interference Mirau microscope with an acousto-optic tunable filter for three-dimensional surface profilometry

Dalip Singh Mehta, Shohei Saito, Hideki Hinosugi, Mitsuo Takeda, and Takashi Kurokawa
Appl. Opt. 42(7) 1296-1305 (2003)

Differential wavelength-scanning heterodyne interferometer for measuring large step height

Sheng-Hua Lu, Ching-I Chiueh, and Cheng-Chung Lee
Appl. Opt. 41(28) 5866-5871 (2002)

Extension of distance measurement range in a sinusoidal wavelength-scanning interferometer using a liquid-crystal wavelength filter with double feedback control

Osami Sasaki, Akihiro Saito, Takamasa Suzuki, Mitsuo Takeda, and Takashi Kurokawa
Appl. Opt. 46(23) 5800-5804 (2007)

Increasing the range of unambiguity in step-height measurement with multiple-wavelength interferometry—application to absolute long gauge block measurement

Jennifer E. Decker, John R. Miles, Alan A. Madej, Ralph F. Siemsen, Klaus J. Siemsen, Sebastian de Bonth, Krijn Bustraan, Sara Temple, and James R. Pekelsky
Appl. Opt. 42(28) 5670-5678 (2003)