ID 113643
Author
Yamagiwa, Masatomo Tokushima University
Trovato, Clément Tokushima University|University of Bordeaux|Utsunomiya University
Ogawa, Takayuki Tokushima University
Abdelsalam Ibrahim, Dahi Ghareab Tokushima University|National Institute of Standards
Kawahito, Yusuke Tokushima University
Oe, Ryo Tokushima University
Shibuya, Kyuki Tokushima University
Mizuno, Takahiko Tokushima University
Abraham, Emmanuel Univ. Bordeaux
Minoshima, Kaoru The University of Electro-Communications
Content Type
Journal Article
Description
Digital holography (DH) is a promising method for non-contact surface topography because the reconstructed phase image can visualize the nanometer unevenness in a sample. However, the axial range of this method is limited to the range of the optical wavelength due to the phase wrapping ambiguity. Although the use of two different wavelengths of light and the resulting synthetic wavelength, i.e., synthetic wavelength DH, can expand the axial range up to several hundreds of millimeters, its axial precision does not reach sub-micrometer. In this article, we constructed a tunable external cavity laser diode phase-locked to an optical frequency comb, namely, an optical-comb-referenced frequency synthesizer, enabling us to generate multiple synthetic wavelengths within the range of 32 μm to 1.20 m. A multiple cascade link of the phase images among an optical wavelength ( = 1.520 μm) and 5 different synthetic wavelengths ( = 32.39 μm, 99.98 μm, 400.0 μm, 1003 μm, and 4021 μm) enables the shape measurement of a reflective millimeter-sized stepped surface with the axial resolution of 34 nm. The axial dynamic range, defined as the ratio of the axial range ( = 2.0 mm) to the axial resolution ( = 34 nm), achieves 5.9 × 105, which is larger than that of previous synthetic wavelength DH. Such a wide axial dynamic range capability will further expand the application field of DH for large objects with meter dimensions.
Journal Title
Optics Express
ISSN
10944087
Publisher
OSA publishing
Volume
26
Issue
20
Start Page
26292
End Page
26306
Published Date
2018-09-25
Rights
This is an open access article distributed under a Creative Commons license(https://creativecommons.org/licenses/by/4.0/).
EDB ID
DOI (Published Version)
URL ( Publisher's Version )
FullText File
language
eng
TextVersion
Publisher
departments
Science and Technology