YAMAGIWA, Masatomo; MINAMIKAWA, Takeo; TROVATO, Clément; OGAWA, Takayuki; IBRAHIM, Dahi Ghareab Abdelsalam; KAWAHITO, Yusuke; OE, Ryo; SHIBUYA, Kyuki; MIZUNO, Takahiko; ABRAHAM, Emmanuel; MIZUTANI, Yasuhiro; IWATA, Tetsuo; YAMAMOTO, Hirotsugu; MINOSHIMA, Kaoru; YASUI, Takeshi

doi:10.1364/OE.26.026292

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YAMAGIWA, Masatomo

MINAMIKAWA, Takeo

TROVATO, Clément
Université de Bordeaux [UB]

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Opt.express. 2018, vol. 26, n° 20, p. 26292-26306

Résumé en anglais

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.< Réduire

Mots clés en anglais

Distributed feedback lasers

Fourier transform interferometry

Phase measurement

Phase noise

Spatial light modulators

Tunable diode lasers

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Multicascade-linked synthetic wavelength digital holography using an optical-comb-referenced frequency synthesizer

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