Prof. Masato Aketagawa Profile

Prof. Masato Aketagawa

Professor at Nagaoka Univ of Technology

SPIE Involvement:

Conference Program Committee | Author

Publications (18)

Proceedings Article | 21 June 2019 Presentation + Paper

Demodulation for sinusoidal frequency/phase modulation interferometer using artificial harmonic series signal and phase-locked loop

Masato Aketagawa, Masato Higuchi, Dong Wei

Proc. SPIE. 11056, Optical Measurement Systems for Industrial Inspection XI

KEYWORDS: Phase modulation, Modulation, Interferometers, Field programmable gate arrays, Demodulation, Frequency modulation

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A new demodulation method for sinusoidal frequency/phase modulation (SFM/SPM) interferometers using an artificial harmonic series signal and a phase-locked loop (PLL) is proposed in the paper. Utilizing a laser diode (LD) as the light source and an electric optic modulator (EOM), frequency/phase modulations of the LD light can be achieved by modulating the LD injection current or the driving voltage to the EOM. The SFM/SPM interference signals for the displacement measurement has have the form of cos(msinω_mt+θ), where m, ω_m and φ are a modulation index, a modulation frequency and a phase change due to optical path movement, respectively. Therefore, the SFM/SPM interference signals is composed by a series of harmonics of the modulation frequency. The two adjacent (2k and 2k+1: k is integer) harmonics include the displacement information. By using the two harmonics, a Lissajous diagram can be drawn to obtain the displacements. In the conventional way, the two harmonics can be demodulated by two lock-in amplifiers. In this paper, we propose new demodulation method for SFM/SPM interferometers using an artificial hormonic series signal and the PLL, which are installed in field programable gate array (FPGA), to obtain sub-picometer (μrad) resolution. An artificial hormonic signals with the form of sin(msinω_mt+θ) can be made virtually by the FPGA, where θ is the target phase controlled by the PLL. The output signal from the interferometer will be firstly digitized by the FPGA, and the digitized output signal and the artificial harmonic series signal are multiplied by a mixer, then the mixer output signal is inserted to a low pass filter (LPF). Then the LPF output signal should be -sin(φ-θ)~-(φ-θ) (if (φ-θ) is sufficiently small). In the system, modulation index should be fixed to some value. To set the LPF output signal (-(φ-θ)) to null, the target phase θ of the virtual artificial harmonic signal is controlled by the PLL. In the paper, we discuss the principle, experimental system and results.

SPIE Journal Paper | 20 November 2018

Phase information-assisted method to obtain position of zero optical path difference for a pulse-train interferometer

Dong Wei, Yusuke Nagata, Masato Aketagawa

OE Vol. 57 Issue 11

KEYWORDS: Interferometers, Mirrors, Michelson interferometers, Signal processing, Interferometry, Fringe analysis, Pulsed laser operation, Light sources, Fourier transforms, Communication theory

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Proceedings Article | 7 November 2018 Paper

Phase determination method for sinusoidal frequency/phase modulation displacement measuring interferometer

Masato Higuchi, Dong Wei, Masato Aketagawa

Proc. SPIE. 10819, Optical Metrology and Inspection for Industrial Applications V

KEYWORDS: Phase modulation, Modulation, Interferometers, Sensors, Phase measurement, Signal detection

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Proceedings Article | 6 November 2018 Paper

Direct phase determination using simple phase lock loop for heterodyne displacement-measuring interferometers

Thanh-Dong Nguyen, Quang-Anh Duong, Masato Higuchi, Wei Dong, Masato Aketagawa

Proc. SPIE. 10819, Optical Metrology and Inspection for Industrial Applications V

KEYWORDS: Phase modulation, Interferometers, Data storage, Interferometry, Phase shift keying, Field programmable gate arrays, Linear filtering, Heterodyning, Phase measurement, Phase shifts

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Proceedings Article | 2 November 2018 Paper

Selection of frequency domain filter based on match of different location-specific points

Dong Wei, Kenta Enoki, Masato Aketagawa

Proc. SPIE. 10819, Optical Metrology and Inspection for Industrial Applications V

KEYWORDS: Fringe analysis, Interferometers, Fourier transforms, Distance measurement

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Proceedings Article | 28 May 2018 Paper

Fast and precision displacement/3D profile measuring interferometers using sinusoidal frequency/phase modulation without lock-in amplifiers

Masato Aketagawa, Takehiro Nakagawa, Dong Wei

Proc. SPIE. 10695, Optical Instrument Science, Technology, and Applications

KEYWORDS: Phase modulation, Modulation, Interferometers, Image processing, Demodulation, Data acquisition, Frequency modulation, Signal detection

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Proceedings Article | 28 February 2017 Paper

Uncertainty change in length conversion affected by change in environmental parameters

Dong Wei, Masato Aketagawa

Proc. SPIE. 10256, Second International Conference on Photonics and Optical Engineering

KEYWORDS: Optical fibers, Refractive index, Femtosecond phenomena, Interferometers, Frequency combs, Optical communications, Fiber optic communications, Pulsed laser operation, Environmental sensing, Standards development

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Proceedings Article | 24 November 2016 Paper

Experimental investigation of correlation between surface amplitude parameters of frosted glass diffuser and size of polishing grit

Dong Wei, Tomoya Katagiri, Masato Aketagawa

Proc. SPIE. 10023, Optical Metrology and Inspection for Industrial Applications IV

KEYWORDS: Polishing, Optical properties, Glasses, Particles, Surface roughness, Diffusers, Abrasives, Mechanical engineering, Radium, Surface finishing

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Proceedings Article | 24 November 2016 Paper

Spindle error motion measurement using concentric circle grating and sinusoidal frequency-modulated semiconductor lasers

Masato Higuchi, Thanh-Tung Vu, Masato Aketagawa

Proc. SPIE. 10023, Optical Metrology and Inspection for Industrial Applications IV

KEYWORDS: Mirrors, Spindles, Optical sensors, Phase modulation, Modulation, Interferometers, Sensors, Semiconductor lasers, Frequency modulation, Motion measurement

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Proceedings Article | 24 September 2015 Paper

Sinusoidal frequency modulation on laser diode for frequency stabilization and displacement measuring interferometry

Masato Aketagawa, Thanh-Tung Vu, Ryo Yamazaki

Proc. SPIE. 9628, Optical Systems Design 2015: Optical Fabrication, Testing, and Metrology V

KEYWORDS: Modulation, Interferometers, Molecules, Semiconductor lasers, Frequency modulation, Laser stabilization, Iodine, Homodyne detection, Signal detection, Absorption

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Proceedings Article | 19 February 2015 Paper

Correction of group refraction index based on pulse trains interference

Dong Wei, Masato Aketagawa

Proc. SPIE. 9449, The International Conference on Photonics and Optical Engineering (icPOE 2014)

KEYWORDS: Optical fibers, Refractive index, Interferometers, Interferometry, Numerical simulations, Frequency combs, Humidity, Turbulence, Distance measurement, Temperature metrology

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Proceedings Article | 13 November 2014 Paper

Correction of refraction index based on adjacent pulse repetition interval lengths

Dong Wei, Masato Aketagawa

Proc. SPIE. 9276, Optical Metrology and Inspection for Industrial Applications III

KEYWORDS: Refractive index, Mirrors, Second-harmonic generation, Numerical simulations, Atmospheric corrections, Frequency combs, Humidity, Turbulence, Distance measurement, Harmonic generation

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SPIE Journal Paper | 9 September 2014

Two-color absolute length measuring method based on pulse repetition interval lengths

Dong Wei, Masato Aketagawa, Kiyoshi Takamasu, Hirokazu Matsumoto

OE Vol. 53 Issue 12

KEYWORDS: Mirrors, Refractive index, Distance measurement, Interferometers, Optical fibers, Second-harmonic generation, Frequency combs, Temperature metrology, Humidity, Optical testing

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SPIE Journal Paper | 11 July 2014

Analysis of the second harmonic generation of a femtosecond optical frequency comb

Dong Wei, Masato Aketagawa

OE Vol. 53 Issue 12

KEYWORDS: Second-harmonic generation, Harmonic generation, Frequency combs, Femtosecond phenomena, Signal detection, Optical amplifiers, Polarization, Dielectric polarization, Optical engineering, Optical fibers

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SPIE Journal Paper | 2 December 2013

Characteristics of an adjacent pulse repetition interval length as a scale for length

Dong Wei, Masato Aketagawa

OE Vol. 53 Issue 05

KEYWORDS: Refractive index, Neon, Standards development, Optical fibers, Environmental sensing, Frequency combs, Humidity, Protactinium, Optical testing, Laser stabilization

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Proceedings Article | 20 November 2012 Paper

Spindle error motion measurement using concentric circle grating and phase modulation interferometers

M. Aketagawa, M. Madden, S. Uesugi, T. Kumagai, Y. Maeda, E. Okuyama

Proc. SPIE. 8563, Optical Metrology and Inspection for Industrial Applications II

KEYWORDS: Diffraction, Mirrors, Spindles, Optical sensors, Phase modulation, Modulation, Interferometers, Motion measurement, Signal detection, Diffraction gratings

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Proceedings Article | 3 October 2008 Paper

Measurement of air-refractive-index fluctuation from frequency change using phase modulation homodyne interferometer and external cavity laser diode

Masato Aketagawa, Yuta Hoshino, Masashi Ishige, Tuan Banh Quoc

Proc. SPIE. 7155, Ninth International Symposium on Laser Metrology

KEYWORDS: Digital signal processing, Phase modulation, Interferometers, Sensors, Semiconductor lasers, Humidity, Laser stabilization, Homodyne detection, Environmental sensing, Temperature metrology

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