Research results

Papers

[2024]

• Yohan Kondo, Akiko Hirai, Toshiharu Katsube, Natsumi Kawashima, and Youichi Bitou, "Two-point diameter calibration of a sphere by a micro-coordinate measuring machine using a silicon gauge block as a reference standard," Precision Engineering, 92, 167 (2025).
• Natsumi Kawashima, Yohan Kondo, Akiko Hirai, and Youichi Bitou, "Novel analysis of alignment error on spherical Fizeau interferometer and uncertainty evaluation of sphericity calibration system based on random ball test," Optics and Lasers in Engineering, 184, 108646 (2025).
• Yasuaki Hori and Satoshi Gonda, "Error investigation for SI traceable pitch calibration of one-dimensional grating by grazing-incidence small-angle X-ray scattering," Measurement, 225, 114036 (2024).

[2023]

• Yasuaki Hori, "Quantitative evaluation and removal of periodic error caused by ghost reflections in a double-path homodyne interferometer," Measurement Science and Technology, 34, 025011 (2023).

[2022]

• Yohan Kondo, Akiko Hirai, Toshiharu Katsube, Natsumi Kawashima, and Youichi Bitou, "Two-point diameter calibration of a sphere using a micro-coordinate measuring machine at NMIJ," Metrologia, 59, 024005 (2022).

[2021]

• Akiko Hirai, Youichi Bitou, Jaeseok Bae, Jungjae Park, and Jonghan Jin, "Precise measurement of the thickness of silicon wafers by double-sided interferometer and bilateral comparison," Metrologia, 58, 054002 (2021)

Reviews, books, etc.

[2024]

• Yohan Kondo, Akiko Hirai, Natsumi Kawashima, and Youichi Bitou"Achieving the World's Highest Level of Accuracy in Sphere Diameter Measurement", AIST press release, January 27, 2025. (Summary of AIST press release on December 16, 2024 in English)
• Natsumi Kawashima, Yohan Kondo, Akiko Hirai, and Youichi Bitou, "High-precision Calibration of the Surface Profile of Reference Spherical Lenses", AIST press release, December 27, 2024. (Summary of AIST press release on November 28, 2024 in English)

Conference presentations

[2024]

• Shusei Masuda, Yohan Kondo, Akiko Hirai, Youichi Bitou, "Scanning deflectometric profiler based on self-calibrationg rotary encoder", IMEKO 2024 XXIV World Congress, August 2024.

Lectures etc.

[2024]

• Akiko Hirai and Youichi Bitou, "Double-sided Interferometer for SI-traceable Thickness Measurement", CLEO Pacific Rim, August 2024.
• Akiko Hirai and Youichi Bitou, "Double-sided interferometer for precise thickness measurements", Optical Technology and Measurement for Industrial Applications (OPTM), Optics and Photonics International Congress (OPIC) 2024, April 2024.

[2021]

• Akiko Hirai, "Precise measurement of the thickness of silicon wafers and bilateral comparison," PRESM2020, November, 2020.