[OPTICAL REVIEW Vol. 14, No. 6 (2007) 362-364]
© 2007 The Optical Society of Japan

Monitoring of Paint Drying Process by Digital Speckle Correlation

Ichirou YAMAGUCHI*, Masayuki YOKOTA, Takasi IDA, Mizuki SUNAGA, and Koichi KOBAYASHI1

Department of Electronic Engineering, Faculty of Engineering, Gunma University, Kiryu, Gunma 376-8515, Japan
1Toyo Seiki Seisaku-sho, Ltd., 1-2-6 Funado, Itabashi-ku, Tokyo 174-0041, Japan

(Received January 31, 2007; Accepted May 29, 2007)

The state of drying paint is monitored from the dynamic behaviors of the speckle pattern arising from laser illumination of the region inspected. Temporal variation of the peak height of the cross-correlation function between successive frames taken with a fixed interval is plotted until the peak maintains a stationary maximum value. We used a speckle pattern in the diffraction field for monitoring of a single region and that in the image field for simultaneous monitoring of various regions. Both the normal and the phase-only algorithms were compared for cross-correlation computation. The former showed more distinct variation of peak height.

Key words: digital speckle correlation, paint drying process, noncontact

*E-mail address: ichiyama@el.gunma-u.ac.jp