TY - JOUR
T1 - A chromatic confocal probe with a mode-locked femtosecond laser source
AU - Chen, Xiuguo
AU - Nakamura, Taku
AU - Shimizu, Yuki
AU - Chen, Chong
AU - Chen, Yuanliu
AU - Matsukuma, Hiraku
AU - Gao, Wei
N1 - Funding Information:
This research was supported by Japan Society for the Promotion of Science (JSPS). The authors thank Prof. Kazuhiro Hane (Tohoku University, Japan) for his helpful comments on our paper.
Publisher Copyright:
© 2018 Elsevier Ltd
PY - 2018/7
Y1 - 2018/7
N2 - The high spatial coherence and high stability of a mode-locked femtosecond laser source make it ideal for chromatic confocal imaging. Nevertheless, the high non-smoothness of spectrum of the mode-locked laser source often restricts its application in chromatic confocal probes for a wide range of depth measurement. To eliminate the spectral non-smoothness of the mode-locked laser source, we propose a new chromatic confocal setup in such a way that the reflected laser beam is divided into two sub-beams which are then made to pass through two optical paths with different confocal settings where two identical fiber detectors are placed at the focal position and a defocus position, respectively, for acquiring two confocal signals. An axial response is then obtained from the intensity ratio of the two confocal signals for depth measurement. With the proposed confocal setup, we can expand the working spectral range of a mode-locked laser source to its whole spectrum. Theoretical and experimental investigation have revealed that the developed chromatic confocal probe with the specific mode-locked laser source employed in experiments has a measurement sensitivity of about −4 nm/μm, a depth measurement range of about 40 μm, and a depth resolution of better than 30 nm, respectively.
AB - The high spatial coherence and high stability of a mode-locked femtosecond laser source make it ideal for chromatic confocal imaging. Nevertheless, the high non-smoothness of spectrum of the mode-locked laser source often restricts its application in chromatic confocal probes for a wide range of depth measurement. To eliminate the spectral non-smoothness of the mode-locked laser source, we propose a new chromatic confocal setup in such a way that the reflected laser beam is divided into two sub-beams which are then made to pass through two optical paths with different confocal settings where two identical fiber detectors are placed at the focal position and a defocus position, respectively, for acquiring two confocal signals. An axial response is then obtained from the intensity ratio of the two confocal signals for depth measurement. With the proposed confocal setup, we can expand the working spectral range of a mode-locked laser source to its whole spectrum. Theoretical and experimental investigation have revealed that the developed chromatic confocal probe with the specific mode-locked laser source employed in experiments has a measurement sensitivity of about −4 nm/μm, a depth measurement range of about 40 μm, and a depth resolution of better than 30 nm, respectively.
KW - Chromatic confocal microscopy
KW - Fiber-based confocal microscopy
KW - Mode-locked lasers
UR - http://www.scopus.com/inward/record.url?scp=85041460742&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85041460742&partnerID=8YFLogxK
U2 - 10.1016/j.optlastec.2018.01.051
DO - 10.1016/j.optlastec.2018.01.051
M3 - Article
AN - SCOPUS:85041460742
VL - 103
SP - 359
EP - 366
JO - Optics and Laser Technology
JF - Optics and Laser Technology
SN - 0030-3992
ER -