Internal stress in material detracts from its usefulness. In this Letter, a stress measurement instrument is reported. The instrument principle is based on a laser feedback effect where the polarization state of the laser with an anisotropic feedback cavity will flip between two orthogonal directions, while the feedback mirror is tuned by piezoelectric transducer sawtooth voltage. The position of polarization flipping in one period on curves reflects the birefringence or material internal stress of the feedback cavity. Hence, when a piece of internal stress material is placed in a feedback cavity, its internal stress can be measured by the polarization flipping position. The internal stress of the vacuum tube, Nd:YAG crystal, and GaN semiconductor are measured, which proved this instrument has very high precision.
© 2012 Optical Society of America
Lasers and Laser Optics
Original Manuscript: March 15, 2012
Revised Manuscript: April 27, 2012
Manuscript Accepted: April 28, 2012
Published: June 18, 2012
Wenxue Chen, Shulian Zhang, and Xingwu Long, "Internal stress measurement by laser feedback method," Opt. Lett. 37, 2433-2435 (2012)