Publication Details

H. Wang, Y. Ruan, L. Cao, Y. Yu, J. Xi, Q. Guo, J. Tong & J. Zhang, "Profile measurement using a self-mixing laser diode," in Semiconductor Lasers and Applications VIII, 2018, pp. 1081211-1-1081211-8.


When a fraction of external optical feedback re-enters inside cavity of a laser diode (LD), the laser intensity and its wavelength will thus be altered. The LD in this case is often called as a self-mixing laser diode (SMLD). This paper presents an SMLD for profile measurement. The LD is modulated by the injection current in triangular waveform and a target to be measured is installed on a mechanic scanning device. The reflection light by the target contains its surface profile. The profile information is then carried in the laser intensity and can be pickup by a photodiode packaged in the rear of the LD. We call this modulated laser intensity as self-mixing interferometric (SMI) signal. In this paper, a new algorithm is developed to retrieve the profile from the SMI signal. Results show that the proposed design is able to achieve the measurement of profile with high resolution.



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