Study on laser spot size measurement by scanning-slit method based on back-injection interferometry

Yuanfu Tan; Wei-hsin Liao; Hay Wong

doi:10.1117/12.3009802

20 June 2024 Study on laser spot size measurement by scanning-slit method based on back-injection interferometry

Yuanfu Tan, Wei-hsin Liao, Hay Wong

Proceedings Volume 13002, Semiconductor Lasers and Laser Dynamics XI; 130020K (2024) https://doi.org/10.1117/12.3009802
Event: SPIE Photonics Europe, 2024, Strasbourg, France

Abstract

Spot size is an important parameter of the laser, which not only represents the resolution of laser, but is also involved in the calculation of other parameters. Nowadays, CCD imaging systems, scanning imaging systems, and other sensors are used to measure the laser spot size. But they are all lacking flexibility when measuring the spot size in different locations, not to mention their high cost. In this study, a new spot size measurement device based on laser back-injection interferometry was presented. The photodiode integrated with the laser diode was used to collect the feedback laser, then the laser spot size was calculated by the feedback current. A commercial CCD imaging system was used to provide the laser spot size as a reference. Results show that our spot size measurement device could measure the spot size (Full Width Half Maximum) of 5 laser diode modules both in the x (Gaussian-like profile) and y (top-hat-like profile) direction through scanning-slit. Though there are variations between the scanning-slit results and spot sizes from the CCD imaging system due to the diffuse and specular reflection, the accuracy of the spot size measurement device ranges from 96.07 % to 99.46 %, which proves the reliability of our device. It is believed that our device could provide an alternate method for laser spot size measurement, which is cost-effective, easy to operate, and accurate.

Conference Presentation

(2024) Published by SPIE. Downloading of the abstract is permitted for personal use only.

Citation Download Citation

Yuanfu Tan, Wei-hsin Liao, and Hay Wong "Study on laser spot size measurement by scanning-slit method based on back-injection interferometry", Proc. SPIE 13002, Semiconductor Lasers and Laser Dynamics XI, 130020K (20 June 2024); https://doi.org/10.1117/12.3009802

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