In-process OCT monitoring to control holographic laser processing

A holographic technique is useful for increasing the processing speed in laser grooving and scribing. In laser grooving, depth control of the processed structure is important for performing precise processing. In this paper, in-process monitoring of the depth of a structure formed by femtosecond laser processing with a line-shaped beam using swept-source optical coherence tomography (SS-OCT) was demonstrated. In laser grooving, the structural depth and the shape were successfully monitored. The proposed method will be effective for precise laser processing with feedback control of the laser parameters based on in-process monitoring of the processed structure.