Novel Microscope based on simultaneous utilization of Third Harmonic Generation (THG) Microscopy and Photoluminescence (PL) Microscopy for Thin Film Analysis and Molecular Detection

Abstract

We report results on a new approach to optical techniques based on third harmonic generation (THG) microscopy, photoluminescence (PL) microscopy, and third harmonic generation profilometers. Our approach focuses on the generation of third harmonic signals in photoactive samples, such as perovskite thin films and microchannel glass substrates, which were used in EMI shielding experiments [J Mater Sci 60, 3333–3345 (2025)]. In this work, we use high-repetition-rate femtosecond laser pulses as the source for generating THG and PL signals in the test samples. With high-speed scanning at 1000 mm/s, the technique enabled us to conduct rapid studies of imaging sample surface with few of ten micrometre resolutions, completing measurements within a few minutes over a 2×2 mm² area. Additionally, we analyzed the composition of the perovskite samples through PL signals generated in thin film, while testing the optical quality of the thin films. THG profilometer measurements were performed on micromachined glass substrates prepared for EMI shielding. The 3D profiles obtained by our method were reliable and comparable to those acquired using interference-based optical profilometers. High-quality 3D profiles of the samples with spacings of 200 µm and 400 µm were successfully obtained.