Novel microscopy based on simultaneous utilization of third harmonic generation and photoluminescence 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 profilometry. 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 [B. Khalil, M. A. Nasr, A. Ali and M. S. El-Shahat, J. Mater. Sci., 2025, 60, 3333–3345]. In this work, we used 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⁻¹, the technique enabled us to conduct rapid studies of imaging the sample surface with a few tens of 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 films, while testing the optical quality of the thin films. THG profilometry 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.