Articles
Publication Date: 2025
Optics Express (10944087)33(10)pp. 21393-21412
We introduce what we believe to be a novel machine learning (ML)-based ResNet algorithm for predicting gas pressure from spectral imagery, eliminating the need for traditional peak fitting. Evaluated using simulated and experimental carbon monoxide (CO) spectra, the model accurately predicts pressures across a wide range (1 mbar - 2 bar), even with noisy data, outperforming conventional methods like PeakFit. The ResNet model demonstrates minimal discrepancies between predicted and actual pressures, achieving a mean absolute error (MAE) of 0.095 and mean squared error (MSE) of 0.009 in simulations, and maximum MAE of 1.2×10−2 and MSE of 1.46×10−4 experimentally below 94 mbar. This approach significantly enhances quantitative spectroscopy by focusing on line shape imagery, showing promising applications in atmospheric science, industrial monitoring, and environmental research. This work is a substantial improvement over our previous models. © 2025 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.
Publication Date: 2025
Journal of Optics (United Kingdom) (20408986)27(8)
This study presents a temperature-tunable liquid lens utilizing silicon oil (SO) to achieve precise focal length modulation without requiring mechanical displacement of the sample, typically required in conventional z-scan methodologies. The lens was fabricated by injecting SO into a cavity formed between two convex glass substrates, with temperature varied from 20 °C to 130 °C to enable a focal length tuning range from 69.30 mm to 77.78 mm, corresponding to an overall change of 8.48 mm. Key performance metrics include a focal length resolution of 7.2 × 10−2 mm, temperature sensitivity of 1 °C, and demonstrated long-term stability under repeated thermal cycling. The lens’s functionality was validated within a z-scan setup, where it replaced fixed-focal-length optics to eliminate sample translation along the z-axis. Nonlinear refractive index measurements of silver nanoparticles dispersed in distilled water at a concentration of 13 mM yielded a value of (−1.03 ± 0.08) × 10−7 cm2 W−1 using the proposed tunable lens, closely matching (−0.97 ± 0.06) × 10−7 cm2 W−1 obtained via the conventional z-scan method. The proposed approach provides a practical modification to the classical Z-scan technique by allowing real-time focal control, which can simplify experimental procedures and potentially improve measurement accuracy. © 2025 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.
