Determination of a CO2 laser beam profile using a Smartphone camera

• Published in: Revista Brasileira de Ensino de Física Vol. 46
• Main Authors: Paula, Gabriel de Toledo, Ribeiro, Nicolas, Cabral, Jader de Souza, Menegatti, Carlos Renato
• Format: Journal Article
• Language: English; Portuguese
• Published: Sociedade Brasileira de Física 2024
• Subjects: beam profile; CO2 laser; knife-edge; Smartphone camera
• DOI: 10.1590/1806-9126-rbef-2023-0370
• ISSN: 1806-1117

Lasers find extensive applications across a spectrum from academic research to industrial use. In various instances, understanding the intensity profile of laser light is of paramount importance, specifically how its intensity changes along its propagation path. In this study, we introduce an economical and alternative technique for determining the waist of a Gaussian laser beam, leveraging the capabilities of a Smartphone camera. Our methodology entails directing a CO2 laser onto a thermochromic liquid crystal sheet for specific exposure duration, resulting in a color pattern that evolves over time. This evolving pattern is captured by a Smartphone camera, and selected frames from the recording are processed and analyzed to quantify the beam’s waist, denoted as w ( z ). Our measurements are compared with those obtained through the traditional knife-edge method, demonstrating a substantial degree of agreement. Furthermore, by interpolating the waists calculated through our approach, we were able to ascertain the beam waist at the focus and the focal point of a converging lens, yielding results consistent with the reference method. Our findings underscore the viability of this approach as a cost-effective alternative for characterizing Gaussian beams, with potential applications in optics, laser technology, and studies related to light propagation.