Risks associated with laser radiation reflections in a healthcare environment: a surface reflectance study in the range 250 nm – 25 μm

Abstract

Biomedical applications relying on optical radiation, particularly with the advent of lasers, have experienced exponential growth in the last 20 years. Powerful optical sources are now found not only in universities, hospitals, and industries but also in beauty centers, used for tasks such as tattoo removal, and even in our homes. Despite their widespread use, managing the risks associated with lasers, particularly in non-research contexts, has not kept pace with their proliferation. While the risks associated with direct exposure to radiation to the eye and skin are relatively well understood, the hazards posed by reflected and diffuse radiation remain less characterized and monitored. Therefore, there is a critical need to assess potential eye and skin hazards in spaces where lasers and non-coherent light sources are used. This necessitates a detailed analysis of reflective surfaces, with particular emphasis on evaluating their reflectance characteristics at relevant wavelength ranges. This study investigates the reflectance and transmittance (where relevant) properties of commonly used materials in biomedical settings, including fabrics, plastics, and metals, across a broad spectrum from 250 nm (UVA) to visible light and into the infrared (IR) region up to 25 μm. Both specular (at 45° incidence) and diffuse reflectance spectra were measured using spectrophotometric techniques and used to provide a straightforward parameter to classify the specular/diffusive behavior of the different surfaces. Besides, small-angle reflectance measurements in the IR range were performed by Fourier transform infrared spectrometry. The knowledge of the material optical properties used in environments where optical radiation is employed allows for accurate assessment of associated risks. This facilitates the determination of appropriate preventive measures and the establishment of safer protocols, for both operators and, where applicable, patients and the general public. For this scope, the creation of a database of material reflective properties has been initiated.