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Effectiveness of Laser Safety Eyewear under Real-World Conditions

Published

Author(s)

Christopher J. Stromberg, Edwin J. Heilweil, Joshua A. Hadler

Abstract

Ultrafast lasers have become increasingly important as research tools in chemistry, which means laser safety is becoming more important. Laser safety glasses represent the last line of defense to protect users from potentially life-altering eye injuries. Laser safety glasses are rated by their optical densities (OD) over different spectral ranges, but OD measurements are usually made under low power, large beam size, and continuous beam conditions, which are vastly different than the high power, small beam size, and pulsed conditions found in the lab. Ultrafast lasers additionally have extremely high peak powers and broad spectra, due to the short duration of the pulses. Many solid state lasers are also tunable over a broad wavelength range, further complicating the selection of adequate laser safety glasses. Samples of laser eyewear filters were tested under real-world conditions using a 50 femtosecond, 80 MHz Ti:Sapphire oscillator and 1 kHz Ti:Sapphire regenerative amplifier centered at 800 nm. With the oscillator, the broadband nature of the pulses meant that the effective OD of the samples were often significantly lower than the rated OD at 800 nm, as the filters often were ineffective at blocking the entire bandwidth of the pulse, letting wings of the laser pulses through. Many of the samples also damaged even under relatively low powers generated by the oscillator. Additional tests at higher peak powers were conducted using the regenerative amplifier. While some samples maintained their integrity under the test condition, many showed signs of failure. Often, those failures reduced the optical densities of the samples, in some cases letting 4-5 orders of magnitude more light through than expected. In general, glass filters performed significantly better than plastic filters, showing both less physical damage to the substrate and less degradation of the absorbers.
Proceedings Title
255th Annual Meeting of the American Chemical Society
Conference Dates
March 18-23, 2018
Conference Location
New Orleans, LA, US

Keywords

Laser Eyewear, femtosecond lasers, laser safety, optical density

Citation

Stromberg, C. , Heilweil, E. and Hadler, J. (2018), Effectiveness of Laser Safety Eyewear under Real-World Conditions, 255th Annual Meeting of the American Chemical Society, New Orleans, LA, US, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=925546 (Accessed March 1, 2024)
Created March 18, 2018, Updated October 14, 2021