Product Code: ILSC2009_603

Phase Distortion Laser Safety Glasses for Protection against All Laser Wavelengths or All Laser Intensities
Authors:
David C. Smith, DCS Lasers & Optics LLC; Old Saybrook CT USA
Presented at ILSC 2009

Phase distortion laser safety glasses have been experimentally demonstrated and, based on the data, all wavelength protection of the retina is provided using glasses with an optical density (OD) of 3 (0.1% transmission)*. The concept is based on the fact that the laser light absorbed by the polycarbonate glass heats it and changes its index of refraction. A grid of varying transmission on the surface produces a non-uniform intensity in the glass. This non-uniformity results in a non-uniform phase distortion of the laser beam and does not allow the cornea to focus the laser strongly on the retina. The absorption of the polycarbonate is chosen to be the same for all wavelengths (sometimes referred to as a neutral density filter) and therefore the glasses protect at all wavelengths. Even though the all wavelength protection is highly desirable, the dark glasses may be unsatisfactory for some applications. Extrapolation of the data to glasses with better properties can reduce this value to an OD of 2 and this is discussed in detail. The phase distortion concept can also be used for multiple wavelength protection and will outperform presently available safety glasses. An additional significant application is to apply the phase distortion concept to existing single wavelength narrow band absorption safety glasses with no additional loss in visibility. The phase distortion kicks in at high intensities and never allows retinal damage. A concept for applying a thin film to existing safety glasses for adding the phase distortion is discussed. All concepts discussed in this paper meet ANSI standards.

* Smith, D.C., Agile Laser Safety Glasses for Protection Against Continuous Wave Laser Sources, SPIE Proceedings, Vol. 6426, Paper 2E-1, Jan. 2007.