Calculating laser eyewear effective OD and VLT using manufacturer OD curves

Abstract

Spectral bandwidth (SB) of ultrashort laser pulses (under 100 fs) in commonly used near-IR range can be tens of nanometers. When selecting laser eyewear for use with ultrashort pulses, the “effective” optical density (ODeff) should be calculated from a convolution of the spectral curve for the filter transmission with the spectrum of the laser pulse. We present model calculations of ODeff curves (ODeff versus wavelength) for selected commercial eyewear filters at different pulse durations, assuming a gaussian laser spectrum.Visible light transmission (VLT) is another important laser eyewear characteristic. We use the definition for photopic luminous transmission in the Z136.7-2008 standard to calculate VLT values by convoluting the manufacturer transmission curves with the photopic luminous efficiency function and the spectrum for a CIE Standard Illuminant C source that approximates average daylight over the visible range. We then compare the calculated VLT with what the manufacturers provide and with “lab VLT” measurements that we have made using a light meter and a source provided by standard lab fluorescent or LED lighting.Spectral bandwidth (SB) of ultrashort laser pulses (under 100 fs) in commonly used near-IR range can be tens of nanometers. When selecting laser eyewear for use with ultrashort pulses, the “effective” optical density (ODeff) should be calculated from a convolution of the spectral curve for the filter transmission with the spectrum of the laser pulse. We present model calculations of ODeff curves (ODeff versus wavelength) for selected commercial eyewear filters at different pulse durations, assuming a gaussian laser spectrum.Visible light transmission (VLT) is another important laser eyewear characteristic. We use the definition for photopic luminous transmission in the Z136.7-2008 standard to calculate VLT values by convoluting the manufacturer transmission curves with the photopic luminous efficiency function and the spectrum for a CIE Standard Illuminant C source that approximates average daylight over the visible range. We then compare the calculated VLT with what the manufacturers provide and with “la...