As far as hazards from visible optical radiation are concerned physiological protective reactions are important. An infrared videography test for 5 different wavelengths (405 nm, 445 nm, 532 nm, 635 nm and 670 nm) under twilight conditions for laser beam powers between 0.1 nW and about 0.8 mW has been conducted. With the participation of several test persons it has been shown that the diameter reduction of the pupillary reflex does not really protect against a possible overexposure within the first quarter of a second. Especially for short exposures the latency period between 160 ms and 340 ms and the respective constriction durations are too long in order to protect efficiently. The relative amplitudes of the pupil diameter depend on the wavelength. Short wavelengths showed a stronger pupillary reaction than could be expected from the spectral sensitivity function.
Temporary blinding might cause remarkable indirect effects. The quantitative reading impairment and the acuity disturbance have been determined with test persons at 5 different wavelengths (405 nm, 445 nm, 532 nm, 635 nm and 670 nm). It was found that the disturbance is mainly in accordance with the spectral sensitivity function as far as the time duration of impairment is concerned. Time durations between about 3 s for 405 nm and about 30 s for 532 nm were measured in the laser beam power range from 1 nW to about 700 µW, when the exposure duration was chosen to be 100 ms.
The investigations have shown that already with a beam power level of about 1 µW impairment durations of more than one second have to be expected.
Based on the functional relationship a consideration for glare from visible laser radiation has been developed in order to forecast the impairment duration to a given exposure duration and laser beam power captured from the eye. In addition an analysis of potentially hazardous situations arising from temporary blinding was performed for several workplaces, e. g. pilots in an aircraft or helicopter, and tested in cockpit simulations.
As well as for the pupillary reflex, acuity impairment due to temporary blinding showed strong individual differences.
Please download the complete report "Glare from artificial optical radiation under twilight conditions" (in German only).
H.-D. Reidenbach, K. Dollinger, D. Beckmann, I. Al Ghouz, G. Ott, M. Brose:
Blendung durch künstliche optische Strahlung unter Dämmerungsbedingungen.
1. edition. Dortmund: Bundesanstalt für Arbeitsschutz und Arbeitsmedizin 2014.
ISBN: 978-3-88261-024-6, pages 407, Project number: F 2310, PDF file, paper
© Federal Institute for Occupational Safety and Health