COMPARISON OF AFTERIMAGE FORMATION AND TEMPORARY VISUAL ACUITY DISTURBANCE AFTER EXPOSURE WITH RELATIVELY LOW IRRADIANCE LEVELS OF LASER AND LED LIGHT

摘要

It is well-known that dazzle, flash-blindness and afterimages may be caused by bright visible optical radiation, but functional relations are not a matter of common knowledge up to now.rnSince there exist several work areas and places where it might become very important not to be impaired to much as far as visual acuity, contrast sensitivity and color vision are concerned, like working with machines or at height, with high voltages, driving a vehicle or flying an aircraft, it was the goal of a study to determine the most important relationships and to compare laser and LEDs as far as the capability of temporary blinding is concerned.rnTwo different laser devices, namely a helium-neon laser (632.8 nm), and a frequency-doubled Nd:Yttrium Vanadate laser (Nd:YVO_4 laser, 532 nm) as well as 4 different so-called high brightness LEDs (HB-LEDs) (red, green, royal blue, and white) have been applied as a dazzling light source. The maximum power levels which have been used were kept at least 20 percent below the maximum permissible exposure limits in the case of laser radiation and a factor of 8 up to 20 as far as LED radiation is concerned.rnA total of 19 persons have been tested with laser light and 26 with LEDs. The exposure duration was chosen between 0.25 s and 10 s and various optical power levels have been adjusted. The resulting temporary impairment was determined either with a standard visual acuity measuring system or in a specially developed computer-assisted reading test. Especially the respective disability threshold as a function of exposure duration has been searched and wavelength-dependent values have been found for both laser and LED radiation.rnThe received functional relationships might be used for the derivation of protection limits as far as indirect effects like temporary blinding are concerned.