Damage thresholds for scanned exposure of the retina

Laser products that emit scanned laser radiation produce a pulsed exposure of the eye, as well as, depending on the accommodation state of the eye, a scan pattern on the retina. IEC 60825-1 does not provide guidance on how to consider the scanned retinal exposure for product safety classification. We discuss the general approach for product classification based on retinal scanning. The hazard relative to the non-scanning case can be characterised with a retinal thermal injury model that was developed at the Austrian Research Centers Seibersdorf. Depending on the laser beam diameter on the deflector and the scan parameters, the allowed output power for “safe” laser classes such as Class 2 or Class 1 can be greatly increased when compared to the assumption of a non-scanning retinal exposure.