TABLE OF CONTENTS Any laser can present dangers to man, both at an ocular level and a cutaneous level. In this section, we do not mention the cutaneous effects, because the energy levels of FSO equipment do not present a significant risk for the skin. However, the human eye is very sensitive to infrared radiation.
Table 7-1 shows the various effects for three ranges of wavelength.
| Wavelength | 550 700 nm | 700 1000 nm | 1500 1800 nm |
|---|---|---|---|
| Emission | visible-red | near-infrared IR-A | far-infrared IR-B |
| Cutaneous effects | no significant effects | ||
| Eye | percentage transmission and absorption of a laser signal | ||
| Transmission | 90% | 50% | 0% |
| Absorption | retina: 90 % | cornea: 0% vitreous humor: 50% | cornea: 90% aqueous humor: 10% |
| Attack of the eye (for thresholds that exceed MPE *) | retina: heating, burns, lesions limited but irreversible | retina: heating, burns, lesions limited but irreversible. crystalline lens: potential lesion | Cornea: potentially opacifying |
The important factors to take into account in order to evaluate the risks are: the signal wavelength, the powers encountered, and the beam form. The characteristics of the various factors of infrared radiation have been studied in depth and there are rules linked to their use or handling. The standards in force in France are (AFNOR - CEI, 1993 and 1994):
NF IN 60825-1: safety of laser apparatus - Part 1: materials classification, regulations and user guide...
