First Case

In a French laboratory, a researcher was exposed to the diffused radiation from a class 4 laser source.

The research institute had nevertheless taken some precautions in order to prevent laser accidents. Indeed, the source was situated in a closed room, whose access was restricted to a few trained persons. The accident occurred in a neighbouring room. The beam was sent from one room to the other through a small hole through the wall. By this mean, the same source could be used simultaneously for several experiments (presently, two other rooms were connected). However, these holes were not protected by protective caps allowing to shut the beam off when the experiments were not in use. So, the room was never freed from laser hazard.

In the present case, a researcher was retrieving experimental data in one of the rooms, without intending to work on the experimental setup. However, he never thought that somebody may be working in the other room, and that the laser may thus be working. He wasn't wearing his safety goggles, although they were correctly placed at the entry of the laboratory.

The laser beam sent to his room was regrettably being reflected by a mirror towards a plastic poster. When the researcher came near this poster, he observed two circular spots on it. The first one was due to the laser beam itself, which he thus didn't look at for long, while he was intrigued by the second one, from unknown source, and then observed it a longer time. After having observed this white spot more than ten seconds, he got bedazzled. Four hours later, a bright spot had appeared in his left eye sight.

We need to remember the following points concerning this accident :

• The research institute had isolated the source in order to prevent that kind of accidents. Still, a protective cap should have been placed on each hole, allowing one to close it when the beam was not in use.

• A light signal should have been placed at the entry of the room, allowing one to be immediately aware of the presence of laser radiation in the room. If this had been done, the researcher would have been wearing the protective goggles adapted to the wavelength and power of the laser beam.

• The present accident could have happened even if the researcher were aware of the presence of a laser beam in the room he was entering. Indeed, the highly diffusing poster shouldn't have been placed at the same level as the laser beam, but should have been isolated from it.

• The laser power should be tunable, so that the operator doesn't bring hazard upon himself when not necessary.