Sixth Case

In a French laboratory, a PhD student was making adjustments on an experiment, in which a beam was briefly directed perpendicularly to the desk by a 45° mirror. During the experiment, the operator had to adjust the beam to be perfectly vertical towards the ceiling, and then to propagate through a vacuum chamber. For this alignment, he closed the shutter at the output port of the laser in order to work perfectly safely. As he believed himself not subjected to any hazard, he took off his goggles and placed his eye right on the vertical of the vacuum chamber, in the trajectory of the beam. Due to a technical problem, the beam shutter briefly opened and sent one laser pulse, which propagated straight to the eye of the operator. Consequently, his macula was destroyed. After the accident, he went to opthalmologic exams. The result was that he had lost about 30% of his visual acuteness, and that a blind area was situated at the center of his sight. These were irreversible injuries. However and with the help of time, the brain is able to correct this blind area.

Although this accident was due to a technical problem and not to a mistake by the student, it illustrates the fact that one must always be cautious, even if one believes oneself not exposed to any hazard. The student shouldn't have taken his safety goggles off, even in the absence of the beam.