That is a good solution! But put an interlock on the door anyway. Costs nothing, and is a belt and braces precaution.
My experience is with pulsed IR lasers, which of course you cannot see. Had to be careful to keep fingernails out of the beam, because that particular laser would blow a fingernail off. Frequency doubled into the green it used to attract flies and wasps, which would explode spectacularly.
An interesting calculation was that a single pulse from that laser, if divided up evenly and without losses, was enough to cause eye damage to the population of London.
It ran at 30 pulses per second.