From Artur Knoth
In your Patents page (24 June), you had a piece about an “eye-friendly” version of a laser weapon that would destroy the video sensors of enemy cameras and night-sights. It was proposed in Britain by DASA (Deutsche Aerospace). One can’t help wondering whether part of DASA’s recent financial problems were partly due to its employees’ innovative thinking and management’s lack of oversight. Applying for a patent is not cheap, more so when the idea seems of little merit.
There is a time lag before the human eye can react to a stimulus it receives. To notice the warning blue-green light sent at 530 nanometres and blink (protecting the eye from the high-powered laser), more than 0.1 seconds must elapse. But any half-decent, though not necessarily expensive, camera will have a shutter with a reaction time well under this. Coupled with a cheap light-sensor chip, the shutter can be made to close automatically if any light shines on it outside a band that the main optical or IR sensor is intended to detect. The 530-nanometre pulse would set off this shutter tripwire, protecting the camera from the subsequent high-powered laser.
If you flash light at a someone, they may well tend to look directly at the source, out of human curiosity if nothing else. Even if soldiers are trained to look away, what about civilians? So the DASA idea won’t destroy cameras, but could well injure humans.
This is an obvious case of a technological solution that was not fully thought through, and which ignores any operational considerations. It is an old maxim that it is not worth investing in something where the obvious countermeasure is both simple and cheap.
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