This Japanese security system deploys lasers against intruders

Directed-energy weapons have a long way to go until becoming a viable alternative to existing technology, but laser is already finding extensive use in various small-scale security systems, like the one detailed in a new patent filing from OPTEX Co. Ltd. of Japan published last week. The design marks a major evolution of automated intrusion prevention.

The basic idea is the same as for a speed gun, except instead of measuring the change of frequency in the returning signal to calculate how fast a car is going, the onboard scanner focuses on the delay from the initial transmission. It’s a surprisingly reliable way to gauge distance given the incredible speeds and time frames involved, but only when the laser hits the intended target.


The problem is not so much with accuracy as the fact that a security system operating all year round will inevitably come under bad weather like rain or snow that can interfere with the trajectory of the light pulse. The solution that OPTEX’s engineers have developed for that challenge is a self-correcting detection mechanism that can isolate and filter out such interference through interpolation.

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The system rotates the scanner on its axis and periodically emits a beam to create a fine-grained snapshot of its field of view that is continuously updated as the motion repeats itself. When a pulse is reflected from a distance shorter than the usual range of that particular vector, say off a raindrop, the firmware fires up its object recognition algorithms to replace the bad measurement and clear up the view.


Because the system fills in the interrupt pulse with data generated based on input from adjacent beams and previous rotation cycles, OPTEX’s signal correction technique works just as well on intruders whose cross section is partially obstructed during a storm. The technology could one day end up saving a lot of trouble for people and companies and with large outdoor properties to protect.

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