[sci.electronics] Security systems using fiber optic cable

siegman@sierra.STANFORD.EDU (siegman) (06/05/90)

It's always seemed to me that fiber optic cables as security systems
(if anyone cuts the cable the loss of transmission is sensed) would be
a GREAT idea, with or without accompanying mechanical security (cable,
chain, etc.), for computers, bicycles, womens' purses in offices,
whatever.  Necessary electronics is cheap and simple, as are
fiber-optic plug-in connections for making and breaking the fiber loop
around or through the protected unit.  Such units could easily be
battery-powered for portable units, and could set off a loud alarm or
a silent alarm, on the protected unit or in an adjacent building.

Tapping into an optical fiber may or may not be easy (the fiber is
normally encased in some kind of covering, and you'd have to cut into
this, right up very close to the fiber itself, without cutting the
fiber, which would NOT be easy); but it's irrelevant.  Even if you
could tap the fiber, so what? -- bypassing the fiber or splicing to it
and coupling in a bypass signal is a laboratory task, not something
you can do in the field, while ripping off a bike or computer.

I'd also like to see a lot more stuff protected by silent alarms --
thief grabs the stuff, alarm goes off inside somewhere, you try to
catch the guy and put him out of business.  Our campus is plagued by
bike thieves who obviously grab a bunch of bikes, and depart in trucks
with them.  I really don't understand why we don't have more
stakeouts, and catch these guys.