Abstract: In an optical supply arrangement, a laser source (10) provides transmitted laser light down an optical supply line (12, 14). A first coupler (16), remote from the laser source (10) along the optical supply line (14), taps off a small proportion of the transmitted laser light to be returned along the optical supply line (14) to a photo detector (26) driving a monitor (28) and a controller (30). If the monitor (28) detects that the photo detector (26) is experiencing a loss of return laser light, possibly due to a break in the optical supply line (14), the monitor (28) causes the controller (30) to extinguish the laser source (10) in less time than escaping laser light can cause damage to property, person or eyesight. A first embodiment has the transmitted light on a transmission fiber optic (12) and the return laser light on a separate return fiber optic (24). A second embodiment has the return laser light being sent back down the transmission fiber optic (12).

Abstract: A selective optical actuation system for a plurality of electrical devices (20) comprises a variable pulse frequency pulsed light source (10) and an optical fibre network (12, 13, 14) distributing the light pulses to actuation gateway for each device, comprising a photovoltaic converter (16) whose correspondingly pulsed electrical output is applied to a ferroelectric transformer (18). Only if the pulse frequency is within the resonant band for a given transformer will the voltage be raised above a threshold value required to actuate that device. Choice of light pulse frequency thereby determines the device(s) to be actuated.

Abstract: In an optical supply arrangement, a laser source (10) provides transmitted laser light down an optical supply line (12, 14). A first coupler (16), remote from the laser source (10) along the optical supply line (14), taps off a small proportion of the transmitted laser light to be returned along the optical supply line (14) to a photo detector (26) driving a monitor (28) and a controller (30). If the monitor (28) detects that the photo detector (26) is experiencing a loss of return laser light, possibly due to a break in the optical supply line (14), the monitor (28) causes the controller (30) to extinguish the laser source (10) in less time than escaping laser light can cause damage to property, person or eyesight. A first embodiment has the transmitted light on a transmission fibre optic (12) and the return laser light on a separate return fibre optic (24). A second embodiment has the return laser light being sent back down the transmission fibre optic (12).