Schlumberger Technology Corporation

James McInnes

Arthur H Hartog

Maxwell Richard Hadley

Yuehua Chen

Timothy Jeffreys

Derek Nigel Leggett

In an optical supply arrangement, a laser source () provides transmitted laser light down an optical supply line (). A first coupler (), remote from the laser source () along the optical supply line (), taps off a small proportion of the transmitted laser light to be returned along the optical supply line () to a photo detector () driving a monitor () and a controller (). If the monitor () detects that the photo detector () is experiencing a loss of return laser light, possibly due to a break in the optical supply line (), the monitor () causes the controller () to extinguish the laser source () 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 () and the return laser light on a separate return fiber optic (). A second embodiment has the return laser light being sent back down the transmission fiber optic (). A reflective key (), monochromatic to the wavelength of the laser source, is selectably removable to disable the laser source () for maintenance or conditional access. The monitor () can operate on absolute levels, averages or rates of change to establish if a loss of transmission has occurred.

Optical supply arrangement

An apparatus for sensing data from a remote optical sensorhas its frequency stabilised by balancing the outputs of narrow band filter, spaced about a desired frequencypositioned at about the 3 db down pointsof a broad band light sourceusing voltage control, current control or temperature control to vary the frequency of the wide band light source. Difference between the outputs through the two narrow band filterscan be used to drive an amplifierto correct the frequency of the broad band light source. The outputs through the two narrow band filterscan be convertedto binary numbers and fed to a microprocessorwhich is used, via analog conversion, to drive the amplifier. The broad band light sourcecan be pulse modulatedto provide temporally separate light pulsesthrough each of the narrow band filtersmeasured at separate times. The corrective output to the amplifiercan be governed by a ratio between the outputs through the narrow band filtersrather than by a difference there between.

Growing community of inventors

Winchester, United Kingdom

James McInnes