Patent ID: 8213002

Claim:
An instrument for examining a single mode optical fiber under test wherein optical pulses are input into the single mode optical fiber under test and a return optical signal is received from the single mode optical fiber under test, the instrument comprising: a low power, long wavelength optical power source for generating the optical pulses; an optical detector compatible with the low power, long wavelength optical power source for receiving the return optical signal from the single mode optical fiber under test; a singlemode optical coupler having two input ports and one output port, the optical pulses from the optical power source being transmitted at one input port and coupled to an output singlemode optical fiber connected to the output port, and the return optical signal being received at the second input port and coupled to the optical detector, the singlemode optical coupler equally dividing the optical power from the optical source and the return optical signal between the associated output port and input ports; an optical delay element between the output port of the singlemode optical coupler and an output fiber such that electrical switching noise due to the laser trigger is separated from the first returned optical pulse; an optical receiver comprised of a bandwidth operational amplifier configured to operate under two diverse gain settings, one for high gain and sensitivity, and one for low gain and high bandwidth; at least one microprocessor for controlling the electronics, acquiring the signals, and processing the signals; a display for reporting the live fiber results and distances to reflections and fiber ends.