US 7,127,132 B1 · Cascade fiber-optic grating-based sensor apparatus and method

Abstract

A fiber optic sensor system includes a plurality m of sensor segments, each sensor segment further comprising a plurality n of sensor gratings for making measurements. Each sensor grating of the sensor segment operates within a unique wavelength channel, such that a plurality m of sensor segments have m sensors in each wavelength channel, and n wavelength channels, for a total of m*n sensors. A broadband optical source is gated for a duration of time which enables all of the sensors on a sensor segment to reflect optical energy corresponding to their measurement, but not long enough to receive reflected optical energy from more than one sensor on a single wavelenghth channel. In this manner, n wavelength channels of measurement can be time-multiplexed to measure m*n sensors.

Claims38

Dependent claims

A fiber-optic sensor system comprising:

an optical fiber having a plurality n of sensor gratings applied sequentially to said fiber, said fiber and sensor gratings forming a sensor segment, said sensor segment having a first end and a second end, each said sensor grating operating within a unique wavelength channel;
a series sensor formed from a plurality m of said sensor segments, each said sensor segment having a said first end of one sensor coupled to said second end of another said sensor segment forming a series string having an bi-directional end and an unused end;
a pulsed source of broadband optical energy applied to said series sensor bi-directional end, said energy reflecting back to said series sensor bi-directional end, being removed, and applied to a wavelength measurement system where a plurality of said sensor gratings provide a plurality of optical responses with only one response per said wavelength channel,
where said pulsed source of broadband energy is limited in duration such that each sensor responds in a unique said wavelength channel.

1 more element

A fiber-optic sensor system comprising:

a series sensor, said series sensor comprising m sensor segments, each of said m sensor segments comprising a plurality n of sensor gratings applied to a single fiber, said series sensor having a single port, said series sensor port returning optical energy in a wavelength unique to each said n sensor grating when optical energy is applied to said single port;
a sensor controller comprising:
a broadband optical source coupled to a first splitter device, said first splitter device having a sensor port, a measurement port, and a source port coupled to said broadband source, said first splitter device coupling optical power from said broadband source to said sensor port, and coupling optical power from said sensor port to said measurement port;
a second splitter having an input port, a comparison port, and a reference port, optical power applied to said input port splitting between said comparison port and said reference port, said second splitter input port coupled to said first splitter device measurement port;
a sine filter having an input port and an output port, the transfer function of said sine filter being an attenuation function which varies periodically over a range of wavelengths, said sine filter coupled to said second splitter comparison port;
a reference WDM filter and a comparison WDM filter, each said WDM filter having an input port and a plurality said n of output ports, each said output port responsive to a wavelength associated with each said n sensor, said comparison WDM filter input coupled to said sine filter output, and said reference WDM filter input coupled to said second splitter reference port;
a plurality said n of detector pairs, each said detector pair coupled to said reference WDM filter output port and said comparison WDM filter output port and providing a reference output and comparison output for each said sensor;
a controller coupled to each said n plurality of detector pairs, converting a reference output and comparison output into an associated sensor measurement for each said n plurality of detector pairs:
where said broadband optical source is providing optical energy for a duration less than the optical length of one of said sensor segments.

6 more elements

Dependencies are inferred from the claim text.

Cascade fiber-optic grating-based sensor apparatus and method

Life of this patent

Cascade fiber-optic grating-based sensor apparatus and method

Life of this patent

Abstract

Claims38