Optical waveguides – Optical waveguide sensor
Reexamination Certificate
1999-05-13
2001-08-28
Healy, Brian (Department: 2874)
Optical waveguides
Optical waveguide sensor
C385S015000, C385S016000, C385S024000, C385S031000, C250S227140, C250S227180, C250S227190, C359S341430, C359S199200, C359S199200, C359S199200, C359S199200
Reexamination Certificate
active
06282334
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to sensor arrays for sensing systems, e.g., acoustic sensing systems.
2. Description of the Related Art
Arrays of fiber optic interferometric sensors show promise in applications where size, electrical interference, and electromagnetic detection make electronic sensors impractical. Such interferometric sensors are capable of measuring a parameter (i.e., a measured) with a very high dynamic range (e.g., 120 dB). Optical sensor arrays are formed by connecting a plurality of sensors using fiber optic lines. If each sensor in an array requires a dedicated fiber to carry the detection signal, the large number of fibers required quickly becomes unwieldy as the number of sensors increases.
Optical couplers are commonly used to couple optical signals from a distribution bus to the sensors, and from the sensors to a return bus. In an array in which amplifiers are not used to periodically boost the signal strength, delivering sufficient optical signal to each of the sensors may be problematic if the number of sensors is too great. In addition, there may be significant variations in the optical power levels returned to the detectors, thereby complicating the signal processing.
Although significant progress has been made in recent years with respect to the sophistication of sensor array configurations and signal processing techniques, there is still need for improved architectures based on standardized components such as 1×2 or 1×4 couplers, in which the return optical signals have respective powers within a relatively narrow range.
SUMMARY OF THE INVENTION
One preferred embodiment of the invention is a sensor array that includes a plurality of distribution fiber lines for distributing respective input optical signals. The respective input optical signals have different wavelengths. A plurality of return fiber lines return perturbed optical signals. A plurality of sensor subarrays have respective inputs and outputs. Each of the subarrays includes a plurality of sensors that receive the input optical signals and that output the perturbed optical signals. Each of the inputs is coupled to one of the distribution fiber lines. Each of the outputs is coupled to one of the return lines. Each of the subarrays is coupled to a unique combination of distribution and return fiber lines.
Another preferred embodiment is a sensor array that includes a plurality of distribution fiber lines for distributing respective input optical signals. The respective input optical signals have different wavelengths. A return fiber line returns perturbed optical signals. A plurality of sensor subarrays have respective inputs and outputs. Each of the subarrays includes a plurality of sensors that receive the input optical signals and output the perturbed optical signals. Each of the inputs is coupled to one of the distribution fiber lines. Each of the outputs is coupled to the return line. Each of the subarrays is coupled to a unique distribution fiber line.
Yet another embodiment is a method of distributing an input optical signal to a plurality of sensors. The method provides a first plurality of sensors having respective inputs and outputs; connects a first plurality of input couplers to the inputs of the sensors via respective optical amplifiers; connects the input couplers to a first distribution fiber line which carries an input optical signal; connects a first plurality of output couplers to the outputs of the sensors; connects the output couplers to a first return fiber line; and amplifies the input optical signal provided to the inputs of the sensors to compensate for reduced optical power.
Yet another preferred embodiment is an optical sensor architecture that includes a plurality of sensors which receive an input optical signal and which output perturbed optical signals. A distribution bus is coupled to each sensor to distribute the input optical signal to each sensor. A return bus is coupled to each sensor to receive the perturbed optical signal from each sensor to be included as a portion of a return signal. A plurality of optical amplifiers are interposed between the distribution bus and the sensors to increase the power provided to each of the sensors. In this preferred embodiment, each of the optical amplifiers may be coupled to an array of sensors, e.g., 4-32 sensors.
Still another preferred embodiment is an optical sensor architecture that includes a plurality of means for sensing a parameter; means for distributing a first optical signal to each of the means for sensing; means for returning a second optical signal from each of the means for sensing; and a plurality of means for amplifying the first optical signal. The amplifying means is located between the means for sensing and the means for distributing.
Another preferred embodiment is a method of distributing an input optical signal to a plurality of sensors in a sensor architecture to generate an optical output. The method couples an input optical signal from a distribution bus to a plurality of sensors; amplifies the input optical signal after the input optical signal leaves the distribution bus but before the input optical signal enters the plurality of sensors; generates output signals from the plurality of sensors; and couples the output signal from each sensor into a return signal carried via a return bus which is coupled to each sensor.
Still another preferred embodiment is an optical sensor array architecture that includes a distribution bus which receives and distributes an optical input signal. A return bus receives a plurality of optical return signals and provides the optical return signals as output signals. A plurality of rungs are coupled between the distribution bus and the return bus. Each of the rungs comprises at least one sensor which receives a respective portion of the optical input signal and which generates one of the optical return signals. A plurality of input optical amplifiers in the rungs are responsive to a pump signal. The input optical amplifiers amplify the optical input signal in the rungs to compensate for reduced signal power.
A further preferred embodiment is a modulator for an optical signal that includes a first intensity modulator that receives and modulates an optical signal. The first intensity modulator produces intensity modulated output in the form of output pulses. An optical amplifier receives and amplifies the modulated output. A second intensity modulator receives the amplified modulated output. The second intensity modulator modulates the amplified modulated output by substantially eliminating optical noise produced by the amplifier during time intervals between the optical pulses.
Another preferred embodiment is a sensor array that includes a first optical source and a second optical source that generate respective first and second optical signals at respective first and second wavelengths. The first and second wavelengths are different. First and second optical amplifiers receive the first and second optical signals, respectively. The first and second amplifiers amplify the first and second optical signals, respectively. First and second bandpass filters receive the first and second amplified optical signals, respectively. The first bandpass filter filters out optical radiation generated by the first amplifier that is near the second wavelength. The second bandpass filter filters out optical radiation generated by the second amplifier that is near the first wavelength. The first and second bandpass filters generate first and second filtered optical signals, respectively. First and second sensors receive the first and second optical signals, respectively. The first and second sensors output first and second perturbed optical signals in response to a stimulus. A return bus receives perturbed, filtered first and second optical signals and directs the first and second perturbed optical signals towards a receiver unit.
Yet another preferred embodiment is a sensor array that includes a first optic
Hodgson Craig W.
Vakoc Benjamin J.
Healy Brian
Knobbe Martens Olson & Bear LLP
Litton Systems Inc.
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