# US 2014/0152995 A1 · Serial weak fbg interrogator > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0152995 A1 - Document ID: US20140152995A1 - Status: Published application - Kind: A1 - Application number: 14/092,212 - Filed: 2013-11-27 - Published: 2014-06-05 - Earliest claimed: 2012-11-27 - Assignees: Sentek Instrument LLC - Applicants: Sentek Instrument LLC - Inventors: Bo DONG; Fabin Shen; Anbo Wang - Web page: https://patentgrep.com/patent/US20140152995A1 ## CPC - G01L 1/246: {using integrated gratings, e.g. Bragg gratings} - E21B 47/135: using light waves, e.g. infrared or ultraviolet waves - G01D 5/35312: {using a Fabry Perot} - G01D 5/35316: {using a Bragg gratings} - G01D 18/00: Testing or calibrating apparatus or arrangements provided for in groups G01D1/00 - G01D15/00 - G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G) - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS - G01D: MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR ## Abstract A serial weak FBG interrogator is disclosed. The serial weak FBG interrogator may include a CW tunable laser or pulsed laser utilized as a laser source and an EDFA. The serial weak FBG interrogator may also be an interrogation of a single sensor system by utilization of a DFB laser which utilizes a single sensor, which may be an interferometer sensor, an extrinsic Fabry-Perot interferometer or a wavelength-modulated sensor. The serial weak FBG interrogator may also include a computer system or CSPU. ## Claims ### Claim 1 A serial weak FBG interrogator, comprising: a CW tunable laser utilized as a laser source, an optical fiber extending from the CW tunable laser; an optical shutter or an electro-optic modulator, receiving the optical fiber extending from the CW tunable laser, wherein light from the laser source is launched into an optical shutter which converts the CW laser into an optical pulse; an optical circulator receiving the optical fiber from the optical shutter, the optical pulse passing through the optical circulator; a laser calibrator receiving the optical fiber from the optical circulator, the laser calibrator to generate information about the CW tunable laser output power and wavelength, the optical pulse enters into the laser calibrator and then propagates to a serial FBG array; a photodetector receiving an optical fiber from the optical circulator and generating an electrical connection to the A/D converter; an A/D converter receiving the electrical connection and converting a continuous physical quantity to a digital number that represents the quantity's amplitude; a computer system receiving the electrical connection from the A/D converter, the computer system having a processor and a memory system, the computer system extends the electrical connection to the CW tunable laser, the computer system is utilized to observe changes of an electrical signal over time; and a pulse driver receiving the electrical connection from the computer system, the pulse driver incorporated into the laser source to drive a pulse from the laser source. ### Claim 2 (depends on 1) The serial weak FBG interrogator according to claim 1, further comprising an EDFA incorporated into a serial weak FBG interrogator. ### Claim 3 (depends on 1) The serial weak FBG interrogator according to claim 1, further comprising a plurality of serial FBGs that reflect in part incident laser power so successive optical pulses are reflected by the serial FBGs. ### Claim 4 (depends on 3) The serial weak FBG interrogator according to claim 3, wherein the serial FBGs utilize one or mandrels in the serial FBG array. ### Claim 5 (depends on 4) The serial weak FBG interrogator according to claim 4, wherein the one or mandrels includes a Faraday mirror that cancels a fiber birefringence effect on FP interference. ### Claim 6 (depends on 1) The serial weak FBG interrogator according to claim 1, wherein the optical circulator is replaced with a fiber coupler. ### Claim 7 (depends on 1) The serial weak FBG interrogator according to claim 1, wherein the photodetector is utilized in combination with an optical band pass filter before the photodetector. ### Claim 8 (depends on 1) The serial weak FBG interrogator according to claim 1, wherein the serial weak FBG interrogator is utilized to calibrate the CW tunable laser. ### Claim 9 (depends on 8) The serial weak FBG interrogator according to claim 8, wherein the serial weak FBG interrogator calibrates CW tunable laser output power and wavelength in real-time. ### Claim 10 (depends on 1) The serial weak FBG interrogator according to claim 1, further comprises a beam splitter, a frequency shifter and a beam controller to generate a pair of lasers at two different frequencies from a single laser. ### Claim 11 (depends on 1) The serial weak FBG interrogator according to claim 1, further comprises a beam splitter, a frequency shifter and a WDM to generate a pair of lasers at two different frequencies from a single laser. ### Claim 12 (depends on 1) The serial weak FBG interrogator according to claim 1, further comprises a sensing span increase by distributed Raman amplification. ### Claim 13 A serial weak FBG interrogator, comprising: a pulsed laser utilized as a laser source, an optical fiber extending from the pulsed laser; an EDFA receiving the optical fiber extending from the pulsed laser, the EDFA is added before light is injected into an FBG array; an optical circulator receiving the optical fiber extending from the EDFA, the optical circulator extends the optical fiber to a laser calibrator, the laser calibrator to generate information about laser output power and wavelength; a photodetector receiving the optical fiber extending from the optical circulator, the photodetector extends an electric connection; a supplemental amplifier receiving the electric connection from the photodetector, the supplemental amplifier is to the EDFA; an A/D convertor receiving the electric connection from the amplifier; a computer system receiving the electric connection from the A/D convertor, the computer system having a processor and a memory system; and a pulse generator receiving the electric connection from the computer system, the pulse generator extends the electric connection to the pulsed laser and the pulse generator controls pulse repetition rate or frequency, pulse width, delay with respect to an internal or external trigger and high and low voltage levels of a plurality of pulses. ### Claim 14 (depends on 13) The serial weak FBG interrogator according to claim 13, wherein the pulsed laser is a wavelength tunable pulse laser. ### Claim 15 (depends on 13) The serial weak FBG interrogator according to claim 13, wherein the optical circulator is replaced with a fiber coupler. ### Claim 16 (depends on 13) The serial weak FBG interrogator according to claim 13, wherein the EDFA is added right before the photodetector. ### Claim 17 (depends on 13) The serial weak FBG interrogator according to claim 13, wherein a plurality of serial FBGs utilize one or mandrels in the serial FBG array. ### Claim 18 (depends on 17) The serial weak FBG interrogator according to claim 17, wherein the one or mandrels includes a Faraday mirror that cancels a fiber birefringence effect on FP interference. ### Claim 19 (depends on 13) The serial weak FBG interrogator according to claim 13, wherein the photodetector is utilized in combination with an optical band pass filter before the photodetector. ### Claim 20 (depends on 13) The serial weak FBG interrogator according to claim 13, wherein the serial weak FBG interrogator is utilized to calibrate the pulsed laser. ### Claim 21 (depends on 20) The serial weak FBG interrogator according to claim 20, wherein the serial weak FBG interrogator calibrates a pulsed laser output power and wavelength in real-time. ### Claim 22 (depends on 13) The serial weak FBG interrogator according to claim 13, further comprises a beam splitter, a frequency shifter and a beam controller to generate a pair of lasers at two different frequencies from a single laser. ### Claim 23 (depends on 13) The serial weak FBG interrogator according to claim 13, further comprises a beam splitter, a frequency shifter and a WDM to generate a pair of lasers at two different frequencies from a single laser. ### Claim 24 (depends on 13) The serial weak FBG interrogator according to claim 13, further comprises a sensing span increase by distributed Raman amplification. ### Claim 25 A serial weak FBG interrogator for distributed acoustic sensing or vibration sensing, comprising: a pulse generator generating a plurality of electrical data links; a CSPU receiving a first electrical data link; a beam combiner receiving a second electrical data link and a third electrical data link, the second electrical data link and the third electrical data link each includes a plurality of length distances, the length distances each having a corresponding light wavelength; an optical circulator receiving a combined first optical data link and second optical data link from the beam combiner; a laser calibrator receiving the combined first optical data link and second optical data link from the optical circulator, the laser calibrator including a plurality of serial FBG arrays; one or more photodetectors receiving the combined first optical data link and second optical data link from the optical circulator; and one or more A/D convertors receiving a third electrical data link from the photodetector, the one or more A/D convertors extending the third electrical data link from the one or more photodetector to the CSPU. ### Claim 26 (depends on 25) The serial weak FBG interrogator according to claim 25, wherein a WDM is disposed between the optical circulator and the one or more photodetectors. ### Claim 27 (depends on 25) The serial weak FBG interrogator according to claim 25, wherein a plurality of couplers and a delay are disposed between the optical circulator and the one or more photodetectors. ### Claim 28 (depends on 25) The serial weak FBG interrogator according to claim 25, wherein the serial weak FBG interrogator offers measurement of the reflection spectrum or reflection spectrum shift for each of the serial FBGs. ### Claim 29 An interrogation of a single sensor system by utilization of a DFB laser or a VCSEL laser, comprising: a single sensor; an optical fiber extending from the single sensor; and a sensor interrogator receiving the optical fiber extending from the single sensor, the sensor interrogator includes the DFB laser, a laser driver, a microprocessor, a first photodetector, a first amplifier, an A/D converter, a second photodetector, a second amplifier and a laser calibrator. ### Claim 30 (depends on 29) The interrogation of a single sensor system according to claim 29, wherein the single sensor is an interferometer sensor. ### Claim 31 (depends on 30) The interrogation of a single sensor system according to claim 30, wherein the single sensor is a Fabry-Perot interferometer. ### Claim 32 (depends on 31) The interrogation of a single sensor system according to claim 31, wherein the single sensor is an extrinsic Fabry-Perot interferometer. ### Claim 33 (depends on 29) The interrogation of a single sensor system according to claim 29, wherein the single sensor is a wavelength-modulated sensor.