Sentek Instrument LLC

Virginia Polytechnic Institute and State University

Senek Instrument LLC

Bo Dong

Anbo Wang

Fabin Shen

Lingmei Ma

Jianmin Gong

A system for measuring pressure, temperature or both includes a diaphragm that responds to a change in temperature or pressure, and a base connected to the diaphragm that has a sapphire element. Between the diaphragm and the base is a cavity. An optical fiber that conducts light reflected off of a surface of the diaphragm is adjacent the cavity. An interrogator is used for detecting a deflection of the diaphragm based on at least two reflected light signals having similar wavelengths and coherence lengths. A quadrature phase detection unit demodulates signals received by the interrogator.

Sapphire sensor for measuring pressure and temperature with improved stress and temperature variation compensation

Forming a light pulse having a plurality of time-dependent frequency components such as a chirped light pulse or a light pulse group and superposing reflected light from different portions of an optical fiber allows detection of changes in effective optical path differences due to physical parameters in the environment of the optical fiber by sensing the optical interference pattern of each light frequency and wavelength. The development of a plurality of interference patterns from each light pulse provides sufficient information for robust demodulation by known methods to produce signals having good fidelity to variations in the physical parameters of interest, particularly vibrations and acoustic waves. The location of the measured physical parameter along the optical fiber can be determined from the time difference between injecting the light pulse and detection of a reflection or Rayleigh backscattering and diffraction index of the optical fiber.

Method and apparatus for distributed sensing

A sensor apparatus and system for measuring pressure, temperature or both with a single interrogator includes a sensor having a cavity, a diaphragm and an optical element or base for conducting energy to and from the cavity and diaphragm. The two surfaces of the diaphragm and a surface of optical element and either surface of the diaphragm are partially reflecting surfaces and respectively define two optical path distances (OPDs) that produce preferential reflections and interference patterns at different optical frequencies or wavelengths that are respectively affected by pressure or temperature. Arranging the OPDs such that the fundamental frequency and harmonics of preferential reflections one OPD do not coincide with the fundamental frequency or harmonics of another OPD provides for both temperature and pressure measurement with a single interrogator and without complex spectral analysis.

Sapphire sensor apparatus including an optical fiber for measuring pressure and temperature

Method for creating an optical sensing fiber having a reflective structure integrally disposed therein, comprising: providing an optical fiber having a core and a cladding layer disposed in optical contact with the core, and having a polymer coating layer disposed in contact with and surrounding the cladding layer, the coating layer at least partially transparent in the wavelengths of 390-600 nm; providing a source of electromagnetic radiation having a wavelength in the range of 390-600 nm; and delivering a selected wavelength of the electromagnetic radiation through the coating layer to a selected location within the fiber core or cladding such that the delivered electromagnetic radiation alters the core or cladding to create at least one reflective structure in the core or cladding at the selected location.

Optical sensing fiber

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.

Serial weak FBG interrogator using pulses of differing wavelengths

A sensor for measuring pressure, temperature or both may be provided. The sensor may include a diaphragm that may respond to a change in temperature or pressure, a base connected to the diaphragm, a cavity, and an optical fiber that may conduct light reflected off of a surface of the diaphragm. The diaphragm and base may be sapphire elements. An interrogator may be provided for detecting a deflection of the diaphragm.

Sapphire sensor for measuring pressure and temperature

Serial fiber Bragg grating interrogator with a pulsed laser for reflection spectrum measurement

An inspection probe for directly measuring a transmission spectrum of a solvent oil in a transformer includes a tube having a plurality of apertures spaced along a side of the tube to allow oil to pass therethrough, and first and second optical collimators disposed at opposing ends of the tube. The first and second collimators are aligned by the tube such that incident light is transmitted through the first collimator, the tube, and the second collimator to a spectrometer.

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Blacksburg, VA, United States of America

Bo Dong