Abstract: Sensors for measuring an environmental input, such as force or moisture, that include fiber-grating sensing elements having differing responses to the environmental input such that the differing responses can be used to effectively solve multiple equations, representing the differing responses, for two unknowns representing, respectively, the environmental input and temperature. The differing responses can be due to any one or more of a variety of factors, including sensor elements having differing effective areas, materials of differing cure states, differing fiber grating wavelengths, differing sensitive materials, asymmetrical deployments, and differing numbers of load balancing elements, among others. Sensor systems employing such sensors and methods of utilizing such sensors are also disclosed.

Abstract: A sensor comprising an optical fiber that includes a Bragg grating and a longitudinal-strain-inducing (LSI) jacket for inducing longitudinal strain into the optical fiber as a function of a transverse load, i.e., pressure or force. As the LSI jacket induces strain into the optical fiber, the fiber grating deforms, thereby changing the character of light reflected from the grating. The changes in character of the reflected light can be measured using suitable optical instrumentation. Additional physical characteristics that can be measured/sensed using an LSI-jacket-based sensor include moisture content/presence, chemical content/presence, and temperature. A transverse-load-sensing sensor can include transverse-load-applying structures that compress the LSI jacket under transverse load, causing the jacket to controllably elongate and thereby induce longitudinal strain into the optical fiber. Chemical and moisture LSI jackets can comprise materials that swell in the presence of the chemical or moisture.

Abstract: A fiber grating sensor system is used to measure key parameters that include pressure, strain and temperature at specific locations and at high speed. The system relies on spectral properties associated with the fiber grating sensors, the light source and the optical detection system to provide these capabilities. The system has been successfully applied to measurement of pressures up to 1,200,000 psi and by increasing the spectral width of the light source extensions of pressure measurements to 4,000,000 psi and higher are possible. Temperature change measurements have been made of 400 degrees C. over a period of 25 micro-seconds limited by the physical response of the fiber sensors and the output detector bandwidth both of which can be greatly improved by reducing fiber sizes and with improved detectors. Novel methods have been devised to lower cost and enable measurements with spatial location, speed and accuracy that have been very difficult or not yet achieved.

Abstract: A fiber grating sensor system is used to measure key parameters that include pressure, strain and temperature at specific locations and at high speed. The system relies on spectral properties associated with the fiber grating sensors, the light source and the optical detection system to provide these capabilities. The system has been successfully applied to measurement of pressures up to 1,200,000 psi and by increasing the spectral width of the light source extensions of pressure measurements to 4,000,000 psi and higher are possible. Temperature change measurements have been made of 400 degrees C. over a period of 25 micro-seconds limited by the physical response of the fiber sensors and the output detector bandwidth both of which can be greatly improved by reducing fiber sizes and with improved detectors. Novel methods have been devised to lower cost and enable measurements with spatial location, speed and accuracy that have been very difficult or not yet achieved.

Abstract: A fiber optic sensing system. The fiber optic sensing system includes an optical source adapted to provide an optical signal at a plurality of wavelengths. The fiber optic sensing system also includes a plurality of wavelength taps for separating the optical signal into signal portions at each of the plurality of wavelengths. The fiber optic sensing system further includes a plurality of optical sensors, each of the optical sensors configured to receive one of the signal portions at a respective one of the plurality of wavelengths. The fiber optic sensing system still further includes a plurality of wavelength combiners for combining signal portions from the plurality of optical sensors into a recombined signal. Also included in the fiber optic sensing system is an optical receiver for receiving the recombined signal. The fiber optic sensing system also includes an optical fiber path between the optical source and the optical receiver.

Abstract: Systems and methods comprise or involve optical fibers having Bragg gratings. The optical fibers can be assembled in a parallel manner into a fiber sensor configuration. Bragg gratings can be written onto different cores of optical fibers. Bragg gratings may be written at a same or nearly same axial position for all optical fibers in the configuration and may be written at the same time and may have a substantially equal index of refraction variation and unequal lengths. Spaced Bragg gratings may also have characteristic sidelobe spectrums for tagging the respective gratings. Gratings can also be written at different wavelengths and over another grating at the same location.

Abstract: A sensor comprising an optical fiber that includes a Bragg grating and a longitudinal-strain-inducing (LSI) jacket for inducing longitudinal strain into the optical fiber as a function of a transverse load, i.e., pressure or force. As the LSI jacket induces strain into the optical fiber, the fiber grating deforms, thereby changing the character of light reflected from the grating. The changes in character of the reflected light can be measured using suitable optical instrumentation. Additional physical characteristics that can be measured/sensed using an LSI-jacket-based sensor include moisture content/presence, chemical content/presence, and temperature. A transverse-load-sensing sensor can include transverse-load-applying structures that compress the LSI jacket under transverse load, causing the jacket to controllably elongate and thereby induce longitudinal strain into the optical fiber. Chemical and moisture LSI jackets can comprise materials that swell in the presence of the chemical or moisture.

Abstract: An instrument system that includes an elongate body, an optical fiber, and a controller is provided. The optical fiber is operatively coupled to the elongate body and has a plurality of strain sensors provided on the optical fiber. Each of the plurality of strain sensors has a reflectivity, wherein one of the plurality of strain sensors has a different reflectivity than another one of the plurality of strain sensors. The controller is operatively coupled to the optical fiber and adapted to: receive one or more signals from the plurality of strain sensors; and determine a position of the elongate body based on the one or more signals.

Abstract: An instrument system that includes an elongate body and an optical fiber is provided. The elongate body has a longitudinal axis and capable of being twisted about the longitudinal axis. The optical fiber is operatively coupled with the elongate body and having a strain sensor provided thereon. The strain sensor is configured to indicate twist of the elongate body.

Abstract: A method for measuring bending is provided. The method includes receiving a reflected signal from a strain sensor provided on an optical fiber; determining a spectral profile of the reflected signal; and determining bending of the optical fiber based on a comparison of the spectral profile of the reflected signal with a predetermined spectral profile.

Abstract: In certain variations, fiber shape sensing or measuring systems, devices and methods are described herein, which allow for measurement of three dimensional bending as well as twist measurements of various fibers, e.g., optical fibers and fiber optic probes of various sizes. In certain variations, the systems are designed to take advantage of unique light guiding properties of optical fibers and various fiber gratings.

Abstract: An instrument system that includes an elongate body, an optical fiber, and a detector is provided. The elongate body is capable of being twisted. The optical fiber includes a first portion coupled to the elongate body and a second portion having a curved shape adapted to reduce transfer of twisting or bending from the elongate body to the second portion, the second portion having a strain sensor provided thereon. The detector is coupled to the optical fiber and adapted to receive a signal from the strain sensor.

Abstract: A medical instrument system includes an elongate instrument body defining a longitudinal axis and capable of being twisted about its longitudinal axis and an optical fiber sensor coupled to the instrument body. A detector is operatively coupled to the optical fiber sensor and configured to detect respective light signals transmitted on the optical fiber sensor. A controller is operatively coupled to the detector and configured to determine a twist of a portion of the instrument body about its longitudinal axis based on an analysis of detected light signals.

Abstract: A method for measuring bending is provided. The method includes receiving a reflected signal from a strain sensor provided on an optical fiber; determining a spectral profile of the reflected signal; and determining bending of the optical fiber based on a comparison of the spectral profile of the reflected signal with a predetermined spectral profile.

Abstract: An instrument system that includes an elongate body, an optical fiber, and a detector is provided. The elongate body is capable of being twisted. The optical fiber includes a first portion coupled to the elongate body and a second portion having a curved shape adapted to reduce transfer of twisting or bending from the elongate body to the second portion, the second portion having a strain sensor provided thereon. The detector is coupled to the optical fiber and adapted to receive a signal from the strain sensor.

Abstract: An instrument system that includes an elongate body and an optical fiber is provided. The elongate body has a longitudinal axis and capable of being twisted about the longitudinal axis. The optical fiber is operatively coupled with the elongate body and having a strain sensor provided thereon. The strain sensor is configured to indicate twist of the elongate body.

Abstract: A medical instrument system includes an elongate flexible instrument body with an optical fiber substantially encapsulated in a wall of the instrument body, the optical fiber including one or more fiber gratings. A detector is operatively coupled to the optical fiber and configured to detect respective light signals reflected by the one or more fiber gratings. A controller is operatively coupled to the detector, and configured to determine a twist of at least a portion of the instrument body based on detected reflected light signals. The instrument may be a guide catheter and may be robotically or manually controlled.

Abstract: A medical instrument system includes an elongate instrument body defining a longitudinal axis and capable of being twisted about its longitudinal axis and an optical fiber sensor coupled to the instrument body. A detector is operatively coupled to the optical fiber sensor and configured to detect respective light signals transmitted on the optical fiber sensor. A controller is operatively coupled to the detector and configured to determine a twist of a portion of the instrument body about its longitudinal axis based on an analysis of detected light signals.

Abstract: In certain variations, fiber shape sensing or measuring systems, devices and methods are described herein, which allow for measurement of three dimensional bending as well as twist measurements of various fibers, e.g., optical fibers and fiber optic probes of various sizes. In certain variations, the systems are designed to take advantage of unique light guiding properties of optical fibers and various fiber gratings.

Abstract: Systems and methods comprise or involve optical fibers having Bragg gratings. The optical fibers can be assembled in a parallel manner into a fiber sensor configuration. Bragg gratings can be written onto different cores of optical fibers. Bragg gratings may be written at a same or nearly same axial position for all optical fibers in the configuration and may be written at the same time and may have a substantially equal index of refraction variation and unequal lengths. Spaced Bragg gratings may also have characteristic sidelobe spectrums for tagging the respective gratings. Gratings can also be written at different wavelengths and over another grating at the same location.