Abstract: A system for distributed heat flux sensing of body tissue includes a distributed sensor, a thermal energy source, and one or more processors. The distributed sensor provides a plurality of temperature measurements corresponding to a plurality of points in a measurement range. The thermal energy source applies thermal energy to the body tissue along the measurement range. The one or more processors are configured to receive the plurality of temperature measurements from the distributed sensor, determine an amount of thermal energy applied by the thermal energy source at each of the plurality of points, and determine heat flux at each of the plurality of points based on the plurality of temperature measurements and the amount of thermal energy applied by the thermal energy source. The plurality of temperature measurements correspond to the plurality of points.

Abstract: Optical polarization control devices that include two pairs of squeezing plates oriented in mutually perpendicular directions are described. Compressive forces exerted by the two pairs of plates onto an optical fiber can be configured for low polarization mode dispersion. Various methods and systems in which the polarization control devices can be employed are also described.

Abstract: A multi-core fiber includes multiple optical cores, and for each different core of a set of different cores of the multiple optical cores, a total change in optical length is detected. The total change in optical length represents an accumulation of all changes in optical length for multiple segments of that different core up to a point on the multi-core fiber. A difference is determined between the total changes in optical length for cores of the set of different cores. A twist parameter and/or a bend angle associated with the multi-core fiber at the point on the multi-core fiber is/are determined based on the difference.

Abstract: An optical frequency domain reflectometry (OFDR) measurement is produced from an OFDR apparatus that includes a tunable laser source coupled to a sensing interferometer and a monitor interferometer. The sensing interferometer is also coupled to a waveguide, e.g., an optical sensing fiber. Sensor interferometric data obtained by the OFDR measurement is processed in the spectral domain (e.g., frequency) with one or more parameters to compensate for the optical dispersion associated with the sensing interferometer data. A Fourier Transform of the dispersion-compensated sensing interferometric data in the spectral domain is performed to provide a dispersion-compensated OFDR measurement information in the temporal (e.g., time) domain.

Abstract: An optical fiber includes multiple optical cores configured in the fiber including a set of primary cores and an auxiliary core. An interferometric measurement system uses measurements from the multiple primary cores to predict a response from the auxiliary core. The predicted auxiliary core response is compared with the actual auxiliary core response to determine if they differ by more than a predetermined amount, in which case the measurements from the multiple primary cores may be deemed unreliable.

Abstract: Example embodiments include an optical interrogation system with a sensing fiber having a single core, the single core having multiple light propagating modes. Interferometric apparatus probes the single core multimode sensing fiber over a range of predetermined wavelengths and detects measurement interferometric data associated with the multiple light propagating modes of the single core for each predetermined wavelength in the range. Data processing circuitry processes the measurement interferometric data associated with the multiple light propagating modes of the single core to determine one or more shape-sensing parameters of the sensing fiber from which the shape of the fiber in three dimensions can be determined.

Abstract: The ends of sensing and interrogating multicore fibers are brought into proximity for connection in a first orientation with one or more cores in the sensing fiber being paired up with corresponding one or more cores in the interrogating fiber. Optical interferometry is used to interrogate at least one core pair and to determine a first reflection value that represents a degree of alignment for the core pair in the first orientation. The relative position is adjusted between the ends of the fibers to a second orientation. Interferometry is used to interrogate the core pair and determine a second reflection value that represents a degree of alignment for the core pair in the second orientation. The first reflection value is compared with the second reflection value, and an aligned orientation is identified for connecting the sensing and interrogating fibers based on the comparison.

Abstract: A tunable laser system includes a tunable laser to be scanned over a range of frequencies and an interferometer having a plurality of interferometer outputs. At least two interferometer outputs of the plurality of interferometer outputs have a phase difference. A wavelength reference has a spectral feature within the range of frequencies, and the spectral feature does not change in an expected operating environment of the tunable laser. Processing circuitry uses the spectral feature and the plurality of interferometer outputs to produce an absolute measurement of a wavelength of the tunable laser and controls the tunable laser based on a comparison of the absolute measurement of the wavelength of the tunable laser with a setpoint wavelength.

Abstract: A flexible tool comprising an optical fiber and a rigid member. The optical fiber includes a proximal end, a distal end, an intermediate portion between the proximal end and the distal end, and an adjustable bend between the proximal end and the intermediate portion. The intermediate portion is fixed within the rigid member, wherein the rigid member is substantially a cylinder with a flat surface along an axial length of the cylinder, and wherein the intermediate portion is constrained to have a single degree of freedom that is translational substantially along an axis defined by the optical fiber at the intermediate portion.

Abstract: A fiber housing includes multiple shape sensing cores and a single optical core. A distal end of the fiber housing is positionable to direct the single optical core to a current point of an anatomical target. Collimated light over a first range of frequencies is projected from the single optical core to the current point. OFDR is used to detect reflected light scattered from the current point and to process the detected light to determine a distance to the current point. Light over a second range of frequencies is projected through the multiple shape sensing optical cores to the distal end of the fiber housing. OFDR is used to measure light reflected from the distal end of the fiber housing back through the multiple shape sensing optical cores and to process the measurement to determine a position in three dimensional space of the distal end of the fiber housing and a pointing direction of the distal end of the fiber housing.

Abstract: An optical force sensor along with an optical processing apparatus and method are disclosed. The optical force sensor includes an optical fiber, a core included in the optical fiber, an instrument including the optical fiber, the instrument having a distal region, and a tubular structure encasing an end of the optical fiber and secured to the first conduit at the distal region of the instrument. When an optical interferometric system is coupled to the optical fiber, it processes reflected light from a portion of the core included within the tubular structure that does not include Bragg gratings to produce a measurement of a force present at the distal region of the instrument.

Abstract: A multi-core fiber includes multiple optical cores, and for each different core of a set of different cores of the multiple optical cores, a total change in optical length is detected. The total change in optical length represents an accumulation of all changes in optical length for multiple segments of that different core up to a point on the multi-core fiber. A difference is determined between the total changes in optical length for cores of the set of different cores. A twist parameter and/or a bend angle associated with the multi-core fiber at the point on the multi-core fiber is/are determined based on the difference.

Abstract: Shape sensing with a multi-core fiber can achieve high accuracy as well as accommodate small bend radii by measuring signals with peripheral waveguide cores placed at multiple different radial distances from the center axis of the fiber, and computing strain metrics from signals of cores selected based on the respective radial distances and a determination of whether the waveguide cores have strained out of range.

Abstract: A multi-core fiber includes multiple optical cores, and for each different core of a set of different cores of the multiple optical cores, a total change in optical length is detected. The total change in optical length represents an accumulation of all changes in optical length for multiple segments of that different core up to a point on the multi-core fiber. A difference is determined between the total changes in optical length for cores of the set of different cores. A twist parameter and/or a bend angle associated with the multi-core fiber at the point on the multi-core fiber is/are determined based on the difference.

Abstract: An optical force sensor along with an optical processing apparatus and method are disclosed. The optical force sensor includes an optical fiber, a core included in the optical fiber, an instrument including the optical fiber, the instrument having a distal region, and a tubular structure encasing an end of the optical fiber and secured to the first conduit at the distal region of the instrument. When an optical interferometric system is coupled to the optical fiber, it processes reflected light from a portion of the core included within the tubular structure that does not include Bragg gratings to produce a measurement of a force present at the distal region of the instrument.

Abstract: An interferometric measurement system measures a spun optical fiber sensor that includes multiple optical cores configured in the fiber sensor. A calibration machine includes a calibration fixture having known dimensions, one or more automatically controllable actuators for wrapping the fiber sensor starting at one end of the fiber sensor onto a calibration fixture having known dimensions, and an actuator controller configured to control the one or more actuators with actuator control signals. Interferometric detection circuitry, coupled to the actuator controller and to the other end of the fiber sensor, detects measured interferometric pattern data associated with each of the multiple cores when the fiber sensor is wrapped onto the calibration fixture.

Abstract: A fiber includes M primary cores and N redundant cores, where M an integer is greater than two and N is an integer greater than one. Interferometric circuitry detects interferometric pattern data associated with the M primary cores and the N redundant cores when the optical fiber is placed into a sensing position. Data processing circuitry calculates a primary core fiber bend value for the M primary cores and a redundant core fiber bend value for the N redundant cores based on a predetermined geometry of the M primary cores and the N redundant cores in the fiber and detected interferometric pattern data associated with the M primary cores and the N redundant cores. The primary core fiber bend value and the redundant core fiber bend value are compared in a comparison. The detected data for the M primary cores is determined reliable or unreliable based on the comparison. A signal is generated in response to an unreliable determination.

Abstract: Where a flexible tool includes a tool body with a flexible portion, a distal end and a first optical fiber within the flexible portion, shape sensing can be achieved with increased accuracy by inserting or otherwise including a second optical fiber within the flexible portion. The increased accuracy can be achieved when the second optical fiber has a diameter larger than that of the first optical fiber. Once the shape of the flexible tool has been determined using at least the second optical fiber, the first optical fiber can be used for subsequent shape sensing. This may be particularly applicable where the tool includes an instrument such as an optical imaging device inserted in a channel of the tool, where not all of the width of the channel is occupied by functional components behind the operable end of the instrument.

Abstract: An optical fiber includes multiple optical cores configured in the fiber including a set of primary cores and an auxiliary core. An interferometric measurement system uses measurements from the multiple primary cores to predict a response from the auxiliary core. The predicted auxiliary core response is compared with the actual auxiliary core response to determine if they differ by more than a predetermined amount, in which case the measurements from the multiple primary cores may be deemed unreliable.

Abstract: Interferometric measurement signals are detected by a single optical interferometric interrogator for a length of a sensing light guide and an interferometric measurement data set corresponding to the interferometric measurement signals is generated. The interferometric measurement data set is transformed into a spectral domain to produce a transformed interferometric measurement data set. The transformed interferometric measurement data set is compared to a baseline interferometric data set to identify a time-varying signal corresponding to a time-varying disturbance. The baseline interferometric data set is representative of the sensing light guide not being subjected to the time-varying disturbance. A compensating signal is determined from the time-varying signal and used to compensate at least a portion of the interferometric measurement data set for the time-varying disturbance as part of producing a measurement of the parameter.