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.

Methods and systems for measuring optical properties of transistor channel structures and linking the optical properties to the state of strain are presented herein. Optical scatterometry measurements of strain are performed on metrology targets that closely mimic partially manufactured, real device structures. In one aspect, optical scatterometry is employed to measure uniaxial strain in a semiconductor channel based on differences in measured spectra along and across the semiconductor channel. In a further aspect, the effect of strain on measured spectra is decorrelated from other contributors, such as the geometry and material properties of structures captured in the measurement. In another aspect, measurements are performed on a metrology target pair including a strained metrology target and a corresponding unstrained metrology target to resolve the geometry of the metrology target under measurement and to provide a reference for the estimation of the absolute value of strain.

A displacement detection device is capable of stably and accurately detecting an amount of displacement. A polarization maintaining fiber has a length not to be equal to a length obtained by dividing, a product of an integral multiple of twice a length of a resonator times a refractive index of the resonator and a beat length obtained from a difference between propagation constants of two polarization modes, by a wavelength of the light source, is selected from a range including a length equal to the above length. The polarization maintaining fiber includes multiple polarization maintaining fibers fitted to each other by removable connectors.

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.

A pressure measuring device 30 installs on a tube 11 for transferring a medium BL so as to measure a pressure of the medium BL inside the tube 11. The pressure measuring device 30 includes a main body portion 31 mountable to the tube 11, polarizing means 34 disposed in the main body portion 31 so that light oscillating in a specific direction is transmitted therethrough, an image acquisition unit 32 disposed in the main body portion 31 so that image information on a pressure receiver that is deformed in response to the received pressure is acquired through the polarizing means 34, and a control unit 100 that converts the image information acquired by the image acquisition unit 32 into pressure information about the pressure.

A polarization maintaining fiber array includes a substrate, a cover, and at least two polarization maintaining optical fibers. The substrate includes at least two main grooves, a first additional groove, and a second additional groove, wherein the main grooves are positioned between the first additional groove and the second additional groove. The fiber array includes at least two polarization maintaining optical fibers positioned in the at least two main grooves, a first dummy fiber positioned in the first additional groove, and a second dummy fiber positioned in the second additional groove. The cover is positioned such that it contacts the polarization maintaining optical fibers, the first dummy fiber, and the second dummy fiber.

An optical device comprises a first polariscope and a set of first photodetectors and an optical retardation generator. The device is configured to analyze the quality of a glazing.

The invention discloses an apparatus for measuring the torsion between a first point (41) and a second point (42) of a test object (1), said second point being spaced apart from the first point. The apparatus comprises the following: a source of polarized light, comprising a polarizing light source (15) that emits polarized light, or a polarizer (20) that is connected to a light source (10) by way of an optical feed; a first optical fibre (40) that is optically connected to the Output of the polarizing light source (15) or to the Output of the polarizer (20) and that is fastened to the test object (1) at the first point (41) and at the second point (42) in such a way that a torsion of the test object about a torsion axis causes a change in the angle of rotation of the first optical fibre from the first point in relation to the second point, and a second polarization-maintaining optical fibre (50), that is connected to the first optical fibre (40) at the second point (42) or downstream of the second point (42) in relation to the light path Coming from the source, for supplying the light to a measuring device (30, 31), wherein the distance between the first point (41) and the second point (42) of the test object (1) is greater than or equal to 5 metres, or greater than or equal to 7 metres, or greater than or equal to 10 metres, and the first optical fibre (40) comprises a non-polarization-maintaining, bending-insensitive fibre.

Provided herein are systems and methods for monitoring radial stresses in glass tubing. In some embodiments, a measurement system includes a light source delivering a light to a tube, and a polarizer receiving the light after the light is refracted through a wall of the tube. The measurement system may further include a detector receiving the light from the polarizer, the detector operable to capture a first image of the light at a first polarization state and a second image of the light at a second polarization state. The system may further include a controller operable to determine a retardation profile related to the stress profile of the wall of the tube by determining a retardation magnitude of the light refracted through the wall of the tube based on a difference between the first image of the light and the second image of the light.

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.