A sensor system includes an optical fiber. A set of wavelength shift sensors are inscribed on the optical fiber. The set includes at least one first wavelength shift sensor configured to reflect a first wavelength band of input light as a first optical output signal. The first wavelength shift sensor has a first value of an optical characteristic that modifies intensity of the first optical output signal. At least one second wavelength shift sensor is configured to reflect a second wavelength band of input light as a second optical output signal. The second wavelength shift sensor has a second value of the optical characteristic that modifies intensity of the second optical output signal, wherein the second value is different from the first value.

Multiplexed reflection and transmission gratings, and methods of their manufacture, are provided that improve uniformity with laser light, that is, reduced banding and other illumination artifacts occurring in waveguides. The mechanism for this can be the multiple reflections between the waveguide reflecting surfaces and the reflection hologram, which promote illumination averaging as beam propagation processes within a waveguide. In some gratings, a beam splitter layer overlapping the multiplexed gratings can be provided for the purposes of reducing banding in a laser-illuminated waveguide. The beam splitter can be provided by one or more dielectric layers. The beamsplitter can have sensitivity to one polarization. The beamsplitter can be sensitive to S-polarization. The beam splitter can be an anti-reflection coating optimized for normal incidence that becomes reflective at high TIR angles when immersed in glass or plastic.

A projection display device comprising a light source and an SBG device having a multiplicity of separate SBG elements sandwiched between transparent substrates to which transparent electrodes have been applied. The substrates function as a light guide. A least one transparent electrode comprises a plurality of independently switchable transparent electrode elements, each electrode element substantially overlaying a unique SBG element. Each SBG element encodes image information to be projected on an image surface. Light coupled into the light guide undergoes total internal reflection until diffracted out to the light guide by an activated SBG element. The SBG diffracts light out of the light guide to form an image region on an image surface when subjected to an applied voltage via said transparent electrodes.

An apparatus has a cassette configured to hold optical fiber comprising one or more optical sensors. The cassette has a spool configured to one or more of extract and retract the optical fiber from the cassette. A pre-strain mechanism is configured to apply a predetermined pre-strain to the one or more optical sensors. An optical fiber installation tool is configured to mount the optical fiber comprising the one or more pre-strained optical sensors to a surface.

An optical fiber with one or more microgratings is disclosed. Methods and apparatus are described for making an optical fiber with one or more microgratings. Methods and apparatus are described for an optical fiber with one or more microgratings. Optical sensing methods and an optical sensing system effectively decouple strain range from the laser tuning range, permit the use of a smaller tuning range without sacrificing strain range, and compensate for ambiguity in phase measurements normally associated with smaller tuning ranges.

Optical fiber connections and their applications in downhole assemblies are described herein. The downhole assembly includes a well completion element with an end that couples with a corresponding well completion element. An optical fiber extends along at least a portion of the well completion element and transmits an optical signal using a first mode. The well completion element includes an optical fiber connector that is coupled to the optical fiber. The connector also includes a mode converter that receives the optical signal from the optical fiber and converts the optical signal from the first mode to a second larger mode. This second larger mode may be more robustly communicated to a corresponding optical fiber connector affixed to the corresponding well completion element.

A cassette for optical fiber includes one or more optical sensors. The cassette has a spool for handling optical fiber. An adjustable shaft is disposed such that the spool is configured to rotate about the adjustable shaft. The adjustable shaft is configured to handle spools having different diameters. A spool controller is coupled to the adjustable shaft and configured to rotate the adjustable shaft to perform one or more of extract and retract the optical fiber. One or more bushings are disposed proximate the spool and are configured to prevent the optical fiber from jumping off the spool.

Optical fiber connections and their applications in downhole assemblies are described herein. The downhole assembly includes a well completion element with an end that couples with a corresponding well completion element. An optical fiber extends along at least a portion of the well completion element and transmits an optical signal using a first mode. The well completion element includes an optical fiber connector that is coupled to the optical fiber. The connector also includes a mode converter that receives the optical signal from the optical fiber and converts the optical signal from the first mode to a second larger mode. This second larger mode may be more robustly communicated to a corresponding optical fiber connector affixed to the corresponding well completion element.

A method for forming a pressure sensor is provided wherein an optical fibre is provided, the optical fibre comprising a core, a cladding surrounding the core, and a birefringence structure for inducing birefringence in the core. The birefringence structure comprises first and second holes enclosed within the cladding and extending parallel to the core. A portion of the optical fibre comprising of the core and the birefringence structure is encased within a chamber, wherein the chamber is defined by a housing comprising a pressure transfer element for equalising pressure between the inside and the outside of the housing. An optical sensor is provided along the core of the optical fibre. The cladding is internally etched by flowing an etchant through the first and second holes along a length of the portion of optical fibre which comprises the optical sensor so as to increase the width of the first and second holes. The chamber is filled with a substantially non-compressible fluid. Consequently, the etched cladding is shaped so as to convert an external pressure provided by the non-compressible fluid within the chamber to an anisotropic stress in the optical sensor.

A shape sensing system for an anthropomorphic test device is disclosed that includes a plurality of body parts and at least one optical fiber that has a plurality of cores in a spaced and parallel relationship with one another that extend between ends of the optical fiber for sensing positions of the body parts. Each of the cores have a plurality of grating sensors disposed along a length thereof capable of determining a position and orientation of the body parts.