Abstract: A method and a system for detection and synthetic aperture (SA) imaging of a target are disclosed. The method may include illuminating a scene with a search signal transmitted from a moving platform, receiving a search return signal from a target present in the scene, and estimating, from the search return signal, the range and the angular location of the target. The method may also include generating an SA transmission signal and a local oscillator (LO) signal with a time delay therebetween based on the estimated range, and illuminating the scene with the SA transmission signal pointed along an imaging direction based on the estimated angular location of the target. The method may further include receiving an SA return signal from the target, mixing the SA return signal with the LO signal to generate SA signal data, and generating an SA image of the target from the SA signal data.

Abstract: Optical assemblies having a barrel and one or more optical elements mounted therein are provided. The optical assembly includes a resilient spacer positioned between two consecutive ones of the components mounted in the barrel. In typical implementations, the contacting surface of either one of the components adjacent to the resilient spacer is precisely centered relative to the center axis of the cavity of the barrel. Furthermore, an outwardly-directed resulting force is applied to the resilient spacer by its engagements with the adjacent components.

Abstract: A triangulation-based optical profilometry system for scanning a three-dimensional sample surface located at a sample plane includes a projection system; an image sensor; a processing unit; an objective lens assembly for imaging onto the image sensor a luminous line formed on the sample plane, a first direction orthogonal to an optical axis and being defined parallel to an extent of the luminous line, a second direction being defined perpendicular to the first direction; and a diaphragm defining a non-circular aperture defined by a first dimension and a second dimension greater than the first dimension, the diaphragm being rotationally oriented such that the first dimension is aligned with the first direction and the second dimension is aligned with the second direction, the objective lens assembly being arranged to form an out-of-focus image of the luminous line on the image sensor.

Abstract: Target devices for characterizing terahertz imaging systems are provided. The target devices include a terahertz resolution pattern having spatially distributed resolution features and one or more prism assemblies configured to provide a variable contrast level within the resolution features when used with terahertz radiation. Each prism assembly includes first and second prisms arranged in a Frustrated Total Internal Reflection (FTIR) configuration.

Abstract: There is described a terahertz illumination source for terahertz imaging.

Abstract: An active LMA optical fiber for mitigating Transverse Mode Instability effects is provided. The core of the fiber includes a center core region having one or more rare-earth center dopants and one or more center co-dopants, and a peripheral core region free of rare-earth dopants and having one or more peripheral dopants. The radial refractive-index profile of the core is generally continuous across a boundary between the center core region and the peripheral core region. The selection and the concentrations and distributions of the rare-earth center dopants, the center co-dopants and the peripheral dopants are such that the temperature coefficient is lower in the peripheral core region than in the center core region.

Abstract: An optical fiber assembly for mitigating stimulated Brillouin scattering (SBS) is disclosed that includes an optical fiber and a winding support configured to hold the fiber in a winding arrangement. The fiber includes a core and one or more claddings surrounding the core. The one or more claddings includes an inner doped region contiguous to the core and having a composition including a glass material doped with an acoustic-velocity-lowering and refractive-index-raising dopant and an acoustic-velocity-lowering and refractive-index-lowering dopant. The composition is selected to provide the fiber with an acoustic velocity profile in which the velocity within the inner doped region is equal to or less by at most 0.5% than that within the core. The acoustic velocity profile and the winding arrangement provide SBS mitigation by reducing a mode overlap between an optical mode guided in the core and acoustic modes including guided and leaky acoustic modes.

Abstract: A heat-loss pressure microsensor for measuring a gas pressure is disclosed that includes a plurality of pressure gauges arranged proximate to one another on a substrate. The gauges may include a pair of gauges, each gauge including a thermistor having an electrical resistance that varies with its temperature, the thermistor's temperature being responsive to the gas pressure, a platform to receive the thermistor, and a support structure to hold the platform above the substrate. Each gauge may be configured to produce a gauge output signal related to the electrical resistance of its thermistor. The two gauges are configured with their platforms having equal nominal perimeters and different nominal surface areas, and their support structures having the same nominal geometry. A differential signal may be obtained from the two gauge output signals. The differential signal conveys information about the gas pressure and exhibits reduced sensitivity to fabrication-related dimensional variations.

Abstract: Described is a system for monitoring deflection of turbine blades of a wind turbine comprising a tower. The system comprises a position detecting apparatus mounted to the wind turbine, the position detection apparatus comprising position detection components each detecting a presence or absence of a corresponding one of the segments of the turbine blades; and a deflection controller configured to receive the presence or absence detection and to use the presence or absence detection to determine a distance of each of the segments of the turbine blades relative to the tower, whereby the distance of each of the segments of the turbine blades relative to the tower is representative of the deflection of the turbine blades.

Abstract: A particle sizing system is provided that includes an optical source generating a light beam for illuminating particles in a monitored volume, a plurality of light deflectors, each positioned to receive and deflect light scattered by the particles, and an image capture device collecting scattered light deflected by each light deflector. The image capture device outputs an image including a plurality of sub-images, each generated from the collected light deflected from a respective one of the light deflectors. Each particle is imaged as a spot in each sub-image, the plurality of spots associated with each particle corresponding to a plurality of scattering angles. The system also includes a processing unit configured to identify the spots associated with each particle in the sub-images, compute a spot parameter associated with each spot, and determine the size of each particle from its related spot parameters. A particle sizing method is also provided.

Abstract: A method and system for imaging a target scene using a microbolometer array having multiple lines of microbolometer pixels are disclosed. Each line is switchable between an exposed state and a shielded state, where the line is exposed to the target scene and a reference scene, respectively. The method may include alternating between generating a target frame of the target scene and generating a reference frame of the reference scene, each of which in a rolling shutter mode. The method may also include, concurrently with the generating steps, alternating between sequentially shielding each line after its readout in the exposed state for its next readout in the shielded state, and sequentially exposing each line after its readout in the shielded state for its next readout in the exposed state. The method may also include adjusting the target frames using the reference frames to generate thermal images of the target scene.

Abstract: Described is a system for monitoring deflection of turbine blades of a wind turbine comprising a tower. The system comprises a position detecting apparatus mounted to the wind turbine, the position detection apparatus comprising position detection components each detecting a presence or absence of a corresponding one of the segments of the turbine blades; and a deflection controller configured to receive the presence or absence detection and to use the presence or absence detection to determine a distance of each of the segments of the turbine blades relative to the tower, whereby the distance of each of the segments of the turbine blades relative to the tower is representative of the deflection of the turbine blades.

Abstract: Assemblies and kits providing the repeatable positioning of a removable component with respect to a reference component are provided. Precision positioning members including a threaded positioning shaft associated with the reference component, a positioning sleeve associated with the removable component and an alignment nut screwed in the positioning shaft and abutting the positioning sleeve are provided. The spatial profile abutments on the positioning sleeve or positioning nut and the thread angle of the positioning shaft threads are selected to provide an automatic alignment of the positioning shaft within the positioning sleeve. A clocking angle lock for locking the relative orientation of the reference component and removable component is also provide, preferably in the shape of precision clocking members. Assemblies including three sets of precision members with slotted sleeves are also provided.

Abstract: Optical assemblies are provided in which an optical element is centered in the cavity of a barrel. The optical element is secured between a seat in the cavity and a retaining ring. The retaining ring has ring threads complementary to the barrel threads. The retaining ring has an abutment surface engaging a peripheral mounting edge of the optical element along a circular edge contact line. In some embodiments, the abutment surface has a frustro-spherical profile having a radius of curvature selected in view of the thread angle to maintain a centering of the optical element even when the retaining ring is decentered in the cavity. In other variants, the abutment surface has a frustro-conical profile having an inclination angle with respect to the center axis of the cavity selected in view of the thread angle to maintain said centering.

Abstract: A multi-clad optical fiber is provided. The fiber includes, concentrically and radially outwards from the center of the optical fiber, a core doped with at least one rare-earth dopant material, a pedestal cladding structure, an inner cladding and an outer cladding. The pedestal cladding structure includes a pedestal layer having a refractive index smaller than a refractive index of the core, and a raised index layer having a refractive index larger than the refractive index of the pedestal layer. The raised index layer has a thickness and a refractive index which preserve the confinement of the core mode in the core and minimize the overlap of one or more pedestal modes with the core.

Abstract: The building of systems on breadboards such as optomechanical systems using reference stop assemblies is presented. Each reference stop assembly has a threaded base engageable with the breadboard to removably mount the reference stop assembly thereto, a support shaft connected to the threaded base and a reference ball. The reference ball is captively mounted to the support shaft and has a translational play in a plane perpendicular to the support shaft. The reference stop assembly also includes a clamping member mounted to the support shaft over the reference ball. The reference stop assembly is configured such that, when the reference stop assembly is mounted to said breadboard, the support shaft projects normally to the mounting surface of the breadboard and the clamping member cooperates with the breadboard so as to apply a clamping force to clamp the reference ball against a circular seat of a mounting hole on the breadboard.

Abstract: Provided herein is a method for measuring the size distribution and/or hardness of free falling rock pieces. The method comprises projecting at least one laser line on the falling rock pieces by a laser device; capturing images of the falling rock pieces at an angle from the at least one laser line by at least one camera; and obtaining size distribution data of the falling rock pieces based on data obtained from a topographical map generated from the captured images. Certain embodiments further comprise: obtaining at least one of the volume and area of individual rock pieces from the topographical map; conducting a data analysis on at least one of the volume and area measurements of the rock pieces to reduce at least one of sampling and measurement errors; determining the size distribution of the falling rock pieces based on the data analysis and, optionally, evaluating a rock hardness index for the rock.

Abstract: A composite material for sensing a chemical species in a medium is provided. The composite material includes a polymer having a glass transition temperature, a porosity promoter dispersed in the polymer in an amount such that the chemical species is transportable from the medium into the composite material at a temperature below the glass transition temperature, and a chemical indicator dispersed in the composite material, the chemical indicator providing an optical response varying with a concentration of the chemical species in the composite material.

Abstract: Microbolometer detectors and arrays fabricated using printed electronics and photonics techniques, including ink-based printing, are disclosed. A microbolometer detector can include a substrate, a platform suspended above the substrate, and a thermistor printed on the platform and made of a thermistor material including an electrically conducting polymer, for example a poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) polymeric composition. The microbolometer detector can also include an electrode structure electrically connected to the thermistor, and an ohmic contact layer interposed between the thermistor and the electrode structure. The electrode structure can be made of an electrode material including silver, while the ohmic contact layer can be made of an ohmic contact material including a PEDOT-carbon nanotube polymeric composition. A microbolometer array can include a plurality of microbolometer detectors arranged in a linear or two-dimensional matrix.

Abstract: An optical component for transforming an input light beam having a Gaussian irradiance distribution into an output light sheet is provided. The optical component includes a first reflective surface extending around the central optical axis of the optical component and across an input light path of the input light beam, and reflects input light rays into transitional light rays defining a transitional light cone. A second reflective surface extends around the central optical axis and across a light path of the transitional light cone, reflecting the transitional light rays outwardly into output light rays defining the output light sheet. The first and second reflective surfaces are configured to distribute optical power within the output light sheet according to a Gaussian irradiance distribution transversally to the output light sheet. The output light sheet may be planar or conical.