Abstract: A method and system for frequency matching a resonant cavity is disclosed. Light is received in a resonant cavity having at least a first mirror and a second mirror defining a path along which light is reflected. At least the second mirror is actuatable to vary the length of the path of the resonant cavity. An intensity of the light exiting or reflecting from the resonant cavity is monitored, and an error correction is determined. The second mirror is actuated towards a pose relative to the first mirror at which a frequency of the light is in resonance with the length of the path. In this manner, the resonant cavity is frequency matched to the light to maintain the resonant cavity in resonance.

Abstract: A resonant cavity and a method for manufacturing the same are provided. The resonant cavity includes a first reflective surface and a second reflective surface, each of the first and second reflective surfaces providing a phase shift of a reflected electric field component of light waves oscillating along a first principal axis that differs by about ? relative to a phase shift of a reflected electric field component of light waves oscillating along a second principal axis that is normal to the first principal axis. At least one of the first and second reflective surfaces having diattenuation. The first principal axis of the first reflective surface is set rotated relative to the first principal axis of the second reflective surface by about an angle ?0 between an unbroken parity-time symmetric region and a broken parity-time symmetric region. As a result, spatial hole burning and dual mode operation can be eliminated.

Abstract: A method and system for frequency matching a resonant cavity is disclosed. Light is received in a resonant cavity having at least a first mirror and a second mirror defining a path along which light is reflected. At least the second mirror is actuatable to vary the length of the path of the resonant cavity. An intensity of the light exiting or reflecting from the resonant cavity is monitored, and an error correction is determined. The second mirror is actuated towards a pose relative to the first mirror at which a frequency of the light is in resonance with the length of the path. In this manner, the resonant cavity is frequency matched to the light to maintain the resonant cavity in resonance.

Abstract: A system for producing single-frequency or near-single-frequency operation of a laser beam includes a laser for emitting a laser beam at each one of a plurality of cavity lengths, A detector is configured to receive at least a portion of the laser beam emitted, and generate a signal. A computer system is configured to identify at least one beat note in the signal for each of at least one of the plurality of cavity lengths, the at least one beat note indicating the presence of one or more higher-order transverse modes, longitudinal modes, or both, in the received at least the portion of the laser beam emitted at the at least one of the plurality of cavity lengths. The cavity is adjusted to one of the plurality of cavity lengths for eliminating or minimizing the at least one beat note.

Abstract: A system for producing single-frequency or near-single-frequency operation of a laser beam includes a laser for emitting a laser beam at each one of a plurality of cavity lengths, A detector is configured to receive at least a portion of the laser beam emitted, and generate a signal. A computer system is configured to identify at least one beat note in the signal for each of at least one of the plurality of cavity lengths, the at least one beat note indicating the presence of one or more higher-order transverse modes, longitudinal modes, or both, in the received at least the portion of the laser beam emitted at the at least one of the plurality of cavity lengths. The cavity is adjusted to one of the plurality of cavity lengths for eliminating or minimizing the at least one beat note.

Abstract: A turbine wheel for a hydrokinetic torque converter. The turbine wheel is rotatable about a rotational axis and comprises a substantially annular turbine shell member coaxial with the rotational axis, and a plurality of turbine blade members axially extending from the turbine shell member. The turbine wheel is a single-piece component such that the turbine blade members are unitarily formed with the turbine shell member. The turbine wheel (22) is made by an additive manufacturing process from a polymeric material.

Abstract: At least a selected one of a first and second engine are connected to a drive train for driving an aircraft accessory. A gearbox is connected to a primer mover propulsor and an actuator operatively associated with the selected engine is moveable between a position in which the selected engine drivingly engages the gearbox for driving the propulsor and a position in which the selected engine disengages from the gearbox. A position signal, a status signal, and a request signal respectively indicative of a present position of the actuator, a governing state and present speed of each engine, and a request for movement of the actuator from the present position to the other position are received. If the selected engine's speed differs from a predetermined threshold, a control signal is output for causing the engine's speed to be adjusted towards the threshold. A control signal indicating that movement of the actuator is permitted is then output.

Abstract: A turbine wheel for a hydrokinetic torque converter. The turbine wheel is rotatable about a rotational axis and comprises a substantially annular turbine shell member coaxial with the rotational axis, and a plurality of turbine blade members axially extending from the turbine shell member. The turbine wheel is a single-piece component such that the turbine blade members are unitarily formed with the turbine shell member. The turbine wheel (22) is made by an additive manufacturing process from a polymeric material.

Abstract: A system for producing single-frequency or near-single-frequency operation of a laser beam includes a laser for emitting a laser beam at each one of a plurality of cavity lengths, A detector is configured to receive at least a portion of the laser beam emitted, and generate a signal. A computer system is configured to identify at least one beat note in the signal for each of at least one of the plurality of cavity lengths, the at least one beat note indicating the presence of one or more higher-order transverse modes, longitudinal modes, or both, in the received at least the portion of the laser beam emitted at the at least one of the plurality of cavity lengths. The cavity is adjusted to one of the plurality of cavity lengths for eliminating or minimizing the at least one beat note.

Abstract: A method and system for obtaining single-frequency operation of a laser system. A laser beam is emitted from a laser cavity, having an adjustable length, at a plurality of cavity lengths. At least a portion of the laser beam is received at a detector, which detects the presence of transverse and/or longitudinal modes in the laser beam, and generates a laser beam signal having a beat-note indicative thereof. The laser beam signal for each of the plurality of cavity lengths can be analyzed, and a cavity length of best mode purity, indicating single-frequency operation, can be selected. The laser beam system can emit a laser and have a laser beam splitter for directing at least a portion of the emitted laser beam to a laser beam detector for generating at least one laser beam signal therefrom, and an actuator for adjusting the length of the laser cavity.

Abstract: An image generating device comprises a light source producing a light beam and a screen (5) traversed by the light beam and designed to modify the light beam so as to form an image. The screen (5) comprises a transparent element (150) traversed by the light beam and designed to evacuate the heat generated at the level of the screen (5). Said transparent element (150) is made of sintered transparent ceramic. Also described are a head-up display comprising such a device, and a method for manufacturing an image generating device.

Abstract: A turbine wheel for a hydrokinetic torque converter. The turbine wheel is rotatable about a rotational axis and comprises a substantially annular turbine shell member coaxial with the rotational axis, and a plurality of turbine blade members axially extending from the turbine shell member. The turbine wheel is a single-piece component such that the turbine blade members are unitarily formed with the turbine shell member. The turbine wheel (22) is made by an additive manufacturing process from a polymeric material.

Abstract: An image generating device comprises a light source producing a light beam and a screen (5) traversed by the light beam and designed to modify the light beam so as to form an image. The screen (5) comprises a transparent element (150) traversed by the light beam and designed to evacuate the heat generated at the level of the screen (5). Said transparent element (150) is made of sintered transparent ceramic. Also described are a head-up display comprising such a device, and a method for manufacturing an image generating device.

Abstract: A method and system for operating an inlet door of an auxiliary power unit are provided. A control signal comprising at least one inlet door command is output. In response to the at least one inlet door command, at least one feedback signal is received and compared to the at least one inlet door command. If the at least one received feedback signal matches the at least one expected feedback signal, operation of the auxiliary power unit is allowed. Otherwise, operation of the auxiliary power unit is inhibited.

Abstract: A method and system for obtaining single-frequency operation of a laser system. A laser beam is emitted from a laser cavity, having an adjustable length, at a plurality of cavity lengths. At least a portion of the laser beam is received at a detector, which detects the presence of transverse and/or longitudinal modes in the laser beam, and generates a laser beam signal having a beat-note indicative thereof. The laser beam signal for each of the plurality of cavity lengths can be analyzed, and a cavity length of best mode purity, indicating single-frequency operation, can be selected. The laser beam system can emit a laser and have a laser beam splitter for directing at least a portion of the emitted laser beam to a laser beam detector for generating at least one laser beam signal therefrom, and an actuator for adjusting the length of the laser cavity.

Abstract: A method and system for operating an inlet door of an auxiliary power unit are provided. A control signal comprising at least one inlet door command is output. In response to the at least one inlet door command, at least one feedback signal is received and compared to the at least one inlet door command. If the at least one received feedback signal matches the at least one expected feedback signal, operation of the auxiliary power unit is allowed. Otherwise, operation of the auxiliary power unit is inhibited.

Abstract: A first and second engine are connected to a drive train for driving an aircraft accessory. A gearbox is connected to a primer mover propulsor and an actuator operatively associated with a selected engine is moveable between a position in which the selected engine drivingly engages the gearbox for driving the propulsor and a position in which the selected engine disengages from the gearbox. A position signal, a status signal, and a request signal respectively indicative of a present position of the actuator, a governing state and present speed of each engine, and a request for movement of the actuator from the present position to the other position are received. If the selected engine's speed differs from a predetermined threshold, a control signal is output for causing the engine's speed to be adjusted towards the threshold. A control signal indicating that movement of the actuator is permitted is then output.

Abstract: For increasing the power emitted by surface emitting lasers and for improving the spatial coherence of the laser beam, emitted in particular by disk lasers, microchip lasers and VCSELs having a relatively wide emitting area, the invention proposes to select a low order transverse cavity mode by means of a mirror structure (12) of high reflectivity, and of high angular selectivity. The mirror structure comprises a multilayer (14) receiving the optical beam (24) and a resonant grating mirror (16) following the multilayer and arranged for highly reflecting the optical beam in a narrow angular range at each side of a determined incidence angle.

Abstract: For increasing the power emitted by surface emitting lasers and for improving the spatial coherence of the laser beam, emitted in particular by disk lasers, microchip lasers and VCSELs having a relatively wide emitting area, the invention proposes to select a low order transverse cavity mode by means of a mirror structure (12) of high reflectivity, and of high angular selectivity. The mirror structure comprises a multilayer (14) receiving the optical beam (24) and a resonant grating mirror (16) following the multilayer and arranged for highly reflecting the optical beam in a narrow angular range at each side of a determined incidence angle.