A speed calculator 16 selects a speed calculation method corresponding to a peak value of an SNR which is detected by a peak SNR detector 15 from among a plurality of speed calculation methods of calculating the speed (wind speed) of an aerosol to calculate the speed (wind speed) of the aerosol according to the speed calculation method. As a result, there is provided an advantage of being able to calculate the speed (wind speed) of the aerosol in a short time with a high degree of accuracy.

An air data system includes a laser emitter, a laser receiver, and an electronics module. The electronics module includes a processor and computer-readable memory encoded with instructions that, when executed by the processor, cause the laser to emit a coherent light pulse into a target volume locating within an exhaust flow aft of an aircraft. The laser receiver detects backscatter produced by the coherent light pulse interacting with the aft target volume, and the electronics module determines an air data parameter based on the backscatter and at least one of an engine parameter indicative of an engine condition of the aircraft and an aircraft parameter indicative of a state of the aircraft before outputting the air data parameter to a consuming system of the aircraft.

An air data system includes a laser emitter, a laser receiver, and an electronics module. The electronics module includes a processor and computer-readable memory encoded with instructions that, when executed by the processor, cause the laser to emit a coherent light pulse into a target volume locating within an exhaust flow aft of an aircraft. The laser receiver detects backscatter produced by the coherent light pulse interacting with the aft target volume, and the electronics module determines an air data parameter based on the backscatter and at least one of an engine parameter indicative of an engine condition of the aircraft and an aircraft parameter indicative of a state of the aircraft before outputting the air data parameter to a consuming system of the aircraft.

A method includes irradiating a target droplet in an extreme ultraviolet light source of an extreme ultraviolet lithography tool with light from a droplet illumination module. Light reflected and/or scattered by the target droplet is detected. Particle image velocimetry is performed to monitor one or more flow parameters inside the extreme ultraviolet light source.

A portable electronic device is operable in a particulate matter concentration mode where the portable electronic device uses a self-mixing interferometry sensor to emit a beam of coherent light from an optical resonant cavity, receive a reflection or backscatter of the beam into the optical resonant cavity, produce a self-mixing signal resulting from a reflection or backscatter of the beam of coherent light, and determine a particle velocity and/or particulate matter concentration using the self-mixing signal. The portable electronic device is also operable in an absolute distance mode where the portable electronic device determines whether or not an absolute distance determined using the self-mixing signal is outside or within a particulate sensing volume associated with the beam of coherent light. If not, the portable electronic device may determine a contamination and/or obstruction is present that may result in inaccurate particle velocity and/or particulate matter concentration determination.

A measurement system according to an aspect of the present disclosure is a measurement system that measures a degree of motion of a moving measurement target. In the measurement system, a calculation unit performs M (M is an integer of 2 or more) types of calculation with respect to a light reception signal generated by receiving scattered light from the measurement target, in order to calculate M calculation values. A calculation determination unit determines, based on M×N of the calculation values obtained by performing N (N is an integer of 2 or more) measurements and based on N standard values corresponding to the N measurements, a calculation to be employed.

A device includes a light source (1) for generating light with a single wavelength; a modulator (3) for modulating the light generated into transmission light; a beam scanner (7) for carrying out beam scanning by which the transmission light modulated is radiated, and the light reflected is received; a beam scanning controller (8) for controlling the radiation direction; a signal processing unit (12) for performing wind measurement through heterodyne detection using the light generated and the corresponding received light; and an optical axis corrector (9) for correcting the optical axis angular shift between the transmission light and the received light, which accompanies the beam scanning, with respect to the received light used by the signal processing unit (12) or the transmission light used by the beam scanner (7), on the basis of the radiation direction of the beam scanner (7), the angular speed of the beam scanning and the wind measurement distance.

A system for measuring supersonic nozzle exhaust flow, comprising a seeding module, an optics module configured to direct an optical signal from the supersonic nozzle, and a streak camera. The streak camera is optically connected to the optical signal, the streak camera configured to image the path of the seed particles traveling in the nozzle exhaust flow. The seeding module includes a seed particle container and a seed particle injector configured to inject seed particles into a supersonic nozzle flow. The streak camera comprises a photocathode, a sweep module, a micro-channel plate, a phosphor screen, and a charged coupled imaging device.

A system for measuring supersonic nozzle exhaust flow, comprising a seeding module, an optics module configured to direct an optical signal from the supersonic nozzle, and a streak camera. The streak camera is optically connected to the optical signal, the streak camera configured to image the path of the seed particles traveling in the nozzle exhaust flow. The seeding module includes a seed particle container and a seed particle injector configured to inject seed particles into a supersonic nozzle flow. The streak camera comprises a photocathode, a sweep module, a micro-channel plate, a phosphor screen, and a charged coupled imaging device.

The present invention is a method of determining an induction factor of the wind for a wind turbine (1) equipped with a LiDAR sensor (2). For this method, wind speed measurements are performed in measurement planes (PM) by use of LiDAR sensor (2), then induction factors between measurement planes (PM) are determined by use of the measurements and of a first linear Kalman filter, and the induction factor between a measurement plane (PM) and the rotor plane (PR) of wind turbine (1) is determined by a second linear Kalman filter.