9 results about "Chirp pulse" patented technology

A system and method for distributed temperature and strain sensing using Chirp-Pulse Coherent Optical Time-Domain Reflectometry (CP-COTDR) utilizes optical flow processing. The method involves constructing a two-dimensional (2-D) waterfall data array from collected CP-COTDR frames. Optical flow processing is applied directly to the 2-D data to estimate the local shift of features caused by external perturbations. The optical flow is preferably calculated using a weighted least squares method with an adaptive analysis window based on the local flatness of signal derivatives. This approach provides versatile and high spatial resolution, reduces accumulative errors, and enables efficient data processing compared to conventional cross-correlation techniques.

The embodiment of the present application relates to the technical field of ultra-high-speed imaging, and discloses a framing imaging device, which comprises a chirp spreading element, a diffraction element, a first Fourier lens, a framing element and a second Fourier lens, wherein the chirp spreading element is used for spreading incident light and emitting chirp pulse light; the diffraction element is used for splitting the chirp pulse light into diffraction beams propagating in different directions; the first Fourier lens is used for emitting the incident diffraction beams into central-symmetrical array beams; the framing element is used for framing the array beams into delay beams; and the second Fourier lens is used for converging the delay beams to the same illumination area. The present application also discloses a framing imaging system. The present application solves the technical problem of how to simplify the structure of a conventional framing imaging device under the premise of the same time resolution.

The utility model relates to four program femtosecond laser compressor, through the light of first time through the compressor output is injected into the compressor for many times, incident chirp pulse is along the compressor light path and is emitted four times, total transmission grating 8 times, finally through the output mirror output completes compression output, make the number of times of light beam through grating increase to 16 times, make the same grating aperture and grating spacing compressor dispersion quantity turn 4 times, adapt to bigger spread width or bigger bandwidth chirp pulse amplifier, many times repeat, expand the use number of times of compression grating, obtain bigger compression under the condition that the grating spacing of compressor is unchangeable, can be compatible with bigger spread width of chirp pulse amplifier, solve the problem of design limit of chirp pulse amplifier, promote femtosecond laser output single pulse energy.

The application discloses a kind of high spatial resolution detection device and method based on hyperspectral, wherein, high spatial resolution detection device includes X-ray response module, detection light generation module, synchronous control system, imaging recording module and calibration light path.Detection light generation module generates chirp pulse as detection light;X-ray response module makes X-ray and semiconductor response medium interact, and the space distribution change of the time-space evolution process of X-ray is converted into carrier concentration in semiconductor response medium;Imaging recording module includes imaging system and hyperspectral resolution camera, and the action area of semiconductor response medium is imaged to hyperspectral resolution camera.Under single exposure, multiple high time resolution (femtosecond to picosecond order) two-dimensional X-ray images are obtained, time resolution is adjustable, spatial resolution is high, system structure is simple, cost is low, efficiency is high, anti-interference ability is strong, suitable for X-ray time-space diagnosis in laser fusion and high energy density physics research.

This invention discloses a laser-induced acoustic underwater communication method and apparatus based on discrete linear frequency modulated pulse intervals, belonging to the field of cross-medium communication technology. The invention first maps the binary data to be transmitted into a pulse time interval pattern, where logic "0" and "1" correspond to pulse sequences with pulse intervals that decrease or increase linearly with time, respectively, and inserts a silence protection interval. A laser is controlled to emit pulses towards the water surface at non-uniform intervals, utilizing the photoacoustic effect to excite a train of acoustic pulses with discrete linear frequency modulated characteristics in the water. After acquiring the acoustic signal, the receiving end uses a local reference signal matching the transmitting end's pattern to perform dual-channel cross-correlation demodulation, achieving data decision-making and self-synchronization based on the amplitude and position of the correlation peaks. This invention combines the cross-medium advantages of laser-induced acoustics with the high processing gain characteristics of linear frequency modulated signals, solving the problem of poor multipath resistance in traditional pulse position modulation and significantly improving communication reliability in complex underwater acoustic channels.

The application discloses an underwater distance measurement system and method based on tunable chirped pulse interference, and a tunable optical frequency comb generates an optical frequency comb pulse signal with a variable repetition frequency, which is transmitted through a monitoring light path, a reference light path and a measurement light path respectively, the monitoring light path uses a photodetector and a frequency counter to monitor the repetition frequency of the optical frequency comb pulse signal in real time; a long optical fiber is used as a reference arm in the reference light path to generate a reference pulse signal; a long optical fiber stabilization unit is further arranged in the reference light path; the measurement light path generates a measurement chirped pulse signal; the reference light path and the measurement light path interfere to generate an interference signal, high-resolution spectral image high-speed acquisition of a spectral signal is carried out based on a calibrated CCD camera, and an underwater target absolute distance measurement value is obtained. Compared with the prior art, the application realizes accurate, fast and highly stable underwater distance measurement.

An optical fiber temperature measurement device (10) comprises: a COTDR measurement unit (1) that measures Rayleigh backscattered light from an optical fiber to be measured, the COTDR measurement unit (1) causing light emitted from a first light source to be incident on the optical fiber to be measured, the first light source performing temperature control by changing the frequency by hopping and being capable of changing the line width of the emitted light; a BOTDR measurement unit (2) that measures Brillouin backscattered light from the optical fiber to be measured, the BOTDR measurement unit (2) causing light emitted from a second light source to be incident on the optical fiber to be measured, the second light source being capable of changing the line width of the emitted light and sweeping the emitted light by changing the frequency by triangular chirp pulses; a calibration optical fiber (8) that calibrates temperature and the like; and an LPR analysis unit (5) that calculates the intensity of the Rayleigh backscattered light and the intensity of the Brillouin backscattered light on the basis of the outputs of the COTDR measurement unit (1) and the BOTDR measurement unit (2), and measures the temperature of the optical fiber to be measured at a prescribed position using a Landau-Placzek ratio obtained on the basis of the outputs of the COTDR measurement unit (1) and the BOTDR measurement unit (2).

This invention belongs to the field of distributed fiber optic sensing technology, specifically relating to a BOCDA fiber optic sensing device and method based on linearly frequency-modulated pulse pumping. The device includes a laser, fiber coupler, first electro-optic phase modulator, first erbium-doped fiber amplifier, optical isolator, sensing fiber, second electro-optic phase modulator, electro-optic intensity modulator, electro-optic pulse signal modulator, polarization scrambler, second erbium-doped fiber amplifier, optical circulator, optical filter, photodetector, low-pass filter, and data acquisition and analysis system. Because the pump light pulse frequency changes linearly, the change in probe light amplitude over time directly carries Brillouin gain spectrum information, thus avoiding scanning the pump-probe light frequency difference. Therefore, only a one-dimensional scan is needed to complete a measurement, significantly shortening the measurement time of the BOCDA fiber optic sensor.

The application discloses a time-frequency modulation laser infrared detection method and device for electronic device integrity, constructs a three-dimensional finite element time-frequency modulation infrared detection simulation model of the electronic device, applies a thermal excitation of a linear frequency modulation chirp pulse signal to the surface of the simulation model, and calculates a three-dimensional temperature field response inside the simulation model; performs photo-thermal truncation correlation analysis on an image sequence of a thermal characteristic temperature original signal, demodulates a cross-correlation amplitude and a cross-correlation phase; iteratively optimizes a frequency range or a pulse width of a detection excitation parameter, obtains optimal detection simulation parameters for the type of device, performs a damage device detection experiment, collects a characteristic sensitivity optimization result image in a detection experiment tomographic image, and performs defect detection and measurement; and stacks and reconstructs the tomographic image to obtain a three-dimensional reconstructed visual model. The application improves the depth resolution and structural spatial resolution of the packaged electronic device infrared detection, and realizes non-contact and non-destructive accurate detection of the electronic device.