10 results about "Optical chopper" patented technology

The invention discloses a reflective pumping detection nondestructive testing device and method capable of saturatively absorbing uniformity in a mirror surface. The device is based on a wavelength degeneracy pumping-detection principle, and comprises a femtosecond laser source, a beam splitter, an optical delay line, a double-frequency optical chopper, a two-dimensional precision translation stage, a coaxial focusing system, a spatial filtering diaphragm arranged in a reflection light path, a photoelectric detector, a lock-in amplifier and a signal processing unit. According to the method, different point positions of a sample are accurately positioned through a two-dimensional translation stage, a nonlinear differential reflectance dynamic curve of each point is measured under low power, the maximum differential reflectance and the carrier lifetime are extracted as characteristic parameters, the spatial relative standard deviation of the characteristic parameters is calculated, and lossless and quantitative in-plane uniformity evaluation is realized. According to the method, the interference of the pump light is effectively filtered through the space filtering diaphragm, the signal-to-noise ratio is remarkably improved in combination with the phase-locked amplification technology, and the problem that the nonlinear optical performance uniformity of the saturable absorber mirror cannot be quantitatively evaluated through a traditional method is solved.

A system may include a broadband light source emitting polarized light that is polarized to two orthogonal polarization states, multiple beam splitters for combining and splitting the polarization states, and interferometric cell for creation of interference patterns with respect to a sample surface, lenses of appropriate design that focus the polarized light at predefined locations, and sensors that analyze the polarized light as a function of angle and wavelength. The system may also include a controller configured to modulate the reference arm through operation of an optical chopper and allow for different data analysis modes to be used on the system produced data.

The application discloses a wide-band micro-region semiconductor photocurrent imaging system and method, and belongs to the technical field of semiconductor testing. The system comprises a temperature adjusting module, a picosecond pulse laser output module, an optical chopper, a microscopic imaging module, an electric piezoelectric displacement table and a lock-in amplifier. The temperature adjusting module is used for adjusting the temperature of a semiconductor device to be tested to 4K to 296K. The picosecond pulse laser output module is used for outputting a pulse laser beam in a wave band of 430nm to 2000nm. The optical chopper is used for modulating the laser beam into an optical pulse signal with a fixed modulation frequency. The lock-in amplifier is used for applying a bias voltage to the semiconductor device to be tested and collecting a photocurrent signal under the fixed modulation frequency. The electric piezoelectric displacement table is used for moving the semiconductor device to be tested point by point under a low-temperature environment. The microscopic imaging module is used for synchronously acquiring a surface topography image and constructing a photocurrent spatial distribution map. The application solves the technical problem that the current technology cannot simultaneously realize multi-wavelength excitation, weak signal extraction and micro-region spatial resolution imaging under an extremely low-temperature environment.

To obtain a flame detector testing device that can achieve stable operational test accuracy when conducting operational tests of flame detectors in various operational test environments. [Solution] The system comprises a light source that outputs light containing infrared and visible light components as continuous irradiation light, an optical chopper that generates flashing light by performing a chopping operation that repeatedly passes / blocks the continuous irradiation light at a chopping frequency corresponding to the flickering frequency of a flame, and a control unit that comprehensively controls the light source and the optical chopper. The control unit has a mode switching function that allows selection between a lighting mode, which generates steady light by controlling the light source to be ON and performing stop position control to stop the optical chopper at a position where the continuous irradiation light passes through, and a flashing mode, which generates flashing light by controlling the light source to be ON and performing chopping control to perform the chopping operation.

The invention discloses a high-stability liquid line intensity terahertz radiation generation device which comprises a femtosecond laser, an optical chopper, a first off-axis parabolic mirror, a liquid line generation unit, a second off-axis parabolic mirror, a third off-axis parabolic mirror, an attenuation piece, a low-pass filter and a terahertz energy detector. Wherein the liquid line generation unit integrates a liquid circulation subsystem and a gas power compensation module composed of a gas storage tank and a pressure regulating valve, and the module provides continuous gas pressure for a liquid flow path in the power neutral period of the peristaltic pump, so that the flow jitter and surface turbulence of a liquid line are effectively inhibited; the problems of terahertz signal fluctuation and intensity attenuation caused by liquid line instability are solved, high-intensity and high-repetition-frequency terahertz radiation output with stability improved by about four times is finally achieved, and a feasible scheme is provided for practicability of a liquid terahertz source.

The invention relates to the field of dynamic testing of materials, and particularly discloses an infrared temperature measuring device for a Hopkinson bar. The device comprises an incident bar, a transmission bar, a sample, a dust cover, an infrared filter, two off-axis parabolic mirrors, an optical chopper, a light splitting cube, a laser, a HgCdTe infrared sensor, a signal amplifier and an oscilloscope. The device is provided with a dust cover and is vacuumized to isolate environmental interference; an off-axis parabolic mirror is adopted to form a focusing light path to collect infrared radiation of the sample; the light splitting cube is used for coupling visible light of the laser and infrared light of the sample, so that coaxial accurate positioning of a temperature measuring point is realized; sensor calibration is carried out by combining an optical chopper; and finally, an infrared signal is converted into an electric signal through the HgCdTe infrared sensor, and the temperature change is recorded by the oscilloscope in real time after the electric signal is amplified. The device realizes real-time non-contact accurate measurement of the temperature of the sample in the dynamic loading process.

The invention discloses a terahertz wave signal intensity detection method, device and equipment and a medium, and belongs to the field of terahertz weak signal detection.The method comprises the steps that a terahertz wave signal is modulated into a periodic intermittent optical signal through an optical chopper according to a preset chopper modulation frequency; the periodic intermittent optical signal is converted into a voltage signal through a terahertz probe; amplifying the voltage signal through an amplification conditioning circuit, and converting the amplified voltage signal into a digital signal through an analog-to-digital acquisition circuit; through the MCU chip, fast Fourier transform is combined with chopper modulation frequency, the digital signal is analyzed, and the intensity of the terahertz wave signal is obtained. Therefore, by implementing the application, the problems of high hardware cost and low detection speed in the terahertz wave signal intensity detection process can be solved.

The invention discloses a single-pixel long-wave infrared spectrum detection system and method based on a metasurface filter. The system comprises a to-be-measured object module, an optical modulation module, a signal acquisition module and a data processing module, the to-be-measured object module irradiates the to-be-measured object through spontaneous radiation of the to-be-measured object or a stable infrared radiation light source provided by a blackbody radiation source; the optical modulation module is integrated with a binary coding mask optimized by a genetic algorithm and a 5 * 5 array type metasurface filter, so that rapid switching of 12 low-correlation coding modes is realized; the signal acquisition module is focused by an infrared lens and modulated by a band-pass optical filter and an optical chopper, optical-electric conversion is completed by a single-pixel infrared detector, and a signal is amplified by a lock-in amplifier; and the data processing module realizes spectrum restoration through a neural network, and completes substance classification in combination with recursive feature elimination and secondary discriminant analysis. The device has the characteristics of high luminous flux, high signal-to-noise ratio, high efficiency, high resolution, low cost and small size, and is suitable for on-site rapid screening.

The invention relates to a tunable terahertz radiation device and method based on metal wire liquid column coupling, and the device comprises a femtosecond laser which is used for outputting pumping laser with high repetition frequency; the optical chopper is used for chopping the pumping laser to the required repetition frequency; the metal wire liquid injection coupling structure comprises a metal wire and a liquid column, and a metal wire liquid column coupling area of a local liquid film is formed on the surface of the metal wire based on the synergistic effect of the metal wire and the liquid column; the chopped pumping laser pulse is focused to a metal wire liquid column coupling area through a first off-axis parabolic mirror, the relative position of the metal wire liquid column coupling area and the pumping laser focus is finely adjusted, and stable terahertz radiation output is achieved; and the pulse width of the pump laser output by the femtosecond laser is changed, so that the strong terahertz source output with tunable frequency is realized. Compared with the prior art, strong terahertz output with high energy and high repetition frequency can be realized, the tunability of the terahertz frequency spectrum is expanded, and remarkable advantages are achieved.

The application discloses a target distance and speed measurement system and method based on radio frequency modulation direct detection laser radar, and belongs to the technical field of target distance and speed measurement.The application solves the problem that the existing direct detection laser radar based on radio frequency phase modulation technology cannot measure the distance information of a target.The application introduces radio frequency technology into the direct detection laser radar by means of laser radio frequency modulation and demodulation technology, and utilizes a beam splitter and an optical chopper to process the echo signals of a reference target and a detection target, so that the detection performance of the target distance and speed can be improved, and the problem that the existing method cannot measure the distance information of the target is solved.Further, the measurement method of the application utilizes the frequency information of the radio frequency signal, and avoids information waste.The method of the application can be applied to the technical field of target distance and speed measurement.