101 results about "Optical chopper" patented technology

An off-resonance photoacoustic spectrometric detection and analysis device consists of a photoacoustic spectrometric module (8). The photoacoustic spectrometric module (8) comprises a light source module (2-1), a photoacoustic signal generation module (2-2), an optical power measurement module (2-3) and a fault diagnostic analysis module (2-4). Optical signals generated by an infrared incoherence light source in the light source module (2-1) are focused by an ellipsoidal reflector to form a focused light beam, the focused light beam is modulated into light of specific frequency and wavelength by chopping blades of an optical chopper and optical filters and then transmitted to the photoacoustic signal generation module (2-2), and the fault diagnostic analysis module (2-4) calculates each gas concentration according to to-be-tested gas photoacoustic signals generated by irradiation, diagnoses faults and alarms. The off-resonance photoacoustic spectrometric detection and analysis device can be used for quantitative detection of gases such as SF6, CF4, SO2F2, SOF2, SO2, SF4 and H2O and is applicable to onsite online monitoring.

A modification to a commercial Fourier Transform (FT) Raman spectrometer is presented for the elimination of thermal backgrounds in the FT Raman spectra. The modification involves the use of a mechanical optical chopper to modulate the continuous wave laser, remote collection of the signal via fiber optics, and connection of a dual-phase digital-signal-processor (DSP) lock-in amplifier between the detector and the spectrometer's collection electronics to demodulate and filter the optical signals. The resulting Modulated Fourier Transform Raman Fiber-Optic Spectrometer is capable of completely eliminating thermal backgrounds at temperatures exceeding 300 DEG C.

Using biased, electrical power feedback to an electrical heater, the output signal from a pyroelectric detector is made to follow the waveform of incident electromagnetic radiation. The feedback power is applied to the detector to reduce the rate of change of the detector temperature that would otherwise be caused by the absorbed radiation. The combined signals from the radiation and feedback power produce a response that follows the radiation waveform with a fast rise time and with substantially less droop than previously reported. The high fidelity of the response waveform allows for a substantial simplification of the optical chopper designs and electronics needed to implement electrical calibration. In contrast to previous electrical calibration with pyroelectrics that needed very specialized electronics, with this method a variety instruments can be used for reading pyroelectric signals. The method allows for signal processing that reduces phase noise and yields very accurate radiation power measurements.

The invention discloses an apparatus for measuring temperature distribution in an alkali metal air chamber of an SERF atom magnetometer. The apparatus comprises a light source system, a heating system, the alkali metal air chamber and a signal detection system, wherein the light source system is used for generating laser for measuring the temperature distribution in the alkali metal air chamber and comprises a laser, a lambda/2 wave plate, a PBS, a coupler, an NPBS, diaphragms and a reflective mirror; the heating system is used for heating the alkali metal air chamber; alkali metal atoms, inert gases and buffer gases are packaged in the alkali metal air chamber; and the signal detection system is used for detecting signals representing the temperature distribution in the alkali metal air chamber and comprises two photoelectric detectors, an optical chopper, two lock-in amplifiers and an oscilloscope. The invention further discloses a method for measuring temperature distribution and thermal stability time in an alkali metal air chamber. According to the invention, a simple, effective and quite-high-precision measurement scheme is provided for evaluating the temperature distribution condition and the thermal stability time in the alkali metal air chamber for the SERF atom magnetometer, and a theoretical reference is provided for improving the sensitivity of the SERF atom magnetometer.

The invention discloses a gas concentration measurement device based on ultraviolet light modulation. The gas concentration measurement device comprises a signal transmission module, a gas measurement module, a signal receiving module and a signal processing module in sequence, wherein the signal transmission module comprises an ultraviolet deuterium lamp light source and an optical wave chopper, which are connected through an ultraviolet quartz optical fiber; the gas measurement module comprises a heat tracing pipe tape, a gas tank and a heating module wrapping the gas tank; the signal receiving module is composed of a spectrograph which takes a CCD (Charge Coupled Device) array as a detection core; gas to be detected is pre-heated by the heat tracing pipe tape and then enters the gas tank; the heating module is used for keeping the gas tank at a pre-set temperature; light emitted by the ultraviolet deuterium lamp light source is modulated by the optical wave chopper and then is transmitted to an incidence opening of the gas tank through the ultraviolet quartz optical fiber; after the gas to be detected is absorbed, a signal is received by the spectrograph and is transmitted to the signal processing module for processing. The invention further discloses a gas concentration measurement method based on the ultraviolet light modulation; a signal-to-noise ratio of measurement signals can be extremely increased, and the gas concentration measurement method is very suitable for monitoring low-concentration gas.

The invention relates to a universal AC measurement method for the external quantum efficiency of a solar battery, which comprises that: an optical part consisting of a xenon light source, a focusing lens and a monochromator supplies monochromatic light; an offset light source provides a working environment for the solar battery; an optical chopper and a phase-locked amplifier use phase-locked technology to measure voltage drops at both ends of a sample resistance; a monochromatic light power meter detects a power of incident monochromatic light; a microcomputer performs instrument control and data processing; and finally, a single-wavelength external quantum efficiency curve of the solar battery is obtained. The invention focuses on the AC measurement method, and the AC measurement method has universality and can be used for various types of solar batteries. The invention also relates to an optoelectronic integrated system, which has the advantages of rapidness and accuracy, reduces the cost of solar battery parameter measurement equipment, improves signal intensity and accuracy, provides more comprehensive battery parameter information, and is used for guiding the improvement on preparation process and performing research on the mechanism of partly batteries.

The invention discloses a medium wave infrared laser power stabilization system which mainly solves the problem that an existing system is not strong in stability and low in precision. The whole system comprises a medium wave infrared laser light source system (1), an infrared environment control chamber (2), an acoustic optical modulator (3), a spatial filter (4), a medium wave infrared thin film beam splitter (5), an optical chopper (6), a photoelectricity front-placing module (7), a feedback control module (8), an acoustic optical modulator driver (9) and a laser power detector (10). The medium wave infrared laser light source system outputs medium wave infrared lasers with power to be stabilized, and the infrared lasers pass through the acoustic optical modulator, the spacial filter, the medium wave infrared thin film beam splitter and the optical chopper and then irradiate a photoelectric detector to generate electric signals. The feedback control module processes the electric signals to obtain feedback information, and the acoustic optical modulator driver is controlled to adjust the acoustic optical modulator so as to stabilize the medium infrared laser power. The medium wave stimulate infrared laser power stabilization system has the advantages of being good in stability and high in precision and is suitable for stabilizing the medium wave infrared laser power with the wave band of 2.5 microns to 5 microns.

A gas sensor, whose chamber uses filters and choppers in either a semicircular geometry or annular geometry, and incorporates separate infrared radiation filters and optical choppers. This configuration facilitates the use of a single infrared radiation source and a single detector for infrared measurements at two wavelengths, such that measurement errors may be compensated.

The invention relates to a light cutting device for an optical chopper and a controlling method thereof. According to the device provided by the invention, a metal light barrier is arranged in the energized electromagnetic coil, the direction of current flowing from the metal light barrier is vertical to the direction of field generated by the electromagnetic coil, the light barrier moves along the set sliding groove under the action of electromagnetic force. The direction of the current flowing through the electromagnetic coil or the light barrier is changed as per the preset frequency, so that the metal light barrier can move back and forth along the sliding groove. The light barriers are arranged in the front and back of the light through hole, the movement of the light barrier can control whether the incident light passes through the optical chopper light cutting device or not, so as to accomplish the modulation of incident radiant. The light barrier is enabled to pass through the position between the coupling luminous diode and the phototriode during movement, so as to collect the modulation frequency of the optical chopper light cutting device. The adjustment of radiation modulation frequency can be accomplished by only one output control of the controller; cost is reduced, practicability and flexibility are increased, and application range is enlarged; measurement accuracy is improved, and utility difficulty of an operator is decreased.

The invention belongs to the field of infrared photodetection and relates to a device and a method for calibrating response characteristic parameters of an infrared photodetector under dim light conditions. The device comprises a calibration light source, an optical chopper, a collimator and a phase-locked amplifier, wherein the optical chopper is located between the calibration light source and an entrance of the collimator; the phase-locked amplifier is separately connected with the optical chopper and an infrared photodetector to be detected; a target surface of the infrared photodetector to be detected is located at an exit of the collimator. According to the device and the method, the optical chopper is used for modulating black body emitting light signals, and the phase-locked amplifier is used for extracting the modulated black body emitting light signals, so that the interference to light source signals caused by environmental radiation signals is effectively avoided.

The invention discloses a film magnetic characterization instrument under vacuum. The instrument includes an ultra-fast laser, beam splitters, a time delay line, reflectors, a polarization splitting prism, a frequency multiplier, two optical filters, at least one rectangular prism, an optical chopper, an optical focusing lens group, a multi-fiber sample rack, a hermetic vacuum cavity, a 1/2 slide, a beam splitter prism, a photodiode, a phase-locked amplifier, a magnet, a constant temperature apparatus, a translation stage, and an imaging apparatus. According to the invention, the instrument, by implementing in situ characterization in the preparation of films, increases measuring efficiency and precision. The instrument can achieve imaging effects by preparing a multi-fiber sample adjusting apparatus with as high as five fibers in combination with the translation stage for samples. Co-axial and vertical incidence of pump and detection beams simplifies light paths and reduces the difficulty in adjusting light paths. In addition, the instrument can enable samples to conduct magnetic characterization inside the vacuum cavity and prevents air or water vapor from polluting the samples.

A holographic recording system with a simple structure is provided that can make a holographic recording beam follow a recording medium traveling even at high speed. The holographic recording system 10 includes a chopper lens 30 that travels in synchronization with and in a same direction as the holographic recording medium 14. The chopper lens 30 is formed so as to move the axes of incident information and reference beams relative to the recording medium and the chopper lens, and to irradiate them to an identical information recording region 15 in the holographic recording medium 14.

The invention provides a time domain heat reflection spectral measurement system. The time domain heat reflection spectral measurement system is characterized in that a polarized pulse laser is incident into a first light-splitting device via a collimating lens after passing through an optical isolation system, and is divided by the first light-splitting device into two laser beams. which are in orthogonal polarization and respectively serve as pump light and detection light; the pump light passes through an electrooptical modulator, is incident into an optical retarder through a section reflecting mirror, is incident into a second light-splitting device via a short-wave pass filter and a third reflecting mirror in sequence, and is reflected by the second light-splitting device; and the detection light is modulated by an optical chopper, then, is reflected by a fourth reflecting mirror, is incident into a long-wave pass filter, is reflected and incident into the second light-splittingdevice via a third light-splitting device, and is merged with the pump light into a laser beam, and the co-linear light is focused onto the surface of a sample through an objective lens. According tothe time domain heat reflection spectral measurement system, non-linear crystals are not used, perfect separation of the pump light from the detection light on a spectrum is realized at a relatively low cost, and the signal-to-noise ratio is greatly increased.

The invention belongs to the technical field of fluorescence imaging, in particular to a laser pump time resolution up-conversion luminescence living imaging system, consisting of a semiconductor laser, a pulse emitter, an optical chopper, an optical camera, a CCD detector and a computer; according to the system, by using the feature of a long luminescence service life of an up-conversion luminescence material, the up-conversion luminescence material is excited by short pulse light, delay fluorescence time periods without existence of excited light are collected, thus realizing real-time, non-invasive, high signal to noise ratio and high sensitivity imaging on a material, a cell or biological tissue marked with an up-conversion luminescence probe. In addition, by using pulse exciting light, the total amount of laser irradiation can be greatly reduced to further reduce the influence on the biological tissue. Signal interference of exciting light in fluorescence imaging is effectively removed, imaging sensitivity and accuracy of fluorescence detection are greatly improved, and a powerful tool is provided for the living optical detection in material science, bioscience and medical research.

The invention provides a full optical fiber narrow linewidth hundred nanosecond pulse signal system; the invention comprises a distribution feedback optical fiber laser, an acoustic and optical chopper, a ytterbium-doped single mode fiber preamplifier, a fiber beam splitter; the 90 percent output end of the optical fiber beam splitter is melted with the signal end of a multimode pumped beam combiner, all of which are interconnected sequentially; the output tail optical fiber of the multimode pumped beam combiner is melted with the optical fiber of a ytterbium-doped doubly clad optical fiber amplifier; the pumped end of the multimode beam combiner is connected with a multimode semiconductor laser; the output end surface of the tail optical fiber of the ytterbium-doped doubly clad optical fiber amplifier is provided with an inclined plane of eight degrees and the backward output monitoring end of the optical fiber beam splitter is connected with an optical fiber isolator. The amplified pulse signal of the invention has the advantages of narrow linewidth, fundamental transverse mode, single longitudinal mode, good stability and no deformation of the pulse shape under high power and the pulse signal is easy to be enclosed and can not be affected by environment significantly.

The invention relates to a high-perturbation-resistance laser seed source system based on single-polarization transmission fibers. The high-perturbation-resistance laser seed source system based on single-polarization transmission fibers comprises a narrow-line-width continuous fiber laser, a single-polarization acousto-optical chopper, a single-polarization fiber amplifier, a phase modulator, a single-polarization amplitude modulator, a clock frequency source, an arbitrary waveform generator and a digital delay generator, wherein the digital delay generator successively triggers the single-polarization acousto-optical chopper and the arbitrary waveform generator; and a phase modulating signal is generated by the clock frequency source, is loaded on the phase modulator, simultaneously is inputted to the arbitrary waveform generator and is used as a reference clock, so that phase locking is realized, and finally laser pulse with arbitrary pulse width is obtained. By the high-perturbation-resistance laser seed source system based on single-polarization transmission fibers, amplitude-frequency modulating caused by phase modulating spectrum broadening can be inhibited effectively, influences of the laser seed source system to laser pulse amplitude-frequency modulating and influences of external environments (including temperature and stress) are reduced, and quality of laser pulses output by a laser seed source is improved.

The invention provides a medium-wave infrared laser power stabilizing apparatus and stabilizing method. The apparatus comprises a light parameter oscillation laser, an acousto-optic modulator, a beam splitter, an optical chopper, an infrared detector, a front amplifier, a phase-lock amplifier, a conditioning circuit, an A/D converter, an FPGA program control unit and a D/A converter. The acousto-optic modulator and the beam splitter are arranged in a vacuum shield chamber; the light parameter oscillation laser generates a tunable middle infrared laser and generates Bragg diffraction through the acousto-optic modulator; and after diffracted light is subjected to light splitting of the beam splitter, one path of light is outputted, and the other path of light respectively passes through the optical chopper, the infrared detector, the front amplifier and the phase-lock amplifier to finish photoelectric conversion. By using such a scheme, the stable control of laser power within a middle infrared wave band is realized, thus filling the gap in domestic research on medium-wave infrared laser power stabilization control.

A nondestructive method and apparatus for testing the optical characteristics of human channels features that such units are sequentially arranged as light source, optical chopper, convergent lens, light wave irradiating and transmitting optical fiber in contact with human channel to be tested, optical fiber probe for receiving the signal reflected from said human channel, photomultiplier tube, phase-locked amplifier, and display.

The invention discloses an outer control ultraviolet laser power stabilizing system, mainly for solving the problem that the existing laser power stabilizing system is low in stability. The outer control ultraviolet laser power stabilizing system comprises an ultraviolet laser light source system (1), an ultraviolet environment control room (2), an electrooptical modulator (22), a sampler (26), an optical chopper (3), an optical filter (4), a photoelectric preamplifying module (5), a feedback control module (6), an electrooptical modulation driver (7) and a laser power detector (8), wherein the ultraviolet laser light source system outputs ultraviolet laser power of which needs to be stabilized, the ultraviolet laser the power of which needs to be stabilized passes through the electrooptical modulator (22), the ampler (26), the optical chopper (3) and the optical filter (4) and vertically reaches an photoelectric detector to generate electric signals; the electric signals generate feedback signals through the feedback control module, to control the electrooptical modulation driver to adjust the electrooptical modulator to stabilize the ultraviolet laser power. The outer control ultraviolet laser power stabilizing system is high in stability, and is suitable for stabilizing the ultraviolet laser power with wave bands of 250-400nm.

The invention relates to a digital automatic frequency locking photoelectric equivalent balance system of an electrical calibration heat radiometer. Through a high-precision optical chopper, optical radiation is irradiated to a pyroelectric detector. The detector outputs a weak electrical signal. After going through a weak signal detection circuit, an automatic tracking band pass filter, an automatic tracking phase sensitive detection circuit, a compensation integrating circuit, and an electric heating signal modulation circuit in order, the signal is modulated into two paths of electric heating signals with symmetrical waveform and alternate polarity. The two paths of electric heating signals are outputted to two electric heating electrodes of the detector respectively. The system can besuitable for reference signals with different frequency and lock and track reference signal frequency, and automatic coupling of phases of an optical radiation heating signal and an electrical power heating signal can be realized. Adaptation capability of an electrical calibration radiometer in different occasions is increased, and a usage scope is enlarged. Simultaneously, according to an automatic phase coupling function, a series precision influence problems brought by a hand-operated adjusting mode can be substantially reduced.