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.

A system for determining polarization profiles of points in a scene from video frames using Stokes parameters includes a scene having a region that emits scene light rays that correspond to the points in the scene, an optical chopper controller, a rotating Stokes filter wheel that includes five trigger holes, three rotating linear polarizers, a circular polarizer, and a reference screen, a color filter, a video camera having a video frame, and a computer system having a frame grabber apparatus. The scene light rays are transmitted through the Stokes filter and the color filter to the video camera. Images corresponding to the scene light rays are projected onto respective pixels in the video frame and recorded as two-dimensional (2-D) arrays, and the images corresponding to the scene light rays from four unique images, obtained from light transmitted consecutively through three linear polarizers and a circular polarizer of the rotating Stokes filter wheel, are used by programming in the computer system to calculate respective Stokes parameters of the points in the scene.

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 is applicable to the technical field of security check and provides a terahertz imaging system and a terahertz security device. The terahertz imaging system comprises a terahertz radiation module, an optical chopper, an imaging objective lens, a light-sensitive surface, a terahertz detection module and a signal processing module; the optical chopper is used for modulating terahertz wave radiated by the terahertz radiation module into terahertz wave with default frequency and radiating the terahertz wave to a to-be-detected object in a covering manner; the imaging objective lens is used for focusing the terahertz wave carried with complex dielectric function information of the to-be-detected object on a focal plane of an image space; the minimal edge length of the light-sensitive surface is greater than or equal to the maximum edge length of an imaging region of the imaging objective lens, and the terahertz detection module is used for converting the terahertz wave carried with the complex dielectric function information into an analog current signal; the signal processing module is connected with the terahertz detection module. By the arrangement, nondestructive detection can be performed on human body or biological tissue, radiation injury can be reduced, complete detection data of the to-be-detected object can be acquired by one radiation, detection efficiency is improved, and high-risk items of metal, poison, explosive and the like can be effectively identified.

An optical chopper includes an optical loop having first and second terminals and includes first and second nonlinear elements. The optical loop is arranged to receive, at the first and the second terminals, a pulse-modulated signal and a continuous beam, respectively. The optical loop is arranged to cause the pulse-modulated signal and the continuous beam to counter-propagate in the loop and to produce in the first nonlinear element an inverted pulse-modulated signal having modulation which is inverted with respect to the pulse modulation of the pulse-modulated signal and to cause the inverted pulse-modulated signal to chop the pulse-modulated signal in the second nonlinear element.

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 femtosecond laser manufacturing device and method of an SFBG. Two optical chopper blades with different diameters and same parameters are overlapped, the relative positions of the two blades can be continuously adjusted, the strength of a femtosecond laser is modulated, the modulated femtosecond laser is focused and then irradiates a fiber core of an optical fiber, the optical fiber is fixed to a high-precision micro displacement platform and moves at the constant speed in the direction perpendicular to a laser beam, and the SFBG with the sampling period and duty ratio continuously adjusted is manufactured by changing the moving speed of the micro displacement platform and the modulation frequency and the duty ratio of an optical chopper. The method and device have the advantages of being convenient to operate, high in manufacturing efficiency and the like, are suitable for manufacturing the SFBG of the complex structure and can be widely applied to a multi-wavelength optical fiber filter and an optical fiber laser system.

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.

A spectrum measurement system which is formed by basic measurement instruments in laboratories and is used for measuring optical signals to be measured is provided. The spectrum measurement system includes the following components of: an optical chopper which converts the optical signals to be measured into periodic alternatively-changed optical signals; a monochromator divides the alternatively-changed optical signals into monochromatic a series of optical signals in different wave bands of which the set is the total wave band in which the optical signals to be measured are; a detector which continuously detects the monochromatic optical signals in different wave bands and converts the monochromatic optical signals into different electrical signals with corresponding intensities and in corresponding wave bands; a phase-locked amplifier which amplifies the electrical signals; a data acquisition card which acquires and transmits the electrical signals which have been amplified by the signal phase-locked amplifier; and a curve processing module which is mounted in a computer, and converts the electrical signals transmitted by the data acquisition card into corresponding voltage strengths, and obtains light intensities of corresponding wave bands according to the direct proportion relations between the voltage strengths and the light intensities of the optical signals to be measured so as to draw a wave spectrum curve diagram in the total wave band in which the optical signals to be measured are.

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.

The invention discloses a photo-thermal deflection spectrum testing device with wide wavelength coverage. The photo-thermal deflection spectrum testing device comprises a pump light source, a monochromator, an optical chopper and a beam splitter which are sequentially arranged along a light path, a photoelectric detector is arranged on a reflection light path of the beam splitter, and an absorption cell is arranged on a transmission light path of the beam splitter; the signal output end of the photoelectric detector is connected with the computer; a detection light source and a position sensitive detector are respectively arranged on two side surfaces, vertical to a transmission light path of the beam splitter, of the absorption cell; the signal output end of the position sensitive detector is sequentially connected with a lock-in amplifier and a computer; the absorption cell is used for accommodating a heat-conducting medium, and a sample table is fixed at the bottom and is used for fixing a to-be-detected film; a focusing lens is arranged between the absorption cell and the beam splitter, and the pump light transmitting through the beam splitter enters the absorption cell through the focusing lens; and the pump light source adopts a laser-driven broadband light source and is used for emitting pump light of 170-2100 nm. According to the invention, the test requirements from a narrow-band-gap material to a wide-band-gap material can be met at the same time.