1210 results about "Lock-in amplifier" patented technology

Controls for an optical scanner, such as a single fiber scanning endoscope (SFSE) that includes a resonating optical fiber and a single photodetector to produce large field of view, high-resolution images. A nonlinear control scheme with feedback linearization is employed in one type of control to accurately produce a desired scan. Open loop and closed loops controllers are applied to the nonlinear optical scanner of the SFSE. A closed loop control (no model) uses either phase locked loop and PID controllers, or a dual-phase lock-in amplifier and two PIDs for each axis controlled. Other forms of the control that employ a model use a frequency space tracking control, an error space tracking control, feedback linearizing controls, an adaptive control, and a sliding mode control.

The invention discloses a multi-wavelength high-sensitivity online monitor of multi-component NH3 and H2O based on semiconductor laser absorption spectroscopy. It contains host chassis and open long-path system. Equip power receptacle, switch, fiber connector and data transmission interface. It is characterized in that: there are near-infrared semiconductor laser, semiconductor laser controller, phase-locked amplifier, signal generator, data collecting and controlling module and infrared detector in host chassis which is connected with field optical system by fiber. Open optical system contains send-receive optical telescope and multielement reflector array. Optical telescope has input and output fiber couplers. The device realizes simultaneous testing of gas multi-component by using multi-wavelength and frequency division multi-signal detecting technique.

The invention discloses a fire scene multi-parameter laser wavelength modulation spectrum detection method and a device thereof, wherein, fire smoke products are treated through a smoke pre-treatment device and then pumped into a white cell through an air extracting pump; a multi-channel laser controller scans and modulates the wavelengths of a plurality of DFB lasers according to the time-sharing and multiplexing working mode, and all waves of laser share an optical fiber and are outputted sequentially through a wave combiner, then are aligned by a fiber collimator and sent to the white cell to detect the fire smoke products; a photoelectric detector converts light intensity signals of laser repeatedly reflected and absorbed by the white cell into electrical signals which are sent to two phase-locking magnifier modules for frequency selecting magnification so as to obtain a fundamental frequency component and a second harmonic component; a multi-channel data acquisition card converts output voltage signals of the phase-locking magnifiers into digital signals which are sent to a micro-computer for real-time data processing, so that the fire scene multi-parameter information containing the oxygen concentration of the fire scene, concentrations of various toxic gases and smoke concentration is obtained. The detection method and device can realize real-time on-line monitoring to fire scene multi-parameters, and have the advantages of being real-time, multi-component and highly sensitive, good selectivity of gas, high reliability and strong environmental disturbance resistance ability.

A multichannel fluorosensor includes an optical module and an electronic module combined in a watertight housing with an underwater connector. The fluorosensor has an integral calibrator for periodical sensitivity validation of the fluorosensor. The optical module has one or several excitation channels and one or several emission channels that use a mutual focusing system. To increase efficiency, the excitation and emission channels each have a micro-collimator made with one or more ball lenses. Each excitation channel has a light emitting diode and an optical filter. Each emission channel has a photodiode with a preamplifier and an optical filter. The electronic module connects directly to the optical module and includes a lock-in amplifier, a power supply and a controller with an A / D converter and a connector. The calibrator provides a response proportional to the excitation intensity, and matches with spectral parameter of fluorescence for the analyzed fluorescent substance.

The invention discloses a biaxial atomic spinning magnetometer. The biaxial atomic spinning magnetometer comprises an alkali metal gas chamber, non-magnetic electric heating equipment, a three-dimensional magnetic coil, a magnetic shielding layer, a pumping laser module and a detecting laser module. The alkali metal gas chamber is filled with alkali metal atoms, a quenching gas and a buffering gas; the non-magnetic electric heating equipment and the magnetic shielding layer enable the alkali metal atoms to work in a high-temperature and low-magnetic field environment, and ensure the alkali metal atoms in a non-spinning exchange relaxation state; the pumping laser module is used for polarizing the alkali metal atoms; the detecting laser module comprises two beams of independent detecting laser which are perpendicular to each other, and are used for sensing the magnetic field intensity in two directions which are perpendicular to each other simultaneously; measurement results are demodulated through a phase-locked amplifier. The biaxial atomic spinning magnetometer can acquire biaxial magnetic field information simultaneously through one alkali metal gas chamber, has the characteristics of high sensitivity, high integration degree and low cost, and has a wide application prospect in the fields of brain magnetic measurement, magnetocardiographic measurement and the like.

An open natural gas leakage multiplex inspecting method and optical channel configuration, based on semiconductor laser absorbing spectrum method, relates to master case and open long optical channel system. The master case sets with electrical source socket, switch, fan, optical fiber linker and data transmission interface. The master case owns closed infrared semiconductor laser, semiconductor laser controller, phase-locked amplifier,signal generator,data collection disposal and control module, light switch, light switch driving circuit and infrared detector and connects with the locale optics system by optical fiber. Open optical system relates to integral optics telescope and more component angle reflector array and the former owns import optical fiber coupling implement and output optical fiber coupling implement. It achieves the time-sharing inspect of more gas component and more multiplex based on optical fiber distributing configuration of the light switch technology.

The invention discloses a microfluidic chip system integrating cell sorting and detection. The system comprises a microfluidic chip, a high-frequency lock-in amplifier and a processor, wherein the microfluidic chip is formed by aligning and packaging a flow channel layer, an electrode layer, a substrate layer and a PCB (printed circuit board) in sequence; a cell sorting spiral flow channel, a detection main flow channel and a retraction flow channel are formed in the flow channel layer; the retraction flow channel is aligned to a planar metal electrode of the electrode layer; liquid electrode structures are formed on two sides of the main flow channel; an electrode of the electrode layer forms a differential high-frequency impedance measurement circuit together with the high-frequency lock-in amplifier through a power amplification circuit and an I / V conversion circuit of the PCB to realize differential detection of cell alternating-current impedance. The system can realize the integration of rare cell sorting and representation function, improves the integrity and accuracy of a cell detection technology, and can be widely used in the fields of rare cell biological study, early disease diagnosis and treatment and the like.

The invention discloses a quartz tuning fork strengthened photoacoustic spectroscopy gas sensor based on an acoustic resonator. The gas sensor comprises a laser (1), a focusing lens (5), a tubular resonator, a quartz tuning fork (11), a function generator (15) electrically connected with the laser (1) and a lock-in amplifier (14) electrically connected with the quartz tuning fork (11), wherein the focusing lens (5) and the tubular resonator are arranged on an optical path (2) of the laser (1); the function generator (15) is electrically connected with the lock-in amplifier (14); the tubular resonator is the acoustic resonator (9) with a slit (91) in the middle; the length of the acoustic resonator is not more than 10mm, the external diameter is not more than 1mm and the internal diameter is not more than 0.6mm; the width of the slit (91) is not more than 0.2mm and the length is not more than the internal diameter of the acoustic resonator (9); prongs (111) of the quartz tuning fork (11) are positioned on the slit (91) and the distances between the prongs (111) and the slit (91) are not less than 0.001mm. The gas sensor has simple structure, small volume and strong anti-jamming property, works stably, is convenient to adjust and use and can be extensively used for detecting the components or contents of the gases.

The invention provides a method for detecting on-line a multi-component gas and the testing arrangement for the method. The method comprises the following procedures: the current and temperature are tuned by a semi-conductor laser; after double modulation, the laser emitted from the semi-conductor laser passes an optic-fiber coupler, partial laser reaches to an open multi-optic-path pond, in which the emitted light that is absorbed by the gas to be measured is again transmitted through an optic fiber to a balance receiver; another partial laser from the optic-fiber coupler is also sent into the balance receiver; the signals picked up by the balance receiver is sent into a phaselocking amplifier after passing a pre amplifier, and then sent into a computer for processing after passing an A / D converter. The testing arrangement comprises a modulation signal generator, a laser driver, a laser spectrum light path, a signal conditioning circuit and a computer that are connected in sequence; the computer is additionally connected with the modulation signal generator, and connected with the laser spectrum optic path through a temperature detector / controller. The invention converts the precision controlling of temperature into the precision controlling of temperature, improves the sensitivity and opaqueness of the detection, so as to achieve the simultaneous testing of a plurality of components.

A system for emitting and detecting terahertz frequency electromagnetic pulses. The system comprises a single transceiver device, which may be an electro-optic crystal or photoconductive antenna, for both emitting and detecting the pulses. A related method comprises using a single transceiver device to both emit and detect electromagnetic terahertz frequency pulses. The transceiver device is excited by a pump pulse to emit a terahertz output pulse, which is modulated with a chopper. An object reflects the terahertz pulse and the reflected pulse is detected in the transceiver using a probe pulse. A lock-in amplifier set to the same frequency of the chopper is used to reduce noise in the signal detected by the transceiver. An image of the object may be created using the intensity or the timing of the peak amplitude of the terahertz pulses reflected from the object.

The use of a superconducting resonator with continuous-wave (CW) excitation allows low-noise quadrupole resonance (QR) detection without the need for a lock-in amplifier. This allows detection times to be greatly reduced. Hence, for the first time, a CW QR spectrometer using a superconducting resonator can be used in a portable device, such as a hand-held wand for detecting explosives.

The present invention relates to a method and system to suppress or eliminate light shift in an optical pumping system, such as an atomic clock. The method uses modulation of a radiation source, such as a radio frequency or microwave source, to simultaneously lock the frequency of the radiation source to an atomic resonance and lock the frequency of the optical pumping source in order to suppress or eliminate light shift. In one embodiment, the method of the present invention directly utilizes the out-of-phase channel of a lock-in amplifier to additionally lock an optical pumping source to a zero-light-shift frequency, where the in-phase channel is used to lock the frequency of the radiation source to an atomic resonance.

The invention relates to a gas parameter online measurement method based on wavelength modulation spectroscopy and belongs to the field of tunable diode laser absorption spectroscopy. According to the method, a gas absorptivity function is fitted by using an odd number of harmonic signals of an X axis and a Y axis output by a phase-locked amplifier based on the wavelength modulation spectroscopy, normalization processing is carried out on the harmonic signals of the X axis and the Y axis by using first harmonic background signals so as to eliminate the influence of factors, such as background signal, laser intensity and modulation factor, and then, the temperature, concentration, pressure and spectroscopic constant of gas are directly measured by using the gas absorptivity function. The gas parameter online measurement method based on the wavelength modulation spectroscopy has the advantages that the problem that the wavelength modulation spectroscopy needs to calibrate experimental measuring temperature and concentration and cannot measure the pressure and spectroscopic constant of gas nowadays is solved, and the application range of the wavelength modulation spectroscopy is widened.

The present invention discloses a magnetic detecting device comprising an apply coil 1 for generating an alternate magnetic field of variable frequency and a power source 2 for the apply coil; a magnetic sensor 5 for detecting a change in the magnetic field induced by a test object 9 placed at a distance from a surface of said apply coil and toward said test object, said magnetic sensor being provided with a cancel coil 6 for canceling a magnetic field generated at the position of the magnetic sensor by a direct magnetic field and / or said apply coil; a measurement circuit 7 for the magnetic sensor for measuring a detection signal of said magnetic sensor; a lock-in amplifier circuit 8 for detecting an output of said measurement circuit for the magnetic sensor into two signals having the same frequency as that of said apply coil and phases different from each other by 90 degrees; and an analysis means 10 for analyzing a phase change of the output of said magnetic sensor 5 using an output signal from said lock-in amplifier circuit 8.

The disclosed sensor is gas sensor of optical crystal fiber with hollow core. The air sensor includes light source, light guiding gas-cell light path, reference light path of general optical fiber, and signal conversion part. Through general optical fiber, and light splitter, the light guiding gas-cell light path is connected to light source. Being setup at another end of the light guiding gas-cell light path and the reference light path, the said signal conversion part including photodiode, and phase-locked amplifier is in use for providing signal for circuit of monitoring external gas concentration. Optical crystal fiber with hollow core of containing gas permeable micropores in micro level is adopted in the light guiding gas-cell. Comparing current optical fiber gas sensor, the invention possesses advantages: simple system, easy of controlling absorbed light path, and coupling loss. The invention raises effective absorbed light path, and response seeped of parts so as to suit monitoring gas in site.

The invention discloses an optical fiber gyroscope frequency characteristic elevating device based on a Faraday effect. An excitation current source comprises a signal generator, a conversion amplifying circuit and a current coil, wherein a sensitive light path comprises a light source, a circulator, a Y waveguide phase regulator, a polarization beam splitter, a polarization-maintaining fiber coil, a gamma / 4 wave plate, a sensing optical fiber, a reflecting mirror and a detector; and an analog optical fiber gyroscope signal processing detection circuit comprises a front amplifying circuit, an A / D (Analog to Digital) converting circuit, a digital signal processing unit, a first D / A (Digital to Analog) converting unit, a second D / A converting circuit and a phase-locked amplifier. The Faraday effect applied in the invention is generated by exciting the sensitive light path with sinusoidal current, and a sinusoidal signal serving as an exciting signal can be output at a high frequency, so that the problem of limitation on the excitation signal output frequency during frequency characteristic test of an optical fiber gyroscope is solved, and evaluation of high bandwidth can be realized.

The invention provides a system and a method for detecting CO gas based on a quartz tuning fork enhanced photoacoustic spectrometry technology, relates to a system and a method for detecting the CO gas and aims at solving the problem of low detection accuracy of the existing CO gas photoacoustic spectrometry detection technology. A data processing module transmits a current control signal to a laser device controller via a function generator, and meanwhile, transmits a temperature control parameter to the laser device controller; the laser device controller drives a laser device to emit near infrared laser which is incident into a gas chamber after being collimated and focused; the gas absorbs optical energy so that the optical energy is converted into heat energy and further converted into an acoustic pressure signal; a quartz tuning fork mounted in the gas chamber converts an acoustic signal into an electric signal; the electric signal of the quartz tuning fork is converted and amplified and then input into the measurement channel input end of a phase-locked amplifier; the phase-locked amplifier inverts the concentration of the CO gas to be detected by performing secondary harmonic detection in combination with the reference signal of the function generator. The system and the method for detecting the CO gas based on the quartz tuning fork enhanced photoacoustic spectrometry technology are applicable to CO gas detection.

An optical IQ modulator with automatic bias control is disclosed. A dither signal is applied to the modulator bias and its signature detected in light tapped from an output of the modulator using a phase sensitive dither detector such as a lock-in amplifier. The detected signal is processed using pre-recorded information defining the direction of the detected signal change relative to a change in the modulator bias, and the bias is adjusted in the direction determined using the information. The IQ phase bias is controlled by dithering I and Q optical signals in quadrature to produce opposite-sign single subband modulation of output light at two different dither frequencies, and detecting an oscillation at a difference frequency using a lock-in detector.

The invention discloses an alcohol gas concentration laser telemetering device comprising a laser device control and emission system and a signal receiving, analysis and display system, wherein the laser device control and emission system comprises a modulating signal generator which is connected with a laser controller, a diode laser device and a laser emission device in sequence; the signal receiving, analysis and display system comprises a phase lock amplifier, a data acquisition and analysis device, a system display and alarm device and a laser receiving device, wherein the phase lock amplifier is respectively connected with the modulating signal generator, the laser emission device, the data acquisition and analysis device and the laser receiving device; and the output end of the data acquisition and analysis device is connected with the input end of the system display and alarm device. The invention can remotely carry out predetection on alcohol content in the air in a vehicle, thereby improving the pertinence and the accuracy of drunk driving checking, improving the enforcement work efficiency and reducing the police strength application.

The invention discloses a multi-component real-time online remote monitoring device and a method for coal spontaneous combustion indicator gas. For the limit of long distance optical fiber sensing band, the near-infrared band with weaker gas absorption line strength is used for real-time online monitoring the typical alkane gas as CO, CO2, C2H2 and C2H4 in the indicator gas. The multi-component weak signal is detected through the multi-frequency wavelength modulation and novel long optical distance multiple reflection pool technology; the device comprises a laser, a laser controller, a signal generator, a novel multiple reflection pool, an optical fiber collimator, a light beam coupler, a photoelectric detector, a lock-in amplifier, a processing system collecting the signal of A / D and terminal and an anti-explosion case. The device adopts the optical fiber for connection without manpower sampling, the responding sensitivity is high, the device and the method can monitor a variety of indicator gases at the same time with simple operation, good stability and small power, the device is easy to carry and install for field experimentation and the dynamic measuring range is large.

The invention relates to a method and a device for detecting gas, in particular to a modulation spectrum gas detection method based on quasi-continuous diode laser, and a device thereof. The invention adopts a technical proposal that a quasi-continuous diode laser spectrum modulation method for gas detection comprises the following steps: a modulation signal generator outputs a modulation signal and a reference signal; the modulation signal is supplied to a laser driver for controlling the injection current of a quasi-continuous diode laser; the reference signal is supplied to a lock-in amplifier and used as the reference signal; laser emitted by the quasi-continuous diode laser passes through to-be-detected gas and then is received by a photodetector; the output of the photodetector is transmitted to a preamplifier, amplified and then sent into the lock-in amplifier; and output signals of the lock-in amplifier are sent into a computer via an AD converter, processed and analyzed, so as to obtain the species and concentration data of the detected gas. The method is mainly applied to occasions needing trace gas detection with high sensitivity and high resolution.

There is provided a glucose monitoring method and apparatus based on the principle of Wavelength-Modulated Differential Laser Photothermal Radiometry (WM-DPTR). Two intensity modulated laser beams operating in tandem at specific mid-infrared (IR) wavelengths and current-modulated synchronously by two electrical waveforms 180 degrees out-of-phase, are used to interrogate the tissue surface. The laser wavelengths are selected to absorb in the mid infrared range (8.5-10.5 μm) where the glucose spectrum exhibits a discrete absorption band. The differential thermal-wave signal generated by the tissue sample through modulated absorption between two specific wavelengths within the band (for example, the peak at 9.6 and the nearest baseline at 10.5 μm) lead to minute changes in sample temperature and to non-equilibrium blackbody radiation emission. This modulated emission is measured with a broadband infrared detector. The detector is coupled to a lock-in amplifier for signal demodulation. Any glucose concentration increases will be registered as differential photothermal signals above the fully suppressed signal baseline due to increased absorption at the probed peak or near-peak of the band at 9.6 μm at the selected wavelength modulation frequency. The emphasis is on the ability to monitor blood glucose levels in diabetic patients in a non-invasive, non-contacting manner with differential signal generation methods for real-time baseline corrections, a crucial feature toward precise and universal calibration (independent of person-to-person contact, skin, temperature or IR-emission variations) in order to offer accurate absolute glucose concentration readings.

A neural probe and method of fabricating same are provided. The probe comprises a plurality of frames connected to each other and to a substrate by respective bimorphs. A probe base is connected by another bimorph to the frames. A probe tip extends from the probe base. The probe can achieve a large vertical motion and out-of-plane curling. The probe can operate according to three modes. The first mode pertains to a large-signal motion for tuning in single-unit neuronal activity. The second pertains to a small-signal motion with lock-in amplifier that increases SNR. The third pertains to burst small-signal motion for clearing tissue responses. Fabrication of a neural probe begins with a processed CMOS chip. Post-CMOS processing incorporates self-aligned selective nickel plating and sacrifices two aluminum layers. The fabrication technique produces a neural probe in which the sensing elements are in close proximity to CMOS circuitry. The fabrication technique obviates the need for post-CMOS masks, alignment, or assembly.

A magnetic levitation device and measurement method used for measuring the angle of spherical rotor polar axes, including low-temperature Dewar (8), superconducting suspension coil (5), superconducting niobium-rotor (1), niobium watts (2), superconducting motor (6), torque (7), centre column (9), copper (10), polar axes optical fiber sensor (3) and rev speed optical fiber sensor (4). The Superconducting niobium-rotor (1) is arranged in the spherical cavity formed by the upper and the lower relative niobium watts whose inner surfaces are spherical, and sleeves on the center column (9); two circular superconducting coils (5) are sleeved on the upper and the lower Niobium watts (2). The top of the rotor is produced into plane with diffuse reflection graphic. Two optical axis of the optical fiber sensor are perpendicular to the top plane of rotor and fix in the copper (10). The measurement method of the invention is used for measuring the angle of spherical rotor polar axes, adopts the non-contact type reflection intensity modulated optical fiber sensor to measure the displacement offset signal of the rotor polar axes, and uses the sophisticated two-phase lock-in amplifier to process signal, which has high precision.

Methods are provided for producing optical carrierographic images of a semiconductor sample. Focused and spatially overlapped optical beams excite carriers across within the semiconductor sample, where the optical beams are modulated such that a beat frequency is substantially less than either modulation frequency. An infrared detector detects infrared radiation emitted from the semiconductor sample in response to absorption of the optical beams, thereby obtaining a plurality of carrierographic signals at different points in time during at least one beat period, which are processed with a lock-in amplifier, with a reference signal at the beat frequency, to obtain an amplitude signal and a phase signal. Carrierographic lock-in images of the sample are obtained in a scanning configuration, or in an imaging format using an imaging detector. The images carry quantitative information about recombination lifetimes in substrate Si wafers and electrical parameters in solar cells, namely photogeneration current density, diode saturation current density, ideality factor, and maximum power photovoltage.

An apparatus is provided that includes a light-emitting component, a light-detecting component, a lock-in amplifier, a frequency generator that is operatively linked to the lock-in amplifier and the light-emitting component, a speaker capable of emitting an audio signal wherein the output audio signal varies depending on the detected fluorescence in the sample, and a visible output of relative fluorescent intensity where the visible output varies depending on the detected fluorescence in the sample. The apparatus may also include a laser that is operatively coupled to the lock-in amplifier through a control switch, and focusing lens or an additional type of filter such as an interference filter, a short-pass filter, a notch filter, a long-pass filter or an infrared filter. The apparatus may be used to identify and / or to remove fluorescent or non-fluorescent material from a sample. Associated methods are also disclosed.

The invention provides a closed-loop detection method of an atomic gyroscope on the basis of photoelastic modulation. The closed-loop detection method comprises the following steps: a Faraday actuator is placed in front of a 1 / 4 wave plate and a photoelastic modulator; detection laser passes through a polarizer, a Faraday modulator, an alkali-metal gas chamber, the 1 / 4 wave plate, the photoelastic modulator and an analyzer in sequence, a fast axis of the 1 / 4 wave plate and an optical axis of the polarizer are in the same direction, a fast axis of the photoelastic modulator and the optical axis of the polarizer form a 45-degree angle, and the analyzer and the optical axis of the polarizer form a 90-degree angle; a deflection angle of the closed-loop Faraday actuator is controlled by a PID (Proportion Integration Differentiation) controller, the output of a lock-phase amplifier is kept to be zero, and at the same time, the rotating angle to be detected is read out by an output angle of the closed-loop Faraday actuator. The closed-loop detection method provided by the invention has the advantages that the rotating angle to be detected is only related to the rotating angle of the closed-loop Faraday actuator and is not related to the light intensity and the photoelastic modulation amplitude, so that the influence of parameter fluctuation on a detection system is isolated on the principle, a scale factor of the closed-loop photoelastic modulation detection is easily stabilized, and the detection accuracy of the atomic gyroscope is improved.

The invention relates to a distributed optical fiber sensing system, and specifically relates to a sub-millimeter spatial resolution distributed optical fiber sensing device and method. According to the invention, the problems of unavailable spatial resolution and sensing distance combination, seriously limited sensing distance and low spatial resolution of the existing distributed optical fiber sensing system are solved. The sub-millimeter spatial resolution distributed optical fiber sensing device comprises a chaos laser, a 1*2 optical fiber coupler, a high-speed electro-optic modulator, a microwave signal source, a first optical amplifier, an optical isolator, an optical scrambler, an variable optical delay line, a low-speed electro-optic modulator, a second optical amplifier, an optical circulator, a sensing optical fiber, a photodetector, a phase-lock amplifier, a signal generator, a data acquisition card and a computer. The device and the method, which are provided by the invention, are applicable to the field of distributed optical fiber sensing.