115 results about "Photoelastic modulator" patented technology

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 discloses a multifunctional reflection-type magneto-optic spectrum measuring system which uses a super-continuous white light source, a grating monochromator, a plurality of polarized lenses, a photoelastic modulator, a broad band 1 / 4 and 1 / 2 wave plate, a non-polarization beam splitter (NPBS), a single-ended differential detector and an OXFORD low-temperature superconducting magnet system to form a spectrum detection system with a flexible and variable structure. The invention can realize the measurement of reflection-type magnetic circular dichroism (MCD), polar magneto-optical Kerr effect, polarized reflection spectrum and magnetic wire magnetic linear dichroism (MLD) on the same light path. The system has high sensitivity and can be used for fields, such as basic physics research, material characteristic analysis, light polarization modulation communication and the like.

This invention relates to a semiconductor material inner residual stress testing device. It includes a signal collecting system, the system is used to process the signal to get stress distributing situation of the sample. Optical bias checking prism, it is connected to collection system. Optical bias generating prism, it is set front of the checking prism. Optical elastic modulator, it is set between the two prisms. Laser source, it provides the signal source of the optical system.

The invention provides a device for high-flux monitoring of micro array biomolecular reaction through light reflex difference method, comprising an incident light path, a sample table, an emergent light path and a data acquisition and processing system, wherein, the incident light path comprises a laser, a polarizer, a photoelastic modulator, a phase shifter and a beam expander arranged between the phase shifter and the sample table; the emergent light path comprises a polarization analyzer and an electrooptical signal converter; the electrooptical signal converter comprises a silicon photodiode array, a pulse switching circuit, a first phase-locked amplifier and a second phase-locked amplifier; the output end of the silicon photodiode array is respectively in electric connection with the input ends of the pulse switching circuit, the first phase-locked amplifier and the second phase-locked amplifier. With a simple structure and easy operation, the device reduces the noise caused by moving a sample and greatly improves signal-noise ratio; meanwhile, the device can complete non-mark quick high-flux monitoring of the reactions of the array elements of a micro array at the same time, thereby greatly increasing monitoring efficiency.

The invention discloses a device and a method for compensating for detection polarization fluctuation of rotation angles of linearly polarized light in an online manner. The device comprises an optical module and a measurement control module. The optical module comprises a reference light path and a signal detection light path and mainly comprises a laser device, a polarizer, a liquid crystal variable-phase retarder, a photoelastic modulator, a 1 / 4 wave plate, a to-be-measured atom gas chamber sample, polarization beam splitting prisms and the like; the measurement control module comprises balance differential detectors, a liquid crystal driver, a photoelastic controller, a phase lock amplifier and a data acquiring and processing unit. The device and the method have the advantages that error sources of various devices do not need to be differentiated for optical detection systems with the multiple complicated polarization devices, only characteristics of input ends and 'black box' type processing modes for signals of output ends need to be considered, accordingly, compensation and correction for eliminating detection random errors of the rotation angles of the light in real time can be implemented on the basis of photoelastic modulation, and the signals can be stably detected in a high-precision manner for a long time.

The invention relates to the technical field of linear birefringence measurement, in particular to a device for measuring micro-linear birefringence through photoelastic modulation and electro-optical modulation cascading. The device is high in speed, precision and sensitivity, convenient to operate, controllable, high in stability and low in cost. Detection laser light is collimated, then passes through a polarizer, a photoelastic modulator, a sample to be measured and an electro-optical modulator in sequence, and finally is output and irradiated on a photoelectric detector after polarization detection is conducted, signal detection is conducted, a direct-current item is obtained through lowpass filtering, photoelastic modulation fundamental-frequency item data are obtained through FPGA digital phase locking, direct-current item data are transmitted to a computer together with the fundamental-frequency item data, and finally linear birefringence data processing, storage and display are achieved through the computer. The device is mainly applied to photoelastic polarization modulation, the amplitude and direction of linear birefringence can be obtained at the same time, mechanical adjustment is not needed, working is stable, industrialized integration is facilitated, and a new theory and a new method are provided for linear birefringence measurement and relevant application fields.

A diagnostic system (24) for a PEM (20) provides optically determined information about the retardance characteristics induced by the PEM (20). The diagnostic system (24) is integrated with the PEM (20) so that the PEM (20) performance may be diagnosed or monitored during operation of the PEM (20). Specifically, the diagnostic system (24) is used alongside an optical setup (22) that employs a primary light beam (28) for conventional purposes such as polarimetry, optical metrology, etc. The diagnostic system (24) includes its own diagnostic light source (50) that is directed through the optical element (32) of the PEM (20) at a location remote from the primary aperture (38) of the PEM (20). Thus, the diagnostic system (24) and the primary PEM (20) operation can be undertaken simultaneously, with one not interfering with the other. The output of the diagnostic system reflects the actual retardance characteristic provided by the PEM (20) and can be used as feedback to adjust the PEM control as needed.

The invention relates to a method of performing an optical measurement on a sample, such as an ellipticity measurement. The sample is irradiated with a polarized irradiation beam and a return beam is linearly polarized. The irradiation or return beam is modulated with a birefringence modulator, such as a photoelastic modulator, in accordance with a primary modulation signal. The return beam is directed onto a multichannel detector. Typically the detector is a slow detector, such as a CCD, having a response time greater than a period of the primary modulation signal. Detection values are generated simultaneously at each detection element and processed to determine a plurality of measurements. Various measurement techniques are described, including detector signal averaging over gated intervals; a design employing coherent modulation of the gain of an ICCD , and a modulator-coherent flash lamp design.

The invention relates to a set of variable-temperature microscopic magnetic photoelectric testing system with flexible measuring geometry, which comprises a titanium-doped sapphire laser as well as a chopper, a wide waveband linear polarizing film, a photoelastic modulator, a first wideband depolarization beam splitting prism, a second wideband depolarization beam splitting prism, a first objective lens and a liquid nitrogen Dewar which are arranged on the emergent light path of the titanium-doped sapphire laser in sequence, wherein the refracted light path of the second wideband depolarization beam splitting prism also comprises a camera and a display connected with the same, a second object lens is arranged on the light path behind the camera, and a monochromator and a matched detector are connected behind the second object lens through optical fibers; the chopper is connected with a controller; the photoelastic modulator is connected with a controller; the refracted light path of the first wideband depolarization beam splitting prism also comprises a lighting source and a detector; the refracted light path of the second wideband depolarization beam splitting prism also comprises the camera and the display connected with the camera; a neodymium iron boron permanent magnet is coaxially sheathed on the front end of the liquid nitrogen Dewar in a contactless mode; and the system also comprises a DC current source, and two output ports of the DC current source are connected with a sample through conducting wires.

The invention relates to a modulation amplitude closed-loop control system and method of a photoelastic modulator based on second harmonics. The modulation amplitude closed-loop control system comprises three parts including a laser intensity sterilization module, a detection optical module and a closed-loop control module, wherein the laser intensity sterilization module is composed of a laser device, a controllable phase delayer, a polarizer, a polarization beam splitter, a first photoelectric detector and a light intensity controller and is used for stabilizing main path laser to a pre-set value; the detection optical module is composed of a sample to be detected, a quarter-wave plate, the photoelastic modulator, a polarization analyzer and a second photoelectric detector and is used for realizing conversion of main path laser photoelectric signals; and the closed-loop control module is composed of a lock phase amplifier, a signal processor and a photoelastic modulator driving circuit and is used for demodulating second harmonic signal feedback to control the modulation amplitude of the photoelastic modulator. According to the modulation amplitude closed-loop control system and method of the photoelastic modulator based on the second harmonics, modulation amplitude fluctuation of the photoelastic modulator, caused by changes of environment factors, can be effectively inhibited, so that long-period stability of a detection system is improved.

The invention belongs to the technical field of signal modulation, and specifically relates to a method for calibrating the peak delay amount of a photoelastic modulator. The technical scheme that the method adopts is as follows: the photoelastic modulator is placed between two polarizers; incident light passes through a polarizer, the photoelastic modulator and an analyzer in sequence, and is then measured by a detector; the peak delay amount of the photoelastic modulator is set, and the detector obtains a waveform; and the waveform is output as a digital signal, and software is adopted to perform fitting on the waveform, thereby obtaining an actual value (i.e., a fitted value) of the peak delay amount. A set value required to obtain any peak delay amount is calculated based on a relation between a set value and an actual value of the peak delay amount. The method provided by the invention can calibrate any peak delay amount of the photoelastic modulator, and is mainly used for signal modulation technology and error correction.

The invention discloses a measuring system for enhancing the dichroism signal of the magnetic circular polarization and improving the speech to the noise ratio. The system comprises an optical source, a monochromator, a first convex lens, a Wollaston prism, a photoelastic modulator, a photoelastic modulator controller, a second convex lens, a temperature changing magnetic body system, a detecting device and a lock-in amplifier. By using the invention, a measuring signal is enhanced and the speech to the noise ratio is improved; meanwhile, the relation between the dichroism signal of the magnetic circular polarization and an external magnetic field can be measured, and be corresponding to SQUID measured magnetic hysteresis loop; the relation between the dichroism signal of the magnetic circular polarization and the temperature also can be measured, and be corresponding to the temperature dependence of SQUID measured saturation magnetization or residual magnetization, and the curie temperature of a ferromagnetic of material can be confirmed; the dependency of the luminous energy of the dichroism signal of the magnetic circular polarization can be measured, to confirm the energy band structure of material.

The invention discloses a calibration method for peak retardation of a photoelastic modulator. A calibration device used by the calibration method comprises two parts of an optical measurement module and a signal processing module, wherein the optical measurement module is composed of a laser, a polarized beam splitter, an eighth-wave plate, the photoelastic modulator and a reflector, and modulation on the polarization state of incident light is completed altogether; and the signal processing module is composed of a photoelectric detector, a signal regulator, a phase-locked amplifier, the photoelastic modulation driver and a computer, and the peak retardation of the photoelastic modulator is obtained. The calibration method has high sensitivity when the photoelastic modulator works in a small-angle modulation state; as laser beams pass through the photoelastic modulator for two times successively, the calibration precision is improved by two times that of the traditional method; the calibration result is not influenced by incident light intensity fluctuation, the offset between the actual peak retardation of the photoelastic modulator caused by external environment and a set value can be corrected, and the precision of an atom spin precession detection result in an atom magnetometer can be improved.

The invention discloses a semiconductor material micro-area stress test system. The system comprises a laser source, a spatial filter, a polarizer, an analyzer, an objective, a carrier, a photoelastic modulator, a detector and a lock-in amplifier, and a computer is adopted to control point-by-point scanning and acquire and process data. By measuring the difference Delta R / R between intensity reflection ratios on two perpendicular directions on the surface of a material, the stress distribution of the tested material is obtained. The system can overcome the adverse affection brought by other test systems, does not injure the material, and characterizes the stress distribution of the material within a small area, the test process is simple and rapid, and the test precision is high.

The invention relates to a laser confocal obliquely-incident ellipsometric high-throughput biomolecular reaction imaging detection device which is characterized in that a sample substrate loaded with a biological sample microarray is arranged on a sample platform, and a multi-channel constant-temperature flow cell which is provided with a liquid inlet and a liquid outlet connected with a multi-channel injection pump is arranged below the sample substrate; the multi-channel constant-temperature flow cell is placed in the position of an objective table of an inverse laser confocal microscope; the two corresponding edges of the sample platform are respectively provided with two flat plates respectively provided with a groove, which are symmetrically and vertically arranged; the insides of the grooves are respectively provided with a mechanical arm, wherein one mechanical arm is provided with a laser device, a polarizer, a photoelastic modulator, a phase shifter and a focusing lens which are sequentially arranged in the direction of an incident light path, and the other mechanical arm is provided with a focusing lens, a chopper, a polarization analyzer and a photoelectric detector which are sequentially arranged in the direction of a reflected light path; and the data inlet / outlet ends of a phaselocked amplifier are respectively connected with the data outlet end of the photoelectric detector and the data inlet end of a data acquisition card, and a computer is respectively connected with the data acquisition card and a controller of the multi-channel injection pump.

A birefringence detection device and detection method based on the sinusoidal modulation of the light intensity of a light source, wherein the sinusoidally modulated laser beam passes through a polarizer, a first photoelastic modulator, a measured object, a second photoelastic modulator and After the polarizer is detected by a photoelectric detector, the signal detected by the photodetector is processed to obtain a harmonic signal, and the delay δ of the birefringence of the measured object and the main axis angle ρ are obtained from the harmonic signal. The measurement result of the invention is not affected by DC noise (DC item, trend item, nonlinear amplification, etc.), and can measure the birefringence of low transmittance optical materials while ensuring accuracy.

The invention provides a quarter-wave plate phase retardation measuring device and measuring method. The device comprises a collimation light source, a round polarizer, a photoelastic modulator, a round analyzer, a photoelectric detector, a photoelastic controller, a phase locking amplifier and a computer. According to the device and the method, only one photoelastic modulator is needed to measure the phase retardation of a quarter-wave plate; the device is simple, has a compact structure and is convenient to operate.

The invention discloses a variable temperature microscopic measurement system for measuring related electron-spin transportation, which comprises an HeNe laser, a Grand taylor prism, a photoelastic modulator, a micro objective, a variable temperature liquid nitrogen Dewar sample holder, a digital voltage current source meter, a sampling resistance, a phase locked amplifier, a half-reflecting and half-transmitting lens group, a white light source, a camera, a display and a neodymium iron boron ring-shaped permanent magnet, wherein, the laser sent out by the HeNe laser is converted into linearly polarized light by the Grand taylor prism; the micro objective is used for focusing the incident lasers onto the platform surface of a sample; the variable temperature liquid nitrogen Dewar sample holder comprises a temperature control meter and a red copper cold finger which is used for fixing the sample to be detected on the top of the red copper cold finger; the control end of the digital voltage current source is connected with a computer through a general purpose interface bus (GPIB); the sampling resistance is used for extracting an alternating current voltage signal of the sample to be detected; the control end of the phase locked amplifier is connected with the computer through the GPIB; the half-reflecting and half-transmitting lens group is positioned on a main optical path; the white light source is used for observing the position on the platform surface of the sample to be detected; the camera and the display are used for displaying and outputting a platform surface image of the sample to be detected and the laser light spot position; and the neodymium iron boron ring-shaped permanent magnet is coaxially sheathed outside the red copper cold finger of the variable temperature liquid nitrogen Dewar sample holder.

An improved system for mounting an optical assembly of a photoelastic modulator (PEM) to permit free vibration of the optical assembly without introducing any stress or strain on the optical element. Moreover, the mounting system, which includes a mounting block (50), elastomeric mount (32), support flanges (36, 38), and a mounting rail (40), facilitates accurate and easy assembly of the optical element into its enclosure (26).

The invention discloses an in-situ measurement system and method for spatial distribution of spin polarizability of an alkali metal atom magnetometer, and belongs to the technical field of precision measurement. The system is mainly composed of a laser, a laser stabilizing system, a laser beam expanding system, a beam splitting prism, a polarization element, a magnetic shielding system, an alkali metal atom gas chamber, a photoelastic modulator, a photoelectric detector, a CMOS sensor, a data collecting, analyzing and processing system and the like. The system has reasonable theoretical basis and simple experimental operation, no additional system disturbance is brought to normal operation of the magnetic measurement system, the electron polarizability distribution of the working state of the alkali metal atom gas chamber can be accurately measured, the measurement sensitivity of the atom magnetometer can be improved on the basis of the polarizability distribution measurement result, and a basis is provided for development of an ultra-high-sensitivity extremely-weak magnetic measurement device.

The invention relates to a method for measuring a cavity mode split of a vertical cavity surface emitting laser under the room temperature condition. According to the method for measuring the cavity mode split of the vertical cavity surface emitting laser under the room temperature condition, laser light emitted by the vertical cavity surface emitting laser is modulated through an optical elastic modulator, the light intensity difference between two laser emitting modes which are modulated by the optical elastic modulator and are polarized in the direction of two perpendicular optical main shafts is included in the light intensity signals detected by a photoelectric detector, optical spectra of the two laser emitting modes which are polarized in the direction of the two perpendicular optical main shafts of the VCSEL can be extracted by changing the phase modulation amplitude phi 0 (actually the value of the phi 0 just needs to be changed two times) of a PEM, and then a cavity mode split value can be obtained. According to the method for measuring the cavity mode split of the vertical cavity surface emitting laser under the room temperature condition, the cavity mode split of the vertical cavity surface emitting laser can be accurately obtained under the room temperature condition by using a light spectrum system with an ordinary resolution ratio, measuring equipment is quite simple, and operation steps are simple. The method for measuring the cavity mode split of the vertical cavity surface emitting laser under the room temperature condition can be widely popularized and used in the future.

The invention discloses a magnetic circular dichroism photoconduction spectrum measurement system which comprises a liquid helium refrigerating machine, a low-temperature superconducting magnet system, an ultra-continuous white light source, a monochromator, a chopper, a Glan-Taylor polarizer, a photoelastic modulator, an achromatic lens, a current source, two phase-locking amplifiers and a computer. By using the magnetic circular dichroism photoconduction spectrum measurement system, the magnetic circular dichroism (PC-MCD) can be measured, therefore, the magnetic properties of a material and the spin-dependent energy band structure and characteristics can be further researched.

A photoelastic modulator excited by a plurality of piezoelectric transducers affixed to the surface of a photoelastic bar for generating elastic waves in a plurality of cells each bounded by piezoelectric node drivers between which an antinode driver is disposed, is described. The standing elastic wave in each cell can be made independent of those in the neighboring cells by controlling the phase and amplitude of the drivers. The resulting elastic waves generate birefringence along the optical axis of the bar such that a linearly polarized optical wave propagating along the axis and having an initial phase, experiences a retardation of the phase as it passes through each cell. The cells may be controlled such that the phase of each standing wave does not change between cells and the phase retardation of the optical wave increases monotonically as the optical wave propagates through the bar, thereby, in theory, permitting an arbitrarily large retardation to be generated.

The present invention relates to a cascade large-optical-path-difference photoelastic modulating interferometer which comprises a light source. A polarizer which modulates emergent light to a certain direction to form an angle with the horizontal direction is arranged in the emergent light direction of the light source. A static birefringent crystal is arranged in the emergent light direction of the polarizer. A plurality of strong light modulators which can make emergent light reflect for a plurality of times are arranged in the emergent light direction of the static birefringent crystal. An analyzer is arranged in the emergent light direction of the strong light modulator. A detector which can acquire interfered light of the analyzer is arranged in the emergent light direction of the analyzer. The cascade large-optical-path photoelastic modulating interferometer generates a periodical driving force through a piezoelectric quartz crystal, and furthermore generates two-dimensional coupling longitudinal oscillation by means of a contour oscillation mode of zinc selenide crystal for obtaining higher modulation optical path difference. Based on a fact that a single photoelastic modulator realizes higher modulation optical path difference, the modulation optical path difference is furthermore increased through a cascade manner, thereby settling a problem of small modulation optical path difference in the existing photoelastic modulating interferometer and ensuring enough light flux.

A high-spatial-resolution vector magnetic field measuring device based on potassium-rubidium mixed pumping provides dual irradiation of a circular polarization pumping light beam and a linear polarization detection light beam for an atom air chamber containing potassium atoms and rubidium atoms, and is beneficial for obtaining polarizability more uniform than that of a single alkali metal atom airchamber. In addition, a detection magnetic field can be obtained through an atomic spin precession signal, atomic spin signals are obtained through a photoelastic modulator, spatial light high-frequency scanning is performed on a detection light field through a spatial light modulator digital micromirror device, magnetic field parameter modulation is performed through a three-axis magnetic compensation coil to carry out vector magnetic field detection, and high-spatial-resolution vector magnetic field measurement is achieved.

A system and method for exploiting the dependance of a photoelastic modulator's (PEM's) resonance frequency on temperature (attributable to driving amplitude and to ambient temperature) to generally improve the performance of PEMs. In one embodiment there is provided a method and system for efficiently driving a series of multiple PEMs. To this end, each of the PEMs in a stack are separately tuned, as by controlling the power dissipated in each PEM, so that the resonance frequencies of all of the PEMs converge to a common frequency. Thus, all of the PEMs are simultaneously at resonance to ensure maximum efficiency and to maintain a selected total retardation amplitude. In another embodiment of the present invention, a single-element PEM is controlled in a manner to account for the subtle changes in the PEM's resonance frequency. To this end a control method and system is provided to keep constant both the retardation amplitude of the PEM and the actual operating frequency of the PEM, which frequency need not necessarily be the resonant frequency.

The invention discloses a photoelastic high-speed Mueller matrix ellipsometer and an in-situ calibration and measurement method thereof, and belongs to the technical field of optical measurement. Thephotoelastic high-speed Mueller matrix ellipsometer comprises a high-speed polarization module, a sample adjustment module and a real-time polarization analysis module. The in-situ calibration methodof the photoelastic high-speed Mueller matrix ellipsometer is implemented based on Bessel function infinite series expansion and discrete Fourier transform, the peak value and the static retardation of the photoelastic modulator are obtained at the same time, and high precision and high sensitivity of the photoelastic modulator in the whole working range are ensured. The measurement method of thephotoelastic high-speed Mueller matrix ellipsometer is carried out on the basis of double photoelastic modulation and spatial light splitting demodulation, and in-situ and high-precision measurement of the sample Mueller matrix can be realized under microsecond time resolution. Benefited from the high temporal resolution acquisition of the Mueller matrix, the method can be used for characterizingthe dynamic optical properties of the material in the rapid reaction process.

The invention provides a device for non-mark monitoring of microorganism array biomolecular reaction, comprising an incident light path, a sample table, an emergent light path and a data acquisition and processing system, wherein, the incident light path comprises a laser, a polarizer, a photoelastic modulator, a phase shifter and a beam expander arranged between the phase shifter and the sample table; the emergent light path comprises a polarization analyzer and an electrooptical signal converter; the electrooptical signal converter comprises a CCD area array, a pulse switching circuit, a first phase-locked amplifier and a second phase-locked amplifier; the output end of the CCD area array is respectively in electric connection with the input ends of the pulse switching circuit, the first phase-locked amplifier and the second phase-locked amplifier. With a simple structure and easy operation, the device reduces the noise caused by moving a sample and greatly improves signal-noise ratio; meanwhile, the device can complete non-mark quick high-flux monitoring of the reactions of the array elements of a micro array at the same time, thereby greatly increasing monitoring efficiency.

The invention discloses a linear double refraction measuring device and measuring method. The linear double refraction measuring device comprises a light source module and a measuring module; the light source module is formed by a collimated light source, a polarizer, a photoelastic modulator, a photoelastic controller and a one-dimensional optical grating; and the measuring module is formed by two polarization analyzers, two photoelectric detectors, two phase-locked amplifiers and a computer. According to the linear double refraction measuring device, the light source module and the measuring module are arranged at the same end of a double refraction sample to be measured, phase delay amount distribution and fast axial azimuth angle distribution are measured through single-end scanning, measuring light beams passes the double refraction sample twice, and the measuring accuracy is improved twice.