20 results about "Photoelastic modulator" patented technology

The invention belongs to the technical field of optical measurement, and particularly discloses double-channel photoelastic modulation ellipsometry equipment and method. The device is constructed based on the ellipsometry principle of photoelastic modulation and comprises a light source, a collimating lens, a first polaroid, a second polaroid, a first photoelastic modulator, a sample table, a second photoelastic modulator, a beam splitter and a plurality of signal collectors. According to the device, the photoelastic modulator utilizes the piezoelectric effect and stress birefringence principle, modulation of signals is achieved by applying an alternating electric field, the modulation method does not need any moving part, and measurement can be completed stably at a high speed. Moreover, through the arrangement of multi-channel detection in the equipment, the equipment can obtain information of multiple wavelengths of the sample at the same time, and the thickness and optical parameters of the film sample are calculated in sequence.

Variable-angle ellipsometry is performed using a high speed polarization state modulator, a photodetector, and a digital micromirror device or spinning disk to encode the angle of incidence of light with a high sampling rate in a time domain or frequency domain. A variable-angle ellipsometer uses a high speed, axially stationary polarization state modulator, such as a photoelastic modulator, and a high speed detector, such as a photodiode, for high speed data acquisition. To acquire data at a plurality of incident angles, a lens is used to generate a large incident angle distribution along an optical axis that is at an oblique angle of incidence and discrete or combinations of incident angles of light are selected in a sequence in the time domain or modulated over a plurality of incident angles in the frequency domain.

In one embodiment, a method includes driving a photoelastic modulator optical element with at least two transducers, and control a phase difference between the driving signals applied to the at least two transducers based on a change in the resonant frequency of the photoelastic modulator optical element and a change in the vibration phase delay associated with a change in the temperature of the photoelastic modulator optical element. Related systems and devices are also disclosed.

This invention provides a method for measuring dielectric constant based on oblique incidence light reflection difference technology. The probe light emitted by the laser 1 is converted into p-polarized light by the polarizer 2, and then modulated into p-polarized light and s-polarized light by the photoelastic modulator 3. The p-polarized light and s-polarized light are emitted alternately at a frequency of 50 kHz, and after passing through the phase shifter 4, a fixed phase difference is generated. Then, the light is focused by the first lens 5 and obliquely incident on the surface of the sample 6 to be tested, with the incident range between 50° and 60°. The signal light reflected from the surface of the sample 6 to be tested is incident on the analyzer 9 after passing through the second lens 8. The analyzer 9 is used to zero the fundamental frequency signal of the system. The signal light after passing through the analyzer 9 is absorbed by the photodetector 10 and converted into an electrical signal. The electrical signal is demodulated by the first lock-in amplifier 11 and the second lock-in amplifier 12 into a DC signal, a fundamental frequency signal I (Ω), and a harmonic signal I (2Ω). The demodulated signal is acquired and processed by the data acquisition and processing unit 13.

The present invention discloses a fire smoke particle detection device and method based on scattering differential spectrum. The combination of an aerosol generator and an air pump can simulate a smoke environment and adjust the concentration of smoke particles in the environment to maintain the stability of the smoke environment. A xenon lamp is used as a light source to provide a wide-band spectral output. A reflective spectrometer detects the spectral characteristics of light, and a polarizer and a photoelastic modulator are used to convert the light into linearly polarized light, which is then irradiated on smoke particles to generate scattered light in different directions. The polarizer can receive scattered light in different directions through a rotating base and only allows light with a specific polarization angle to be transmitted to the detector, thereby simulating different smoke particle emission conditions and obtaining corresponding scattered photoelectric signals. Finally, a Labview program is used to deduce the matrix elements of the fire smoke particles, and then the type and particle size of the smoke particles are calculated, so that the present invention has good real-time performance and accuracy.

The utility model provides a power supply and control integrated circuit unit for a photoelastic modulator, which relates to the technical field of control circuits, and comprises a management unit module, a power supply delay circuit and a DAC (Digital to Analog Converter) module, the DAC module comprises a DA (Digital to Analog) conversion output module and a DA conversion data storage module, the management unit module comprises a single chip microcomputer, a serial data interface, a USB interface, a power supply, an analog control output interface and a management unit indicating lamp, the power supply delay circuit comprises a power supply input interface, a power supply control switch and a power supply indicating lamp, the DAC module comprises a DAC channel A and a DAC channel B, and the management unit module corresponds to the power supply delay circuit and the DAC module. According to the utility model, the power-on process is controlled through the external switch, so that large overshoot caused by instantaneous power-on or disordered power-on time sequence of other module circuits can be prevented; the amplitude, frequency and other parameters of the output analog signal can be flexibly adjusted through programming of the single-chip microcomputer, so that the device can be used in different application scenes.

A circular dichroism measurement apparatus includes a laser light source (QCL) capable of sweeping a wavenumber of a laser light in an infrared wavenumber range containing at least one peak of the sample; a sample chamber where the sample is disposed; a photoelastic modulator that modulates a polarization state of the laser light before or after the laser light of a specific wavenumber in a wavenumber sweep transmits the sample; a detector that detects a variation in intensity of the laser light which transmitted the sample and of which its polarization state is modulated; and a signal processing device that extracts an alternating-current component (AC) that synchronize with a modulation frequency and a direct-current component (DC) from a detected signal of the detector, and calculates a value of infrared circular dichroism of the sample based on a ratio (AC / DC) of the AC and DC.

The invention belongs to the field of optical measurement, and particularly relates to a device and a method for high-precision measurement of tiny refractive index change. The invention aims to provide a device capable of efficiently measuring the change of the refractive index. The device comprises a laser light source, a half-wave plate, a beam splitter prism, a polarizer, a reflector, a sample to be detected, a photoelastic modulator, a photoelectric detector, a signal acquisition and digital phase locking module and a computer. Laser is split into reference light and measuring light, the measuring light and a sample act to generate phase change, the two light beams are combined and then periodic phase modulation is applied through the photoelastic modulator, the photoelectric detector converts an optical signal into an electric signal, the signal acquisition and digital phase locking module synchronously acquires and processes the signal and transmits the signal to the computer, and the computer reversely deduces the refractive index variation. Through precise polarization regulation and control and modulation and phase-locking phase-source design, the measurement precision and the anti-interference capability are improved, the response is fast, the structure is simple and easy to integrate, and the device and the method are suitable for micro refractive index change detection in multiple fields such as biosensing and material characterization.

The application belongs to the technical field of spectral ellipsometry devices and methods, and particularly relates to a spectral ellipsometry accurate measurement device and method based on a single photoelastic modulator, wherein a polarizer, a photoelastic modulator and a measured sample are sequentially arranged in the light path direction of the monochromator, and a polarizer and a detector are sequentially arranged in the reflection light path of the measured sample. By scanning the single photoelastic modulator and the wide-band monochromatic light of the monochromator, and by combining the phase-locked amplification of the multiple frequency signals of the modulated photoelectric signals, the signal noise ratio is improved, the fluctuation of the modulation phase amplitude of the photoelastic modulator is obtained in real time by combining the theoretical calculation of the amplitude of the multiple frequency signals, the problem of the unstable phase delay amplitude of the photoelastic modulator caused by long-time work and environmental influence is solved, and the driving voltage of the photoelastic modulator can be adjusted in real time according to the different output wavelengths of the monochromator, so as to ensure the optimal modulation efficiency.

The application relates to the technical field of photoelectric detection, and provides a surfactant adsorption behavior detection system based on oblique incidence light reflection difference technology, which comprises a laser, a polarizer, a photoelastic modulator, a phase shifter, a first lens, a sample stage, a second lens, a detector, a photoelectric detector, a first lock-in amplifier, a second lock-in amplifier and a computer; the laser emits detection light; the detection light becomes p-polarized light through the polarizer; the p-polarized light and s-polarized light are modulated by the photoelastic modulator; the p-polarized light and s-polarized light are alternately emitted, and a fixed phase difference is generated between the p-polarized component and the s-polarized component by the phase shifter; the p-polarized light and s-polarized light are focused by the first lens and obliquely incident on the sample surface of the sample stage; the laser reflected from the sample surface is incident into the detector through the second lens, then is received by the photoelectric detector and is converted into an electric signal; and the fundamental frequency signal and the multiple frequency signal are recorded by the computer. The application can analyze the surfactant adsorption process and the adsorption state and other properties.

Variable-angle ellipsometry is performed using a high speed polarization state modulator, a photodetector, and a digital micromirror device or spinning disk to encode the angle of incidence of light with a high sampling rate in a time domain or frequency domain. A variable-angle ellipsometer uses a high speed, axially stationary polarization state modulator, such as a photoelastic modulator, and a high speed detector, such as a photodiode, for high speed data acquisition. To acquire data at a plurality of incident angles, a lens is used to generate a large incident angle distribution along an optical axis that is at an oblique angle of incidence and discrete or combinations of incident angles of light are selected in a sequence in the time domain or modulated over a plurality of incident angles in the frequency domain.

The present application relates to precision optical measuring instrument calibration technology, disclose a kind of four photoelastic modulator type mueller matrix polarization system parameter calibration method and system, the method comprises: conducting polarization experiment;Introducing the detection polarization arm base vector and polarizing arm base vector containing dynamic parameters, establish the calculation model of light intensity signal and these base vectors and light intensity projection matrix;Through polarization experiment and calculation model, the dynamic parameters in detection polarization arm and polarizing arm base vector are calibrated using nonlinear regression method, these dynamic parameters include the peak retardation of photoelastic modulator, modulation frequency and initial phase.Further, the matrix containing system static parameters is obtained by eigenvalue calibration method, directly used for measurement, static parameters include the azimuth angle of polarization element and the static retardation of photoelastic modulator.The method introduces base vector, realizes the calibration of dynamic parameters by detecting light intensity through nonlinear regression projection, then the static parameters are calibrated using eigenvalue, easy to operate, and high calibration accuracy.

A spin-orbit torque (SOT) measuring apparatus includes a photoelastic modulator (PEM) configured to periodically modulate a polarization direction of linearly polarized incident light and emit a periodically modulated light, a first polarization rotator configured to rotate a polarization direction of the periodically modulated light, a voltage generator configured to generate an AC current to a sample to which light with the rotated polarization direction is to be emitted, a prism configured to split light reflected into first light and second light having different polarization directions, a balanced detector configured to output a signal corresponding to an intensity difference between the first light and the second light, a changing circuit configured to change a frequency component to the intensity difference, and an amplitude measurer configured to measure an amplitude of a frequency component corresponding to a modulation frequency of the PEM with the changed frequency component.

The invention relates to the technical field of electronic equipment, and provides a head-up display. The head-up display comprises a microcontroller, a photoelastic modulator, an optical coupling area, an optical waveguide, a grating area and a light absorption area. The microcontroller is configured to process pixel shifts of the image. The photoelastic modulator is electrically connected to the microcontroller and is configured to modulate the spatial polarization state of the image to a spatial frequency. The optical coupling region is optically coupled to the photoelastic modulator and is configured to couple the image. The optical waveguide is optically coupled to the optical coupling region and is located between the optical coupling region and the photoelastic modulator. The grating region is located beside the light coupling-in region and directly contacts the optical waveguide, and is configured to couple out the image of the spatial frequency. The light absorption area is arranged around the optical waveguide. Therefore, light (namely stray light) which does not conform to the spatial frequency modulated by the photoelastic modulator can be filtered out by the grating when being coupled out, so that the influence of the stray light on the viewing experience is reduced, only the structured light modulated by the photoelastic modulator is left in the eyes of a user, and the overall viewing experience is clearer.

The present invention discloses a Stokes vector measurement system and method based on model optimization, relating to the technical field of optical measuring instruments. The system comprises a first photoelastic modulator, a second photoelastic modulator, an analyzer, a light intensity collector, and a computer. The present invention treats system parameters such as the optical element's principal optical axis deflection angle, the incident angle of the vector light beam, the photoelastic modulator's modulation phase delay peak value, and the static phase delay as optimizable parameters. The Stokes vector is obtained by fitting actual measurement data with model simulation data. Compared with existing measurement systems, the present invention fully considers the impact of errors in the system parameters themselves, correcting these errors through model optimization, thereby improving measurement accuracy.

Laser processing device (1) comprising: a clamping table (36) operable to hold a workpiece (W); and a laser beam irradiation means (5) which can be operated to irradiate the workpiece (W) held by the clamping table (36) with a laser beam, wherein the laser beam irradiation means (5) comprises: a pulse laser oscillator (51) designed to oscillate a pulsed laser beam (LB) at a predetermined repetition frequency, a first (52a) and a second (52b) condenser designed to collect the pulsed laser beam oscillated by the pulse laser oscillator (51), and a beam splitter means (53) arranged between the pulse laser oscillator (51) and the first (52a) and the second (52b) condenser for splitting the pulsed laser beam oscillated by the pulse laser oscillator (51) and directing the resulting beams (LB1, LB2) alternately towards the first (52a) and the second (52b) condenser, wherein the beam splitter means (53) includes a photoelastic modulator (532) having a piezoelectric element (532a) and a synthetic quartz (532b) formed in one piece, and modulates the laser beam so that a polarization plane of the laser beam is alternately at 0 and 90 degrees by applying a high-frequency voltage having a frequency to the piezoelectric element (532a), which corresponds to the natural frequency of the synthetic quartz (532b), where the beam splitter means (53) from one side of the pulse laser oscillator (51) towards one side of the first (52a) and second (52b) condensers includes: a first λ / 2 plate, a photoelastic modulator (532), a second λ / 2 plate, and a polarization beam splitter (534), and wherein, if the frequency of the photoelastic modulator (532) is f PEM , the repetition frequency of the pulse laser oscillator (51) with f Laser and a natural number is denoted by m, the repetition frequency f Laser from the following formula: f Laser = 4 f PEM ( 2 m + 1 ) [ H z ]

The application discloses a kind of temperature measurement method and device based on photoelastic modulation magneto-optical Kerr optical system, belong to magneto-optical detection and temperature measurement technical field, comprising: S 1, the optical axis azimuth angle of the polarizer and the photoelastic modulator is adjusted, so that the detection light intensity of the photoelectric detector only has direct current component;And the optical axis azimuth angle α of the polarizer is set to be less than 45°, and under the azimuth angle α, the detection light intensity is greater than the quantization error of data acquisition;S2, according to the detection light intensity, the direct current amplitude, the first harmonic amplitude and the second harmonic amplitude of light intensity at photoelastic modulation frequency are obtained by Fourier transform;S3, the magneto-optical signal of magnetic nanometer film sample is calculated;S4, the temperature of the magnetic nanometer film sample is changed, and the numerical relationship between the magneto-optical signal MO (T) and temperature T is calibrated.The application can directly measure temperature based on photoelastic modulation magneto-optical Kerr optical system, and the resolution of temperature measurement on the surface of sample can reach mK level.

This application belongs to the field of precision optical measurement, specifically disclosing a three-photoelastic modulation type Mueller matrix polarization system and its parameter correction method. In this application, the polarizing arm includes a first photoelastic modulator and a second photoelastic modulator, while the analyzing arm contains only a third photoelastic modulator. The three photoelastic modulators have different modulation frequencies. For the optical path after the third photoelastic modulator, a beam splitter divides the optical signal into two sub-beams for separate polarization analysis. By controlling the azimuth angles of the analyzers in the two split paths, two different three-photoelastic azimuth angle polarization system configurations are achieved. The measured two sets of 12 Mueller matrix elements are combined into a complete Mueller matrix element, thus achieving the measurement of the complete Mueller matrix element in a single measurement. This application, by combining three photoelastics with different modulation frequencies and the splitting principle, achieves high-speed acquisition of the entire Mueller matrix of a sample in a single measurement, filling the gap in mid-infrared high-speed Mueller matrix ellipsometers.

The application discloses a kind of left and right circular polarization state fast response's optical orbital angular momentum high-speed detector and method.The present application is based on high-speed polarization modulation technology and orbital angular momentum detector, realize the information of high-speed detection light orbital angular momentum;Compared with the detection speed of minute order based on traditional detection method, the present application will light orbital angular momentum The detection speed of momentum is promoted to millisecond order, while the number of quantum of light orbital angular momentum can be directly distinguished by the circular polarization dependent component of radial photocurrent extracted by phase-locked amplifier, without additional calculation and data processing by computer;Since photoelastic modulator has a large wavelength range, the present application can also be applied to light orbital angular momentum detection in a larger wavelength range;The present application is applied to various light orbital angular momentum detection application occasions, such as infrared imaging, military investigation and focal plane imaging.

A spin-orbit torque (SOT) measuring apparatus includes a photoelastic modulator (PEM) configured to periodically modulate a polarization direction of linearly polarized incident light and emit a periodically modulated light, a first polarization rotator configured to rotate a polarization direction of the periodically modulated light, a voltage generator configured to generate an AC current to a sample to which light with the rotated polarization direction is to be emitted, a prism configured to split light reflected into first light and second light having different polarization directions, a balanced detector configured to output a signal corresponding to an intensity difference between the first light and the second light, a changing circuit configured to change a frequency component to the intensity difference, and an amplitude measurer configured to measure an amplitude of a frequency component corresponding to a modulation frequency of the PEM with the changed frequency component.