11 results about "Photoelastic modulator" patented technology

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 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.

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.

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 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.