lock-in amplifier การใช้

• Digital lock - in amplifier based on dsp and sampling adc
• Lock - in amplifiers
• A computer controls the whole process of measurements by communicating with the lock - in amplifier via rs232 interface
• A lock - in amplifier is used to supply the driving signal and to detect the output signal corresponding to the sample ' s strain
• Photoelectric detecting circuit is constituted of four parts , i / v conversion , lock - in amplifier , low - pass filter and operation
• The core of the lock - in amplifier used to measure response of laps consists of a high precision modulator / demodulator and dds as signal generator
• For the signals are very weak , the lock - in amplifier is employed to extract the signals in the circuit design . it can inhabit the noise in the most and maximize the signal - to - noise
• Using the home made device , the relationship between the 3 voltage and the heating frequency is obtained by lock - in amplifier , thus the thermal conductivity of the fluid is calculated with the least square fit method
• The experiment results show that : the frequency stabilization of the optimized doppler modulator has already reached rms error about 1 % , which could meet the need of reference signal of the lock - in amplifier
• Choosing y type reflection fiber optic detector , this thesis create a tiny displacement - detecting sensor that is made up of led ( light emitting diode ) , fiber optic detector , electric eye , lock - in amplifier , display and other electro circuits
• At the same time , this thesis also did the reasonably research about the weak light telecommunication technique , and designed an optic - electricity signal handling system , in which the lock - in amplifier is the core . the gain of this system could be 10 ^ 6 , and snr ( signal - to - noise ) could be 1000 : 1
• The instrument is integrated with a multi - channel high precision open circuit potential measurement system for the ion selective electrode and a potentiostat used in voltammetry , an analog lock - in amplifier is also presented to measure the response of light addressable potential sensor
• According to the principle of correlation detection , an automatic measurement system for extinction ratio of polarizer consisted of monochromator and dsp lock - in amplifier and compurer is designed not only to eliminate the influence on measurement accuracy caused by drift of intensity of light source but also to obatain approximate extinction spectrum
• Based the research on the laser beam drift feedback control technique , analysing the beam drift and its frequency components , a laser beam directional stability method is studied in the thesis in detail , with its measurement and control circuit system that combines the laser beam intensity modulation and the beam drift feedback control technique . in this method , at first the laser beam intensity is modulated with the acoustooptic modulator , then the lock - in amplifier is applied to detect and demodulate the modulating signal , at last a feedback control signal is generated by the dsp control circuit at last , including : 1