Laser Diode Self-Mixing Interference Based on Phase Measurement Method

2008 ◽  
Vol 381-382 ◽  
pp. 247-250
Author(s):  
Ming Wang ◽  
Dong Mei Guo
Keyword(s):  
Laser Diode ◽  
Phase Modulation ◽  
Signal Analysis ◽  
Measurement Method ◽  
Measurement Accuracy ◽  
Phase Measurement ◽  
External Cavity ◽  
Experimental System ◽  
Measurement Results ◽  
Measurement Principle

In order to improve the displacement measurement accuracy of the laser diode self-mixing interference (SMI), phase measurement method is introduced in the SMI signal analysis. In this paper, three modulation technique have been proposed: injection current modulation, external cavity length modulation and sinusoidal phase modulation. Measurement principle of the three modulation techinque are briefly explained. Design of the experimental system, measurement results of micro-displacement will be reported.

Block Thickness Measurement of Using the Structured Light Vision

2018 ◽  
Vol 33 (01) ◽  
pp. 1955001 ◽  
Author(s):  
Fenghui Lian ◽  
Qingchang Tan ◽  
Siyuan Liu
Keyword(s):  
Machine Vision ◽  
Measurement Method ◽  
Measurement Accuracy ◽  
Thickness Measurement ◽  
Base Plane ◽  
Vision Measurement ◽  
Measurement Results ◽  
Measurement Equations ◽  
Structured Light Vision ◽  
Measuring Base

A method for measuring block thicknesses is proposed by the machine vision measurement. Equations of the measuring base plane and the light plane are formed by calibration. Then, the equation of the light strip image, that is, the image of the intersection between the base plane and light one, is established by the projection relation. Equation of the image of the light strip on the measured plane can be determined by the fitting. Since the light strip on the measuring base plane is parallel to one on the measured plane, the thickness of the measuring block is measured by using the two equations. The experiment evaluates the measurement accuracy of the measurement method and analyzes the influence of some factors on the measurement results.

scholarly journals A Real-Time Measurement Method of Air Refractive Index Based on Special Material Etalon

2018 ◽  
Vol 8 (11) ◽  
pp. 2325 ◽  
Author(s):  
Guo-Ying Ren ◽  
Xing-Hua Qu ◽  
Shuang Ding
Keyword(s):  
Refractive Index ◽  
Real Time ◽  
Direct Measurement ◽  
Measurement Method ◽  
Measurement Accuracy ◽  
Laser Interferometry ◽  
Measurement Technology ◽  
Measurement Principle ◽  
Environmental Responses ◽  
Realization Process

In the precise displacement measurement based on laser interferometry, the measurement technology for the refractive index of air is widely used to improve the measurement accuracy. However, the existing measurement method of the refractive index of air based on direct measurement is not easy to realize in practical work because of its complex measurement principle and the huge volume of the measurement device; while the measurement accuracy and speed based on the indirect method cannot adapt to the real-time, fast and accurate measurement requirements of industrially changing environments, resulting in distortion of the results. In this study, a measurement method of the refractive index of air based on a special material etalon is proposed. The method enables rapid and direct measurement of the air refractive index when the environment changes and it is given the realization process. Finally, the experimental results show that the deviation between this method and the modified Edlen formula is about 2.5 × 10−7, and that this method can quickly reflect the changes of the environment, which prove the correctness of this method and its ability manage rapid environmental responses. This method is worth popularizing in industrial measurement.

A Novel Method of Establishing “Datum Reference” for the Coaxiality Measurements Using the Multi-Section and Multi-Probe Gauges

2011 ◽  
Vol 317-319 ◽  
pp. 1759-1768 ◽  
Author(s):  
Lian Hu Xu ◽  
Yi Bao Yuan ◽  
Wei Ying Piao
Keyword(s):  
Mathematical Method ◽  
Measurement Accuracy ◽  
Coordinate Measuring Machine ◽  
Measurement Results ◽  
Manufacturing Errors ◽  
High Measurement ◽  
Measurement Principle ◽  
Manufacturing Accuracy ◽  
Measuring Machine ◽  
Measurement Efficiency

The electronic or pneumatic multi-section and multi-probe gauges are widely used for diameter and coaxiality measurements due to their high measurement efficiency in workshops. However, their measurement accuracy is determined mainly by the manufacturing errors of the assembly coaxiality master, therefore, how to establish coaxiality measurement datum reference is the key technology. The physical coaxiality masters are expected to be the impossible "zero error datum reference". The higher manufacturing accuracy of the masters, the more expensive for their manufacturing costs. A novel mathematical method on the basis of error separation principle was proposed in order to separate the manufacturing errors of the master. The basic principle is that the eccentric error of the coaxiality master can be expressed as the first harmonic function and the ideal zero-error datum reference could be established by the mathematical method of two sampling operations in phase difference of 180° in coaxiality master for gauge initialization. This method can be called as "mathematical datum reference" for coaxiality measurement. Experimental results indicate that the coaxiality measurement results of the multi-section and multi-probe gauge by the novel mathematical method coincide with those of the three-coordinate measuring machine and the maximum difference of both is about 0.0014 mm. The new coaxiality measurement principle can separate the datum error of the coaxiality master theoretically and can improve the coaxiality measurement accuracy greatly with the common accuracy coaxiality master.

Self-Mixing Interferometer Based on Four-Bucket Integration Technique for Micro-Displacement Measurement

2008 ◽  
Vol 381-382 ◽  
pp. 53-56
Author(s):  
Dong Mei Guo ◽  
Ming Wang
Keyword(s):  
Phase Modulation ◽  
Signal Analysis ◽  
External Cavity ◽  
Laser Cavity ◽  
Interference Signal ◽  
Analysis Method ◽  
Integration Technique ◽  
Electro Optic ◽  
Signal Analysis Method ◽  
Electro Optic Modulator

A novel self-mixing interference signal analysis method is proposed based on the use of an electro-optic modulator (EOM). Self-mixing interference occurs in the laser cavity by reflecting the light from a mirror-like target in front of the laser. Sinusoidal phase modulation of the beam is obtained by an EOM in the external cavity. The phase of the interference signal is calculated by four-bucket integration technique. The interferometer is applied to measure the displacement of a high-precision commercial PZT with an accuracy of a few nanometers.

An Algorithm to Eliminate Stochastic Jump Measurements of Ultrasonic Flow-Meter with Time Difference Method

2011 ◽  
Vol 267 ◽  
pp. 414-421
Author(s):  
Qiang Liu ◽  
Rang Ding Wang ◽  
Ying Zhu ◽  
Cheng Tou Du
Keyword(s):  
Measurement Accuracy ◽  
Time Difference ◽  
Test Results ◽  
Flow Meter ◽  
Newton Interpolation ◽  
Improve Measurement ◽  
Measurement Results ◽  
Stochastic Jump ◽  
Ultrasonic Flow Meter ◽  
Measurement Principle

This article describes the time difference ultrasonic flow meter measurement principle, by analyzing the ultrasonic flow meter test results, using the theory of Newton interpolation correction calibration constants, solves the problems that the measurement results will suddenly appear more random beating and further improve measurement accuracy of the ultrasonic flow meter.

scholarly journals Comparative Study of AC Signal Analysis Methods for Impedance Spectroscopy Implementation in Embedded Systems

2022 ◽  
Vol 12 (2) ◽  
pp. 591
Author(s):  
Ahmed Yahia Kallel ◽  
Zheng Hu ◽  
Olfa Kanoun
Keyword(s):  
Fourier Transform ◽  
Impedance Spectroscopy ◽  
Signal Analysis ◽  
Measurement Accuracy ◽  
Phase Measurement ◽  
Nonlinear Least Squares ◽  
Hardware Acceleration ◽  
Fitting Method ◽  
Overall Performance ◽  
Memory Constraints

For embedded impedance spectroscopy, a suitable method for analyzing AC signals needs to be carefully chosen to overcome limited processing capability and memory availability. This paper compares various methods, including the fast Fourier transform (FFT), the FFT with barycenter correction, the FFT with windowing, the Goertzel filter, the discrete-time Fourier transform (DTFT), and sine fitting using linear or nonlinear least squares, and cross-correlation, for analyzing AC signals in terms of speed, memory requirements, amplitude measurement accuracy, and phase measurement accuracy. These methods are implemented in reference systems with and without hardware acceleration for validation. The investigation results show that the Goertzel algorithm has the best overall performance when hardware acceleration is excluded or in the case of memory constraints. In implementations with hardware acceleration, the FFT with barycentre correction stands out. The linear sine fitting method provides the most accurate amplitude and phase determinations at the expense of speed and memory requirements.

Detection and Analysis of Rats’ Bioelectromagnetic Signal

2014 ◽  
Vol 536-537 ◽  
pp. 13-17
Author(s):  
Hong Long Cao ◽  
Fen Ju Qin ◽  
Xue Guan Liu ◽  
He Ming Zhao
Keyword(s):  
Standard Deviation ◽  
Automatic System ◽  
Measurement Method ◽  
Measurement Accuracy ◽  
Biological Activities ◽  
Measurement Data ◽  
Measured Data ◽  
The Mean ◽  
Frequency Window ◽  
Window Effects

In this paper, we designed an automatic system and automatic test software, and they can carry out Kunming rats bioelectromagnetic measurement in standard status and anesthesia automatically in anechoic chamber where the electromagnetic field outside is shielded, the reflection wave is absorbed, and the measurement accuracy will be improved. We get a great number of measurement data with frequency-sweep measurement method. The mean and standard deviation of amplitudes vs. frequencies is calculated and analyzed. The results show the measurement method is feasible. We have plotted the means of measured data as multiple sets of Y values in a series of bars with standard deviations bars included and distributed in the frequency axis of X. It is found that the fluctuation of the mean and standard deviation in some frequencies is not evident which may explain frequency window effects, while in other frequencies, such a fluctuation can be obviously observed, which may suggest that bioelectromagnetic signal is influenced by biological activities (standard and anaesthesia status) in these frequency points.

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