Research On Displacement Measurement System Of Energy Balance

With the development of the society,new demand is needed with Mass Natural Standard.The stability and accuracy of the former substance standard has gone beyond the uncertainty of international comparison and can not satisfy the metering standard required by mordern industry and technology.The substance standard would been replaced by Quanta Mass Standard if only the accuracy of Quanta Mass Standard were less than 2×10-8.The project Energy Balance is put forward and can satisfy the requirement of Quanta Mass Standard.But the precision value of coordinate z is needed when establishing Energy Balance.And it can be achieved by laser interferometer.On the basis of introduction of high precision laser interferometers and their developing status in the thesis,a high precision polarizing laser interferometer with common mode inhibiting technique has been developed.Stabilized He-Ne laser is chosen to ensure the stability of the light source.Integrated arrangement is adopted in homodyne interferometer to improve stability and sensitivity of the measurement system. Resolution of the interferometer is improved by using optical path difference doubling technique. Polarized laser phase shifting method and common mode inhibiting technique are used to reduce influence from environment and"zero shift"of the laser intensity by difference processing technique with the four orthogonal mutual signals.Photoelectric detection circuit is designed to realize the detection and pre-amplification of the interference signals.DC adjustment, operational amplification and lowpass filter are achieved by the following processing circuits. The displacement signals are got through A/D converter and software process.The influence on division precision of three errors (zero offsets, unequal amplitude of two signals and quadrature phase shift error) are analysed. Then the three errors are compensated by Heydemann model to get better signals.The methods to minish and reduce errors are proposed after analyzing errors sources of the laser interferometer.The performance of the measurement system is tested.Measuring precision is estimated by the comparison experiment with heterodyne interferometer.