Brief Introduction of the Radial Velocity Spectrometer

Measurement of radial velocity and the historical development of the radial velocity spectrometer(RVSM) are briefly introduced in this paper.The principle of the RVSM and its key parts such as the mask,pendular parallel plane plate,photomultiplicr,control system,etc.,are also described.As compared with other devices for measuring radial velocity,the RVSM has three prominent advantages high accuracy,high speed and high sensitivity.On the other hand,the RVSM now avaiaiblc has also some shortcomings as follows:1) For the same star,it can not be used to determine the different radial velocities by making use of different spectral lines at the same time,and therefore it can not be applicable to the stars with strong turbulent flow;2) The radial velocity spectrometer is also not applicable to the stars with strong emission lines and earlier than those of a type,such as galaxies;3) For a star with the absolute value of radial velocity greater than 100km/s,the spectrometer will make the spectrum of the star unmatched with the mask.A tentative idea to solve the problem of the spectrum of a star unmatched with the mask is given in this paper.When I used RVSM of McDonald,Dr. T. G. Barnes gave me halp and answered my questions.The author is greatly indebted to Dr. T. G. Barnes.