The Research And Application Of Absolute Gravimeter Based On Free-Fall Theory

NIM-3absolute gravimeter based on free-fall theory is designed and realized in this thesis with the support of two projects of " The research of key technology in typical absolute gravimeter" and "The build of site for global international comparison of absolute gravimeter" in NIM. The application of NIM-3absolute gravimeter and the technical working about NIM’s applying for hosting global international comparison of absolute gravimeter in2017are also introduced in this thesis.Firstly, the technology of precise absolute gravity measurements including based on free-fall theory and based on atom-interferometer theory are both described.More emphases will put on the theory of free-fall.Secondly, the development of NIM’s type absolute gravimeter and the main research on mechanical system、motor drive system、optical system of NIM-3absolute gravimeter are introduced. This thesis put the emphases on the new method of realizing to measure free-falling’s distance and time interval by "FPGA" and "Verilog" computer language.The SOPC system based on DE2electric board and NOIS-II processor which produced by Altera company and the application of "digital phase-shift" are introduced.This thesis also described the software system based on the browser/servrer mode using JAVA EE computer language system.Then, universal calculated method about some gravity correction factors such as earth tide、air pressure、polar are given.The acurate and uncertainty estimation by experiment and calculation including the application situation of NIM-3absolute gravimeter are introduced.Some metrological consideration on absolute gravimeter such as correction of laser modulation effect of self-attraction、effect of laser diffraction、effect of limited speed of light、effect of instrumental recoil are decribed in brief which as the reference for improving NIM’s type absolute gravimeter in the near future.At last,the situation on international comparison of absolute gravimeters and the technical working aboμt NIM’s applying for hosting global international comparison of absolute gravimeter in2017are introduced in this thesis.The research result on this thesis will apply in "energy balance" project which redefine the "Mass" basic unit using natural standard.