Technical Development of Absolute Gravimeter: Laser Interferometry and Atom Interferometry

Absolute gravimeter is a precise metrological instrument for absolute gravimetry. Absolute gravimetry refers in particular to the measurement of acceleration of gravity on the earth directly which finds important applications in earth sciences and metrology. The earliest absolute gravimetry was performed in the year of 1590. From 1590 to 1960, pendulum principle was the main method to perform the absolute gravimetry. From 1960, with the invention of the laser technology, people began to use laser absolute gravimeter to perform the absolute gravimetry by measuring the free motion (falling or rising freely) of an object, which is the big progress in the history of precise gravity measurement. In 1991, the group of professor Steven Chu from Standford University used the free motion of laser cooling atoms and atom interferometry technology to perform the absolute gravimetry for the first time, which successfully developed the first atom interferometry absolute gravimeter in the world. National Institute of Metrology (NIM) China is the first organization to research absolute gravimeter in China. Taking the example of development of absolute gravimeter in NIM, we review the technical development of laser absolute gravimeter and atom interferometry absolute gravimeter, especially reveals the revolutionary contribution to the development of absolute gravimetry due to the invention of laser technology.