报道中国计量科学研究院（NIM）在微波－光学频率计量研究的新进展：用NIM４激光冷却－铯原子 喷泉钟复现国际单位制（SI）时间单位秒（s），用飞秒（FS）光学频率梳间接复现长度单位米（m）并标定稳频 激光波长实际实施米定义。NIM４铯原子喷泉钟的不确定度达到5×10^-15，飞秒（FS）光梳锁定到NIM４钟控制的 氢钟后，其频率不确定度为2.2×10^－14。在此基础上讨论铯原子喷泉钟、稳频激光、FS光梳的作用、意义和相互 关系。最后简要介绍NIM５铯原子喷泉钟的研究进展和2006年起NIM立题研制锶原子存储

  The paper presents the realization,  at NIM,  of SI time unit second using the NIM4 cesium fountain clock,  SI length unit meter using a femto-second (FS) optical frequency comb and calibration of wavelengths of stabilized lasers by this FS comb. The uncertainty of NIM4 fountain clock was evaluated as 5 × 10 ^{- 15}.  The frequency uncertainty of the FS optical comb locked to a H-maser, which is steered by NIM4 clock,  was estimated as 2. 2 × 10 ^{- 14}.  The function,  significance of Cs fountain clock, stabilized lasers,  optical comb and relationship among them are discussed. Finally the progress of NIM5 fountain clock and the construction of a Sr atom optical clock started in 2006 at NIM are reported.

李天初（1945－），男，河北秦皇岛市人，博士，中国计量科学研究院研究员，现从事铯喷泉时间频率基准研究