激微波 

第一个氨丙烷激微波器原型和发明家查尔斯·汤斯。 The ammonia nozzle is at left in the box, the four brass rods at center is the quadrupole state selector, and the resonant cavity is at right. The 24GHz microwaves exit through the vertical waveguide Townes is adjusting. At bottom are the vacuum pumps.
一台氢微波激射器

激微波（英语：MASER），音译为激微波，义译为激微波或微波激射器，是受激放大微波辐射（英语：Microwave Amplification by Stimulated Emission of Radiation）的头字母。它指通过受激辐射放大和必要的反馈，产生同一波宽、准直、相干的微波的过程及仪器。

利用激微波原理的“惰性氢微波激射器原子钟”，可制作“比铷原子钟精确十倍，每三百万年还差不到一秒”的原子钟。