刀口法测量铬原子激光冷却温度

Thermometry of Cr Laser Cooling via Knife-Edge

介绍了刀口法测温原理。在自主研制的铬原子光刻系统上,利用稳定到52Cr的7S3→7P04跃迁上的真空波长为425.5 nm的激光,对高温原子炉喷射的铬原子束进行了一维多普勒冷却准直。设计搭建了刀口法测温实验装置,对激光多普勒冷却准直效果进行了定量评价。在激光功率为45 mW,失谐量为-2.5 MHz,光斑大小为1 mm×20 mm的条件下,观察到了明显的冷却现象。在此基础上采用刀口法测温,测得激光冷却后铬原子束角分布的半峰全宽为(0.616±0.007)mrad,横向温度为(418±10)μK。这些结果为优化调整铬原子束激光冷却准直实验提供了依据。

The principle of knife-edge thermometry is introduced.A chromium beam which is jetted from high temperature atomic crucible is collimated by one-dimensional laser Doppler cooling on self-designed system of chromium atom lithography.The laser wavelength in vacuum is 425.5 nm,corresponding to 7S3→7P04 transition of 52Cr.The setup of knife-edge thermometry is designed and built to quantify the effect of the chromium beam collimation by laser cooling.The obvious cooling phenomenon is observed with power of 45 mW,spot size of 1 mm×20 mm and detuning of-2.5 MHz.Then,based on it,the knife-edge measurement is carried out.The results show that the full-width at half-maximum（FWHM） of chromium beam angular distribution is（0.616±0.007） mrad and the transverse temperature is（418±10） μK by laser cooling.The results provide a basis for optimizing the chromium beam collimation by laser cooling.