Laser can be used to cool and manipulate neutron atoms via momentum exchange between photons and atoms. Laser cooling and trapping is well established on alkali, alkali earth, and noble gas elements. Noble gases, with stable physical and chemical properties, no reactions with other elements, have great potential uses in cold collision, spectroscopy measurement, photo-association, atom optics, etc. However, trapping noble gas atoms is generally more difficult because of the lack of suitable UV lasers. Some of these problems will be overcome with future advances in UV laser technology. Excited by electron collisions, noble gas can reach the long life metastable state for the use of laser decelerating, focusing and trapping. In this paper some main methods which are used to achieve cooling and trapping metastable noble gas atoms are discussed.
The parameters of combustion flow field such as temperature, velocity, pressure and mole-fraction are of significant value in engineering application. The laser spectroscopy technology which has the non-contact and non- interference properties has become the most important method and it has more advantages than conventionally contacting measurement. Planar laser induced fluorescence (PLIF/LIF) is provided with high sensibility and resolution. Filtered Rayleigh scattering (FRS) is a good measurement method for complex flow field .Tunable diode laser absorption spectroscopy (TDLAS) is prosperity on development and application. This article introduced the theoretical foundation, technical principle, system structure, merits and shortages. It is helpful for researchers to know about the latest development tendency and do the related research.