approved gas detector是什么意思

用法例句

The paper analyses the causes of the optics path difference which come from the twocoherent lights that arc produced by interference system of the optics coal gas analyzer and re-searches the formation causes of the interference fringes and the interference types.

本文从对光学瓦斯检定器干涉系统两相干光光程差产生原因的分析，探讨其干涉条纹的成因和干涉类型。