The Approach to some Problems Concering Precision Laser Alignment

Owing to the increasing use of laser alignment technique in engineering surveying,the problems of how to utilize it properly and to improve its precision have been raised.Further study of laser alignment is necessary.This paper deals with three major problems,the circular zone plate,the atmospheric effect and the detection of laser beam.Having derived the formulae to compute the intensity of the image formed by a circular zone plate,the author has come to the preliminary conclusion that a circular zone plate with 5-7 clear zones and opaque central zone is considered most suitable in practice and by properly designing zone plate,the number of the plates used on an aligned line can be minimized.Then atmospheric refraction and air turbulence causing random deflections are discussed in the paper,for they impose restrictions on alignment accuracy,The effect of atmospheric refraction is mathematically analyzed,some measures to reduce the effect are introduced and the design of the detector is discussed.