Abstract: The near stalk interference of the space laser can produce Newton's ring whose centre is very marked.The extremely high accuracy aexamination of linearity can be based on the laser interference Newton's ring.This Newton's ring can be applied in many engineering such as the dam transforms the examination,the examination of the orbit straight line.A method checking the laser Newton's centre by video is introduced.The result of the trials shows that fast Hough transform can produce a good result.