Light knife of laser with long field depth for measuring free surface

A technique for sharpening the laser with long field depth is developed to enhance the process of reverse engineering where free surface needs to be reproduced on-side. The process makes use of a cylindrical reflector where the laser is scattered into a strip the width of which varies in accordance with the reflective position of a facula. The field depth increases with compressing divergent angle of laser. Computer could be used to assist data collection. Advantage of the method is presented.