一种制作投影灰度正弦光栅的新方法

A Novel Method for Projection Gray Sinusoidal Grating Fabrication

针对传统方法难以制作结构光三维投影测量设备的灰度正弦光栅元件,并以Ronchi光栅代替从而影响测量准确度,提出了一种制作灰度按正弦分布的光栅模板的新方法.通过对银盐全息干板透过率特性曲线的理论分析,指出在对比度为一的正弦干涉条纹下曝光不能得到线性记录和变换的原因,并提出了采用均匀非相干光预曝光提供偏置点来实现线性记录的新方法.实验表明,采用空间滤波法能够获得对称双光束正弦干涉条纹记录,并准确控制正弦干涉条纹曝光在干板的线性区域,可以达到线性记录并获得尽可能高的反衬度.

Traditional methods are difficult to fabricate the gray sinusoial grating in structured-light three-dimension projection measuring system,and if replaced by Ronchi grating will affect the measurement accuracy.A novel method for gray sinusoidal grating plate fabrication is presented.Through the analysis of transmittance curve of holographic silver halide plate,the reason that sinusoidal interference pattern of contrast degree for 1 can not be linearly recorded and transformed is pointed out.A new method of linear recording is proposed,which provides a pre-exposure uniformly incoherent light bias point.The experimental results show that the sinusoidal interference fringes record of symmetrical two-beam can be obtained by the spatial filtering method,and the linear and high contrast record of sinusoidal interference fringe can be achieved by exposure controlled accurately in the linear region of the holographic silver halide plate.