双频虚拟光栅投影三维测量技术

Three-Dimensional Measurement Technology Based on Virtual Grating of Double Frequency

莫尔三维测量中的傅里叶变换轮廓术(FTP)采用单一频率进行测量,存在着由于待测物体高度变化率过大引起的相位解调困难问题。为解决该问题提出了利用双频虚拟光栅投影的三维测量方法。通过双色光干涉同时形成双频虚拟光栅,将双色干涉条纹投影到被测物体上得到被物体形貌调制的变形彩色干涉条纹。变形的彩色干涉条纹经过光学接收系统成像在彩色CCD探测器上。彩色CCD探测器所接收到的是双色光通道复合的变形虚拟光栅图。通过色度学方法对同一幅彩色变形虚拟光栅图的不同色光通道进行分离,并对分离后的双频虚拟光栅调制图进行综合。既兼顾了效率,又有效地解决了被测物体高度变化率过大引起相位解调困难的问题。

The Fourier transform profilometry （FTP） adopted single frequency for Moire three-dimensional （3D） measurement. There existed the problem on phase unwrapping in FTP. So a method of 3D measurement technology based on virtual grating of double frequency was present in the paper. The method produced double space frequency virtual cosine grating by multiple beam interference with double frequency laser. The color distorted grating was recorded when the double space frequency virtual cosine grating was projected on the object. The color charge coupled device （CCD） camera recorded an image of double frequency distorted virtual grating compounded with two color channels. Images of distorted grating with different frequency were separated from an image of distorted color grating by chroma method. Profile of the object was obtained by processing and integrating two distorted grating images from CCD camera in computer. The method resolved the problem on phase unwrapping of the object with larger height grads and ensured measurement efficiency.