正弦结构光场普遍应用于精密光学的三维测量,其正弦性直接或间接影响三维测量的精度。根据正弦条纹的周期性和对称性等几何特征,以计算机产生的标准正弦条纹单个周期作为编码对象,提出一种“S”型路径误差扩散的二元编码方法。整个正弦结构光模板通过周期性复制编码单元来实现,再通过高分辨率光刻技术加工制作在镀铬玻璃基板表面上。模板调制照明光源后,表征二元编码特征的高频信息直接被投影光学系统滤波,而表征正弦条纹信息的低频信息得以保留,从而实现正弦结构光场。最后建立光学系统的光学传递特性模型,对其固有的低通滤波机制进行解释。通过计算机模拟和实验进行验证,结果表明提出的正弦结构光场编码方法和制作工艺具有可行性。

Sinusoidally structured light fields are widely used in three-dimensional (3D) measurements of precision optics, and their sinusoidality directly or indirectly affects the accuracy of the 3D measurement. Using geometric features such as the periodicity and symmetry of sinusoidal fringes, this study proposes the use of a single cycle of the standard sinusoidal computer-generated fringe as the coding object, coupled with a binary coding method of an S-path error diffusion. The entire sinusoidal light mask is obtained by periodically copying the coding unit, and it is then processed on the surface of the chrome-plated glass substrate using high-resolution photolithography technology. After the mask modulates the illumination form a light source, the high-frequency information that characterizes the binary coding feature is directly filtered by the optical projection system, whereas the low-frequency information that characterizes the sinusoidal fringe information is retained, thereby realizing a sinusoidally structured light field. Finally, the optical-transfer characteristics model of the optical system is established to explain its inherent low-pass filtering mechanism. Using computer simulation and experiments, results show that the proposed sinusoidally structured light field coding method and the manufacturing process are feasible.