Design And Experimental Study Of Sinusoidal Structured Light Mask With "S" Shaped Binary Coding

Sinusoidally structured light fields arc 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 arc feasible.