Design of diffractive optical element projector for a pseudorandom dot array by an improved encoding method.

Here we achieved the structured light patterns of a pseudorandom dot array by a single diffractive optical element. The dot array can be applied to achieve three-dimensional imaging. First, the pseudorandom dot array was generated by the proposed improved encoding methods, which are an improved formula-method-based encoding algorithm and an improved enumeration-method-based encoding algorithm. Second, diffractive optical elements were designed as dot projectors to generate pseudorandom dots by the Gerchberg-Saxton algorithm. Pseudorandom dot arrays with different sizes were generated to validate the proposed encoding methods. A pseudorandom dot array with a maximal size of 713×449 was experimentally achieved. By analyzing the intensity distribution of the projecting pattern, the projected dots have a unique window of 7×7, and the dot array is distortion free. The proposed encoding methods, optimization algorithm, and applied fabrication technology have potential applications in three-dimensional imaging, three-dimensional sensing, shape measurement, and deformation measurement with high decoding speed.