Highly compressed and freely switchable Talbot effect enabled by DMD and a 4f system

The ability to rapidly switch and generate Talbot effect light fields with small spatial periods is essential for applications in optical metrology, lithography, and biological microscopy. Currently, existing generation schemes that use static gratings, digital micromirror devices (DMD), and Liquid crystal spatial light modulators (LC-SLM) often fail to produce Talbot effect light fields that simultaneously exhibit high pattern refresh rates and small spatial periods. In this paper, we propose a dynamic Talbot effect light field generation method based on a DMD and a 4f optical system composed of a tube lens and a microscope objective. Using this method, we successfully achieved a spatial light field with a Talbot distance of 35 µm and a spatial period of 3 µm and observed clear fractional Talbot effects. We established a multi-beam interference model to analyze the influence of the optical properties of the 4f system, wavelength, DMD pixel size, and projection pattern on the Talbot effect light field. The experimental results and simulations are in close agreement, and the results show that the scaling factor is determined by the focal length ratio of the 4f system, whereas the clarity of the pattern and the complexity of its spatial distribution are affected by the entrance pupil of the microscope objective.