3D positioning and autofocus of the particle field based on the depth-from-defocus method and the deep networks

Accurate three-dimensional positioning of particles is a critical task in microscopic particle research, with one of the main challenges being the measurement of particle depths. In this paper, we propose a method for detecting particle depths from their blurred images using the depth-from-defocus technique and a deep neural network-based object detection framework called you-only-look-once. Our method provides simultaneous lateral position information for the particles and has been tested and evaluated on various samples, including synthetic particles, polystyrene particles, blood cells, and plankton, even in a noise-filled environment. We achieved autofocus for target particles in different depths using generative adversarial networks, obtaining clear-focused images. Our algorithm can process a single multi-target image in 0.008 s, allowing real-time application. Our proposed method provides new opportunities for particle field research.