Optimal focal stack capturing strategy in large depth-of-field microscopic structured-light 3D imaging system

This paper presents an optimized capturing strategy for large depth-of-field (DOF) 3D microscopic structured-light imaging with the focus stacking technique. Different from the conventional focus stacking method that captures fringe images under a series of pre-defined focus settings, the proposed method automatically determines effective focus settings for the measured objects and only captures fringe images under these effective focus settings. Specifically, the proposed method first roughly measures the depths of objects using the focal sweep technique, then calculates the effective focus settings that locate the camera focal plane on the valid depths of the objects. Finally, the focus stacking technique is applied to reconstruct the 3D point cloud using the fringe images captured under the effective focus settings.