Autofocus System for Imaging Multiple Cells across Thick Liquid Layers in Differrent Focal Planes

Obtaining microscopic images of all cells in a specimen with thick liquid layers as clearly and accurately as possible is essential for the diagnosis of disease or infection in patients using an automated in vitro diagnostics (IVD) analyzer. However, the autofocus method used by traditional analyzers can only clearly image cells located on the same horizontal plane. For cells distributed on different horizontal planes in a thick liquid layer, it is challenging to image all of them clearly. In this paper, combining technologies such as autofocus, dynamic fusion, and adaptive trajectory planning, we present and validate a novel system to achieve the rapid localization and accurate imaging of all cells in thick liquid layers. Through the Non-False MultiFocus image fusion algorithm, the clear cell images located in different liquid layers are fused together. The adaptive path planning is further used to shorten the multi-field autofocus time and improve the analyzer's working efficiency. This system includes a microscope, CMOS camera, light grating, stepping motor, motion control circuit, and other hardware modules, which are controlled by a software algorithm. The feces sediment analyzer has been successfully deployed to the pathology departments of multiple hospitals.