A robust autofocusing method for microscopic imaging based on an event camera

Autofocusing is a crucial method for enhancing the efficiency of biological detection workflows. Traditional methods involve calculating various focus metrics on images captured by standard frame-based cameras at multiple static positions to determine the focal point, which can be time-consuming. In contrast, event cameras have the capability to asynchronously detect brightness changes within the field of view of the microscope and provide a continuous stream of events triggered by axial motion. A completely automated coarse-to-fine method is proposed for event based autofocusing, independent of the objective-sample distance. Two criteria for autofocusing in sufficient and low illumination are respectively proposed. The results show that the dynamic accuracy and dynamic repeatability is less than 5 mm.