An Image-based System for Real-time Correction of Defocus in Optical Microscopy

Defocus severely reduces image sharpness in various optical microscopy techniques. Indeed, in wide-field methods, specimen-induced aberrations or thermal drifts of the microscope hardware can result in a walk-off between the focal plane of the detection objective and the sample. When imaging living specimens in a 3D environment, the sample itself may move along the optical axis, changing its focal position. The same problem can occur in light sheet microscopy, if the illumination light sheet goes slightly off the focal plane [1].