Extended depth-of-field microscopic imaging with a variable focus microscope objective

Increasing the depth-of-field (DOF) while maintaining high resolution imaging has been a classical challenge for conventional microscopes. Extended DOF (EDOF) is especially essential for imaging thick specimens. We present a microscope capable of capturing EDOF images in a single shot. A volumetric optical sampling method is applied by rapidly scanning the focus of a vari-focal microscope objective throughout the extended depths of a thick specimen within the duration of a single detector exposure. An EDOF image is reconstructed by deconvolving the captured image with the response function of the system. Design of a vari-focal objective and algorithms for restoring EDOF images are presented. Proof-of-concept experimental results demonstrate significantly extended DOF compared to the conventional microscope counterparts. (C) 2010 Optical Society of America