In typical microscopy approaches, a 'Z-stack' of up to 100 images are recorded and combined computationally into a single sharp image with an extended depth of field (DOF). Other more sophisticated techniques have been developed for high-resolution 3D microscopy, such as light-sheet fluorescence microscopy, confocal/multiphoton microscopy, and localization super-resolution microscopy (although the latter two are not strictly 3D techniques in themselves). Due to their scanning nature, however, none of these techniques can be used for snapshot or video-rate imaging.
Researchers at the University of Glasgow (Glasgow, Scotland) have developed a new approach, called complementary kernel matching (CKM) that can be used to extend the DOF by a factor of 10 in a single snapshot, thus enabling its use for time-resolved or video-rate microscopy. Furthermore, 3D ranging of the sample is achieved simultaneously in the technique.
CKM--a computational imaging technique--involves optical encoding of the captured image, as well as digital decoding that is used to reconstruct a sharp output image. To achieve optical encoding, the researchers use a phase plate at the aperture of the microscope objective and capture two distinct images with complementary information. In one such implementation of CKM, a microscope is equipped with the CKM-encoding element (a phase plate) and a CKM-splitting element (consisting of a beam splitter, and mirrors to replicate the desired image) that separates the two encoded images onto a single camera to realize snapshot operation.