Resolution improvement in optical projection tomography by the focal scanning method.

Optical projection tomography (OPT) requires the depth of field (DOF) of the lens to cover at least half of the sample. There is a trade-off between obtaining high resolution with a high-NA lens and obtaining large DOF with a low-NA lens. The DOF of a high-NA objective lens can be extended by scanning its focal plane through the sample. We call this extended DOF image a "pseudoprojection." Images reconstructed from these pseudoprojections have isometric resolution, which can be the same as the lateral resolution of the high-NA objective. The focal scanning method produces an over 10× improvement in OPT resolution.