Tissue Imaging using Optical Projection Tomographic Microscopy

Conventional Optical Projection Tomography (OPT) can image tissue samples both in absorption and fluorescence mode. Absorption image can show the anatomical structure of the sample, while fluorescence mode can determine specific molecular distribution. The depth of focus (DOF) of the lens in conventional OPT needs to transverse the whole sample. As a result, resolution will be poor due to the low numerical aperture (NA) needed to generate large DOF. In conventional pathology, the specimens are embedded in wax and sliced into thin slices so that high NA objective lens can be used to image the sections. In this case, the high resolution is obtained by using high NA objective lens, but 3D images can be only obtained by stitching different sections together. Here, we propose a new method that can image entire specimen without sectioning with the same high resolution as the conventional pathology. To produce high resolution that is isotropic, the original OPTM system scans the focal plane of the high NA objective through the entire specimen to produce one projection image. Then the specimen is rotated so that the subsequent projection is taken at different perspective. After all the projections are taken, 3D images are generated by the filtered back-projection method. However, the scanning rate is limited by scanning objective lens due to the large mass of the lens. Here we show a new OPTM system that scans the mirror in the conjugate image space of the object to produce projections.