Optical computed-tomography microscope using digital spatial light modulation

A computed-tomography microscope using a digital spatial light modulator has been developed and has demonstrated cytological and histological three-dimensional (3-D) image acquisition. The system consists of two high NA objective lenses, a Digital Micromirror Device (DMD) placed conjugate to the back pupil plane of the illumination objective, a sample stage, a light source, and a CCD detector. Each DMD micromirror can control the illumination of a specific angle. A single 3-D reconstruction is obtained from parallel ray projections acquired by changing the polar angle of illumination -phi (max) less than or equal to phi less than or equal to phi (max) while holding the azimuthal angle theta constant. The polar angle is limited by the NA of the objective. To compensate for an incompleteness of information due to the limited polar angles, several reconstructions acquired at multiple azimuthal angles are combined to create a final reconstruction. A reconstruction algorithm was developed using simulation software based on the 3-D Radon transformation and 3-D synthetic objects. Microscopic 3-D volume reconstructions of quantitatively absorption-stained cells have been demonstrated. 3-D reconstructed images enables the analysis of cell morphology and tissue architecture, as well as virtual two-dimensional slices with the distance between slices of 0.3 mum.