Conventional microscopy requires viewing a thin-cut “section” of fixed or frozen tissue, and therefore cannot be used to view thick tissue samples or for in vivo investigations. In vivo microscopy requires a virtual, rather than a physical, section of the specimen. Confocal microscopy, developed and patented by Marvin Minsky in 1955, uses optical imaging to create a virtual slice or plane, many micrometers deep, within the tissue. It provides very-high-quality images with fine detail and more contrast than conventional microscopy. In addition, the imaging technique allows for reconstruction of virtual 3-dimensional (3-D) images of the tissue when multiple sections are combined.