This document is the operating manual for the Olympus BX51 microscope, which describes the usage of different modes of the microscope, including brightfield, fluorescence, phase contrast, Nomarski differential interference contrast (DIC), simultaneous fluorescence and phase contrast, simultaneous fluorescence and DIC, and polarized light. The manual provides detailed instructions on the steps to operate the microscope, such as turning on the light, adjusting brightness, adjusting interpupillar distance, placing slides, finding and focusing on specimens.