Optical instrument having a binocular viewing port

A stereo microscope comprises: a main objective; a main observation output configured so that a left-hand beam path and a right-hand beam path are formed between the main objective and the main observation output; at least one input reflection beam splitter in each of the left-hand and right-hand beam paths configured to reflect additional information into its corresponding beam path; at least one output reflection beam splitter in at least one of the left-hand and right-hand beam paths; at least one first switchable shutter associated with at least one of the left-hand and right-hand beam paths, located in front of a corresponding input reflection beam splitter; and at least one second switchable shutter associated with at least one of the left-hand and right-hand beam paths, located between the main observation output and a corresponding output reflection beam splitter.