Imaging optical system, microscope apparatus and stereomicroscope apparatus having the imaging optical system

摘要

Provided is an imaging optical system capable of avoiding an increase in size of the entire optical system of a microscope apparatus while having a wide distance between optical axes, and enabling expansion to a low magnification range. The variable magnification optical system 3 used in the parallel system stereomicroscope apparatus 100 or the like has a plurality of optical paths in which optical axes are arranged substantially in parallel, and changes the diameter of a light beam incident substantially parallel to each of these optical paths. And at least two lens groups move along the optical axis in each optical path according to zooming, and at least of the plurality of optical paths, At least two of the lens units in one optical path move so as to have a component in a direction orthogonal to the optical axis in accordance with the zooming in at least a part of a section in which zooming is performed from the high magnification end state to the low magnification end state. .