Definition: Inverted Optics (IO): This Optics is called " Inverted ", Not because the Light would travel in the opposite direction, but because some important optical Comp…onents have exchanged/inverted there place on the Optical-Workbench , compared to the " Standard " Optics. .
This Definition holds not only for Spectrometers, it holds also for Microscopes, where Observer (Your Eye) and the Light-Source (Lamp) have inverted there place on the Optical-Workbench, and so You are viewing the Bottom of the Object and not its Top anymore (You have always to take care for that!). This means, that in case for Microscopes also the Light is traveling in the opposite Direction. ( Full Answer )