The footsteps continued their light path, across the landing, down the remaining stairs.
The lens is the first component in the light path.
A moment later a third crossed the light path of an enormous star.
Other models have a drawer where cut filters can be inserted into the light path.
This means you do not want to change anything about the illumination source, or the light path, during the experiment.
Way up the street, somebody had moved across a light path from a store window.
This is shown in the figures by red light paths.
These high frequency images are shown in the figures by blue light paths.
It's relatively short and compact, since the light path is "folded" inside it.
The design, as described in 1936, consisted of an instrument with two parallel light paths.