Scan Relay
An angular scan can be generated by a motor-driven mirrors. A common type is
called a “galvanometer mirror”:
This kind of system works OK, as long as the scan doesn’t have to go through a
remote aperture, such as the entrance pupil of a microscope objective. Just
using a free-space setup as above results in significant beam traversing on the
aperture, and consequently does not allow the use of the full aberture or the full
resolution of the objective:
The solution is to use a scan relay:
Scan Mirror
4-F
This allows the beam to fill the entire entrance pupil. The objective can therefore
operate at its full design F/# and resolution.