Hello, I am currently an undergraduate working on a project with a few professors. I don't want to state to many specifics but I am worried that there may be some flaws in the confocal microscope design.
The design basically has four different lasers being sent parallel in the same direction down toward a target. Each laser has a beam expander added onto the front of it. Once the four lasers are directed parallel in the same line they are sent through an infinity lens system which consists of a 1st lens, pinhole, and 2nd lens. Although there is a beam expander added on to each laser, by the time they are directed toward the infinity lens system they are far smaller than necessary. The goal was to expand the laser beam diameter to fill an objective opening that was setup after the infinity lens system.
For now, to fix the issue, the 2 lenses used in the infinity lens system were changed to expand the beam to the necessary size. But, with that done, I see no point in expanding the original beams with beam expanders. I am not able to see any obvious flaws with the system but was curious if more experienced users of confocal microscope systems were able to point any faults out. So, my basic question is, does there need to be beam expanders on each of the lasers in the beginning? Why would the beam grow smaller?
Note: Two mirrors are used for the alignment of the laser. The mirrors are used to direct the beams toward the infinity lens system, then toward the objective.
Thank you for any input.