I am trying to build a coaxial microscope with a camera as a college project but am having trouble with the beamsplitter.
My light source is beamed onto a 50/50 beam splitter behind which sits my camera but I cannot seems to eliminate ghosting from the surface of the beamsplitter. I am not getting a usable image and would hugely appreciate some help.
I have tried placing pinholes in front of my light source to limit beam size but this did not remove the haze. I have also cross polarized my optical system but again, this did not help.
Any tips would be really appreciated and I hope to hear from someone soon.
Additional information in response to early answers:
I am currently using a plate beamsplitter set at 45 degrees.
The reason for using this set up is to align my imaging and illumination source.
Most of the reflection I am getting seems to be from the edge of the beamsplitter which is quite small, its only 12.5mm x 12.5m and is 1.1mm thick. The white LED I am using is a 5mm led.
The entire object of this experiment is to have my light source perfectly aligned with my camera to avoid any shadowing on my imaged object.
I have painted the edges with a matte black paint. That helped, to some extent to reduce the reflections.
Unfortunately, I can see the surface of the beam splitter when the light is on. Small specs of dust. I will try to completely clean the surface and see if that helps.
If you have a better method of achieving this, please feel free to share.
Best Answer
I assume that you're building an infinity corrected microscope (because I don't see why else you would need a beam splitter)?
If that is the case, I would immediately assume you're using a cube beam splitter? If so, replace it with a plate beam splitter, which would eliminate the ghosts, because there would be no optical surfaces perpendicular to the optical axis. Take into consideration that a plate will displace your optical axis laterally, so you'll have to compensate for that.