User:Andy Maloney/Notebook/Lab Notebook of Andy Maloney/2009/02/22/Optical tweezers/Spatial filtering

To get rid of higher order modes in a laser beam, one needs to filter the higher orders out of the beam. To do this, we can use either a single mode fiber that only allows the TEM00 mode to propagate through it, or we can use a spatial filter. I have a design for a spatial filter and the parts list can be found below.

I am a fan of spatial filters because they are cheaper than single mode fiber launches and because the optomechanics you use for them can be harvested for other uses if you don't need it anymore. As Alton Brown would say, a single mode fiber launch is a uni-tasker and the only uni-tasker I want in my kitchen is the fire extinguisher.

Unfortunately both a spatial filter and a fiber launch have advantages and disadvantages over each other. If anyone reading this is on the fence about purchasing one, then I'd suggest a pro/con list for your setup.