Although I am no longer associated with the company, when I worked for
Media Cybernetics, a subsidiary of Roper Industries, several people
from the camera companies, also owned by Roper Industries, told me
that they used First Contact from Photonic Cleaning Technologies
(Platteville, WI; www.photoniccleaning.com) to clean their cameras.
Based on this recommendation, I purchased some and have used it
several times. This stuff comes in a finger nail polish type bottle
and is brushed on the camera or lens.  A small piece of stiff paper is
embedded in the coating and it is allowed to dry.  Once it is
completely dry, you can peel it off of the lens in a single sheet,
taking with it any bits of dirt, fuzz and even grease (i.e finger
prints).

I am not associated with Photonic Cleaning Technologies in any way
except as a satisfied user.

With that said, by paying careful attention to the live image from
this camera and rotating the camera and various optics in the imaging
system (use a bright field image) it should be fairly easy to identify
which surface actually holds the contamination.

Chris


Chris Tully
Microscopy and Image Analysis Expert
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240-888-1021
http://www.linkedin.com/in/christully