"Ghost Halo"

Gary W Brown · Post by **Gary W Brown** » Tue Mar 11, 2008 1:05 pm

Hi all, I have a Chinese/Indian microscope that produces a "ghost halo" image of the condenser anulus in the field of view while using the 10X objective. All aspects of the system are properly aligned and the image is good, considering the microscope. Any/all ideas are eagerly awaited. Thanks, Gary

Ken Ramos · Post by **Ken Ramos** » Wed Mar 12, 2008 3:11 am

If your condenser is one that can be moved up or down, try moving it upwards to its highest point near the microscope stage. From past experiences, I have had to replace the condensers on these models of microscopes because they did not match the rest of the optical system or had other defects.

Gary W Brown · Post by **Gary W Brown** » Wed Mar 12, 2008 4:56 am

Thanks, Ken. The condenser is in its uppermost position and the iris is wide open. The anuli are centered porperly. This is a new microscope so the condenser is the one that came with it...although that does not mean that all is well. Gary

Ken Ramos · Post by **Ken Ramos** » Wed Mar 12, 2008 5:09 am

The iris being wide open may be part of the problem Gary. Place a prepared slide or some other on the scope and then adjust your iris for contrast while looking through the scope. Once the contrast is adjusted to your satisfaction, remove the slide and see if the ghost image is still there.

Gary W Brown · Post by **Gary W Brown** » Wed Mar 12, 2008 5:32 am

Thanks, Ken. I will adjust the iris and let you know if it makes a difference. Usually when I use phase contrast I keep the iris open so I don't accidentally close it too far. Gary

Ken Ramos · Post by **Ken Ramos** » Wed Mar 12, 2008 5:52 am

Phase!

Sorry it did not dawn on me (annulus) that you were using phase

Well try it anyway and see what results. I have little to no experience with phase. Though there are quite a number of "scope masters" here who do.