We are using Leica DM5500b microscope to do our microscopy on Giardia intestinalis. However, despite the fact that around 3 years ago we were able to obtain amazing DIC pictures, the DIC pictures I am obtaining now look the same as they would in brightfield. I even imaged the slide with both brightfield and DIC on this microscope and got the exact same image. I am wondering what can be the issue? Attached is a word document with examples of how it looked and how it looks now
I can not view your image files, but the most common reason for DIC images looking like std Brightfield is that the microscope was not setup properly for DIC. DIC is rather complex and requires correct focusing (filament) and positioning of the two polarizers (for maximum extinction). Changes to the optical path and even the specimen slide (thickness) can change results.
Dear , you will find useful information in the links below:
https://www.microscopemaster.com/differential-interference-contrast.html
https://www.sciencedirect.com/topics/.../differential-interference-contrast-microscopy
As stated above, the setup is important. You should have at least one prism and two polarizers in the light path. The prisms must be orthogonal to each other and at 45o to the prism. One polarizer is in the illumination path and the other is in image path. Typically, one polarizer will be fixed and the other will have a thumb wheel that allows you to adjust the angle. With the prism(s) removed and no sample in the field of view, you should rotate one polarizer until you have no light visible in the eyepiece. Reinsert the prism(s) and your sample to get an image.
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