Nikon Microphot-SA DIC questions

[Chris1366]

I just purchased a used Nikon Microphot SA with DIC and have some questions. This Microscope came from a local university and seems to be fairly complete. It is missing the power supply for the Fluorescence lamp and was missing the parts required to attach a camera. After lots of searching and several different purchases, I was able to put together a working C-mount video camera setup. The current set up is; a Rising cam 20 MP 1" Sony IMX183 Camera, using a PL1x/16 projection lens in the front port. The Camera seems to be Parfocal with the eyepieces. The camera magnification seems to be slightly more than what I get with 10x eyepieces. I had initially tried using a PL2.5 lens, that was far to much magnification and was not parfocal, so I now use the 1x lens.

The stand looks like this:

IMG_3497.jpg (123.32 KiB) Viewed 243 times

I have two questions to start with:

1. I just noticed that I my DIC prism slider (Analyzer?) is missing a part that I have seen on other similar scopes. There is a slot in the top of the slider that accepts a plastic insert that has a small lens of some sort. I don't know what this extra lens is for, I have two polarizing lens in the path, which are set a 90 degrees to each other, in addition to the DIC prisms in the condenser turret and the prism in the slider. Does anyone know what this missing lens is for?

IMG_3499.jpg (51.01 KiB) Viewed 243 times

,

IMG_3500.jpg (63.42 KiB) Viewed 243 times

2. I have a photo taken using this setup. These are with a Plan Apo 20x objective , when I adjust the slider the background color varies from Violet, to Blue, Red, Black and a neutral brown. I am not sure what criteria is used for adjusting the slider or if this range of colors is expected. The image below is what I think may be the best setting. My questions are, is this expected? Does the DIC setup and adjustment appear to be ok based on this photo, or is the missing lens creating an issue?

dic_slider_diff_pos_20x_planApo20240525094744919.jpg (69.03 KiB) Viewed 243 times

Thanks for your help,
Chris

[Sure Squintsalot]

My guess is that slot accepts some sort of a wavelength plate; not critical for doing DIC. In fact, a wavelength plate is far more useful in the absence of DIC, at least as far as looking at crystalline materials go. There are specialized applications in biology but are way above our pay grade.

Diatoms are not great subjects for testing a DIC set-up, especially in a water mount. The large difference in refractive indeces between water and silica aready provide contrast too high for DIC to highlight. Your best bet for testing a set up is using cheek cells between slide and coverslip. A reasonably good set-up will yield something like this:

Screenshot 2024-05-26 224748.jpg (66.77 KiB) Viewed 192 times

....a greyish field with clear "topography" and "illuminated" from some manner of 45 degrees. Colors indicate partial engagement of a prism. Note that Tweaking a DIC set-up involves a LOT of fiddling with condenser height, field diaphragm, condenser diaphragm, not to mention assuring that you even have the correct prism in your condenser.

The Nikon University website has great resources for aligning prisms and learning DIC theory.

Looks like you're learning to drive with a Formula 1 car. Good luck!

[einman]

What a great find! Enjoy!!