Mathematical relations of a Modified Wollaston DIC prism and microscope objective

[urbanpiper3]

What is the mathematical relationship between a Microscope objective's NA and Modified Wollaston Prism (Nomarski) DIC prism shear amount? What defines the shear amount in a DIC prism. Specifically in a reflective microscope design using a Nomarski prism.

For instance, if the Rayleigh resolution of microscope objective is 1μm, how much shear amount should the Prism produce(separation between the e and o rays) in order to show a interference contrast ? What parameters of the prism dictates the shear amount.

Any references that clearly dives into the technicality of this relationship is much appreciated.

[patta]

I think the shear is set to be about equal to the resolution, or a bit less. Not from hard mathematical formulas, but a tradeoff choice:
- more shear, makes stronger contrast
- but too much shear, makes the image double and loses resolution

So if Rayleigh resolution is 1 micron, appropriate shear would be between 0.5 and 1 micron.
Also will depend on the subject; if you have very small, hard lines, then I'll take the shear small. If you just want to see the contour of large cells, I'll take shear large.
So, anyway shear smaller than the features to be observed, and smaller than the coherence length of light used (otherwise the interference trick breaks down)
Like in Phase Contrast, there is no hard rule on how exactly it should be calibrated, different subjects work better with different settings.

See for example the Olympus DIC page, about midway:
https://www.olympus-lifescience.com/en/ ... /dicintro/

Disclaimer : I've started looking at DIC just recently, and don't have such prisms. The PlastDIC sounds affordable...

[urbanpiper3]

Can the PlasDIC be incorporated into reflected light microscope?

[patta]

It is possible, the threads about PlasDIC are very long, likely somebody sorted that out there.

In reflected, is it the same prism that shears and ricompose the image?