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pgwerner

Axial Transmitted Light Transformation Imaging: A version of RTI for oblique illumination?

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I've been looking into oblique transmitted light microscopy as an inexpensive way of generating both optical contrast and resolution closer to the Abbe limit. A recent review and evaluation of the technique can be found here:

https://www.sciencedirect.com/science/article/pii/S0968432817303888

Oblique illumination is a technique where the specimen is illuminated via axial light from the condenser via a patch stop with an open slit or crescent, placed on the bottom of the condenser.

Oblique illumination is unusual in that it shifts the placement of the zero order and higher orders of light on the rear focal plane off-center, allowing higher orders of light to enter into image formation on one side of the zero order, but losing orders of light on the other side of the zero order. This actually enhances resolution, but only in part of the image, and oblique illumination has the unusual effect of having better resolution on the illuminated side of the image than on the shaded one.

It is also possible to set up a movable slit on the condenser such that one can illuminate the specimen from several directions. My thought is that this in combination with some version of RTI might be able to generate a composite image which can recreate illumination from multiple directions, and perhaps even a composite image that could give a single image with optimal resolution throughout the image. Obviously, this is a novel technique using a directional form of transmitted light rather than reflected light and may require some modification of the RTI algorithm.

I'll note that my background is in biological microscopy and that I am far from an specialist in optics or imaging algorithms, however, this is an idea I'd like to bounce off of others and see if it could be developed.

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