This has been the main challenge to our engineering team over the last year or so: Build a combined UV/visible microscope with one specialized purpose: Allow for the reliable detection of protein crystals.
UV light has a particular advantage for protein crystal detection as many proteins contain tryptophan and tyrosine which fluoresce for a fairly narrow UV band. The first challenge was to match this band as closely as possible in order to avoid irradiating the crystal to the point where proteins would denaturate. This is a non-trivial problem, so when our engineers came up with a unique solution the US patent office felt that our solution was worth a patent.
Optics is a whole other challenge. Our approach was to take optical and UV images from the same optical train. This would allow us to take UV and visible light micrographs from exactly the same field of view, allowing us to exactly correlate both images without further processing. Because of strongly varying absorption coefficients, the optics had to be highly customized.
Combine everything with an industry leading 5.1 megapixel UV capable camera and voila: We can clearly resolve protein crystals below 2.5 microns. Using UV light.
A needle in a haystack. Sure, there are many, but they give us a very clear idea on the size of nuclei we should be able to detect with this UV microscope. Click on the image for a larger view.
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