“These are compound microscopes with a special condenser (what focuses the light onto the slide underneath the stage) that lights the samples from an angle around a surface that blocks direct light, giving you a dark background. Used commonly for live blood analysis.”
What is darkfield microscopy?
Darkfield microscopy is a technique used to bend light to still pass it through a sample, but uses a disc in the condenser to block direct light onto the sample. This is used for two main effects–the first, to light the edges of a sample up with greater detail, and secondly, to contrast those bright edges against a black background instead of a bright, white background.
What is a darkfield condenser and how does it work?
A darkfield condenser is the part that would need to be changed on a brightfield microscope’s substage condenser in order to convert it into a darkfield microscope. Instead of just focusing the light from the base illuminator up into the sample, the light hits a reflective conical pyramid shape structure in the condenser. This reflects the light outward from the condenser onto another angled reflective plate, which is angled up towards the sample. This bends the light around the disc, but allows it to hit the sample. Since it hits the sample at an angle, the sides of the sample are the most illuminated, called oblique lighting.
Here is an illustration of basic darkfield microscopy in action:
Darkfield microscopy of blood analysis looks something like this here:
Darkfield is commonly used in live blood analysis, as it gives the cells the bright edge you see above, and can help clearly distinguish between blood cells and other compounds within the blood. Parasites, viruses, and other contaminants differ quite vastly from blood cells in appearance, and allows for easy identification for treatment.
Can you recommend any basic darkfield microscopes? I’m new and don’t want to get the wrong kind of microscope.
If you’re looking for a darkfield microscope, here are a few examples to help you shop:
AmScope’s T490B-30W-DK
I have used this unit for my darkfield needs in the past, and thoroughly enjoyed it. You can find my review on the unit here: T490B-30W-DK
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