Regarding Charles' recent post of the butterfly wings, I was wondering if it is possible to use above stage lighting on a regular light microscope. Also I have seen fiber optic lighting units (the kind with dual articulating heads) in a couple of science supply catalogs but the cost is very prohibitive to me. I think they run about 300 - 600 dollars US. If above-stage lighting is possible with a light microscope, is there an alternative method of lighting for opaque subjects that will give decent results? I guess I'm looking for a "Walmart solution". Will a couple small halogen or Xenon lamps work?
George
Alternatives to Fiber Optic Lighting
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Charles Krebs
- Posts: 1200
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- Location: Issaquah, WA USA
George,
One of the limitations to lighting subjects from above on a compound microscope is the short working distance of the objectives. I can do it with my 3X and 4X. I can't use my high na 10X because the working distance is too small. I have another 10X that lets me get some light in, albeit at a fairly oblique angle. Above a 10X objective you will rarely have enough "room" (unless you go to specialty objectives with longer working distance).
The reason fiber optic illumination is used so often is that it allows you to conveniently concentrate a large amount of light onto a small area, with minimum heat. If used at full voltage it also has a color temperature of 3200 degrees kelvin, which fits nicely with the "tungsten" preset of digital cameras. It is expensive, but used ones are pretty common at a significantly lower prices.
But there is no reason you could not use other light sources. Don't laugh, but for occasional use I think you might be able to find some fairly bright flash-lights that could work. (I seem to remember Ken Ramos once posted an image or two he took using a flash-light to illuminate from above). Perhaps a couple of those flashlights with the bulb at the end of a small "goose-neck" arm.
Small AC powered halogen light lights could work too. But they are tough to position, you have a much greater problem with heat, and it's hard to avoid illuminating (and heating up) a much larger area than needed with bright, hot light, making it uncomfortable to work.
Charlie
One of the limitations to lighting subjects from above on a compound microscope is the short working distance of the objectives. I can do it with my 3X and 4X. I can't use my high na 10X because the working distance is too small. I have another 10X that lets me get some light in, albeit at a fairly oblique angle. Above a 10X objective you will rarely have enough "room" (unless you go to specialty objectives with longer working distance).
The reason fiber optic illumination is used so often is that it allows you to conveniently concentrate a large amount of light onto a small area, with minimum heat. If used at full voltage it also has a color temperature of 3200 degrees kelvin, which fits nicely with the "tungsten" preset of digital cameras. It is expensive, but used ones are pretty common at a significantly lower prices.
But there is no reason you could not use other light sources. Don't laugh, but for occasional use I think you might be able to find some fairly bright flash-lights that could work. (I seem to remember Ken Ramos once posted an image or two he took using a flash-light to illuminate from above). Perhaps a couple of those flashlights with the bulb at the end of a small "goose-neck" arm.
Small AC powered halogen light lights could work too. But they are tough to position, you have a much greater problem with heat, and it's hard to avoid illuminating (and heating up) a much larger area than needed with bright, hot light, making it uncomfortable to work.
Charlie
Thanks Charlie. Yeah, the lens-to-subject distance on the higher magnification objectives does make it challenging. I suppose what I need to do is look around for a used lighting unit. I had not considered color balance and heat as you pointed out. I tried one of those little battery powered lights they sell at bookstores that clamp on a book. That was awkward. Then I had one of those little keychain "laser" lights that shoots a strong narrow beam of ruby red light. Though I managed to put some red highligts on the subject, it was doubly awkward squeezing it and holding it in position. I don't think I've tried any of them using my 4X. At least I know it is possible, as you so aptly demonstrated with your shot of the butterfly wings. Thanks.
George
George
Cheapest possible solution, which works
I have used on occasion one or a pair of bright-white LEDs running off a battery. These cost very little, a few dollars or pounds at the most. The logic of using them is that the light intensity at the subject falls off with the square of the distance to the source... so a source 10mm from the subject will illuminate it 100x brighter than the same source 10cm away.
LEDs give off no heat and have a good daylight colour temperature. Stick a small lump of kids' modelling dough on the side of the objective, embed the LED wires in it and bend to position as close as possible to the subject.
This is so easy to do, it even works well with 40x objectives. Try it and forget $600 fibre-optic goosenecks.
Peter (planapo)
LEDs give off no heat and have a good daylight colour temperature. Stick a small lump of kids' modelling dough on the side of the objective, embed the LED wires in it and bend to position as close as possible to the subject.
This is so easy to do, it even works well with 40x objectives. Try it and forget $600 fibre-optic goosenecks.
Peter (planapo)