Best light source for flourescence

[pwnell]

I am looking for a light source for epi-fluorescence on my Olympus BX53. My sales rep suggested this device:

http://www.quorumtechnologies.com/docum ... 20copy.pdf

It seems to be using a metal halide bulb - so now I am wondering whether this is sufficient for excitation in the blue / ultraviolet spectrum as I'd like to photograph corals, and they are usually excited by wavelengths between 400 - 520nm. Or should I get a mercury vapour light source?

[Peter De Smidt]

Could you say a little more about how you want to photograph? Are you taking pictures of corals in your reef tank, or are you taking samples, making slides, and using a microscope?

[pwnell]

Sorry, I was not being clear.

The light source is to attach to my Olympus BX53 microscope's fluorescent arm, and I will be taking tissue samples from various coral, place it on a microscope slide and observe it using epi-fluorescence under the microscope.

[enricosavazzi]

If you are into building/adapting your own equipment, there are now relatively cheap 3W or higher LEDs available at wavelengths down to 365 nm. They can be mounted into older microscope illuminators designed to take halogen or mercury bulbs, often without too much modification (adequate cooling is the main problem to solve).

3W does not sound like much power, but LEDs emit over 50% of radiation within + or - 10 nm, so there is actually a lot of radiation at the nominal wavelength.

[Peter De Smidt]

There is a lot of info on DIY LED lights on aquarium sites, including on what leds make the corals look good. I expect that lights that make your aquarium look good in your tank would use the same LEDs that would make a good light source for your microscope.

[Pau]

Metal halide light sources seem to have some advantages over traditional mercury arc lamps:
http://zeiss-campus.magnet.fsu.edu/arti ... alide.html

But you can consider LED alternatives, for exemple:
http://www.laser2000.co.uk/lumencor_whi ... source.php

Disclaimer: I have no actual experience in this field

Note: PM sent

[g4lab]

These lamps have totally supplanted the previous standard for microscope fluorescence, the HBO103 lamp.

That said, they are indeed feeling the nip at their heels, of UV emitting LEDs.

They are based on the OSRAM HXP 120 watt reflectorised lamp, which is a metal halide. Osram makes two versions, a blue centered, and a near UV centered. Compared to LEDs , quartz halogen, and xenon arcs, these have a warmup period, while the dosing in the lamp tube heats up and vaporizes. It is an even longer warmup, than the slight warmup of an HBO lamp. About two to three minutes. Contrasted to the instant on characteristics of the aforementioned three types. Furthermore both HBO and HXP lamps like to be operated for at least an hour when started.

One rather serious annoyance of the Exfo X Cite lamp which you link to is what they like to call "Intellilight technology" this is a chip that prevents you from purchasing the replacement lamp directly from Osram. The chip records the number of hours on the lamp, and when it reaches 4,000 hours or so, it will not allow the unit to light the lamp. Although the UV would probably have fallen off quite a bit by then. It also monitors the temp of the lamp ceramic, and turns the lamp off if the cooling fan fails, and enforces the no restrike period, if the power is interrupted and various other stupid tricks.
And makes the $200 osram lamp sell for $600. Fortunately the life of these lamps is very long, which is one of their advantages, over the HBO lamp they are intended to replace. HBOs are rated about 200 hours (though they routinely exceed that by five or more times) These are rated at one to two thousand hours. I have worked with several of thes,e and have a lamp which the Intellichip retired at 4,096 hours. But it still will light(Using a raw Osram power supply /ballast). I have not measured its UV output. I have only seen the HXP UV lamp with the Intellichip, but I would suspect that with some research, you might find the blue peaked lamp, with the chip, at EXFOs adhesive curing division. That division uses both lamps, and I would guess the chip is the same for both. It is epoxied on tightly.

Exfo sells these with LumaTec.de liquid light guides, or perhaps clones from China now. These are reputed to have limited life, but I have some VERY old ones that still transmit apparently well, though I have not quantitatively measured their UV transmission. The light guide plugs into the back of the unit and also into a collimator, which has a bayonet specific to your microscope. It outputs a parallel UV and white light containing beam, which enters the fluorescence optics chain.

The lamps were originally designed by osram, for the adhesive curing folks, and someone at Exfo or a microscope company figured out that they would be good for microscope fluorescence too. Which they are.

Exfo has lots of graphs comparing them to mercury lamps in many different characteristics and dimensions. They are certainly far superior to mercury lamps.

You can buy the lamps and the special ballast to run the lamp directly from Osram. No optics are need nor are present in the exfo system. They focal point of the reflectorized lamps sits right on the entrance pupil of the liquid light quide. No heat filter since the reflector is dichroic and radiates the IR away.

If you want to try one of these I can help you obtain a brand new one for a fraction of what a microscope dealer will charge you. Send me a PM if interested.

http://www.osram.com/osram_com/products ... /index.jsp

http://hitechlamps.serveronline.net/HTL ... 20Lamp.pdf

http://www.ldgi-xcite.com/

[pwnell]

Thanks for all the responses, especially g4lab's in depth comments.