UV first attempt

Images made through a microscope. All subject types.

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kit1980
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Joined: Thu Aug 18, 2016 11:14 pm
Location: Bellevue, WA, USA

UV first attempt

Post by kit1980 »

So I've got my UV source. The LEDs claim to be 365nm, but there are significant visible light leaks. I've ordered ZWB2 filters, but shipping from China will take some time.

Also it looks like the camera picks up some reflected UV light - purple color is the picture is invisible through the oculars.

Image

The object is a laundry detergent grain, 10x objective, stack of 40+ photos.
Omax microscope with Nikon CF objectives
Olympus OM-D E-M10 Mark II camera
http://sdymphoto.com/

houstontx
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Post by houstontx »

I too put the zwb2 filters on the led lights and it seemed to cut the visible light by about half, but not fully...Any little bit helps I guess...you get what you pay for :)

Pau
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Post by Pau »

Kit, Please, tell (or refresh) us the equipment used: UV LED source and filters used.

The image is surprising for me because several wash machine detergents I've tested produce a very strong blueish white fluorescence emission and what I see is mostly violet and purple, like if the image was showing more the visible reflected emission light than the actual fluorescence (the blue points). Maybe, as you suspect, there is UV reaching the sensor (and eyes!) and the camera shows it as violet.
Do you use any emission filter to cut UV and violet before reaching the sensor/eyepieces?

houstontx, my cheap zwb2 filters mounted on the Convoy S2 Nichia UV torches cut off most violet emission, there is some still remaining but much less than 50%, 10% maximum I would say without actually measuring it.
Last edited by Pau on Fri May 19, 2017 2:23 pm, edited 1 time in total.
Pau

kit1980
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Joined: Thu Aug 18, 2016 11:14 pm
Location: Bellevue, WA, USA

Post by kit1980 »

Pau wrote:Kit, Please, tell (or refresh) us the equipment used: UV LED source and filters used.

The image is surprising for me because several wash machine detergents I've tested produce a very strong blueish white fluorescence emission and what I see is mostly violet and purple, like if the image was showing more the visible reflected emission light than the actual fluorescence (the blue points). Maybe, as you suspect, there is UV reaching the sensor (and eyes!) and the camera shows it as violet.
Do you use any emission filter to cut UV and violet before reaching the sensor/eyepieces?
I used AmScope illuminator https://www.amazon.com/AmScope-Powerful ... 880&sr=8-8

I didn't use any emission filters (but I wore UV-resistant prescription glasses plus UV-safety goggles on top of them). Most of the violet is from visible violet light from LEDs, the thing that camera sees but not eyes is more reddish-purple stuff. I tried using my old unused "UV" camera filter, but it turned out that the filter doesn't filter UV at all.
Omax microscope with Nikon CF objectives
Olympus OM-D E-M10 Mark II camera
http://sdymphoto.com/

Charles Krebs
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Post by Charles Krebs »

You really should filter the LED UV lights and also have an "emission" filter.

You could use a Tiffen Haze 2A ( https://tiffen.com/protection-uv-control/ ) for a readily available and low priced emission filter (most camera "UV" filters are inadequate). Tiffen purchased the "Wratten" filter business from Kodak, and you could also use a Wratten 2A or 2E gel. These are much more delicate but can be easily cut to size and are optically good.

Even the best UV LEDs have some spillover into visible violet/blue. Some are much worse than others. The ZWB2 filters you have ordered should be adequate. You can also search around for filters made of Hoya U360 or Schott UG11 glass.

Charles Krebs
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Post by Charles Krebs »

kit1980 wrote: the thing that camera sees but not eyes is more reddish-purple stuff.
Check your separate RBG channel histograms. It is really easy in a case like this to "blow out" the blue channel and then the resulting recorded image really becomes "reddish-purple".

Pau
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Post by Pau »

I agree, you do need an adequate emission filter. Very likely you could just drop it inside the microscope body under the trinocular head (first check if there is enough room for it)
Omega, one of the main microscope filter makers has an outlet ebay store with low prices, I've bought some of my filters from them:
http://stores.ebay.com/OmegaFiltersEbuy ... c=1&_sop=1

This one would be fully adequate but it is very small:
http://www.ebay.com/itm/Optical-Longpas ... 488fdcccd6

This one also will do but because it lets to pass all visible you need an excitation filter able to cut off all violet:
http://www.ebay.com/itm/Optical-Filter- ... 2561c8f209

If a 18mm diameter round filter can fit, I have some surplus ones (I bought two sets and only need one)
Pau

kit1980
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Location: Bellevue, WA, USA

Post by kit1980 »

Thanks Charles and Pau, I'll order couple more filters for experimenting and also that Convoy flashlight to compare with AmScope's LEDs.
Pau wrote:This one would be fully adequate but it is very small:
http://www.ebay.com/itm/Optical-Longpas ... 488fdcccd6
Interesting, so it also removes some visible violet. This should work good as long as nothing actually has violet fluorescence...
Omax microscope with Nikon CF objectives
Olympus OM-D E-M10 Mark II camera
http://sdymphoto.com/

WalterD
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Post by WalterD »

Very interesting Kit, did you have time to experiment with other objects? Just curious :)

kit1980
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Location: Bellevue, WA, USA

Post by kit1980 »

WalterD wrote:Very interesting Kit, did you have time to experiment with other objects? Just curious :)
Thanks! Not yet, I'm waiting for some filters.
Omax microscope with Nikon CF objectives
Olympus OM-D E-M10 Mark II camera
http://sdymphoto.com/

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