Full spectrum fluorescence macroscape

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Lou Jost
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Full spectrum fluorescence macroscape

Post by Lou Jost »

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Most living things fluoresce under UV light; the world is an amazingly colorful place! Here I tried to capture both the visible light fluorescence and the equally-intense infrared fluorescence of some ordinary green liverworts. I used a modified full-spectrum Sony A7R, with a Kolari IR Chrome filter, which passes visible light without modification and passes infrared light as orange or red (depending on the camera model). So the image above is showing the true colors that the eye sees, with the addition of orange for things that are fluorescing in the infrared. Note the fluorescing blue harvestman on the right side.

Here is a landscape photo taken with that filter so you can see what it does. All the vegetation is green to our eyes. Snow, clouds, blue sky, and gray ash near the top of the volcano are unaffected by the filter, but the sparse vegetation creeping up the flanks of the volcano is dull orange, and tree leaves are brighter orange. The same thing is happening in the above image, except that the visible light is not reflected light but consists entirely of fluorescence light.
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MarkSturtevant
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Re: Full spectrum fluorescence macroscape

Post by MarkSturtevant »

Very cool! I know from time spent outdoors at night with a UV flashlight that plants tend to fluoresce red. Some more intensely than others. I think its the chlorophyll that does that.
Mark Sturtevant
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Lou Jost
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Re: Full spectrum fluorescence macroscape

Post by Lou Jost »

Yes, chlorophyll fluoresces red in the visible spectrum, but also has a more or less equal amount of infrared fluorescence. That's why the liverwort thalli are orange-red in this photo. Their fluorescence looks red-purple to the eye.

While chlorophyll fluoresces red, many leaves fluoresce light blue, especially on their top surfaces. I think this is some kind of protective material, perhaps a UV-blocking layer to protect the leaf.

Also, mysteriously, some bryophytes just fluoresce plain green, with no visible red fluorescence or IR fluorescence. You can see some of that in this photo. I don't know why. They have chlorophyll.

Pau
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Re: Full spectrum fluorescence macroscape

Post by Pau »

Nice macroscape
While chlorophyll fluoresces red, many leaves fluoresce light blue, especially on their top surfaces. I think this is some kind of protective material, perhaps a UV-blocking layer to protect the leaf.
Cutine, suberine and some waxes produce this kind of fluorescence, so you're right. Cellulose also does at least in some cases
I have this downloaded table (sorry I don't remember the source).
For sure it is not complete (for example it says nothing about UV excitation of chlorophyll that is very evident although not so intense than with blue EX and it has several emission peaks)
AutoFLplants.jpg
Pau

Lou Jost
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Re: Full spectrum fluorescence macroscape

Post by Lou Jost »

Thanks Pau, that's a useful starting point. I use UV excitation instead of blue excitation so that I can get all possible colors of visible and IR fluorescence, including violet-purple fluorescence. As you know (but I will say it for readers who may not know) it is impossible to get fluorescence of a shorter wavelength than the exitation wavelength.

Pau
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Re: Full spectrum fluorescence macroscape

Post by Pau »

...it is impossible to get fluorescence of a shorter wavelength than the exitation wavelength
It was impossible until the invention of two-photon and other multi-photon fluorescence techniques, BTW not available for us mere mortals :D :(
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Lou Jost
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Re: Full spectrum fluorescence macroscape

Post by Lou Jost »

Yes, I thought about adding a multiphoton caveat, but figured we are just mortals...

jmc
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Re: Full spectrum fluorescence macroscape

Post by jmc »

Nicely done Lou. I enjoy going round the garden with a UV torch (I have a 15W 365nm one) at night and taking photos. This was the cut end of some Acaccia logs, taken using a Schott KV-418 filter on the lens (to ensure no UV gets through, as my Canon's internal filters do not block all the 365nm light), and on a normal un-modified camera. Whitebalance was left as Daylight. The Acaccia are unusual with their bright yellow/green fluorescence.
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Jonathan Crowther

Lou Jost
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Re: Full spectrum fluorescence macroscape

Post by Lou Jost »

Yes, I like to do that as well, and as you know, the full-spectrum camera is not necessary, I usually use regular cameras for this. I actually prefer it to the full spectrum look. But sometimes the IR fluorescence is also interesting to capture, especially when there is a lot of dead vegetation which does not fluoresce strongly in the visible spectrum but does fluoresce in IR.

BugEZ
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Re: Full spectrum fluorescence macroscape

Post by BugEZ »

JMC mentioned the fluorescent yellow-green color of acacia log ends. I have noticed that the sap wood of black walnut (abundant in Illinois) occasionally will fluoresce. I use a UV cure lacquer on my wood working projects. In my ukulele UV tanning booth the finish fully hardens in 20 minutes. The fluorescent response of black walnut is weak, but it contrasts with the maple and oak that don’t fluoresce at all.

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Lou Jost
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Re: Full spectrum fluorescence macroscape

Post by Lou Jost »

I didn't know there was such a thing!

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