Pistachio Fluorescence

[Nate]

Surprised when I shinned a UV light in a bowl of pistachios and easily saw the ones out of the shell. I decided to check them with some different lights.

Camera used was a Canon 77D Full Spectrum. 

Lens is the EL Nikkor 80mm metal version.

WB was done on grey plumbers tape.

 

Here's the visible. Filter is a Hoya uv/ir cut, Light is the cfl I have in the room.   iso100,  1.6sec   f8

 

 

UVIVF. Filter is an astro 1.25in uv/ir cut (different from above because of sharpness for some reason) Light is the 365nm UV Beast v3.  iso200,  .13sec  f8

 

 

UVIIRF. Filters are Hoya R72 and a 950nm from amazon. Light is the UV Beast v3 also.  iso400,  13sec.  f8

 

 

UV.  Filter is the Baader U, light,  UV Beast v3,  iso100,  .6sec,  f11

 

I used DXO and darktable(better WB capabilities)

 

[colinbm]

Really great series Nate
I love the IR glow in the UVIIRF.

[Nate]

Thanks Colin, I was surprised at how bright some things were in uviirf.  Another thing that was bright is some glass polish with cerium oxide.

[Andy Perrin]

Nice. Usually vitamins are very bright. If you take vitamin supplements, try them...

[Nate]

Thanks Andy, Another thing I tried was the black lettering on prescription bottle labels. The lettering was bright white with dark background in uviirf.

 

I was running around the house with a uv torch and camera looking at everything.

[Akira]

Oh, yes, the UVIIRF looks amazing.  Thank you for sharing!

 

Do you know the exact UV wavelength to induce it?

[ulf]

1 hour ago, Akira said:

Do you know the exact UV wavelength to induce it?

It looks like UV Beast v2  is based on 385-395nm LEDs that has a spectrum spreading quite a bit into VIS:

https://uvbeast.com/pages/catalog

 

AFAIK most fluorescence do not depend on a narrow wavelength band for excitation.

[Nate]

@Akira  @ulf

I'm sorry, I don't know why I put v2 when I have v3, I hope nobody went out and bought one.  I edited my post to the correct torch,

 

This is the one I use

[ulf]

No problem, it just shows that you are human. 

I do those kinds of errors all the time, so I think I'm human too. 

 

That torch might be a good one, possibly better than a high power UV-torch I analysed some time ago.

That and your torch are "365nm" torches with a peak likely around 367-368nm and with a well filtered output without light in the visual range.

Almost all power LEDs in that range tend to have an output slightly above 365nm. The peak wavelength is also not super stable, but varies by chip temperature and current.

 

[Nate]

Thanks for the info ulf.

I just ordered some more 18650's and a better charger, this eats them up.

[Akira]

12 hours ago, ulf said:

It looks like UV Beast v2  is based on 385-395nm LEDs that has a spectrum spreading quite a bit into VIS:

https://uvbeast.com/pages/catalog

 

AFAIK most fluorescence do not depend on a narrow wavelength band for excitation.

 

Thank you for the explanation.  Good to know about the fluorescence's independency of the specific wavelength.

[Akira]

8 hours ago, Nate said:

@Akira  @ulf

I'm sorry, I don't know why I put v2 when I have v3, I hope nobody went out and bought one.  I edited my post to the correct torch,

 

This is the one I use

 

No worries!  this V3 looks tempting.

[Andy Perrin]

4 hours ago, Akira said:

 

Thank you for the explanation.  Good to know about the fluorescence's independency of the specific wavelength.

That is not quite true. It is not independent of specific wavelength. The wavelengths that come out of the substance depend on the wavelengths you put in. Colin has even made some nice recent posts showing how his rocks glow many different colors depending on the excitation. What IS true is that you will usually get SOME fluorescence out, for any input, with most substances. But if you shine e.g. 365nm light on your flower vs. 405nm light, it will glow differently, with different colors. 

[photoni]

2 hours ago, Andy Perrin said:

That is not quite true. It is not independent of specific wavelength. The wavelengths that come out of the substance depend on the wavelengths you put in. Colin has even made some nice recent posts showing how his rocks glow many different colors depending on the excitation. What IS true is that you will usually get SOME fluorescence out, for any input, with most substances. But if you shine e.g. 365nm light on your flower vs. 405nm light, it will glow differently, with different colors. 

 

@Andy Perrin an excellent consideration

[ulf]

6 hours ago, Andy Perrin said:

That is not quite true. It is not independent of specific wavelength. The wavelengths that come out of the substance depend on the wavelengths you put in. Colin has even made some nice recent posts showing how his rocks glow many different colors depending on the excitation. What IS true is that you will usually get SOME fluorescence out, for any input, with most substances. But if you shine e.g. 365nm light on your flower vs. 405nm light, it will glow differently, with different colors. 

That is correct but then I would not call 365nm to 405nm narrow. Some physical reactions need quite well tuned wavelengths, but here there is

more slack.

I should have defined what I meant with narrow.

 

I fully agree that different wavelength of the illumination give different responses.

That is another interesting dimension of induced fluorescence.

If you match the excitation light with a suitable blocking filter on the camera for each different light source there is much to be explored.

 

Then a FS-converted camera will add the possibility to see fluorescence further up into the NIR band 

[Andy Perrin]

11 hours ago, ulf said:

That is correct but then I would not call 365nm to 405nm narrow.

You misunderstand me, maybe? or vice versa? — I am not talking about a single source that covers 365-405nm, I am talking about if you have a 10nm FWHM source centered at 365nm, the same material will give a different fluorescence spectrum than in response to a different 10nm FWHM source centered at 405nm. I see you agreed with that idea in the statement below, but I'm not sure if what I said needed clarification.

 

 

Quote

AFAIK most fluorescence do not depend on a narrow wavelength band for excitation.

Like, yes, you can use a narrow wavelength band (even a laser, as I did elsewhere on the board) for excitation, but you shouldn't expect to get the same colors as using a broad source like a flash, or even a different wavelength of laser. So it matters what source you use, is what I was trying to get at!

[ulf]

@Andy

 

We fully agree on this here.

What you said was and is quite clear to me. No clarification is needed.

I saw it as a good expansion of the matter that I left out, even if I thought about it.

 

Remember the beautiful images that were deleted by a (former?) member of different plants where the fluorescence was exited by several different wavelengths?

 

Maybe my original comment was unnecessary and confusing. If so I apologise.

[Akira]

Guys, thank you for the clarification.

 

5 hours ago, Andy Perrin said:

You misunderstand me, maybe? or vice versa? — I am not talking about a single source that covers 365-405nm, I am talking about if you have a 10nm FWHM source centered at 365nm, the same material will give a different fluorescence spectrum than in response to a different 10nm FWHM source centered at 405nm. I see you agreed with that idea in the statement below, but I'm not sure if what I said needed clarification.

 

That should make sense, considering the mechanism of the fluorescence.

[Doug A]

Excellent series @Nate. So for the UVIIF you used two different IR filters stacked? Did this make a visual difference vs only one filter? Also, unlike UVIVF, no UV blocking filter is needed on the camera lens?

Thanks,

barondla

[Nate]

Thanks @Doug A I think I used 2 filters to make sure I wasn't going to see any visual spectrum. I didn't test with only one filter, but It probably would have looked pretty cool too.

I think with those filters stacked, I wasn't going to see any UV. 

Now that I think about it, I could use my Rokinon 135 for that, because it doesn't allow any UV through,  but the framing might be off a bit.

[Andrea B.]

And fun too to see glowing pistachios.