Spectralon fluorescence?

[Andrea B.]

Well, what? Everyone was making lots of comments on the Spectralon fluorescence question and then suddenly none??

I'm hoping to see more examples.

[dabateman]

I see something very faint with my PTFE block. But thats will a high power 365nm light. Also its not spectralon, so don't know if people care.

[Andrea B.]

well, Spectralon is made from PTFE, so, yes, any info would be of interest.

 

Thing is, there are different formulations (?) of PTFE. I don't know what kind I have and why my particular PTFE disk fluoresces while my Spectralon really doesn't seem to.

[Andy Perrin]

David, you have a spectrometer, right? Any way you could measure what's coming back from the PTFE?

[dabateman]

Yes I actually have a proper reflectance probe. It came with my light source.

But I haven't used it yet. Will have to figure it out. I don't have a stand to ensure a consistent angle. I also have a color checker with known values. So I do have a standard.

I will see if I can scratch together some time to play with it.

[dabateman]

Ok quick and dirty test.

 

I didn't use the reflectance probe, just a regular 600um fiber direct to my grating #1 spectrometer.

 

This is Nemo light with stock filter shining on PTFE block:

 

This is The probe just measuring the Nemo light directly:

 

This is a 2A gel cut to 6mm and placed in my probe holder, on the probe and catching the light reflected by the Nemo off the PTFE block: (most likely seeing dust on block and dust on Nemo shinning down)

 

 

Now this might be crazy talk. But I wonder if the PTFE is reflecting the UV for Cadmium to his Camera filter. The Camera filter is now fluorescing and that is part of what he is seeing. I am either seeing the 2A fluroescence in the last image or dust being excited as I couldn't keep the block clean for long periods of time. The last image has integrated time 300 ms, the others are 30ms

[dabateman]

Ok Andy the answer is no.

Firstly my PTFE block is not fluorescence at all as brightly as Cadmium's with distinct bluish foci.

Second my house is so full of dust in a nanosecond I see dust that lands and may confuse a more though test.

 

Funny as just changed all filters today. But maybe that's the problem. I need the house dust to settle as it landing quickly on the block.

[Stefano]

Now this might be crazy talk. But I wonder if the PTFE is reflecting the UV for Cadmium to his Camera filter. The Camera filter is now fluorescing and that is part of what he is seeing. I am clearly seeing the 2A fluroescence in the last image and not from off the PTFE block.

PTFE diffuses light, it isn't like a mirror, so it can't reflect a narrow beam in a filter. Any filter fluorescence would be uniform.

[dabateman]

PTFE diffuses light, it isn't like a mirror, so it can't reflect a narrow beam in a filter. Any filter fluorescence would be uniform.

 

You beat my edit. I think I am seeing dust.

[Stefano]

If you have a dust snowfall, you might put a "roof" above the PTFE. It could help.

[dabateman]

Ok new problem dust on front of Nemo gets excited and shines that visible light on to the PTFE block and that is picked up on the spectrometer.

 

Simple conclusion is I can't measure it. I would need a sample with the foci. Only then would I have some hope.

[dabateman]

New test with freshly sanded PTFE block under water. I don't see much that is fluorescent with my eyes. What was more interesting is its reflecting light.

 

Edit: Confirmed that the below spectra is from Kodak Wratten 2A fluorescence Not block of PTFE.

 

Freshly sanded PTFE with 2A on probe and Stock Nemo with stock single filter:

 

2A on probe looking direclty at the stock Nemo:

 

4mm U340 filter on a Convoy shinning down on freshly sanded PTFE block with 2A on probe:

 

4mm U340 filter on Convoy with 2A probe looking direclty at the Convoy:

 

2mm U340 filter with 48mm Baader Venus U filter on Convoy shinning directly at probe with 2A filter on:

 

All 500 milli seconds integration time

 

Even with 4mm U340 on Convoy I am still pushing 365nm through the glass to hit the PTFE. I don't know exactly what the other peak is but there is dust on the U340 glass of the convoy that I can't seem to get off.

 

So my conclusion is that 2A seems to still leak 365nm. As its reflecting off the PTFE and being detected. the visible band might be dust excited or fluorescence from PTFE or fluorescence from 2A filter. These tests aren't conclusive. being dust free is the hard part.

[Ninjin]

I tried such test: just put UG11, S8612_2mm, and a pressed PTFE target right on the MTE, light from MTE goes through, 'right through'.

On camera - a diffraction grating, bg38 + ЖС4 (420).

The result on the grating is 'light-blue color'. There 420 - 3 mm UV block on the camera, glass that does not have its own luminescence.

[Cadmium]

I tried such test: just put UG11, S8612_2mm, and a pressed PTFE target right on the MTE, light from MTE goes through, 'right through'.

On camera - a diffraction grating, bg38 + ЖС4 (420).

The result on the grating is 'light-blue color'. There 420 - 3 mm UV block on the camera, glass that does not have its own luminescence.

 

Excellent!

I have drawn a diagram of how I understand your description and set up, I am not sure exactly where the grating is placed, thus my "?" with two arrows.

Please let me know if my diagram is accurate according to your setup.

 

 

 

I HAVE the ЖС4, I tested it earlier today, and it doesn't fluoresce at all. However, according to the graph ЖС4 dips slightly below 400nm. So I am wondering if ЖС3 or ЖС11, or ЖС12 are fluorescent,

because if those don't fluoresce either, then perhaps those would be an even stronger test. I don't have any other ЖС# than the ЖС4 (it fluoresces none, like KV-418 or Zeiss T*...).

 

 

[Ninjin]

Put the PTFE on the MTE. Like a filter. Thread to thread.

In the drawing there is air in between.

Diffraction grating all as In the drawing, or no matter where. You can just put the diffraction grating on the table, especially if you have a roll ..I don't have a roll, so I put it on the camera.

 

Жс4 is not necessary, another one is possible, I just showed as an example that this is not UV. Or one can use a stock camera?

 

Жс - Numbers 4 and 3 only have no luminescence, all others are like GG420.

[Cadmium]

ЖС3 is more like GG435, which is my preference, because it totally cuts off anything below 400nm.

I would try ЖС3 + S8612 2mm.

And with U-340 2mm on the torch. Shine through PTFE sheet.

Then if you see light, it has to be fluorescence.

[dabateman]

So lets see if I understand the new test.

On UV light add U340 with S8612 to block all visible and IR leakage.

Shine that on or through PTFE.

This part is ok as PTFE is used in cosine correction probes, at a thickness much greater than standard PTFE plumbing tape.

 

The hard part is the detector. It needs a really strong UV blocking filter but also must not fluorescence on its own. And must be clean as the UV passing through the PTFE will cause any dust anywhere to fluorescence.

 

I am thinking a lens might be best. As in if I cut the UV light to just 365nm, with nothing in 380nm. Then using a plastic non-fluorecent lens may work.

 

I may be able to test this with some more careful thought

[Ninjin]

My main doubt In this test is about the shape of the glow. Trace direct in the 'center' of MTE - no luminescence. Only like a donut.

I think this is strange. But I still don't understand what the matter is.

There is a white element with a similar shape on the MTE LED, but it cannot go through Ug11 probably. Or maybe?

 

I think under these conditions PTFE has luminescence, and at the same time does not, and I think the 'donut' is mixed in this affairs somewhere here.

[Cadmium]

Here is the set up I will test:

365nm UV torch with U-340 2mm (or 4mm installed) > up close against the back of PTFE sheet > Camera/lens with Zeiss T* (or use ЖС3 instead if you have it) + S8612 2mm (or thicker).

 

ЖС4 is very impressive, but it transmits lower than 400nm and there is a difference when comparing ЖС4 with T*, T* blocks higher and better. I believe ЖС3 would work the same as T*.

 

The big difference between this and other tests is the light passes through PTFE rather than being reflected off the PTFE.

PTFE will pass light, depending on thickness of course, but if the light passing though it is UV only, then should it illuminate? Does a U-340 2mm thick filter illuminate when UV passes through it?

In my opinion, PTFE and Spectralon both fluoresce.

[dabateman]

Cadmium,

Add a convoy with u340 next to the convoy with u340 and PTFE. That should give context for dust or other agents fluorescing.

 

It might bee too dark with PTFE, so you might need a couple exposures to blow out one of the filtered flashlights.

 

[Cadmium]

Do what? Na, I will be using the MTE for this because I can screw filters on the front of it. Any torch alone will shine through PTFE.

See the example? You don't think PTFE fluoresces? Uh huh, OK.

 

Aren't you waiting for the rumored upcoming Saturday morning video?

I am! Very excited here... Not the photo below, the actual video!!!

 

Yes, this torch has a U-340 2mm filter in it too! The blue you see, that is fluorescence, not visual violet blue leak from the torch.

[Cadmium]

A very masive Primordial Mega Blob (PMB) has been detected forming near our solar system. Scientists have no explanation about the nature or origin of 'The Blob' as it is now being called.

The Blob seems to be moving closer to our world, but even the most advanced instrumentation has not been capable of determining the Blob's direction if any!

(disclaimer - in case anyone is confused, the previous paragraph is intended as humor)

 

Convoy 365nm light passes through U-340 2mm + PTFE sheet (3mm, 1/8" thick).

Camera (full spectrum) with S8612 2mm + Zeiss T* on lens.

You are viewing -400nm UV light passing though 1/8" PTFE. Visible range is 400nm to 680nm.

 

[Cadmium]

Blak-Ray UV meter test.

[Andy Perrin]

A very masive Primordial Mega Blob (PMB) has been detected forming near our solar system. Scientists have no explanation about the nature or origin of 'The Blob' as it is now being called.

The Blob seems to be moving closer to our world, but even the most advanced instrumentation has not been capable of determining the Blob's direction if any!

 

I think you found him. It's...it's...OMEGA BLOB!

[dabateman]

Your blob looks greenish with some blue. Kind of like my spectral peaks off PTFE, which were different than straight on to just the flashlight. So maybe I was catching something similar to what you are seeing.