Infrared Fluorescence

[Shane]

Major Correction:

 

Sorry - I just found my original document rather than the jpgs and realized I screwed up earlier.

 

The 668nm and 730/732nm emission lines are artifacts (I had forgotten about that). They are second order emission line artifacts from 334 and 365nm.

[colinbm]

I know now that the MTE U301 365nm LED light gives the best & purist, light for UV & UVIVF photography, with an added U340 filter. So far it seems satisfactory to use three of these lamps.

With the HID mercury vapour, Blak-Ray lamps, it is difficult to further filter the lamps.

I think the best practice, with the HID mercury vapour, Blak-Ray lamps, would be to filter the camera/lens with a Schotts S8612 for UV photography & additionally a GG420 filter for UVIVF photography. This prevents the contamination from any stray UV or IR from entering the camera's sensor. The longer wavelengths are more difficult to attenuate than the shorter wavelengths. I think the Baader UV/IR cut filter is too wide a bandpass, for the application in UVIVF photography.

All these filters are available from eBay seller, uviroptics.

Col

[Shane]

Really it all comes back to a simple test:

 

Baader UVIR & Blak Ray red leakage test: Using the same exposure parameters that were implemented in shooting the subject, repeat in complete darkness but substitute a ball bearing. If the ball bearing is black then whatever red leakage is present is not a problem for those exposure conditions.

[Andrea B.]

Shane I need a brief explanation of "2nd order emission artifacts". Thank you.

Do I need to go back and correct my interim summaries w.r.t. 668 & 730nm? Thank you.

 

Col, good filter suggestions. Thank you.

If a person wanted to pursue UVIVF at a more rigorous level they would probably look into getting some narrow bandpass filters.

[colinbm]

The other 'simple' test with the Blak-Ray lamps is with their J221 UV meter.......

"Accurate ultraviolet measurements with no infrared interference can be achieved by using the included Clear Snap-On Contrast Filter. Make one reading without the filter, which will include ultraviolet plus any infrared present. Make another reading by snapping on the Contrast Filter over the sensor cell. As the contrast filter absorbs all ultraviolet and the meter sees no visible light, the resultant reading will be infrared only. When the second (infrared) reading multiplied by 1.06 (an insertion loss correction) is subtracted from the first reading, the resultant figure will be ultraviolet energy only."

An older Blak-Ray type lamp I have, the IR reading is approx 70% of the total reading of UV + IR, on the UVP's J221 meter.

Col

 

PS, Damon has a J221 meter.

[Shane]

In a normal fluorescence spectrometer situation, the excitation and emission monochromators are synched so that the appropriate 2nd order filters are inserted at the correct time during data collection. These are present to remove 2nd order artifacts that originate in the excitation monochromator as light passes through it.

 

A second order artifact occurs at twice the original wavelength e.g. 365nm x 2 = 730nm and 334 nm x 2 = 668nm.

 

I had collected the original spectrum from the lamp using the emission side of a fluorescence spectrometer by measuring the lamp emission directly through the emission monochromator. When processing the spectra, I realized that I had neglected to implement some form of second order filtering and therefore had to rerun the test. Unfortunately, it has been 14 years since I ran the test and the spectrum I posted is the one that exhibits the second order artifacts.

 

Anyway, feel free to remove previous info as you see fit because it will be misleading.

[colinbm]

Hi Andrea

Yes, I was very confused a few years ago when I took-up this road of out-of-spectrum photography & spectroscopy.

I use both, an Amici Prism Spectrograph & a USB Diffraction Grating Spectrometer.

The diffraction gratings give overlapping 2nd order, third order spectrums, The Amici Prism doesn't. They both have differing advantages & disadvantages.

Try & wade through these three pages of explanations.....

http://lightforminc....on_grating.html

http://lightforminc.com/second_order_diffraction.html

Col

[Shane]

The other 'simple' test with the Blak-Ray lamps is with their J221 UV meter.......

 

I sold my J221 meter and replaced it with an ORC UV-MO2 which comes with interchangeable UV25, UV35 and UV42 sensor heads. These are broadband sensor attachments meant for SWUV, LWUV and UV-Blue. I also have a calibrated Si photodiode for 200-1100nm and an OO 250-850nm CCD spectrometer. These are all helpful tools to provide an insight into possible issues.

 

However, none of them are as useful for evaluating a light leakage issue as the ball bearing test in combination with DSLR/filter and a given set of exposure conditions

 

The ball bearing costs nothing.

[colinbm]

Thanks Shane, I have to agree....

I polish my balls regularly & photograph them B)

Col

[Damon]

I see now that the Brain waves have dropped a bit at the end here, I will chime in.

 

First, thanks for grinding away at this with such cerebral ferocity and taking it seriously. It is a pleasure to follow the dialogue. It's one of many reasons I continue to post and soak in what I can and I suspect is also why this forum has not bitten the dust.

 

So like awhile ago with the red sand dilemma--it all comes down to taking a picture of a chrome bearing.

We are suggesting here that I use the Baader UV/IR cut filter I have which is new and shine the B-Rays on the bearing and look for the magenta reflection? Is that right or am I looking to get another filter to add to the stack?

 

Shane--Re:a given set of exposure conditions

Am I taking more than one picture of this bearing?

If so, Can you lay out what you envision I do as far as exposure conditions so I don't shoot the wrong stuff?

Re:The 5D & 5D MkII has quite strong UVIR blocking capabilities similar to that of the Nikon D200

Cool that you have that data--I will be able to test both them camera soon so it will be fun to confirm your findings.

 

Col, don't post your results please...

 

Other things--

--Don't know if they changed the Blak-Rays any over the years but the ones I am using have brand new filters on them. I found that some of the older ones seem to pass too much visible light--like something had happened to the glass over the years--so I just got new glass

--The 1D that Bjorn tested was quite old in Digital terms--~10 years? Mine was the last in the line of 1D mark...cameras. So it's all the more surprising to me.

 

Anyway getting off topic.

 

-D

[Damon]

Shane I just red through this again and found your exact suggestion:

--"Using the same exposure parameters that were implemented in shooting the subject"

No prob--I will go do that now...

 

-D

[Damon]

OK so right off the bat I can tell you that it is 4 degrees F and I warmed up by having some wine.

 

I most likely will need to do this again.

What I did was photograph a large chrome cap that covers the front hub of my old Piney 4X4 Toyota pickup. It is very chromie and shiny. The ball bearing was too small to show multiple Blak-Rays on its surface.

 

I took 1 generic visible pic with no filters at all and then pics with Baader UV/IR cut filter progressing in length of shutter until I began to see the magenta reflection--which I did.

 

I will gladly do it again but here is what I got: All photos taken at iso 1600 El-Nikkor 80 @f5.6 and RAW directly from camera and converted to JPEG/re-sized for forum

I got in there for a cameo.

 

Visible--No Filters at all--*What I saw with my eyeballs was purple reflections--which I could not duplicate with any WB change so left it as captured.

 

.25s UV/IR Cut Filter

 

0.3s UV/IR Cut Filter *you can just barely start seeing the Blak-Ray reflections creeping in

 

0.4s UV/IR Cut Filter

 

0.5s UV/IR Cut Filter

 

0.6s UV/IR Cut Filter

 

0.8s UV/IR Cut Filter

 

1s UV/IR Cut Filter

 

2s UV/IR Cut Filter

 

5s UV/IR Cut Filter

 

If I went any higher it was a total blowout

 

-D

[JCDowdy]

Shane I need a brief explanation of "2nd order emission artifacts". Thank you.

Do I need to go back and correct my interim summaries w.r.t. 668 & 730nm?

 

Sorry, I did not recognize the 2nd order lines B), my usual measuring gear has order sorting filters.

 

Andrea, here is some second order exercise for your math brain! The net effect is that without a blocking filter the 2nd order falls on the detector at ~double the wavelength. Thus the big 365nm line also shows up as a less intense ~2x365=730nm line. So to measure 730nm the filter has to block 365nm from hitting the grating.

[JCDowdy]

Damon,

 

Wow, those are some rare selfies!

 

Interesting how even with the considerable UVIVF coming off your goggles we can still see the hot electrodes through the lamp filter. What is really striking is the apparent effect of the absence of the UV-IR cut filter in your 1st image. That is pretty solid evidence supporting Andrea's earlier comment for the need for the extra UV-IR blocker.

[Andrea B.]

My question to Shane about 2nd order artifacts was supposed to be -- like, what happened dude?

I do understand 2nd order artifacts. In theory, anyway. :D

Although with no hands on experience in spectroscopy, I certainly did not notice that doubling in the first Blak-Ray spec chart.

 

John, that is an excellent reference link. Thanks.

 

********************

 

But whatever. We have gone thru quite a slog here. As Shane pointed out -- remember to perform your shiny metal test. For those of us who do not have the - uhhhhhh - - "balls" to use in such a test, a shiny metal spoon will do for a shiny metal test, doncha think?

 

Srsly guyz, you all have ball bearings just sitting around available for shiny metal tests? Where do these things come from anyway? If I were challenged to produce a ball bearing within the next 10 minutes in order to claim a nice milion-dollar reward, I would go home poor as a little church mouse. Can you buy ball bearings at Home Depot? Is there a ball bearing store somewhere?? B) :P :P

[Andrea B.]

ADMIN NOTE:

Shane and I agreed that the thread deserved some editing to correct the references to the 2nd order artifacts which would be misleading in the context of what were trying to achieve. So I have edited the thread for that. If someone would please look back and see if it all makes a little sense, that would be helpful.

 

Andrea Note: Now, what was it exactly that we were trying to achieve? It almost seems like we were giving Damon some kind of torture hoops to leap through. Sorry 'bout that, Damon!! I hope you have come out the other end of this with your sanity somewhat restored. I want to give this another day to all soak in and then I will try to write a very succinct summary. But anyone else may also write a nice succinct summary of using the Blak-Ray for fluorescence studies. Damon, you could give it a try if you like.

[Andrea B.]

Ya know what? I think I should start a post entitled Using the Blak-RayAP 100 in Fluorescence Studies or some title like that. It would then provide a handy reference link and not force a newcomer to the subject to have to slog thru a thread like this. I will go do that.

[Shane]

Damon

 

although you are on the right tracks the test should be performed in total darkness. Also if your "ball bearing" was smaller than the lamp sources the entire ball bearing would appear red/orange under the conditions of your first shot. When performed in total darkness, if no leakage passes your combined filter setup (Blak Ray and lens filter) then the subject should not be visible. What is the yellow light in the background? and your goggles are fluorescing so strong as to reflect off the subject.

 

No Baader UVIR filter - the entire lamp filter appears red/orange

With Baader UVIR filter - 0.4sec only the lamp filament is visible but the rest of the lamp filter appears black (would be more striking in complete darkness)

 

Adding the Baader UVIR appears to do a good job at removing the light leakage* at the 0.4s exposure (similar to the flower exposure duration).

 

* Should have added - to an acceptable level.

[Damon]

Sneaking a quick look while at work...keep that on the low

 

Shane, it was complete utter darkness.The yellow is a piece of plastic I used to prop the cap forward and apparently it fluoresces as well. Uggh.

It looks lke the chrome cap was too big and shiny causing all manner of unwanter reflections etc.

I will use a ball bearing cause I have tons of them lying around. Tripped on mine this morning getting out of bed--not sure what Andrea is talking about...

Anyway, I don't see why the back of a spoon wouldn't work.

 

I will end this tonight...(key in dramatic music)

 

-D

[Shane]

A spoon should work fine but you need to exclude your goggles from the area to prevent their strong fluorescence illuminating the area.

[Andrea B.]

oh geez, the goggle fluorescence can contaminate too? B)

[JCDowdy]

My question to Shane about 2nd order artifacts was supposed to be -- like, what happened dude?

I do understand 2nd order artifacts. In theory, anyway. B)

Although with no hands on experience in spectroscopy, I certainly did not notice that doubling in the first Blak-Ray spec chart.

 

Apologies, in my decaffeinated state I did not recognize the rhetorical nature of your question.

[Andrea B.]

It is always best to fully respond, John. That was a valuable link. I've saved it. And as mentioned I have absolutely no hands-on experience with this sort of thing. I'm not squeany about what I know & don't know.

 

Then too, on occasion in these threads, I actually ask questions which I might know about in order to keep a good informative flow of conversation going. Nobody would have any way of knowing that.

 

Here is one thing I did not know recently:

I was asking Shane in a PM about the colour seen in the Shiny Metal Test (using ball bearings to those of you who own some). It was not clear to me whether white balance was a factor in such a test because we might see red/blue/magenta variations depending on what in-camera wb was set. But Shane pointed out that what we are looking for is simply colour versus no-colour in the Shiny Metal Test.

 

Now that seems spec-tacularly obvious!!!

 

But, you see, I was not sure whether particular shiny metals could fluoresce or not. So many minerals fluoresce and some of those minerals are metal. Maybe some metal minerals don't fluoresce? Maybe some do. I was not sure. So I got hung up on the white balance thing. But I can rest easy because ball bearings and stainless steel spoons do not fluoresce. And so no reflected colour = no recording of excitation wavelengths. Yay B)

 

Added: All of us really really need to keep the Shiny Metal Test in mind. We could have used it straight off in this test. C'est ma faute! Oh well.

[Damon]

Re:We could have used it straight off in this test. C'est ma faute! Oh well.

 

I learned quite a bit during this discussion so see it as a delightful look into Infrared and Blak-Rays.