Dabbling with fluorescence on a budget

ChrisR · Post by **ChrisR** » Thu Feb 16, 2017 8:51 am

One fellow's effort here: http://www.theremino.com/downloads/auto ... ectrometer

enricosavazzi · Post by **enricosavazzi** » Fri Feb 17, 2017 1:55 am

ChrisR wrote:One fellow's effort here: http://www.theremino.com/downloads/auto ... ectrometer

That link makes for interesting reading. As far as I can see, there is a reticle grating and an optical slit, as well as focusing optics (the lens of the webcam), so all the basic components of a spectrometer are there.

For the present application in UV, the UV transmission of a webcam lens may be a problem (commercial spectrometers use focusing mirrors instead of lenses for this reason). The first thing that comes to my mind is that there are quite a few legacy C-mount lenses that transmit UVA well enough for UV imaging down to about 370-380 nm. Some of the legacy Pentax 110 lenses also work well enough in UV. These lenses should work better than a webcam lens in UV, and by using a longer focal length one should be able to increase the wavelength resolution of the spectrometer (at the price of recording a narrower portion of the spectrum and requiring a higher radiation intensity).

BugEZ · Post by **BugEZ** » Mon Feb 20, 2017 6:54 pm

Inspired by this thread, I purchased a 365nm LED flashlight, and lowpass filter and UV safetyoggles. I have not gathered any images, but an explore of my bug boneyard (a pile of dead dry insects glued to toothpicks) with the flashlight was quite interesting. A very non descript black horsefly (Tabanus atratus) with enormous black eyes surprised me as the eyes glowed pale blue. Who knew?

K

Smokedaddy · Post by **Smokedaddy** » Mon Feb 20, 2017 7:38 pm

Excellent thread! So how do you do DIC on a Optiphot on a budget?

banania · Post by **banania** » Sun Mar 05, 2017 2:36 am

Received my flash and did a small comparison against a dedicated Raytech UV lamp which I bought 2013 for about 400 dollars as it was the best price/quality solution for photographing mineral fluorescence back then.

The Raytector unit has both SW and LW and both are 6W, but I believe the battery is not fully charging anymore (more than 50% though).

I tried to evaluate the relative luminous flux per unit area from the two sources for an area that is small enough to be inside the cone of light from the flash. I got about the same brightness with the following values of exposure

Torch ISO100, 0.5s, 5.6
Raytector ISO1000, 20s, 5.6

If I am not mistaken this means that in terms of luminous flux per unit area the torch is about 400 times more powerful than my Raytector. If I had chosen a larger area for measurment the difference would have been much smaller as Raytector lits up a much larger area (from the same distance).

To illustrate the difference here is a set of images (Hazelnut leaf) all taken with ISO100, 0.5s, 5.6. These are unedited Jpgs straight from camera, single shots at 10X. First one is shot with a single 24W energy saving lamp fairly close, second one is shot with the torch as close as possible and third is shot with Raytector LW 6W as close as possible

zzffnn · Post by **zzffnn** » Sun Mar 05, 2017 7:50 am

Thank you for sharing, Banania.

Your 2nd hazelnut leafy image was shot with one single torch, not two, correct? I just want to double check. It revealed structures (those tiny purple dots) not easily visible from regular light. Thank you again.

banania · Post by **banania** » Sun Mar 05, 2017 8:30 am

zzffnn, yes it is just one torch.

I also tried to paint larger areas (than the light cone) by using longer exposure times and painting different areas of the image with the torch and the torch compared also here very favorable with the Raytector.

zzffnn · Post by **zzffnn** » Sun Mar 05, 2017 8:46 am

Thank you, Banana!

I was debating on ordering one or two torch. In the end, I ordered only one. Your exposure time ISO100, 0.5s, 5.6 (F/5.6?), with 10x (microscope objective?) indicates that one torch could be enough for some subjects.

ChrisR · Post by **ChrisR** » Sun Mar 05, 2017 9:10 am

I've just had five , 5W "365nm" 20mm mounted LEDs arrive. Total cost was £/$/E 12.50 or thereabouts.

IMHO 5W is too much to dissipate in this type of torch construction for very long, I have a white one which gets HOT. Stuck to suitable pieces of metal, they may make a better lamp, as long as there's enough UV.
I'll do some tests.

A cheap "UV" torch has just failed, so I'll solder one in. That has a regulator (hackable)to limit the current to 700mA. (2.5W) It's less bright than the nichia - but I don't know how much, yet.

ChrisR · Post by **ChrisR** » Sun Mar 05, 2017 9:18 am

Didn't expect to see Cree on the Nichia:

To clarify - this is inside the Convoy S2+.

I wonder who glues the Nichias onto the Cree boards - and how well.

The Ebay 5W led is much bigger, four sqares visible, total about 5mm lens diameter. The same size as the 5W white LED torch (1.4A at 3.x volts)

banania · Post by **banania** » Sun Mar 05, 2017 9:23 am

zzffnn, I used 20x with 100mm tube lense. I ordered also just one, at first, but after a little contemplation ordered another one. The bargain seemed just too good to be true, had to jump at it. My precious and expensive portable Raytector is now totally antiquated...

ChrisR · Post by **ChrisR** » Mon Mar 06, 2017 3:59 am

This is a cheap "365nm" torch - #201758695190
It claims AA snd it claims Zoomable, in the title, though it is neither!

The battery current is only 400mA, and the output seems is obviously lower than the Convoy.
A relatively large LED though.

Tests for later.

MacroLab3D · Post by **MacroLab3D** » Wed Apr 26, 2017 3:02 am

Thank you, Charles, for this interesting info. I bought FGL420, and ZWB2 filters and both of them have no effect on final image at all. So am i missing something here?

This is Convoy S2+ 365 torch, no filters: https://farm3.staticflickr.com/2930/340 ... af3e_b.jpg

ChrisR · Post by **ChrisR** » Wed May 03, 2017 11:33 am

My Convoys emit enough visible light to show in many images, but not all.

johan · Post by **johan** » Wed May 03, 2017 12:03 pm

What white balance settings are people using for autofluorescence?