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UVIVF around the garden with the Nemo torch

Fluorescence
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#1 JMC

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Posted 23 October 2020 - 09:06

I eventually got my batteries and charger for the Nemo torch that Ulf discovered (only 2 months after the torches arrived - the joys of eBay). Amazing how bright these are. Here's a little night time tour around the garden, taken using one torch, and a KV418 filter on a 40mm pancake lens on my Eos 5DSR. All shots hand held, ISO 2000, f5 and between 1/15s and 1/100s. No light painting - just point and shoot. Daylight white balance in the camera, and cropped and auto contrast for sharing.
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The log store proved interesting. Some of the wood - Acacia and Sumak - light up bright green/yellow under UV in the heart wood.
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And of course an equipment shot.
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I was really surprised by how bright the torches are, certainly very usable.
Jonathan M. Crowther

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#2 colinbm

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Posted 23 October 2020 - 09:34

Looking good Jonathan, could you have used more light ?

#3 JMC

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Posted 23 October 2020 - 09:37

Could have Colin (either the second torch or longer exposures), but I couldn't be bothered to get the tripod out so just went for a wander around the garden with one torch. I was just amazed at the colours it produced.
Jonathan M. Crowther

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#4 Stefano

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Posted 23 October 2020 - 13:08

The cut trunks/branches turned out so nice.
I have to get one. They are very powerful.

#5 UlfW

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Posted 23 October 2020 - 16:43

View Postcolinbm, on 23 October 2020 - 09:34, said:

Looking good Jonathan, could you have used more light ?
More light is almost always nice to have.
However for portable designs it is very fast becoming difficult to handle the need for supplying power and cooling the system.
The designs gets big, heavy and less portable.
Ulf Wilhelmson
Curious and trying to see the invisible.

#6 Andy Perrin

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Posted 23 October 2020 - 18:04

The need is clearly for higher efficiency LEDs, right? If more of the energy went toward making light then the heating requirements would be decreased.

#7 Stefano

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Posted 23 October 2020 - 19:09

View PostAndy Perrin, on 23 October 2020 - 18:04, said:

The need is clearly for higher efficiency LEDs, right? If more of the energy went toward making light then the heating requirements would be decreased.
Ideally at 100% efficiency there is no heat generated, but that's in the dream world. 40%+ efficiency is real, maybe swapping the LED for a better one may be a solution? We need to know the working voltage. It may be roughly 3.5 V, 7 V or 14 V depending on how the chips are wired.

#8 UlfW

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Posted 24 October 2020 - 04:54

The LED in the Nemo is already rather efficient compared to those currently available.
Naturally there might be selection-versions with a slightly higher efficiency, but the improvement would not be that big.
Generally the group of power LEDs for 365nm and longer wavelengths are relatively efficient as light sources.

For an environmental point of view improvements from 30% to 35% or 40% will be a good thing decreasing the energy demand in the world.

For practical usage of an UV-torch it will be less significant and not worth the trouble of swapping LEDs.
We already know that the LED in Nemo is running on 3.5-3.6V as it use one LiPO cell and no switching converter.

To get more light than from one Nemo the easiest way is to bundle several together.

Edited by UlfW, 24 October 2020 - 04:55.

Ulf Wilhelmson
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#9 colinbm

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Posted 24 October 2020 - 05:14

View PostUlfW, on 23 October 2020 - 16:43, said:

More light is almost always nice to have.
However for portable designs it is very fast becoming difficult to handle the need for supplying power and cooling the system.
The designs gets big, heavy and less portable.

Ulf, For the 50w 365nm LEDs, I have some copper heat sinks & they are working many times extremely better then the aluminium heat sinks, just no comparison.
The 'heat' that I have a problem with is the energy in the photons after they leave the LED, I call this the 'light front'.
When a filter is placed in front of the LED say 100mm it is getting hot, like 60 degrees, I don't want to be breaking filters as I have been barred from the seller.

#10 UlfW

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Posted 24 October 2020 - 06:10

View Postcolinbm, on 24 October 2020 - 05:14, said:

Ulf, For the 50w 365nm LEDs, I have some copper heat sinks & they are working many times extremely better then the aluminium heat sinks, just no comparison.
The 'heat' that I have a problem with is the energy in the photons after they leave the LED, I call this the 'light front'.
When a filter is placed in front of the LED say 100mm it is getting hot, like 60 degrees, I don't want to be breaking filters as I have been barred from the seller.
You are right, Col.

Copper is almost two times as efficient at conducting thermal energy.
Then you must have a good geometry of the heat sink design and a big surface area to get rid of the heat.
For designs with higher power a fan cooled system will be good and more compact.

The heating of filters is the third challenge with higher output designs.
With Nemo's 8W that is not very noticable, but with your 50W lamp it is beginning to be a problem.
All energy that is supplied that are not emitted as light will be converted to heat.

Assume an optimistic efficiency of 30% in your 50W LED array. That leaves 15W optical power.
A 2mm thick UG1 has a transmission of 70% at 365nm. 30% of the energy is absorbed.
4.5W of the emitted 15W will then be heating the filter, quite significantly.

Filtering light with different peak wavelengths like 380nm will be even worse.

One good thing is that filter glass is rather tolerant to some elevated temperature and for illumination you do not really need the best type of glass.
Often cheaper glass will work OK and can be replaced with less painful costs if/ (when) it cracks.

It is important to be aware of that the filter can be very hot after some time in such higher power systems.
No such problem with Nemo

Edited by UlfW, 24 October 2020 - 06:11.

Ulf Wilhelmson
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#11 Cadmium

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Posted 24 October 2020 - 06:33

Jonathan, Nice photos! :smile:
Is that a 1200 or 1400 Pelican?

#12 JMC

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Posted 24 October 2020 - 08:36

Thanks Steve. Good eye - it's a 1200. I just bought a few Peli cases as I have too many things just wrapped in bubble wrap and stuffed into drawers. Expensive things though - this was second hand, with a big cut out in the foam, and was still much more than the torches.
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#13 ins13

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Posted 24 October 2020 - 12:15

It's very beautiful! And apparently convenient :smile:
Eka

#14 dabateman

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Posted 24 October 2020 - 13:56

Funny how Jonathan's great photos got us quickly talking about hot air.
Yes we need super conductors and zero heat. Just wondering what pressures we will need.


#15 Stefano

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Posted 24 October 2020 - 14:31

If we only had 80%+ efficient LEDs... maybe in 20-30 years. LED and laser diode technology improved so much in the last 20 years...

#16 Andy Perrin

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Posted 24 October 2020 - 16:40

View PostUlfW, on 24 October 2020 - 04:54, said:

The LED in the Nemo is already rather efficient compared to those currently available.
Naturally there might be selection-versions with a slightly higher efficiency, but the improvement would not be that big.
Generally the group of power LEDs for 365nm and longer wavelengths are relatively efficient as light sources.

For an environmental point of view improvements from 30% to 35% or 40% will be a good thing decreasing the energy demand in the world.

For practical usage of an UV-torch it will be less significant and not worth the trouble of swapping LEDs.
We already know that the LED in Nemo is running on 3.5-3.6V as it use one LiPO cell and no switching converter.

To get more light than from one Nemo the easiest way is to bundle several together.
I feel like you were misunderstanding me. I did not mean a 5% improvement, nor did I mean immediately, I meant a long-term substantial improvment, to like to the 50-60% range.

#17 Stefano

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Posted 24 October 2020 - 18:21

In 10 years we will hopefully reach 60%. Now the maximum I saw is around 50%.

#18 Cadmium

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Posted 25 October 2020 - 02:57

View PostJMC, on 23 October 2020 - 09:37, said:

Could have Colin (either the second torch or longer exposures), but I couldn't be bothered to get the tripod out so just went for a wander around the garden with one torch. I was just amazed at the colours it produced.

Yeah, I love Pelican cases. The 1200 is about $55 with foam, new of course, and you can get all sorts of them used on eBay.
Did you know one place sells a red 1200 Pelican case!? It is not sold by Pelican, it is a custom color, costs about $5 more, but I like the red. I have one of my flash sets in it. You know, RED for FLASH! :wink:
Pelican makes an orange 1200 case, but I don't like orange Pelican cases any more than I like 'orange foliage'...
Reason I asked was because I have my two in the same exact case, yellow even, but my Nemos look bigger in my case than they do it yours, maybe because yours are deeper down.
I was originally thinking of getting a bigger one, because I wanted the goggles in there also, but I used a smaller charger and got the goggle in too, BUT I use the TrekPak dividers which are another expense.
Anyway, yours looks good, and so do your photos! :smile:

Attached Image: NEMO_KIT_FULL_CASE_1080.jpg

Edited by Cadmium, 25 October 2020 - 03:11.


#19 UlfW

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Posted 25 October 2020 - 07:32

View PostAndy Perrin, on 24 October 2020 - 16:40, said:

I feel like you were misunderstanding me. I did not mean a 5% improvement, nor did I mean immediately, I meant a long-term substantial improvement, to like to the 50-60% range.
Andy-
I think I understood you quite well and agree completely with your statements.
We will eventually have more efficient LEDs and that will decrease the problem with cooling.
That is a logical development driven by the market needs, both for visual illumination and UV-curing in the industry.

There was a technology leap, a decade or two ago, for LEDs taking them from being indicators to being light sources.
Lately the gains, I think, has been due to process optimisations and not leaps in new technology.
That might slow improvement down if no new technology leaps are done.

My long reply above was more of my thoughts about what can be done reasonably easy today and a bit as response to Cols's "could you have used more light?".
As we enjoy improvements in illumination exponentially, the need for more light quickly increase to high levels where new unexpected problems surface.
By doubling the intensity repeatedly quickly lead to high power designs.
I simply wanted to point out some of the added challenges that has to be dealt with.

Edited by UlfW, 25 October 2020 - 10:49.

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#20 JMC

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Posted 25 October 2020 - 10:35

Steve, yeah those sort of things are more expensive in the UK (as are a lot of things actually). New Peli 1200 with foam is £61 (about 80USD). The case above was second hand, with a load of foam already removed, but because the charger is bigger it's not a problem.
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