Sunflower in UVIVF with Quad LED

[colinbm]

Sunflower in UVIVF with Quad LED.

Taken with an unconverted Sigma fp, with 410nm long pass filter, to be sure of blocking any stray light.

The Quad LED has 365, 375, 385 & 395nm LEDs & is filtered with some Hoya U360 to block any stray light.

 

First, here is the Directors Cut, so you can see the PTFE used for the CWB & click WB in PN. The PTFE is hand held at I ran out of supports.

Normally I will crop the flower.

 

Second is a photo of my setup....Mach 1

 

 

 

 

[ulf]

The U-360, 2mm filter has a transmission Ti of 10% at 395nm.

Those of the 395nm LEDs will mostly spend their optical power to heat up the filter.

At 385nm the transmission is around 35%. There 2/3 of the optical power will be used for heating.

 

With that filter on the LEDs you will mainly utilize light from the 365nm and 375nm LEDs.

 

I guess that is OK as Australia is known for its cold weather.

[colinbm]

No heat being generated by anything, all under control with the 80mm fan & It is a cold 20 deg C here, winter is here

[ulf]

Maybe I should have said thermal energy instead of heat.

If the LEDs emit something like 10W optical energy and the filter absorbs 90% you have 1W optical energy left and the remaining 9W is absorbed by the filter glass.

If you blow a lot of air by the filter it will not be hot because the air is transporting the energy away from the filter, but it is still a thermal loss heating the air in the room.

[Stefano]

I think it is still worth it to waste all that energy, especially if you want to simulate sunlight and have something up to 400 nm. Removing the 395 nm LED probably makes little difference, but I would keep the 385 nm one and below.

[colinbm]

I just don't understand......even the 365nm LED torches need filtering...!

[ulf]

I just don't understand......even the 365nm LED torches need filtering...!

Only when you want the LED light to generate fluorescence to avoid any stray light above say 400nm from the LED.

If you want to emulate sunlight in the UV area there is no need to filter out the tiny amount of visual light from the LEDs

Compared to what the sun emmitt above 400nm the visual light from the UV-LEDs is rather small to say the least.

 

UV-LEDs to replace sunlight do not need any filtering.

UV-LEDs for UVIVF need filtering.

[colinbm]

The title if this post says UVIVF

[ulf]

So it does, now when I look again..

I missed reading that little detail.

As I have said before I have a mild form of dyslexia and do do sometimes not see all the text.

My fault. I apologise for that.

 

You still lose almost all power in the light from the two LEDs with the longest wavelengths by filtering, making their contribution to the UVIVF very tiny.

To allow more energy through the filter would have to be a compromise with less attenuation and that can ve done with a thinner glass or possibly a different glass type.

A UG2A would then be better than a U-360.

[colinbm]

I don't have a large 150mm square of UG2A & don't know where I could get one ?

The U360 I have cuts off at 405nm.

[ulf]

The U360 I have cuts off at 405nm.

NO it does not!

At least not when it is 2mm thick.

 

According to Hoya's data sheet there is not very much coming through a U-360 at 405nm:

 

In the diagram it looks like 0.1% of the light is passing the filter at 405nm

99.9% will be absorbed and converted to thermal energy at that wavelength.

[colinbm]

I'll do it again tonight without the U360 & see what I get, but I will use the 410nm long pass filter on the camera.

 

Your graph is from Hoya laboratory, mine shows 300-405 in my laboratory at 50% on my sample.

[colinbm]

90watts is not enough power.

It was enough for the Sunflower but the flower tonight it was duller & the camera wouldn't take the picture.

I need to learn to use the flash.....

Back soon.

[Doug A]

@colinbm this project is really interesting. Any updates?

Thanks,

Doug A

[colinbm]

13 minutes ago, Doug A said:

@colinbm this project is really interesting. Any updates?

Thanks,

Doug A

No Doug, I am waiting to find shorter wavelength LEDs with the same volt & current specs to match.

[Doug A]

@colinbm  hope you find LEDs with the specs your project needs.

Thanks,

Doug A

[Guest]

Here is a product for machine vision I don't know much about but it goes down to 365nm. There is a data sheet available and some technical white papers on that site as well. Don't you think they are driving each set of diodes separately?

 

https://www.prophotonix.com/led-and-laser-products/led-products/led-line-lights/cobra-multispec-multispectral-led-line-light/

[Andy Perrin]

They clearly are driving them separately. With a graphical user interface no less! I don’t know what that gizmo costs, but I’m betting $5000US at least.  

[Guest]

Coding is one thing. To some that is like growing your own vegetables.

 

The real question is how much for the parts and where to get em'?

[Guest]

Could one use an off the shelf high power LED grow lamp from Amazon $50-150 as a multi driver platform? I see some go down into the high 300s and have 4 or 5 sets of LED groups. 

[Stefano]

As a general idea you can run each LED set with a DC-DC converter with a current-limiting feature (very important for LEDs), and that will allow you to power everything from a cell/battery pack (which of course has a DC voltage). Or you could connect all LEDs in series if they require the same forward current (and use only one DC-DC converter).

[Craigo79]

Very cool and like the BTS shot