What is the Good, the Bad & the Ugly of this light please ?

[colinbm]

What is the Good, the Bad & the Ugly of this light please ?
After making my rig very sturdy & with 1.25um steps & getting suitable photos with a 60x objective, I have started getting deeper into Microscope Objective Macro Photography, now with a 100x magnification.
All went OK, except the lighting for the 60x objective wasn't enough for the 100x objective.
The problem is the working distance is now only 2mm, & it is hard to get a strong light in that gap.
I found this LED down light to be suitable with some modifications.
The LED COB in this one is 7mm square & rated at 50w equivalent.
Many other specs are useful, like 12v AC/DC & either polarity in 12v DC.
The Data Sheet....
https://www.ledvance.com.au/en/product-datasheet/6864/31735

 

The plastic lens pops out with a thin lever, revealing the 7mm Cob LED.

 

I then added an aluminium heatsink with a 16mm tube 150mm long.

 

I will make four of these to place close to the 100x objective.

[Andy Perrin]

Could you use some kind of fiber optic setup to get the light in there?

[colinbm]

2 hours ago, Andy Perrin said:

Could you use some kind of fiber optic setup to get the light in there?

I could, but I don't have one & they are an expense in money & space on my desk top.
Four of these made-up lights cost me under AUD100 & hang on the side of the frame.
The light is 6500K which is cooler then the optic fibre ones I saw.

PS, edit, Oh & you didn't answer my question.

[Andy Perrin]

I don't know the anything about that particular light. I did INdirectly address your issue, "The problem is the working distance is now only 2mm, & it is hard to get a strong light in that gap" by suggesting fiber optics. The fibers just transport the light, it's possible to hook up other light sources to them, by my understanding. Maybe the other microscopy people can be more help.

[ulf]

Actually the tube acts as a primitive light guide if it is reflective enough inside. This is a light guide on a shoestring.

The transfer of heat to the heatsink cold be improved if there isn't already thermal compound between the lamp's edge and heatsink.

In some situations this material can be useful for the same purpose:https://www.aliexpress.com/item/1005002842166246.html

Difficult to tell if it id usable here and if the lamp need more cooling.

[colinbm]

Yes thanks Ulf, the Aluminium tube is shiny inside & compound added to the connection points.
I tried a 50mm tube, but that got very hot like 80 degrees C.
So I now have the 150mm tube.

[ulf]

I think the tube is acting as the main heat sink and that it is not well connected thermally to the heat sink. 

You need to get rid of 5W and the tube conduct heat well.

Here are some alternative heat sinks https://www.aliexpress.com/item/1005004982987992.html 

One of the ones with a big core, bigger than the tube diameter and with a hole drilled through matching the tube's diameter will cool the tube better. 

 

An alternative to an aluminium tube might be a solid flat ended glass rod in a diameter that just covers the COBs and placed rather close to their surface.

However that might be difficult to obtain and more brittle. If what you have works good enough that is enough.

 

When working with a diverging light source like this it is a bit tricky to collect and feed the light into a fiber optics.

Some lens/es are needed for good performance.

[colinbm]

Thanks Ulf
The heatsink on the original light works well for it.
With the tube on, I think the tube gets hot because the light is trapped & can't expand to dissipate its heat normally.
I will look at these more solid round heatsinks to place on the tube. The light is 50mm OD & the tube is 16mm OD.
At present the tube is under 50 deg C, & cool at its tip where the light exits, so I am happy with that, a more solid heatsink will be better, when I get some.

[ulf]

If you later want to expand to a more fancy fiber optic light source a MORITEX MHAA-100W is a good alternative.

https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2047675.m570.l1313&_nkw=MORITEX+MHAA&_sacat=0

Some even come with a split fiber optic:

https://www.ebay.com/itm/164061199841

 

A few years ago I got one of them.

[colinbm]

@ulf @Andy Perrin I also wanted to try this system to be adapted in the future for UV illumination too.

[ulf]

Then the current one you have might be better.

A Nemo could replace the LED lamp you have today.

 

The Moritex is using halogen lamps and at least the fibers I got was not that good for more than upper UV-A

[colinbm]

Yes thanks Ulf.
I found last night that my nemo has now only three active LEDs 
But I have plenty of other 365nm lights.