DIY COB reflectors

Mostly for verifying /double-checking the above assumptions ,I've made up a new reflector simulation .

Firstly starting with SketchUp software ..


A made a COB ( ~ 29 mm LES ,50 mm outer diameter :VERO 29 ) ...
Draw the cob's 120° FWHM angle ..
Taking into account COBS physical LES dimensions ,this time ..
And then draw the desired 80° FWHM angle ..

And then draw a possible reflector profile sitting at one side of the cob ...
Used the desired FWHM angle to find the shielding point of the reflector's aperture .
The reflectors is just 12.3 mm high and has an outer diameter of 50 mm (same as COB's )

Then moved to engauge software ,to digitze the profile of the reflector into x s' & y s ' ....


Used those values ,along with the VERO 29 3K-80cri IES file into SHAPE software ...



Nice clean reflections...Some light rays seem to converge(hot-spots ) ,but that is happening outside the reflectors cavity ..



From one meter height ,all the light stays well within to a 1.6 m diameter circle ...
Not just the FWHM cone light ....Brilliant !



And used an exported combined (vero29 +reflector ) IES file from shape to IES viewer ,
to see a 'render' of the combo's light ...


Nice "side-ways" power distribution ...
Not just directly under the COB ...
(Imagine the 2D render in 3D ..." Spin 360° "...)


The calculations are done with a 100% specular reflection.
Utilising white paint ,will further 'even -out the reflectors power distribution pattern ,
as then ,reflection is >80% diffusive .

Even with less than 2cm of height of/for a reflector ,the difference from "bare" COB , is rather great !

Cheers.

Great info as always SDS. Looks like I am going to try putting short reflectors on my CXA3070s running at 800mA, 15-20cm (6-8") above the canopy. Even if it is a small gain that will translate into a lot of bud

Reflector base " COB aperture " diameter : 32 mm
Reflector exit aperture diameter : 50 mm
Reflector height : 8 mm !!!

A tiny reflector ,with great characteristics ...

Cheers.

I was thinking about cone shape versus cup shape as well. Just tested a small cone shape with the best performing paint (7751) versus a cup shape with the same paint. 22" from the canopy, Vero 29 dissipating 103W.

No reflector:
center of grid: 107
halfway to edge of grid:86
edge of grid: 55

Cup shape:
center of grid: 155 (145%)
halfway to edge of grid: 121 (141%)
edge of grid: 73 (133%)

Cone shape:
center of grid: 177 (165%)
halfway to edge of grid: 136 (158%)
edge of grid: 60 (109%)

So the cup gives a more even spread but the cone may be preserving more of the light overall, less escaping out the sides.

SupraSPL said:

I was thinking about cone shape versus cup shape as well. Just tested a small cone shape with the best performing paint (7751) versus a cup shape with the same paint. 22" from the canopy, Vero 29 dissipating 103W.

No reflector:
center of grid: 107
halfway to edge of grid:86
edge of grid: 55

Cup shape:
center of grid: 155 (145%)
halfway to edge of grid: 121 (141%)
edge of grid: 73 (133%)

Cone shape:
center of grid: 177 (165%)
halfway to edge of grid: 136 (158%)
edge of grid: 60 (109%)

So the cup gives a more even spread but the cone may be preserving more of the light overall, less escaping out the sides.

View attachment 3317754

Click to expand...

See what happens (regarding always SPECULAR reflection and not diffuse ) ,if the previous design ,
alters by a single point !!! (profile made more "straight -linear " ) ...





At one meter height all reflected light ,is concentrated inside a ~18 cm diameter circle !!!!
From 1 m height !!!
A single dot added to profile to make it more straight ..
A slight change ...


Draw your conclusions....
....

Although ,white paint ,for sure decreases enough the importance of reflector's profile shape ..

Can anybody guess what this is about ?



I will help you a bit ..
" high-tech Photon mapping ,caustic photons included "
30 Watts of radiated light

....Black tile layered room ...
Virtual ,of course ...

So ...
Anybody ?

At 1 meter height .....

A bare Vero 29 3000K -80 CRI ,irradiating 30W of light ...


The same Vero with Ledil Angelina attached ...


With my DIY INOX bowl reflector ...


With a slightly curved conical one ..


Pronounced Curve -conical ...

Should I do some of the branded reflectors ?
Give me some IES file links ..
I 've the virtual lab open for anybody's testing ..

...
Cheers.

Did you try the ledil angelina 90 degree?

Only available in large quantities but it looks like a nice reflector..

http://www.ledil.com/node/2/p/13547

Well,you'll have to excuse me ...
All the above renders are BS ...
It is not so simple as I thought ....

Thanx ,Pos ..A visit to the link ,made me realise some things ..
The IES files provided are with CXAs driven at 250mA ...

So ,with notepad I've opened up the IES file of the Angelina to change the lumens setting ...
http://docs.autodesk.com/ACD/2010/ENU/AutoCAD 2010 User Documentation/index.html?url=WS73099cc142f48755f058a10f71c104f3-3b1a.htm,topicNumber=d0e177687

I ve put to the test a CXA 3070 AB bin ,Tc=55 C .
That at 1400 mA outputs 6620.1 lumens ,at 51.892 W pwr dis.
That is 127.6 lm/w or 0.3926 readiometric efficiency ...

So at the angelina IES file .... 6620.1 - 6% reflector losses (efficiency of reflector =94% )=6222.894 lumens=~6223 lm

At rendering software....
0.3926 rad .efficiency x 51.892 W= 20,373 watts of irradiated light ...
(with efficiency setting at 100% )
LES diameter of CXA3070 = 23 mm (radius=11.5 mm )
Uploaded the corrected angelina IES file and ....


....hit render ....

Here you are ...
As close to real photon map[ping , as possible ...
I think ...

Thanks sds..interesting to say the least.

Now quite sure how to interpret that though. So...the 90 degree is still throwing a rather tight pattern. Maybe a shorter reflector is more what we need?

Im almost thinking a oversized tir to collect and throw the light more evenly than a reflector can...but that'd be $$$$. Not to mention it would need to be ventilated on top of that if running hard..nevermind..thinking aloud

so, isn't only the reflected portion of the light going to experience an decrease in intensity due to the reflector?

Yes that is correct, a good portion of the light never even interacts with the reflector. When using a lens though, all the photons interact with the glass.

A tad off-topic ,but I forgot to mention the rendering software used ,to simulate .
Along with Sketch Up 2015 version ,the Twilight V2 renderer was used .

The hobby version ,is free to download and use ,while it can be used for many things ..
Like making " logos" ...or sticker themes ...

Example following:


Starting at sketch up with a simple 3D model ... and


To have these after rendering at Twilight V2 ..




Merry Christmas to everyone ,folks.

Cheers.

Yes, Merry Christmas to all.

Positivity said:

Theres always the reflector adapter from ledil for 3070s and maybe various similar/smaller types too. Less than a buck and it tightens the beam up a little. You could probably mount without the ideal holder if you wanted to...it has its own screw mounts.

Leaks a little light but i like it. Even when I'm not using my reflectors i like having them there for a little extra focus.

Cheap option..might even be able to silicone it on at the screw spots

View attachment 3316892View attachment 3316895

Click to expand...

This morning I purchased some Ideal Chip Lok holders from Newark and they had both the 50-2100AN and the 50-2100LN, which has more of a bowl shape, but is steeper.

Picked up two each with my holders, to see the effect, but really just for anticipation of finding Ledil reflectors, a little more cheaply eventually...


Also using the beam angle calculator, I figure I am going to running my 3070's at around 10 inches away from the tops, so a 5 degree difference can reduce the beam angle pattern, about 8cm2.

120 degrees


115

Pic of the LN
and the An

Finally got around to testing the value of short reflectors on low powered (700mA) CXA3070s at close distances (5-7") to the canopy with a 12-15"" grid. The results are awesome and disturbing in some ways. Awesome because I am seeing 48% more light in the center, 36% more light halfway to the corner and 17% more light at the corner, (6" away from the center, at 5.5" distance). Disturbing because even an unpainted piece of clear plastic improves the light significantly. Also disturbing because of the implication that I have been missing out on yield by NOT using them all along. There is just a lot more light escaping sideways than I thought there would be and it needs to be redirected.

For these short reflectors I am using plastic water bottles painted with the white heat paint. Very easy and quick to make and install. Hopefully it will show up in some improved gpw numbers and deeper reach into the canopy.

Great work supra, iv'e been disturbed by how bright the walls are, hoping that light was still reflecting basically.. down.. but in a narrow cabinet 120* really shows. (2nd from last image)

Haven't left a lot of room for individual reflectors but I'll be definitely working on something.

IMO leds should not be used without reflectors, too much light leaking from the sides lens are also important and give a big lift in light reaching the canopy. Run them softer if you don't have the hight