Mechmike
Well-Known Member
How about using these? http://www.ebay.com/itm/281156277541?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:ITEgg cups kinda fit in with the fried egg thing!
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DIY COB reflectors
- Thread starter SupraSPL
- Start date
How about using these? http://www.ebay.com/itm/281156277541?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:ITEgg cups kinda fit in with the fried egg thing!
stardustsailor
Well-Known Member
Simulation of an DIY COB reflector ....
1)First of all a good photo of the reflector ...
2) Then ,use the " engauge digitizer " to "digitize " the reflector profile ...
3) use the COBs IES file supplied by the manufacturer
and the x,z ( or y ) values from the digitizer on the free (locked )edition of "shape "..
I'm sure you'll figure out how ...
And ....
Not so good those reflectors (the particular ones ..)
Way high concentration of luminus intensity ..
The shape can export an IES file of the reflector ....
For reference ..Ledil Angelina manufacturers IES (on " IES viewer " freeware )
And my DIY reflector ...
Quite weird pattern ...Lots of power at the center ..
...
Better luck ,next time ...
Ain't so easy to make a good reflector ...
1)First of all a good photo of the reflector ...
2) Then ,use the " engauge digitizer " to "digitize " the reflector profile ...
3) use the COBs IES file supplied by the manufacturer
and the x,z ( or y ) values from the digitizer on the free (locked )edition of "shape "..
I'm sure you'll figure out how ...
And ....
Not so good those reflectors (the particular ones ..)
Way high concentration of luminus intensity ..
The shape can export an IES file of the reflector ....
For reference ..Ledil Angelina manufacturers IES (on " IES viewer " freeware )
And my DIY reflector ...
Quite weird pattern ...Lots of power at the center ..
...Better luck ,next time ...
Ain't so easy to make a good reflector ...
stardustsailor
Well-Known Member
I've tried a hypothetical conical shaped -reflector ...
Like the ones Supra is using ...
Much better ,I've to admit ...
The reflector "profile " ...
The Shape ,takes that "profile " and "spins" it a full circle..
There's your reflector ...
So this one has these dimensions in 3D :
-32 mm diameter of -base
-70 mm diameter of ' shield lips ' (aperture )
-30 mm height .
Place VERO / CXA series cob product IES file ..For light source data
Edit and import
In the next tab ,place manually one -by-one (no copy/paste allowed )
reflector x,y ( " z" ) values Set : |Cartesian profile |
And hit calculate..
Very easy to learn software ,plenty of (hidden somewhat ) settings ..
Working space set at 1m height ..
Follow these steps to extract an new IES file of the reflector ..
Download freeware "IES viewer " and view the render ...
Like the ones Supra is using ...
Much better ,I've to admit ...
The reflector "profile " ...
The Shape ,takes that "profile " and "spins" it a full circle..
There's your reflector ...
So this one has these dimensions in 3D :
-32 mm diameter of -base
-70 mm diameter of ' shield lips ' (aperture )
-30 mm height .
Place VERO / CXA series cob product IES file ..For light source data
Edit and import
In the next tab ,place manually one -by-one (no copy/paste allowed )
reflector x,y ( " z" ) values Set : |Cartesian profile |And hit calculate..
Very easy to learn software ,plenty of (hidden somewhat ) settings ..
Working space set at 1m height ..
Follow these steps to extract an new IES file of the reflector ..
Download freeware "IES viewer " and view the render ...
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nogod_
Well-Known Member
churchhaze
Well-Known Member
tenthirty
Well-Known Member
Positivity
Well-Known Member
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
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
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nogod_
Well-Known Member
I have a question regarding penetration:
I have seen countless times that folks use reflectors and lenses to increase penetration. This doesnt really make sense to me. In order to reach deeper into the canopy dont you want the photons hitting your canopy at a variety of angles rather than straight down ie. perpendicular?
In other words, doesnt adding more emitters not only improve the evenness of your coverage but also your penetration because you have a better chance at hitting the gaps between the topmost leaves?
I have seen countless times that folks use reflectors and lenses to increase penetration. This doesnt really make sense to me. In order to reach deeper into the canopy dont you want the photons hitting your canopy at a variety of angles rather than straight down ie. perpendicular?
In other words, doesnt adding more emitters not only improve the evenness of your coverage but also your penetration because you have a better chance at hitting the gaps between the topmost leaves?
Positivity
Well-Known Member
Lots of ways to look at it..
Ideally you'd have them spaced perfectly over the canopy at just the right height.
In a tent the light gets reflected mostly so its not really needed.
But if someone wanted to run a simple setup of one light hid style, in an open area, the reflectors would give a nice and tight footprint. probably more suitable for tree style growing.
Ideally you'd have them spaced perfectly over the canopy at just the right height.
In a tent the light gets reflected mostly so its not really needed.
But if someone wanted to run a simple setup of one light hid style, in an open area, the reflectors would give a nice and tight footprint. probably more suitable for tree style growing.
stardustsailor
Well-Known Member
In a trial not overpopulate the LED section with new threads for the same topic,I think Supra will allow me to keep posting long posts about reflectors ...
Her's some further thoughts and research from a dedicated DIY designer (yes,that's me,myself and I ,all together ...
..)
Huge "EGO" issues,I'm trying to get over with ...
Anyway ....
Reflector basic thoughts ....
Now,that it's been understood what the "shielding angle " of a reflector is ...
Let's move from a bulb to a COB ...
Say the COB is a VERO29 with a LES diameter of 29.2 mm .
On top there's a cylinder- shaped reflector ..
(Cylindrical it's the name ? )
Dimensions of the cylindrical reflector are :
Height: ~ 38 smthng mm
Diameter (inner ) 49.8 mm ,outer diameter is ~ "nobody gives a $hit right now " ..
Now ..
The Vero29 has a " Full Width Half Maximum " angle of 120 ° ...
The rest 10-20 % of radiant power is emitted from 120° to 180° ,360° around the light source (the COB in our case ) .
So ,for which reasons reflectors could or should be used in a grow site ,using COB solid state light ?
Mainly for three reasons ...
1) To 'restrict " the light within certain limits and / or "projected" shape / pattern .
2) To aid homogenize the light power-wise.
Make power distribution of incident light more even.
Via light diffusion ,of course .
3) Make use of that 50% of light power ,otherwise irradiated from 120° up to 180°.
From the COB -reflector unit ,direct light exits the combo,at a cone with 78.5°.
( ! COB not speculated to be dimension-less "point source" ,as for measuring the FWHM angle ! )
Total Shielding angle of reflector is 92.5°.
FWHM angle - Slielding angle = 27.5°
/2 = 13.75° of light from the Half width half max ( 60°) is being reflected ,at each "side" ..
So ,some % of light within the 80-90% power of FWHM cone ,will be reflected ,at the upper part of the reflectors
sides or "profiles" ...(red colored part )
The rest light ,from the part " 10-20 % @ 120°-180° " of COBs irradiated cone ,
will be reflected from the lower part of the profile ,towards the base and from the base itself ...
Those are some basic thoughts ...
Now ,some more complex ,to follow .......
Her's some further thoughts and research from a dedicated DIY designer (yes,that's me,myself and I ,all together ...
..)Huge "EGO" issues,I'm trying to get over with ...
Anyway ....
Reflector basic thoughts ....
Now,that it's been understood what the "shielding angle " of a reflector is ...
Let's move from a bulb to a COB ...
Say the COB is a VERO29 with a LES diameter of 29.2 mm .
On top there's a cylinder- shaped reflector ..
(Cylindrical it's the name ? )
Dimensions of the cylindrical reflector are :
Height: ~ 38 smthng mm
Diameter (inner ) 49.8 mm ,outer diameter is ~ "nobody gives a $hit right now " ..
Now ..
The Vero29 has a " Full Width Half Maximum " angle of 120 ° ...
So ,80-90% of radiant power is " within" a cone of emitted light ,with a (full ) cone angle of 120°.
The rest 10-20 % of radiant power is emitted from 120° to 180° ,360° around the light source (the COB in our case ) .
So ,for which reasons reflectors could or should be used in a grow site ,using COB solid state light ?
Mainly for three reasons ...
1) To 'restrict " the light within certain limits and / or "projected" shape / pattern .
2) To aid homogenize the light power-wise.
Make power distribution of incident light more even.
Via light diffusion ,of course .
3) Make use of that 50% of light power ,otherwise irradiated from 120° up to 180°.
So...Back in the example ....
From the COB -reflector unit ,direct light exits the combo,at a cone with 78.5°.
( ! COB not speculated to be dimension-less "point source" ,as for measuring the FWHM angle ! )
Total Shielding angle of reflector is 92.5°.
FWHM angle - Slielding angle = 27.5°
/2 = 13.75° of light from the Half width half max ( 60°) is being reflected ,at each "side" ..
So ,some % of light within the 80-90% power of FWHM cone ,will be reflected ,at the upper part of the reflectors
sides or "profiles" ...(red colored part )
The rest light ,from the part " 10-20 % @ 120°-180° " of COBs irradiated cone ,
will be reflected from the lower part of the profile ,towards the base and from the base itself ...
Those are some basic thoughts ...
Now ,some more complex ,to follow .......
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stardustsailor
Well-Known Member
So ...
Once again ....
"Why I should use a reflector with my COBs ? "
1) To 'restrict " the light within certain limits and / or "projected" shape / pattern .
Easily ,becomes understood ,that the shielding angle of the reflector plays a crucial role here,
as also the reflector overall shape itself .
A side note : It will be wise the reflector to reflect as less as possible of the
FWHM light cone .A good starting point is 80-90° total cone angle for circular light patterns .
2) To aid homogenize the light power-wise.
Make power distribution of incident light more even.
Via light diffusion ,of course .
Here ,things become complex .....White paint or aluminium/metallised polymer ?
Later on,more thoughts about the subject ..
3) Make use of that rest 10-20 % of light power ,otherwise irradiated from 120° up to 180°.
The lower part (towards the light source ) of the reflector it is the case ...
Info bit :
http://ledil.fi/sites/default/files/Documents/Technical/Articles/Article_1.pdf
Once again ....
"Why I should use a reflector with my COBs ? "
1) To 'restrict " the light within certain limits and / or "projected" shape / pattern .
Easily ,becomes understood ,that the shielding angle of the reflector plays a crucial role here,
as also the reflector overall shape itself .
A side note : It will be wise the reflector to reflect as less as possible of the
FWHM light cone .A good starting point is 80-90° total cone angle for circular light patterns .
2) To aid homogenize the light power-wise.
Make power distribution of incident light more even.
Via light diffusion ,of course .
Here ,things become complex .....White paint or aluminium/metallised polymer ?
Later on,more thoughts about the subject ..
3) Make use of that rest 10-20 % of light power ,otherwise irradiated from 120° up to 180°.
The lower part (towards the light source ) of the reflector it is the case ...
Info bit :
http://ledil.fi/sites/default/files/Documents/Technical/Articles/Article_1.pdf
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alesh
Well-Known Member
Interesting post, but this statement is not true. It's 50% of maximum value, not 50% of (total) radiant power.
For Vero29, about 80-90% of radiant power is within 120° cone.
stardustsailor
Well-Known Member
1) To 'restrict " the light within certain limits and / or "projected" shape / pattern .
&
3) Make use of that 50% of light power ,otherwise irradiated from 120° up to 180°
So ,it's the physical shape and dimensions ,playing probably the most crucial role here ....
Shape,it's a reflector designing software ,but amongst others it lacks plenty of features ..
One of these -a great one- is the type of reflection ..
Specular or diffuse ?
Shape ,only calculates with specular reflection routines and only accounts for the reflectivity ,
which can be adjusted. (% of light reflected vs absorbed by reflector materials )
So ..The cylindrical reflector simulated at Shape ..
Shape only simulates the reflected by the reflector rays .It does not show the direct -"unreflected" - light rays .
Simulated is "the profile " of the reflector ..Say that your seeing an X-ray of a reflectors half.
Red dot is the light source .
Extreme reflections of light ,both under and over the Half ...(ok you can have Full if the whole reflector was shown ) Width of Half Maximum power angle ,towards the ' opposite ' side ..
Whgere the other part of the reflector is located ,to reflect some of the rays ...
As whole ....
Actually a cylinder-shaped reflector turns out to be a very bad idea ...
It actually spreads the light ,rather than "restricting " it ....
Most Cobs have a FWHM angle of 120°
That translates ,that if one of them is hanged 'bare' ,at 1 meter height from ground ,
the circle of 80-90% of total power ,(the base of the 120° cone ) has a diameter of 3.46 meters ...
That is way much ...Hanging a COB at one meter ,one should/would expoect a growing area of 1 square meter ..
1 x1 m ..
A bare COB will have much of it's light to be reflected by side-walls of site ,if hanged bare ,at 1 m height ...
If FWHM was 80° ?
Then the 80-90% power circle would had a diameter of 1.68 m ..
Much-much-much better ...
So ..
Regarding purchasing small circular aperture reflectors,those the ready made kind, from various brands,
a COB LED grower should choose within the 70°-90° range ,for most of cases .
&
3) Make use of that 50% of light power ,otherwise irradiated from 120° up to 180°
So ,it's the physical shape and dimensions ,playing probably the most crucial role here ....
Shape,it's a reflector designing software ,but amongst others it lacks plenty of features ..
One of these -a great one- is the type of reflection ..
Specular or diffuse ?
Shape ,only calculates with specular reflection routines and only accounts for the reflectivity ,
which can be adjusted. (% of light reflected vs absorbed by reflector materials )
So ..The cylindrical reflector simulated at Shape ..
Shape only simulates the reflected by the reflector rays .It does not show the direct -"unreflected" - light rays .
Simulated is "the profile " of the reflector ..Say that your seeing an X-ray of a reflectors half.
Red dot is the light source .
Extreme reflections of light ,both under and over the Half ...(ok you can have Full if the whole reflector was shown ) Width of Half Maximum power angle ,towards the ' opposite ' side ..
Whgere the other part of the reflector is located ,to reflect some of the rays ...
As whole ....
Actually a cylinder-shaped reflector turns out to be a very bad idea ...
It actually spreads the light ,rather than "restricting " it ....
Most Cobs have a FWHM angle of 120°
That translates ,that if one of them is hanged 'bare' ,at 1 meter height from ground ,
the circle of 80-90% of total power ,(the base of the 120° cone ) has a diameter of 3.46 meters ...
That is way much ...Hanging a COB at one meter ,one should/would expoect a growing area of 1 square meter ..
1 x1 m ..
A bare COB will have much of it's light to be reflected by side-walls of site ,if hanged bare ,at 1 m height ...
If FWHM was 80° ?
Then the 80-90% power circle would had a diameter of 1.68 m ..
Much-much-much better ...
So ..
Regarding purchasing small circular aperture reflectors,those the ready made kind, from various brands,
a COB LED grower should choose within the 70°-90° range ,for most of cases .
stardustsailor
Well-Known Member
Correct !
stardustsailor
Well-Known Member
So ,still in the "shape " issue ...
A bowl shaped reflector .. ( a weird synthesis between cylinder and hemisphere,of a profile )
Much light ray concentration points ..
That ,apart from creating "glare " reflections ,
also may cause the air to heat up ,inside the reflector cavity ,
as the air is relatively stagnant at that area ....
A cone shaped reflector ...
A bowl shaped reflector .. ( a weird synthesis between cylinder and hemisphere,of a profile )
Much light ray concentration points ..
That ,apart from creating "glare " reflections ,
also may cause the air to heat up ,inside the reflector cavity ,
as the air is relatively stagnant at that area ....
A cone shaped reflector ...
stardustsailor
Well-Known Member
So ..One way of using reflectors with COBs is the small individual ,
cup-shaped reflectors with cylindrical aperture .
-Those reflectors with a FWHM angle rated at 70°-90° ,seem to be the best for most cases .
-From possible shapes ,the conical one seems to be much superior,regarding specular reflected light distribution,
than cylindrical or bowl-shaped ..No glares ,no light concentrations ,no possible reflector cavity hot -spot issues ...
cup-shaped reflectors with cylindrical aperture .
-Those reflectors with a FWHM angle rated at 70°-90° ,seem to be the best for most cases .
-From possible shapes ,the conical one seems to be much superior,regarding specular reflected light distribution,
than cylindrical or bowl-shaped ..No glares ,no light concentrations ,no possible reflector cavity hot -spot issues ...
stardustsailor
Well-Known Member
Which leaves the " 2) To aid homogenize the light power-wise.
Make power distribution of incident light more even.
Via light diffusion ,of course . " part for last ....
It has been proven that most plants benefit from diffused evenly distributed light ,both
power wise and spectrum wise ...
http://www.ncbi.nlm.nih.gov/pubmed/18028265
http://aob.oxfordjournals.org/content/early/2014/04/29/aob.mcu071
http://www.actahort.org/books/957/957_4.htm
Regarding the power -wise part ...
An attribute of a COB reflector should be the diffusion of light ...
http://en.wikipedia.org/wiki/Diffuse_reflection
With as less "cost" regarding light absorption ,possible .
Two ways-options open up here ...
White Paint Reflective Surface.
A flat (matte) /satin finished white layer is almost 100% diffusive regarding quality of reflection ..
But ,it presents ,some losses ,reflection -quantity -wise , due to light absorption from paint material.
Those losses can be as high as 20% ,in some cases ,
though at average range somewhere between 5-10 % .
Notes :
-Myself have measured temperatures reaching up to 90° ,10 cm in front of a CXA3070 LES (@2100 mA ).
Any possible paint used on DIY or commercial reflectors ,better be the "high temperature grade " kind .
It should be rated " 150° temperature " ,at least.
-Possible VOC outgassing from paint .
Aluminium Reflective Surface.
Shape software simulates the reflections ,as if the reflector has a reflective surface ,
resembling the one flat mirror-polished aluminium has ...
While the light losses from absorption is usually at the 2-5% range ,the diffusion is rather poor ...
A flat mirror polished aluminium surface is almost 100% specular reflective ..
Still,this type of surface seems to be the most favourable option of LED dedicated reflector manufacturers .
But ...
They seldom ,if not at all ,utilise flat mirror-polished aluminium /metalised poilymer surfaces ..
Either it is satin finished (brushed & anodised -transparent protective layer )
or it has some sort of "patterns" ,in order to diffuse the light .
(Honey-comb ,diamond,hammertone,etc .
More kinda like a "digital" version of the "analog" white paint diffusion....
By adding "texture" to flat mirror -finish .Multiple tiny mirrors ..)
More sophisticated solutions ,of that type , include more complex reflective / refractive surface designs , based on Fresnel phenomena ,where multiple "micro-scales" at the reflecting surface ,create a very even light distribution ,as light rays are "guided" with high precision ,power-wise .
(Utilising a design like that a reflector or lens can "disperse " concentrated light rays -say at the middle point of a LES ,for a lens -or on the contrary "concentrate " diffused light -at the edges of the same lens )
.A wide range of light power distribution patterns and shapes ,can be achieved with this way ,
while the reflector remains compact enough .
As a DIY option ,I think that is beyond reach ,to back-engineer ,copy,design and finally build .
Make power distribution of incident light more even.
Via light diffusion ,of course . " part for last ....
It has been proven that most plants benefit from diffused evenly distributed light ,both
power wise and spectrum wise ...
http://www.ncbi.nlm.nih.gov/pubmed/18028265
http://aob.oxfordjournals.org/content/early/2014/04/29/aob.mcu071
http://www.actahort.org/books/957/957_4.htm
Regarding the power -wise part ...
An attribute of a COB reflector should be the diffusion of light ...
http://en.wikipedia.org/wiki/Diffuse_reflection
With as less "cost" regarding light absorption ,possible .
Two ways-options open up here ...
White Paint Reflective Surface.
A flat (matte) /satin finished white layer is almost 100% diffusive regarding quality of reflection ..
But ,it presents ,some losses ,reflection -quantity -wise , due to light absorption from paint material.
Those losses can be as high as 20% ,in some cases ,
though at average range somewhere between 5-10 % .
Notes :
-Myself have measured temperatures reaching up to 90° ,10 cm in front of a CXA3070 LES (@2100 mA ).
Any possible paint used on DIY or commercial reflectors ,better be the "high temperature grade " kind .
It should be rated " 150° temperature " ,at least.
-Possible VOC outgassing from paint .
Aluminium Reflective Surface.
Shape software simulates the reflections ,as if the reflector has a reflective surface ,
resembling the one flat mirror-polished aluminium has ...
While the light losses from absorption is usually at the 2-5% range ,the diffusion is rather poor ...
A flat mirror polished aluminium surface is almost 100% specular reflective ..
Still,this type of surface seems to be the most favourable option of LED dedicated reflector manufacturers .
But ...
They seldom ,if not at all ,utilise flat mirror-polished aluminium /metalised poilymer surfaces ..
Either it is satin finished (brushed & anodised -transparent protective layer )
or it has some sort of "patterns" ,in order to diffuse the light .
(Honey-comb ,diamond,hammertone,etc .
More kinda like a "digital" version of the "analog" white paint diffusion....
By adding "texture" to flat mirror -finish .Multiple tiny mirrors ..)
More sophisticated solutions ,of that type , include more complex reflective / refractive surface designs , based on Fresnel phenomena ,where multiple "micro-scales" at the reflecting surface ,create a very even light distribution ,as light rays are "guided" with high precision ,power-wise .
(Utilising a design like that a reflector or lens can "disperse " concentrated light rays -say at the middle point of a LES ,for a lens -or on the contrary "concentrate " diffused light -at the edges of the same lens )
.A wide range of light power distribution patterns and shapes ,can be achieved with this way ,
while the reflector remains compact enough .
As a DIY option ,I think that is beyond reach ,to back-engineer ,copy,design and finally build .
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stardustsailor
Well-Known Member
So,proceeding with DIY reflectors project for COB those 'guides' should be kept in mind :
-Shielding angle should be around the 70°-90° range .
-Overall shape should be as conical as possible .
-If white paint is utilised ,it should be of "High Temperature" grade ,flat or satin finish .
-Shielding angle should be around the 70°-90° range .
-Overall shape should be as conical as possible .
-If white paint is utilised ,it should be of "High Temperature" grade ,flat or satin finish .