PL-L refector shapes

[marvil701]

Those look really nice! Although I have now used five line segments (1+1+1+1.8+2.5 cm per side) to approximate my design, those could be very close to what I want. What are the measurements on them?

Thanks for the offer ceylon. But I haven't been able to register at hanfburg and even if I would be able to, I doubt I would order those directly from hanfburg/pflanzburg. If I could buy those in a store close to Frankfurt, however ...

 

[marvil701]

Nevermind, see this post:
https://www.icmag.com/ic/showthread.php?t=132787&page=56

 

[hush]

This thread rocks, so thanks to all who have bumped it up over the years!

Sorry for reviving this old thread, but making a new one wouldn't be justified just by looking at the useful information this one already has. This thread should be in the Growroom Lighting subforum.

Looking at the reflector shapes so far, it should be obvious that the M-shaped double parabola design is the way to go if you want the reflector to be almost perfect. The Adjust-A-Wings reflectors have the same shape for good reasons.
A user from the German hanfburg (= cannabis fortress) forum has used GeoGebra to design a reflector for PL-L tubes. He tried finding the ideal measurements, curvature and position by playing with various parameters of a parabola, something which programs like Mathematica would also be able to do automatically (it's called fitting functions). This is what his result looks like:
http://www.s14.directupload.net/file...ce7ig7_png.htm
Which is very close to the Adjust-A-Wings design.

Unfortunately the curvature makes it very impractible in reality, at least if you wanted to construct it yourself, because shaping aluminium is next to impossible without the right tools. Of course you could create a mold out of wood and glue mylar onto it, but that's not a pretty solution either.

I guess what bakelite and DItrY have suggested on page 1 (the M-shape with out the curvature) would probably be a good compromise, although it would be nice to have a computer model verify which of those designs reflects the most light (while still being simple enough to construct easily).

Unfortunately I have no idea where to start when it comes to ray-tracing software (which would be great to find close-to-ideal shapes). Most software that I have come across so far is either very expensive (OSLO, Zemax, ...) or quite complex. Does anyone here have an idea how different designs could be easily tested (ideally using just the computer)? Any programs you guys could recommend?

I just want to say that post of yours was very informative. I didn't know much about this type of software before you mentioned it, and now I am all over it. Also, I want to say that the first thing that comes to mind while reading that post is...

3D PRINTERS ARE ABOUT TO CHANGE EVERYTHING!!!!

I almost want to go out and invest the thousand bucks myself specifically so I could print out reflectors for tube/pll fluorescents, and then sell them for lots of money. lol

Seriously, couldn't a 3D printer print out what we needed, in short segments, which could then be "interlocked" together to make it as long as needed for whatever wattage you are working with? Think about it, the product would be computer designed and printed out, for accuracy, and then you just need to make a reverse mold of it for further production! How badass will THAT be?!

 

[ceylon]

Those look really nice! Although I have now used five line segments (1+1+1+1.8+2.5 cm per side) to approximate my design, those could be very close to what I want. What are the measurements on them?

Thanks for the offer ceylon. But I haven't been able to register at hanfburg and even if I would be able to, I doubt I would order those directly from hanfburg/pflanzburg. If I could buy those in a store close to Frankfurt, however ...

they are 60 cm length ~12,5 cm wide and high is ~5 cm.
they are "selfmade", they didn'T sell them @pflanzburg. they are a leftover of my pll-cabinet.
i could throw them out of the train when i am at the musikmesse in april

 

[SICE]

Great info on this thread.

Need some reflectors on a set up. M shape it is. But build out of what?

 

[queequeg152]

i got some pebble stone reflective aluminum for my PLL fixture at the local hydro store.
it was easily the most expensive sheet metal ive ever purchased. like 50-60 bucks for a 2x4 or 2x3 sheet i cannot recall the exact dimensions.

im a DIY enthusiast(and in case you are as well)... so if i had to do it again, i would just buy some aluminum cutoffs from the metal depot by me... or buy some of that fancy brushed and filmed aluminum they sell for finishing cabinets.
you can polish it with ease if you wish.

 

[TiHKaL]

After reading THIS paper on reflector design.

https://buildings.lbl.gov/sites/all/files/lbl-35253.pdf

I made this for proof of concept:



The results are quite blinding.

The bulb runs very significantly cooler compared to on a flat board,
almost zero light is reflected back to the bulb.

Will see how it works on some plants.

The end template I used is attached.