How to design a reflector for LED street light

[venci]

Hi everyone, I have a project where I have design a a reflector for LED street light and I need some help on how to do that.
Currently I have mostly written about what materials are used for making it(PMMA, PC and silicone), methods on how to create it based on the material, calculated the angle of reflection depending on the material,
added some information about calculating the lumens of the led lamp, wrote about how the dimensions of the reflector depend on the height and positioning of the poles and will be adding some information about Ray tracing with the Monte Carlo method.

Is what I have done so far correct and what else do I have to write about. Just looking for some advice from an expert who works in the field.
I hope that I am not breaking any rules with this question and thanks if someone can help me out.

 

[1503-44]

A reflector for an LED street light.
The reflectors for a street lamp I know go behind a conventional type light bulb, a bulb that illuminates all directions. The reflector makes use of the light that would normally be sent up to space by reflecting it downward towards something you want to see on the ground.

Since LED s basically only emit light in one direction, how is a reflector useful?

Perhaps I do not understand how your reflector is supposed to work. Do you put the reflector on the ground to reflect the light to some other direction?

 

[MacGyverS2000]

^^^ this...

I suppose you could use a reflector and aim the LEDs at it (rather than directly towards the object to be illuminated), perhaps to change the color/density of the illumination itself, but generally it's easier to do that through straight optics and/or LED choice.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[venci]

1503-44 and MacGyverS2000

Well by reflector I mean a type of secondary optics like the lens or TIR Optics. I asked my teacher for a photo/example and this is what he showed me:

https://imgur.com/a/YSTuNIm

. I think that the LED get's attached first, then the reflector get's put over it and when the LED sends the light, the cone like shapes of the reflector reflect the light depending on the angle. I tried searching on the Internet and while there is a lot of info on LED, I wasn't able to find a lot of info about secondary optics or more specifically about how to design a reflector. In the end I might just write what I have already decided and see what happens. He even told me not to make a 3D model so in the end I am mostly just writing some steps/stuff that I think are correct without any pictures.

 

[MacGyverS2000]

Difficult image to process, but I don't see any reflectors in that package, just optics.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[venci]

MacGyverS2000

yeah, I have no idea why my teacher calls it a reflector, everything I read on the Internet and saw in images clearly just states optics. well I will write whatever I stated above and just send it to him. Hopefully I somehow manage to pass otherwise I will just ask him to tell me what to look at.

 

[drawoh]

...

Since LED s basically only emit light in one direction, how is a reflector useful?

You are confusing LEDs and lasers. Lasers at best are fairly collimated. Diode lasers have a substantial beam dispersion.


--
JHG

 

[drawoh]

venci,

I have done lots of optics design. I do the mechanical packaging, not the optical analysis. You are on your own as far as analysis is concerned. Most lighting systems featuring incandescent lamps or LEDs feature a reflector and a lens. Look at the tail lights on any automobile.

If this is indeed a street light, look into weather proofing. Your light will need to meet the NEMA[ ]4 and/or IP66 standards, both of which are able to withstand violent jets of water.

--
JHG

 

[venci]

drawoh

Thanks for the info, will check those out. Can you explain what does the mechanical packaging involve. And thanks again.

 

[drawoh]

venci,

By "packaging", I mean the light's housing. Street lights encounter rain, snow, and pigeon poop.

--
JHG

 

[venci]

drawoh

Thanks again for the information.

 

[1503-44]

Drawoh,

I think we know the difference between Light emitting diodes and laser emitting diodes..

 

[IRstuff]

LEDs, at the single diode level, typically have a 10 degree by 40 degree beam divergence. A cylindrical lens is needed to "square up" the beam, although the beam probably needs to be closer to 50 degrees or so

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

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[MacGyverS2000]

You are confusing LEDs and lasers.

No, I don't think he is... look at the context. Incandescent light bulbs, for example, radiate light equally in (essentially) all directions. LEDs, on the other hand, have built-in reflectors and optics that aim the light in one general direction... viewing angle may vary from 10-160 degrees, but it's still generally pushed along one main axis. I believe this is what 1503 meant...

Dan - Owner

http://www.Hi-TecDesigns.com

 

[1503-44]

Thanks Dan. All LightEDs start out emitting from a flat surface, no? Ssome do have wierd lenses on top to stick through a device casing, but the latest ones i've seen are pancakes. I wasn't thinking they're using those kinds on the phone chargers and my WiFi router. If so, don't.

The low profile ceiling lights these days don't have any reflectors behind the LEDs. At least nothing more than white colored plastic. I dont think the LED dental and surgical lamps have reflectors. Seems to be little benefit to be gained when all light is basically produced in the other direction. What is there to reflect?