Shape of a reflector for perfect flood?

[malow]

anyone know that? the shape of a reflector for a light beam be a perfect flood? i mean, no brighter spot on center, no dim light on sides, with no lens, only bare led + reflector.

led is a Seoul P4, it have a wide light angle, but of course, center light is stronger.

 

[was.lost.but.now.found]

anyone know that? the shape of a reflector for a light beam be a perfect flood? i mean, no brighter spot on center, no dim light on sides, with no lens, only bare led + reflector.

led is a Seoul P4, it have a wide light angle, but of course, center light is stronger.

I don't build flashlights and have no experience with that, but I'm an analyst for a living so I'll take your question from that perspective and see what I can come up with.

With "perfect" flood as you say, you would want completely even light from side to side. The easiest way I can see to do that is with a diffuser film like Desertrat21 employed on his TK30.

But to think about it from just the reflector standpoint, you have to either reduce the amount of light going to what is currently the hotspot, or increase the amount going to what is currently the spill and flood area. There are a number of ways you could block or re-direct light from the hotspot to the remainder of the spill, but I don't think they would be very efficient. The only way I can imagine to do it efficiently is to have a lens like Coast employs on their lights.

I think the diffuser film is really the best option for what you seem to want.

 

[ltiu]

Is this post in the wrong forum ?

 

[qwertyydude]

It's not just the shape of the reflector it's also the led's positioning inside it. to get maximum flood light out the front with only a reflector simply raise the led higher than the focal point and it defocuses the light. If you want a smooth flood without rings you'll still need heavy orange peeling on the reflector.

 

[malow]

yup, i posted in the wrong section. noobs...

im gonna build a light for a video camera, so, it need to be uniform.

current reflector on a halogen lamp, its in a "V" format, and light is in the middle. light is very uniform.

but led does not have a round 360° light, so, im thinking in test with tinfoil to find a shape/distant/position to do that... :duh2:

 

[NutSAK]

For a "perfect" flood, I would think you wouldn't want a reflector at all.

Take a look at the Zebralight headlamps, for example.

 

[vtunderground]

You need a conical reflector.

The best available option is the Carclo "wide angle" reflector. They can be a little hard to find, but I believe Cutter has them in stock. I believe that you'll need the 20mm optic holder too.

http://www.candlepowerforums.com/vb/showthread.php?t=185217&page=2

Scroll down to post # 43 for a beamshot.



edit: Here you go... http://www.cutter.com.au/proddetail.php?prod=cut884

 

[Tomcat!]

For a "perfect" flood, I would think you wouldn't want a reflector at all.

Take a look at the Zebralight headlamps, for example.

+1. That's the whole point of a ZeebLight.

For a perfect disc of diffuse light from a reflectored torch, just remove the reflector. I do that a lot when I want pure flood from my Jet III Pro-ST and a LED upgraded Mini-Mag for close up continuous work.

 

[rmteo]

+1. That's the whole point of a ZeebLight.

For a perfect disc of diffuse light from a reflectored torch, just remove the reflector. I do that a lot when I want pure flood from my Jet III Pro-ST and a LED upgraded Mini-Mag for close up continuous work.

Not quite - and stated by the OP in his first post. Here is a graph of the spatial distribution of a typical LED (Cree XRE, 90 degree FWHM viewing angle). Notice that the luminous intensity is 100% at 0 degrees (head on), tapers to 60% at 40 degrees and is only 20% at about 55 degrees off center.

 

[Tobias Bossert]

anyone know that? the shape of a reflector for a light beam be a perfect flood? i mean, no brighter spot on center, no dim light on sides, with no lens, only bare led + reflector.

led is a Seoul P4, it have a wide light angle, but of course, center light is stronger.

It depends strongly upon what you define a 'perfect flood'.

If you are standing in front of a plain wall and wish a homogeneous brightnes of that wall, you will need a light with a non-uniform spatial pattern. The point in front of you is nearest to you and thus you will need the lowest candella value direct in front of you.
The smooth conical reflector Carclo 10170 does this job very well with SSC-P4 or with other lambertian leds. Those reflectors ar good for lights in the ceiling, because they deliver a constant illumination at the floor.

The differece between flat pattern illuminating a plane wall and a flat spatial pattern is demonstrated here:

http://www.candlepowerforums.com/vb/showpost.php?p=2791872&postcount=103

I'm not sure what will be suitable for your application, flat with respect to a plane object or flat with respect to angular pattern.

 

[asdalton]

Given that an LED emitter is a 2-dimensional die that projects a smaller viewable area as the viewing angle away from the center increases, I suspect that a "perfect flood" as defined by the OP is not possible.

 

[rmteo]

Although it may seem counter intuitive, using a reflector (as pointed out by vtunderground and Bossert) such as the one shown below, is the best solution for very wide beams (up to 80 degrees FWHM).

 

[divine]

Have you seen beamshots of a Zebralight headlamp?

http://www.candlepowerforums.com/vb/showthread.php?t=194427

 

[rmteo]

Have you seen beamshots of a Zebralight headlamp?

http://www.candlepowerforums.com/vb/showthread.php?t=194427

Yes.

 

[bluepilgrim]

This gets into things above my pay grade, but see http://www.led-replacement.com/faq.html and lambertian vs side emitting leds (two terms to explore) ... in other words, it's not just the reflector but the the nature of the led used.

 

[gcbryan]

The use of a diffuser is probably the quickest and easiest way.

I have a 10W HID (UK Light Cannon). It comes with a diffusion screen for use with video. Basically, when used the hot spot just disappears.

 

[rmteo]

I have found a better way to achieve very wide angle (up to 130 degrees), even illumination using these 20mm. optics.

 

[Gunner12]

I was also thinking that a wide angle optic will do the task.

Now to find one for the Seoul P4.

Edit: Just realized that the optic posted above will also work with the P4.

 

[DM51]

Interesting thread. I wonder if that ultra-wide-angle optic is similar to the one McGizmo uses in the SunDrop.

 

[Th232]

Fairly different, the lens Don uses in the Sundrop is a plano-convex lens, not a TIR. Gotta say though that the output looks very similar though.