Nonstandard LED placement: facing inwards

Hi!
From what I've seen so far, most lightasabers use either 1 or 3 high-powered LEDs facing down the direction of the blade. While my own saber currently only exists in the design stage, I've been thinking about placing a rim of less powerful LEDs facing inwards, with a reflector in the center/focus. Theoretically it should give me a more evenly lit blade and more flexibility for different shimmer and light up effects, as well as better heat management. Does anyone here have any type of LED in mind for this kind of project?

something like this maybe? https://www.adafruit.com/product/1222

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Originally Posted by Cern

something like this maybe? https://www.adafruit.com/product/1222

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Sorry if it wasn't clear the first time, I'm asking about the LEDs themselves, not controllers or drivers.

A "reflector" in the middle of the blade? Wires going up the length of the blade? Even if your theory did yield more even light, wouldn't those oddities kinda make for a fruitless effort?

Why not just do a neopixel build?

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Originally Posted by darth_chasm

A "reflector" in the middle of the blade? Wires going up the length of the blade? Even if your theory did yield more even light, wouldn't those oddities kinda make for a fruitless effort?

Why not just do a neopixel build?

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The reflector is located fully inside the hilt. Nothing goes into the blade itself.

something like this?

something like this but smaller then?

https://www.aliexpress.com/item/WJ-6...012231215.html

Welcome to the Forums.

I think your “premise” is wrong. Amongst other things, the heatsink you’d need will block a lot of the light you think you’ll get.

I don't think you are explaining your concept clearly enough. Even a rough diagram may help illustrate what you are thinking. I think everyone here is imagining a different arrangement. I originally thought you meant to put LEDs at both ends of the blades with a reflector in the middle.

Do you mean something more like this?
https://i.imgur.com/HCIZVr3.png

Sorry for the long wait, forum stopped notifying me for some reason.
I meant something like this (reflector shape not final):
Attachment 17570

Thanks by the way, FJK.
Also, I'm not adding an extra heatsink here. The heat is drained straight into the emitter.

Heat is drained directly into the emitter? What kind of LEDs do you think you’re going to be using on this?

I'm thinking about some flatter (not cylindrical) LEDs, I believe some of the more powerful models have the heatsink on the bottom. But again, "what kind of LEDs" was my question here. I'd probably want to go with RGBs, but I'm not certain here. Again, most builds use either one really strong LED or a up to 3 weaker ones. A lot depends on the LED choice. The directional diagram is one of tha factors that you will determine the shape of my reflector.

I think you will find this isn't as efficient as you hope. The light won't be as directional and using weaker LEDs will just make it worse. 6 LEDs do not produce 6 times the apparent brightness that 1 does, so using more won't make up for that fact. (6 LEDs will be somewhat less brighter than 3 times the brightness of one) The design will also waste some of the light through absorption.

This arrangement will produce a more diffuse light, but that is not desirable in this application, a focused beam makes more efficient use of the light.

It is possible to use the mass of the hilt as a heatsink, but an LED worth using will require a heatsink. Using an array like this the surface of the saber will get very hot and may not be able to dissipate the heat fast enough. If your LEDs aren't producing this kind of heat, they won't be making enough light to effectively illuminate your saber.

In any case, experimentation is fun and interesting even when it doesn't produce a desired result. if you go forward with it, please share the results!

Why exactly do I want a directional light? I want to illuminate the whole blade, not just the tip, or am I missing something?
How exactly does "apparent brightness" affect anything, if we are not looking directly at the LEDs themselves?
About heat, I don't really see how a heatsink inside the hilt is any better than one on the surface.

Yes you are missing quite a bit. You asked questions about topics it seems you don't grasp very well and we are trying to provide informed answers.

You want a focused beam to maintain it's intensity. This is why the headlights in a car are focused and not just providing ambient light. Any light shining out through the side it won't make it to the tip, if most of your light ends up shining out of the sides, then the end of the blade will be dimmer still. Typically there is a mirror in the tip to help reflect some of the light back down. As it is, the end of the blade is already notably dimmer, if not to the naked eye than it is very obvious to a camera at any exposure level.

Apparent brightness is what your eyes see, it's not a made up term, it's how bright your blade will look. The brightness is logarithmic. A sunny day is 100,000+ lux and a rainy day could be 5, but your eyes don't see this as 20,000+ times different.

As for the heat, it's thermodynamics. If you don't have enough mass to dump it, and you can't get rid of it fast enough your LEDs will burn out. The heatsink has a mass that can absorb the heat and radiate into the walls of the saber. If you eliminate the heatsink and add more LEDs then you are going to make it harder to get rid of the heat.

That is why more, weaker LEDs aren't going to give you a brighter blade, and they will die an early death.

There are many threads on this topic talking about how to properly diffuse and build a blade. I recommend reading a few of these so you can have a better idea of how we typically build blades. There are also many excellent videos on YouTube.

Don't get me wrong, but I'm sure that a car's headlights and a lightsaber's blade lights serve a fairly different purpose,the first having to illuminate everything to a certain distance and the other needs to illuminate an object of a certain shape.
I know about the logarithmic scale of brightness, but I still think that it's equally possible to light the blade uniformly either way. "Apparent brightness" from my experience (and a few extra sources I just read after your answer) has to do with the size and distance to an object. In our case the object is the blade and no matter how many LEDs are there, it's apparent brightness is going to depend on how they're directed, not on the amount of LEDs that brightness is distributed between.

As per heatsinks, there is a reason why a 10-ribbed radiator is a better heatsink than a block of aluminium of 3 tea the mass. The purpose of the heatsink isn't to store maximum amount of heat, it is to radiate that heat into the outside as efficiently as possible.

I will go ahead and follow your advice, lokking for blade building threads, thank you.

They may serve different purposes, but the theory is basically the same, a “focused” beam of light.

And while I don’t discourage people from experimenting, I will state this: “theory” is way different from “practical application”. People in this hobby have been experimenting and making technological advances for all the years this hobby has been around. “The Pros” use the technology which is the best balance of power use, light output, etc. and that’s not going to change. And though it’s not commonly known, even the LED manufacturers have been following along with what has been going on in this hobby over the past several years.

Well since I did decide to go with the experiment, here's one question. Is it worth going with RGB or better to start with single-color LEDs? I'd like the flexibility Of RGBs, sure, but I see that these are harder to find.

No, I don’t think so. You’ll learn your lesson with single color LEDs