Help needed to create a curtain of light

Forums › Gadgets, robotics, home automation, electronics (including wearables) › Help needed to create a curtain of light

NZVengeance

134 posts

Master Geek

#175863 14-Jul-2015 11:15

I am trying to find a way to create a curtain/wall of light without having to have the light sit inside a rigid surface.

Essentially I want a circle 8-10" in diameter and around its circumference I want a solid beam of light that will travel at most 18-24"

Think kind of like a force field of visible light without of obvious force field bit.

I have been hunting around on the internet and started looking at L.E.Ds and Lasers and thought I might try on here in case someone has had experience with light shaping etc.

Ive attached a cheezy UFO image to give you the idea im talking about with the light (best representation I could find)

timmmay

20575 posts

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#1342918 14-Jul-2015 11:32

Can you give more context about why and what you're trying to achieve? Also why the limitation of no fixed cover / guide?

macuser

2120 posts

Uber Geek

#1342919 14-Jul-2015 11:35

Basically what you need to do is recess the light source behind a cylinder lined with a reflective surface.

The light source would be placed inside a dish that it reflects most light straight down in one direction, then the cylinder will help focus the light...

A bit will spill as it bounces down the tube...you could make the tube inner black velvet to prevent it reflecting but you would lose too much light.

You also need to add some smoke to the environment , so that the beam will be pronounced and reflected off the smoke particles

If you want to ensure the light is even more straight you can insert a honeycomb grid at the exit point so any light heading sideways gets knocked out (pictured below)

Beam

wellygary

8312 posts

Uber Geek

#1342926 14-Jul-2015 11:43

basically you want a theatre follow spot....

NZVengeance

134 posts

Master Geek

#1342948 14-Jul-2015 12:13

Actually Yes, A miniaturized theatre followspot that is 8-10" in diameter and only a max of 2-3" deep which has to project the light 18-14"

Edit: and L.E.D since it will be around plastics and I dont want a halogen to melt the plastic

jurgensp99

68 posts

Master Geek

#1342987 14-Jul-2015 13:27

wellygary: basically you want a theatre follow spot....

This will work however seeing the throw distance is only 24" or +-600mm a followspot may be overkill.

More info is required eg how bright does it need to be, what colour temp, fixture size restrictions etc.

Am happy to help out.

jurgensp99

68 posts

Master Geek

#1342994 14-Jul-2015 13:36

NZVengeance: Actually Yes, A miniaturized theatre followspot that is 8-10" in diameter and only a max of 2-3" deep which has to project the light 18-14"

Edit: and L.E.D since it will be around plastics and I don't want a halogen to melt the plastic

That is very shallow. The only way to get a hard edge beam is to put the source behind two lenses and focus them to a point like a followspot. Some depth is required to fit all of this in.

We can scale all of it down to something like a profile fixture eg Selecon pacific with a narrow zoom lense. These run on 1000w lamps.

Even smaller would be a ETC Source 4 mini LED

NZVengeance

134 posts

Master Geek

#1342995 14-Jul-2015 13:36

So the light needs to wholly bit inside a cylinder that is 74mm high and 2500 in diameter

Colour either Blue (9,000-10,000 Kelvin) or Red (1,000-1,1500 Kelvin) Being able to switch between the two would be cool.

Brightness I am undecided (perhaps 250+ lumens so that the brightness is maintained across the beam distance)

Edit: saw your reply I could make it taller. Like 5" but that would be at the outside.

Also the light cant produce any real heat as it will be around plastic models.

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NZVengeance

134 posts

Master Geek

#1343021 14-Jul-2015 13:54

The problem with the ETC Source 4 mini LED is that it is 9" deep at only 2.5" in diameter

jurgensp99

68 posts

Master Geek

#1343028 14-Jul-2015 14:06

NZVengeance: So the light needs to wholly bit inside a cylinder that is 74mm high and 2500 in diameter

Colour either Blue (9,000-10,000 Kelvin) or Red (1,000-1,1500 Kelvin) Being able to switch between the two would be cool.

Brightness I am undecided (perhaps 250+ lumens so that the brightness is maintained across the beam distance)

Edit: saw your reply I could make it taller. Like 5" but that would be at the outside. Also the light cant produce any real heat as it will be around plastic models.

How about a LED MR16 lamp in warm white with a narrow beam angle. Try to get single a source lamp as multi source will cast multi shadows. Fashion a snoot from some black wrap and put colour gell on the front.
You could step it up to an RGB MR16 but that would require allot more drive gear/controllers.

Additionally to this you'll need some haze in order to see the beam in the air.

Edit:
Am I thinking in the right direction here or are you looking for a parallel beam rather than a cone shape?

NZVengeance

134 posts

Master Geek

#1343031 14-Jul-2015 14:13

That could work, Ive also just been reading this and wondering how hard it would be to focus the light using a couple of lenses like the ones from here.

frankv

5680 posts

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#1343050 14-Jul-2015 14:38

I think the shape of the reflector around the light source is most important. A good reflector would mean you wouldn't need a tube. From my 5th Form Physics, if the reflector is parabolic, with the (infinitely small) light source at the focus, then all light rays come out parallel. Presumably some other shape near to a parabola would give a conic beam of light as per your image rather than just parallel. Probably any torch reflector would more or less approximate this.

To get around the height limitation, could you put the reflector + LED + tube thing in macuser's diagram horizontally, and then use a 45 degree flat mirror to shine the beam downwards? With a bit of knowledge and maths, you could probably design a non-flat mirror to shape the beam, but that's beyond me.

Do you really want a round spotlight? How about some crosshairs? That would be much easier with two line-beam lasers (http://www.aliexpress.com/item/650nm-5mW-Red-Laser-Line-Module-Focus-Adjustable-Laser-Head-5V-good/1989170400.html) mounted vertically at right angles to each other. Or if you had one line-beam laser and spun it fast, it would appear to the eye to be a circle.

Can you make the cone out of perspex or similar? Or does it need to be in the open air? As others have said, if it's open air then you need a fog machine or similar to make the beam visible. Shining LEDs into the edge of a perspex sheet makes the perspex glow.

NZVengeance

134 posts

Master Geek

#1343064 14-Jul-2015 14:42

It needs to be open air which makes it harder and I don't know how practical it will be to try and get smoke in around it.

That line laser is cool and will work for another task but not this one

NZVengeance

134 posts

Master Geek

#1343075 14-Jul-2015 14:55

Perhaps not the perfect example but here is something from a movie where two people are being lifted up in a beam of light like some kind of tractorbeam / gravity elevator.

This is the effect I'm trying to create.