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  Simulating a *visible* laser beam (Message 1 to 7 of 7)  
From: INVALID ADDRESS
Subject: Simulating a *visible* laser beam
Date: 10 Feb 2008 01:55:00
Message: <web.47ae9f01e7ebe4ed140a26e60@news.povray.org>
I'm an Optics guy. I have a hard time getting a "visible" light beam from
POVRay.
I would like to generate a beam (e.g. spot light source) which can be visible
and directed towards an object or lens.

I have enabled photons mapping and stuff for the light source and objects, but
the beam is only visible when it hits the object. It's not visible in air or
the background.

How can I simulate a laser beam? Can anybody point me to the right resources
(tutorials, example pov files, etc...)?

I would like to illustrate simple concepts like reflection, refractio,
diffraction on lenses and some other optical objects. But I need to actually
control the beam size and see it. I don't want a *virtual* light source. Thanks
for any help.


--
Cheers,
Peter "Excalibur"


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From: Simon
Subject: Re: Simulating a *visible* laser beam
Date: 10 Feb 2008 06:43:27
Message: <47aee35f$1@news.povray.org>
"Peter" wrote:
> I'm an Optics guy. I have a hard time getting a "visible" light beam from
> POVRay.
> I would like to generate a beam (e.g. spot light source) which can be visible
> and directed towards an object or lens.
> 
> I have enabled photons mapping and stuff for the light source and objects, but
> the beam is only visible when it hits the object. It's not visible in air or
> the background.
> 
> How can I simulate a laser beam? Can anybody point me to the right resources
> (tutorials, example pov files, etc...)?
> 
> I would like to illustrate simple concepts like reflection, refractio,
> diffraction on lenses and some other optical objects. But I need to actually
> control the beam size and see it. I don't want a *virtual* light source. Thanks
> for any help.
> 
> 
> --
> Cheers,
> Peter "Excalibur"
> 
> 
Have a look at the "Optics.pov" scene. What you'll need is media which 
the light can pass through (like dusty air), the light/laser will then 
highlight the media, making it see "visible" just like IRL

You should get something like this : 
http://www.soware.co.uk/POVRay/player.php?id=11

(but obviously without the jitter due to me animating the media at too 
low a quality

Regards,

Simon


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From: Blue Herring
Subject: Re: Simulating a *visible* laser beam
Date: 10 Feb 2008 11:05:01
Message: <web.47af1f65c0351d35b05f96f70@news.povray.org>
"Peter wrote:
> I'm an Optics guy. I have a hard time getting a "visible" light beam from
> POVRay.
> I would like to generate a beam (e.g. spot light source) which can be visible
> and directed towards an object or lens.
>
> I have enabled photons mapping and stuff for the light source and objects, but
> the beam is only visible when it hits the object. It's not visible in air or
> the background.
>
> How can I simulate a laser beam? Can anybody point me to the right resources
> (tutorials, example pov files, etc...)?
>
> I would like to illustrate simple concepts like reflection, refractio,
> diffraction on lenses and some other optical objects. But I need to actually
> control the beam size and see it. I don't want a *virtual* light source. Thanks
> for any help.

I was playing with this a bit recently, with some frustration.  You might want
to check out the examples and tutorials on http://weblog.sitewww.ch/ as well.
He starts showing visible beams of light passing through lenses and off mirrors
in various combinations on page 10, though its probably useful to read the pages
leading up to it.

My frustration stemmed from getting a reflected beam to be visible after being
reflected.  The beam showed in the scattering media until it hit the mirror,
and the light showed reflective caustics on a target, but the beam wasn't
visible between the mirror and the target.

Eventually I found I needed to turn up the media parameter of the photons, and
significantly turn up the samples of the media to see anything.

I'll post the test scene I got some basic results from in p.t.s-f in case its
helpful.

-The Mildly Infamous Blue Herring


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From: Blue Herring
Subject: Re: Simulating a *visible* laser beam
Date: 10 Feb 2008 11:25:00
Message: <web.47af24dec0351d35b05f96f70@news.povray.org>
"Blue Herring" <bhe### [at] tinfoilcatcom> wrote:
> I'll post the test scene I got some basic results from in p.t.s-f in case its
> helpful.

Scene file:
http://news.povray.org/web.47af219494e592ceb05f96f70%40news.povray.org

Image: http://news.povray.org/web.47af23af94e592ceb05f96f70%40news.povray.org


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From: John VanSickle
Subject: Re: Simulating a *visible* laser beam
Date: 10 Feb 2008 13:00:06
Message: <47af3ba6$1@news.povray.org>
"Peter" wrote:
> I'm an Optics guy. I have a hard time getting a "visible" light beam from
> POVRay.
> I would like to generate a beam (e.g. spot light source) which can be visible
> and directed towards an object or lens.
> 
> I have enabled photons mapping and stuff for the light source and objects, but
> the beam is only visible when it hits the object. It's not visible in air or
> the background.
> 
> How can I simulate a laser beam? Can anybody point me to the right resources
> (tutorials, example pov files, etc...)?

cylinder {
   StartPoint,EndPoint,Radius hollow
   texture {
     pigment { rgbt 1 }
   }
   interior {
     media { emission LaserBrightness absorption LaserBrightness }
   }
}

Regards,
John


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From: INVALID ADDRESS
Subject: Re: Simulating a *visible* laser beam
Date: 10 Feb 2008 15:35:01
Message: <web.47af5f02c0351d35140a26e60@news.povray.org>
Thanks to Blue Herring an Simon. I'll look into those.


John VanSickle <evi### [at] hotmailcom> wrote:
*snip
> cylinder {
>    StartPoint,EndPoint,Radius hollow
>    texture {
>      pigment { rgbt 1 }
>    }
>    interior {
>      media { emission LaserBrightness absorption LaserBrightness }
>    }
> }
>


Thanks for the reply John, but this is not what I had in mind. I actually want a
real "light_source" to act as a laser as I want to have some realistic
refraction/reflection or dispersion effects.

But if I use a basic cylinder, then it's not meaningful if let's say I redirect
it to a lens. It won't have the same effect as a real light beam


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From: Eric Freeman
Subject: Re: Simulating a *visible* laser beam
Date: 1 Mar 2008 06:38:59
Message: <47c94053$1@news.povray.org>
<Peter> wrote in message 
news:web.47ae9f01e7ebe4ed140a26e60@news.povray.org...
> I'm an Optics guy. I have a hard time getting a "visible" light beam from
> POVRay.
> I would like to generate a beam (e.g. spot light source) which can be 
> visible
> and directed towards an object or lens.
>
> I have enabled photons mapping and stuff for the light source and objects, 
> but
> the beam is only visible when it hits the object. It's not visible in air 
> or
> the background.
>
> How can I simulate a laser beam? Can anybody point me to the right 
> resources
> (tutorials, example pov files, etc...)?
>
> I would like to illustrate simple concepts like reflection, refractio,
> diffraction on lenses and some other optical objects. But I need to 
> actually
> control the beam size and see it. I don't want a *virtual* light source. 
> Thanks
> for any help.
>
>
> --
> Cheers,
> Peter "Excalibur"

There's a scene I made a long time ago. It doesn't work with POV v. 3.7, but 
works with versions 3.5 and 3.6.

It's not a true laser. Basically, a light source is placed a long way from 
the scene (999,900 units, in this case) and the scene is in a box with a 
hole in the wall for the "laser" to enter the scene. A media-filled box 
allows the laser to be seen. I'll post the image that this scene file 
produces in .binaries.images. The code is a bit on the spaghetti-ish side, 
and it's been a long time since I wrote it, so I'm not real familiar with 
the specifics of it anymore. Feel free to cut-and-paste the parts you need. 
Hope it helps.

I've posted the POV file in pov.text.scene-files and the resulting image in 
pov.binaries.images

Eric


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