Welcome to Laser Pointer Forums - discuss green laser pointers, blue laser pointers, and all types of lasers



Laser Pointer Store

Lasers for VFX

space

New member
Joined
Aug 8, 2011
Messages
5
Points
0
Hello,

I am new to lasers and don't really know much. I am a VFX supervisor and am interested in using lasers to create a grid of points on a green screen for film/visual effects purposes.

So far I have been using 5 mW green lasers with diffraction grating to give me the desired grid effect. My only problem with them is that the center point is nice and bright but the surrounding points in the grid start to fall off considerably. I need all the points in the grid to be slightly brighter and I was considering switching my lasers to 15 mW. Before I do that, however, I figured it would be smart to come to this forum and ask the experts.

Will a 15 mW laser with diffraction grating be safe to look at the projected grid without eye protection?

Thanks in advance!
 
Last edited:

Trevor

Well-known member
Joined
Jul 17, 2009
Messages
4,513
Points
113
As long as no one takes a direct eye it, it should be fine.

Is this for display purposes or for alignment or something?

-Trevor
 

space

New member
Joined
Aug 8, 2011
Messages
5
Points
0
Thanks for the quick response. This would be for tracking/alignment purposes on large green screens, instead of using velcro or tape "x" marks. The lasers are mounted on tripods, quick and easy to manipulate from shot to shot. No one is at risk of taking a direct eye hit, as the lasers are pointed directly at the screen. Foot traffic is kept to a minimum between the lasers and the screen. However, one of my animators was trying to convince me that a 15 mW laser with diffraction grating would still be too powerful to look at it's projected dot without eye protection, but I wanted to find out for sure.
 
Last edited:

Helios

New member
Joined
Jan 7, 2011
Messages
1,341
Points
0
Hold up

Where did you get the 5mW your using now?

Some will be way under rated. Ive bought 5mW greens on ebay that showed metered over 50mW. MOST of the cheap chinese "5mW" green pens will be over 5mW.
 

ShortyInCanada

New member
Joined
Mar 1, 2011
Messages
617
Points
0
Just to be clear though...
Using the diffraction grating will ALWAYS have the centre point brighter than the area surrounding it. So the most powerful part will be at the centre with the rest being less so as you go. The outer part will only be a percentage of the brightness. A higher power laser will exaggerate the effect. You could end up with a fairly dangerous intensity at the centre (but it still won't be full strength) while being harmless towards the edges.
You may have difficulties with cameras picking it up consistently across the whole frame.
 

Kevlar

New member
Joined
Apr 26, 2010
Messages
1,353
Points
0
Just to be clear though...
Using the diffraction grating will ALWAYS have the centre point brighter than the area surrounding it. So the most powerful part will be at the centre with the rest being less so as you go. The outer part will only be a percentage of the brightness. A higher power laser will exaggerate the effect. You could end up with a fairly dangerous intensity at the centre (but it still won't be full strength) while being harmless towards the edges.
You may have difficulties with cameras picking it up consistently across the whole frame.

This is why I was thinking a green only projector but I'm not sure how much money you are willing to invest in this.

I think by using a green only projector you could get the dots relatively the same brightness and be able to control the grid dimensions.
 

space

New member
Joined
Aug 8, 2011
Messages
5
Points
0
My lasers are from JasperLaser.com: Welcome!

The warning label on the laser pointer itself says max output power <5mW.

I realize that the grid will always have a falloff and that is ok. On the flip side I do not want a center that is too powerful, that would be bad. So maybe my solution is just to add more 5mW lasers instead of switching them out for 15's.

Could you please elaborate on the green only projector? I have no knowledge of it and it may be helpful.

Thanks ALL!
 

Trevor

Well-known member
Joined
Jul 17, 2009
Messages
4,513
Points
113
Conversely, you could just mount more than one module in such a way that you got a properly expanding (with increasing distance) grid.

-Trevor
 

jcranmer

New member
Joined
Mar 23, 2011
Messages
2,110
Points
0
All I can add to this, is that I must have a dirty mind, cause this pointer shape made me laugh. :D

JasperLaser.com: Welcome!



My lasers are from JasperLaser.com: Welcome!

The warning label on the laser pointer itself says max output power <5mW.

I realize that the grid will always have a falloff and that is ok. On the flip side I do not want a center that is too powerful, that would be bad. So maybe my solution is just to add more 5mW lasers instead of switching them out for 15's.

Could you please elaborate on the green only projector? I have no knowledge of it and it may be helpful.

Thanks ALL!
 

ARG

Well-known member
Joined
Feb 27, 2011
Messages
6,987
Points
113
My lasers are from JasperLaser.com: Welcome!

The warning label on the laser pointer itself says max output power <5mW.

I realize that the grid will always have a falloff and that is ok. On the flip side I do not want a center that is too powerful, that would be bad. So maybe my solution is just to add more 5mW lasers instead of switching them out for 15's.

Could you please elaborate on the green only projector? I have no knowledge of it and it may be helpful.

Thanks ALL!
You have a laser pointer at mirrors on motors called galvos One for X one for Y. Then you use software to control what the motors draw out. IE a grid. Unfortunately this is pretty costly and will take some time to put together.
 

Helios

New member
Joined
Jan 7, 2011
Messages
1,341
Points
0
My lasers are from JasperLaser.com: Welcome!

The warning label on the laser pointer itself says max output power <5mW.

I realize that the grid will always have a falloff and that is ok. On the flip side I do not want a center that is too powerful, that would be bad. So maybe my solution is just to add more 5mW lasers instead of switching them out for 15's.

Could you please elaborate on the green only projector? I have no knowledge of it and it may be helpful.

Thanks ALL!
That site does claim to tune their lasers between 4-5mW. Cheaper lasers are often labeled <5mW as you described but actually output a seemingly random power between 1 and 70mW.

As for the laser projector its basically a laser show scanner that you program to only display points. This will be hundreds of dollars even if you build it yourself with cheap parts. If your budget can allow it though the possibilities are infinite.

Here is a video just showing a laser scanner displaying images.
 
Last edited:

Kevlar

New member
Joined
Apr 26, 2010
Messages
1,353
Points
0
Could you please elaborate on the green only projector? I have no knowledge of it and it may be helpful.

ARGLaser's description is correct. Like I said, I'm not sure how much money you plan to spend but there are members that can build it for you. Maybe using pointers is OK for the short-term but this might be a better idea in the long run.

Most projectors are Red Blue and Green to give you millions of different hues but for your purpose just green would do and that would knock the price down a bit. Here is a video that might give you an idea of what a "green only" projector can do but one of our members Andycon


You would just program the software (which you would have to buy BTW) to project you dots at whatever distance away from each other you like.

Do some searches for laser projectors on Google, You Tube, etc... You'll get a better idea of how they are built, whats inside them, and the different software used to run them. Also check out www.photonlexicon.com. Their forum is devoted mainly to projectors.

EDIT: I believe this is Andycon's site. If you contact him, he can probably give you an idea of how much it would cost to build you a projector. http://www.laser-man.co.uk/guides/58-building-a-laser-scanner.html. Even if you don't contact him, it's a great resource for information.
 
Last edited:

ARG

Well-known member
Joined
Feb 27, 2011
Messages
6,987
Points
113
Well, if you want to go low budget you could get some PT-20K's for 114$. A 15mW 532nm TTL laser for 50$. Not sure if Spaghetti still has it's 20$ sale, but if not LFI player could work. Then just draw a grid with monkey tools. A DAC will cost around 150$ (cheaper if you build a sound card DAC). Case/accessories will probably cost around 50$ if you shop right.

So about 350$ give or take 50$ if you choose to go with a projector, that is if you make it which will take heaps of time in planning/construction. It will cost lots more if you get a member to make it for you.

Probably best to stick to the diffraction grating :)
 
Last edited:

rhd

New member
Joined
Dec 7, 2010
Messages
8,492
Points
0
This might be blasphemous to suggest.... but why not buy a Casio projector, and use it... as a projector?

IE, retain it's normal function as a data projector and just project a grid of green dots?

EDIT: I feel ok about name dropping the manufacturer since, after all, I'm suggesting that you buy it and use it as per the manufacturer's intended use :)
 
Last edited:

ARG

Well-known member
Joined
Feb 27, 2011
Messages
6,987
Points
113
This might be blasphemous to suggest.... but why not buy a Casio projector, and use it... as a projector?

IE, retain it's normal function as a data projector and just project a grid of green dots?

EDIT: I feel ok about name dropping the manufacturer since, after all, I'm suggesting that you buy it and use it as per the manufacturer's intended use :)
A projector being used as a projector? :eek:

In all seriousness though, that is a great idea.
 

Kevlar

New member
Joined
Apr 26, 2010
Messages
1,353
Points
0
@RHD. Not a bad idea. Then if he ever leaves the filming business he he could use it to watch tv (although I've heard the picture isn't that great) or sell it to someone here who could use it for... uhh... watching tv! Lol
 




Top