Laser pointer discussion. Read/write reviews of laser pointers and laser pointer companies. Learn about all types of laser pointers and lasers

 Welcome to Laser Pointer Forums! If you are looking for a laser pointer or want to compare different laser pointer companies, you may want to check out the LPF Laser Pointer Company Database. The link will open in a new window for your convenience.

One laser store meets all your needs

 Laser Pointer Forums - Discuss Laser Pointers Spreading beams and power
 User Name Remember Me? Password

Menu

LPF List of Laser Pointer Companies (link opens new window)

08-27-2008, 04:45 PM #1
 Member Join Date: Jul 2008 Posts: 35 Rep Power: 0
Mille
Member

Join Date: Jul 2008
Posts: 35
Rep Power: 0
Spreading beams and power

I was wondering if there are a formula (or more than one) to calculate the exact amount of power of a beam that is spread in circle.
For example i make a &quot;tunnel&quot; with a rotating mirror with a 100Mw green laser. How can i calculate the power of a single spot on the projected circle?
Or a single spot if i make a line beam?
I think know it would be very useful about safety especially in laser shows.

LPF List of Laser Pointer Companies (link opens new window)

08-27-2008, 05:09 PM #2
 Super Moderator Join Date: Mar 2008 Location: Sunny Southern California Posts: 16,636 Rep Power: 1877
daguin
Super Moderator

Join Date: Mar 2008
Location: Sunny Southern California
Posts: 16,636
Rep Power: 1877
Re: Spreading beams and power

Quote:
 Originally Posted by Mille I was wondering if there are a formula (or more than one) to calculate the exact amount of power of a beam that is spread in circle. For example i make a "tunnel" with a rotating mirror with a 100Mw green laser. How can i calculate the power of a single spot on the projected circle? Or a single spot if i make a line beam? I think know it would be very useful about safety especially in laser shows.
When making &quot;tunnels&quot; or simply scanning multiple &quot;stops,&quot; or waving the beam back and forth to create a &quot;line&quot;, you are NOT SPLITTING the beam. You are simply moving it around. It retains the full power at any point in the shape.

Peace,
dave
__________________
How To Get Along In and Be Accepted in the Forum

If you got some value out of reading this forum, how about donating \$2 to keep it going?
Click Here to donate

Love all, trust a few, do wrong to none.
-William Shakespeare

08-27-2008, 05:35 PM #3
 Member Join Date: Jul 2008 Posts: 35 Rep Power: 0
Mille
Member

Join Date: Jul 2008
Posts: 35
Rep Power: 0
Re: Spreading beams and power

Ok, if the beam is currently reflected around (in tunnel) it will stop in the same spot less time than a &quot;single still&quot; beam, right?
So the power in that spot gotta be less, or im wrong?

08-27-2008, 05:39 PM #4
 Class 3R Laser Join Date: Jul 2008 Location: Eugene OR Posts: 1,415 Rep Power: 92
thesk8nmidget
Class 3R Laser

Join Date: Jul 2008
Location: Eugene OR
Posts: 1,415
Rep Power: 92
Re: Spreading beams and power

yep... the beam keeps full power unless its being modulated. which wouldnt be the case unless its in a projector

__________________
-Josh

08-27-2008, 05:41 PM #5
 Class 3R Laser Join Date: Jul 2008 Location: Eugene OR Posts: 1,415 Rep Power: 92
thesk8nmidget
Class 3R Laser

Join Date: Jul 2008
Location: Eugene OR
Posts: 1,415
Rep Power: 92
Re: Spreading beams and power

Quote:
 Originally Posted by Mille Ok, if the beam is currently reflected around (in tunnel) it will stop in the same spot less time than a "single still" beam, right? So the power in that spot gotta be less, or im wrong?

no the beam will have the same power through the whole tunnel..

you gotta think if you move the laser in a circle or anywhere every spot that it hits will have been at the same power as before. but since it is moving it wont have to to say burn or heat up the spot because its only getting that full power for a small amount of time.
__________________
-Josh

08-27-2008, 05:50 PM #6
 Member Join Date: Jul 2008 Posts: 35 Rep Power: 0
Mille
Member

Join Date: Jul 2008
Posts: 35
Rep Power: 0
Re: Spreading beams and power

Yes i was talking about average power, like W/s or something similar.
Is average or instant power that count in laser safety?
And coming back to first question: is there some formula to calculate the average power of a single spot in a circle or line?

08-27-2008, 06:03 PM #7
 Class 3R Laser Join Date: Aug 2007 Posts: 2,045 Rep Power: 239
pullbangdead
Class 3R Laser

Join Date: Aug 2007
Posts: 2,045
Rep Power: 239
Re: Spreading beams and power

Power is always energy per time, J/s, aka W. *If it's moving, you get less energy into one spot because of the shorter time, but the power (energy per time) will still be the same. *What you're looking for is energy. *

As far as safety, it's both. *It's how much energy you put into a spot on your eye. *The energy input is what damages cells. *But with higher powered lasers, the time it's on a spot on your eye may be very short, but the energy imparted could still very easily be enough to hurt your eye.

As far as average power vs. peak instantaneous power: *The peak instantaneous power will the the power of the laser. *The average power will be the fraction of the time the laser spends on that spot multiplied by the power of the laser. *Say: 100mW laser spends 1% of the time on a particular spot, average power is 1mw. *But, peak instantaneous power is still 100mW, and that is still very damaging. *For what you're asking, I think you should be more worried about the peak instantaneous than the average over time, because that peak can do damage where that average over time may not.

For example, let's say I use a 250mW laser for one minute a day. *Over the course of a day, that's .06% of the day. *That means the average laser power over the day would be .17mW. *That average power, while still low enough to look safe, doesn't imply that using the laser for only one minute a day is still safe because the average is lower, especially since a 250mW can do damage in a shorter time than the blink of an eye. *The peak instantaneous power of the laser would do damage, even though the average power is very low.

At least I think it answers the question you are asking. Every situation is different though. You're asking about short flashes of a higher-powered laser. Another situation may be about very long exposures to dim laser light, like 5mW constantly all day in a lab, and that would call for a different evaluation of what to check for. But this stuff has all been looked at, there are standards/guidelines to go by for safety glasses for what is good enough for short flashes of light, and what is good enough for all-day exposure to laser light. FrothyChimp could contribute a lot more about such things.

08-27-2008, 10:19 PM #8
 Member Join Date: Jul 2008 Posts: 35 Rep Power: 0
Mille
Member

Join Date: Jul 2008
Posts: 35
Rep Power: 0
Re: Spreading beams and power

So, how expert people in laser show can calculate if a combination of fat beams scanning the audience can be dangerous or not?
This is my final point
There are restrictions in law about scanning audience, but how can be sure to be under the threshold?

09-02-2008, 12:34 PM #9
 Class 3R Laser Join Date: Jun 2007 Posts: 1,636 Rep Power: 14605
steve001
Class 3R Laser

Join Date: Jun 2007
Posts: 1,636
Rep Power: 14605
Re: Spreading beams and power

Quote:
 Originally Posted by Mille So, how expert people in laser show can calculate if a combination of fat beams scanning the audience can be dangerous or not? This is my final point There are restrictions in law about scanning audience, but how can be sure to be under the threshold?

looky here free software http://www.laservisuals.com/sglite.htm

09-02-2008, 02:46 PM #10
 Class 3R Laser Join Date: Jul 2008 Location: Eugene OR Posts: 1,415 Rep Power: 92
thesk8nmidget
Class 3R Laser

Join Date: Jul 2008
Location: Eugene OR
Posts: 1,415
Rep Power: 92
Re: Spreading beams and power

software itself will not make you know how safe it can be.. you need a lot of practice and a lot of knowledge! audience scanning is not an easy thing to make safe... but here are a few links

http://www.pangolin.com/resguide09a.htm

http://www.pangolin.com/resguide09b.htm
__________________
-Josh

09-03-2008, 04:57 PM #11
 Member Join Date: Jul 2008 Posts: 35 Rep Power: 0
Mille
Member

Join Date: Jul 2008
Posts: 35
Rep Power: 0
Re: Spreading beams and power

Yes yes i know.
I don't really look to do scanning audience, im just curious about safety systems.
Is better to know about it that don't

 Thread Tools Display Modes Linear Mode

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

Loading

Privacy Policy | Advertising Disclaimer | Terms of Use

All times are GMT. The time now is 05:45 PM.

 -- DarkShadows V5 -- Responsive LPF -2562016 -- Default Style Contact Us - Laser Pointer Forums - Archive - Top

Powered by: vBulletin
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO
Privacy Policy | Advertising Disclaimer | Terms of Use
Copyright (C) 2017 Laser Pointer Forums, LLC