Old 10-13-2013, 06:32 AM #1
Junior Member
 
Join Date: Dec 2012
Posts: 15
Rep Power: 0
Mrnewbie is on a distinguished road
Mrnewbie Mrnewbie is offline
Junior Member
 
Join Date: Dec 2012
Posts: 15
Rep Power: 0
Mrnewbie is on a distinguished road
Default How the heck does it work?

We all know that Lasers are dangerous gadgets. So I have a hypothetical question on how it all works.

If we all go back to when we were kids with a magnifying glass, we know the light beem has to be focused pinpoint beam to burn that ant!

We know a 100mw laser when pinpoint focused is more than capable of burning black tape or to cause injure the human eye.

If one had a 100mw laser..but focused to a 120inch beam at 100ft, would it be dangerous to look at from 100ft?

My way of thinking is something like this. Not taking beam signal distance losses into account

100mw/120in=.833mw per inch

I'm thinking the human eyes ..about 1 in wide would only be exposed to .833mw...each eye

Not a bright thing to do, but I would think it would not be harmful

There has to got be a math formula for this..

So, How does it work?


Mrnewbie is offline   Reply With Quote


















Old 10-13-2013, 06:47 AM #2
Wolfman29's Avatar
Class 3B Laser
 
Join Date: Jan 2011
Location: Davis, CA
Posts: 3,830
Rep Power: 37168
Wolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond repute
Wolfman29 Wolfman29 is offline
Class 3B Laser
Wolfman29's Avatar
 
Join Date: Jan 2011
Location: Davis, CA
Posts: 3,830
Rep Power: 37168
Wolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond repute
Default Re: How the heck does it work?

You've got that exactly right. But just because it's below 5mW does not mean it's not dangerous. It's just 5mW is the threshold for damage in under 0.25 seconds. I would bet that damage could occur even at <1mW.
Wolfman29 is offline   Reply With Quote
Old 10-13-2013, 06:56 AM #3
Hap's Avatar
Hap Hap is online now
Super Moderator
 
Join Date: Sep 2013
Location: Arcata, CA, USA
Posts: 8,413
Rep Power: 21474874
Hap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond repute
Send a message via Skype™ to Hap
Hap Hap is online now
Super Moderator
Hap's Avatar
 
Join Date: Sep 2013
Location: Arcata, CA, USA
Posts: 8,413
Rep Power: 21474874
Hap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond repute
Send a message via Skype™ to Hap
Default Re: How the heck does it work?

Quote:
Originally Posted by Wolfman29 View Post
You've got that exactly right. But just because it's below 5mW does not mean it's not dangerous. It's just 5mW is the threshold for damage in under 0.25 seconds. I would bet that damage could occur even at <1mW.
Of course damage could occur at <1mW, but even when focused, that is such low power that it would still take awhile for any eye damage!

Hint: Just never point any laser at you're eyes/anyones eyes, and you will be alright.
__________________
635nm: Laserglow Libra 5mW *North Pole Edition*



"Open your eyes, look within. Are you satisfied with the life you're living?" -Bob Marley
"The stars should fall and the earth be riddled, imagine all your problems be seem so little, funny how the world so brittle." -Tribal Seeds
“The universe is a pretty big place. If it's just us, seems like an awful waste of space.” -Carl Sagan
You are important: Pale Blue Dot

Hap is online now   Reply With Quote
Old 10-13-2013, 07:17 AM #4
cantthinkofone's Avatar
Class 2M Laser
 
Join Date: Jul 2013
Location: Ohio, USA, Earth
Posts: 707
Rep Power: 132
cantthinkofone has a reputation beyond reputecantthinkofone has a reputation beyond reputecantthinkofone has a reputation beyond reputecantthinkofone has a reputation beyond reputecantthinkofone has a reputation beyond reputecantthinkofone has a reputation beyond reputecantthinkofone has a reputation beyond reputecantthinkofone has a reputation beyond reputecantthinkofone has a reputation beyond reputecantthinkofone has a reputation beyond reputecantthinkofone has a reputation beyond repute
cantthinkofone cantthinkofone is offline
Class 2M Laser
cantthinkofone's Avatar
 
Join Date: Jul 2013
Location: Ohio, USA, Earth
Posts: 707
Rep Power: 132
cantthinkofone has a reputation beyond reputecantthinkofone has a reputation beyond reputecantthinkofone has a reputation beyond reputecantthinkofone has a reputation beyond reputecantthinkofone has a reputation beyond reputecantthinkofone has a reputation beyond reputecantthinkofone has a reputation beyond reputecantthinkofone has a reputation beyond reputecantthinkofone has a reputation beyond reputecantthinkofone has a reputation beyond reputecantthinkofone has a reputation beyond repute
Default Re: How the heck does it work?

Look at laser tag.... .95 mW of 532 in the hands of 7 year olds. And WE'RE the ones the FDA worries about...
__________________
my lasers-
405nm 111mw china laser
Dragon Laser 589nm
670nm radioshack LX1000

Working on-
"The Neptune" 2w 445
"The Evergreen" 80mw 520

Coming soon to a FS thread near you-
The Hades line of lasers. got 3/4 the parts! will announce when time...
cantthinkofone is offline   Reply With Quote
Old 10-13-2013, 12:07 PM #5
Junior Member
 
Join Date: Dec 2012
Posts: 15
Rep Power: 0
Mrnewbie is on a distinguished road
Mrnewbie Mrnewbie is offline
Junior Member
 
Join Date: Dec 2012
Posts: 15
Rep Power: 0
Mrnewbie is on a distinguished road
Default Re: How the heck does it work?

Ok, well we figure it not a good thing, but you won't be joining the land of the blind.
.83mw exposure...and all exposure to be avoided.

Next question, same senario 100mw,120" beam, 100ft.

This time its you..your pointing twards a wall 100ft away, throwing a pretty 120" RED or Blue laser at it.
So the laser is traveling 100ft to wall, then bounce back 100ft to your eyes. I would think the reflectivity of the wall would play a major part in this one..lets call it 50%.

Your not wearing any goggles.. your not looking directly at the laser, your looking at the bounce back from the wall.
How would this one work out? 100mn/120in=.83 .83 x50% = .415mw

I suspect no problems at all, but just kinda currious

Last edited by Mrnewbie; 10-13-2013 at 12:12 PM.
Mrnewbie is offline   Reply With Quote
Old 10-13-2013, 12:12 PM #6
Hap's Avatar
Hap Hap is online now
Super Moderator
 
Join Date: Sep 2013
Location: Arcata, CA, USA
Posts: 8,413
Rep Power: 21474874
Hap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond repute
Send a message via Skype™ to Hap
Hap Hap is online now
Super Moderator
Hap's Avatar
 
Join Date: Sep 2013
Location: Arcata, CA, USA
Posts: 8,413
Rep Power: 21474874
Hap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond repute
Send a message via Skype™ to Hap
Default Re: How the heck does it work?

Quote:
Originally Posted by Mrnewbie View Post
Ok, well we figure it not a good thing, but you won't be joining the land of the blind.
.83mw exposure...and all exposure to be avoided.

Next question, same senario 100mw,120" beam, 100ft.

This time its you..your pointing twards a wall 100ft away, throwing a pretty 120" RED or Blue laser at it.
So the laser is traveling 100ft to wall, then bounce back 100ft to your eyes.

Your not wearing any goggles.. your not looking directly at the laser, your looking at the bounce back from the wall.
How would this one work out?

I suspect no problems at all, but just kinda currious
Hey Mr,

I can say from experience a 120mW red will not cause any harm to you're eyes at all a wall 100ft away. Hec, my 500mW green is easy to look at 50ft away.

Also when light hits a wall it does not reflect, concrete being a non reflective surface will instead absorb the light and spread it out.

If this was GLASS instead of a wall at 100ft away you would be screwed

So if you are worried about 100ft away, then no. No damage possible.
__________________
635nm: Laserglow Libra 5mW *North Pole Edition*



"Open your eyes, look within. Are you satisfied with the life you're living?" -Bob Marley
"The stars should fall and the earth be riddled, imagine all your problems be seem so little, funny how the world so brittle." -Tribal Seeds
“The universe is a pretty big place. If it's just us, seems like an awful waste of space.” -Carl Sagan
You are important: Pale Blue Dot


Last edited by Hap; 10-13-2013 at 12:14 PM.
Hap is online now   Reply With Quote
Old 10-13-2013, 12:45 PM #7
Junior Member
 
Join Date: Dec 2012
Posts: 15
Rep Power: 0
Mrnewbie is on a distinguished road
Mrnewbie Mrnewbie is offline
Junior Member
 
Join Date: Dec 2012
Posts: 15
Rep Power: 0
Mrnewbie is on a distinguished road
Default Re: How the heck does it work?

I was more concerned about understanding the math end of things.
The theory and reasoning behind it.
Mrnewbie is offline   Reply With Quote
Old 10-13-2013, 12:48 PM #8
Hap's Avatar
Hap Hap is online now
Super Moderator
 
Join Date: Sep 2013
Location: Arcata, CA, USA
Posts: 8,413
Rep Power: 21474874
Hap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond repute
Send a message via Skype™ to Hap
Hap Hap is online now
Super Moderator
Hap's Avatar
 
Join Date: Sep 2013
Location: Arcata, CA, USA
Posts: 8,413
Rep Power: 21474874
Hap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond reputeHap has a reputation beyond repute
Send a message via Skype™ to Hap
Default Re: How the heck does it work?

Quote:
Originally Posted by Mrnewbie View Post
I was more concerned about understanding the math end of things.
The theory and reasoning behind it.
Ahhh, then sorry man. Can't be of very much help

Math isn't my best subject!
__________________
635nm: Laserglow Libra 5mW *North Pole Edition*



"Open your eyes, look within. Are you satisfied with the life you're living?" -Bob Marley
"The stars should fall and the earth be riddled, imagine all your problems be seem so little, funny how the world so brittle." -Tribal Seeds
“The universe is a pretty big place. If it's just us, seems like an awful waste of space.” -Carl Sagan
You are important: Pale Blue Dot

Hap is online now   Reply With Quote
Old 10-13-2013, 08:54 PM #9
Junior Member
 
Join Date: Dec 2012
Posts: 15
Rep Power: 0
Mrnewbie is on a distinguished road
Mrnewbie Mrnewbie is offline
Junior Member
 
Join Date: Dec 2012
Posts: 15
Rep Power: 0
Mrnewbie is on a distinguished road
Default Re: How the heck does it work?

(If one had a 100mw laser..but focused to a 120inch beam at 100ft, would it be dangerous to look at from 100ft?

100mw/120in=.833mw per inch

I'm thinking the human eyes ..about 1 in wide would only be exposed to .833mw...each eye)

You know guys, I think the above thinking is flawed.

Some of you fellas have tools to measure laser power..not sure how it works.
But here is what I was thinking.

When you measure your laser output..are you not measuring it in a focused beam. Lets just call it 1/16th of an inch beam.

So if you were to take a 100mw laser ..stretch it out to 1 inch..it would it not be measured as a 100mw laser it anymore. It would have 1/16 of the output power of 100mw. Or 6.25mw because the original beam is already enlarged by a factor of 16.
I think a more correct version of the posted hypeteticl formula should be.

(100mw* .0625(1/16th))/120in = output
100x.0625= 6.25mw 6.25mw/120in= .0520mw...

Just hinking aloud....
Mrnewbie is offline   Reply With Quote
Old 10-13-2013, 09:02 PM #10
Wolfman29's Avatar
Class 3B Laser
 
Join Date: Jan 2011
Location: Davis, CA
Posts: 3,830
Rep Power: 37168
Wolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond repute
Wolfman29 Wolfman29 is offline
Class 3B Laser
Wolfman29's Avatar
 
Join Date: Jan 2011
Location: Davis, CA
Posts: 3,830
Rep Power: 37168
Wolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond reputeWolfman29 has a reputation beyond repute
Default Re: How the heck does it work?

Quote:
Originally Posted by Tha Greenlander View Post
Hey Mr,

I can say from experience a 120mW red will not cause any harm to you're eyes at all a wall 100ft away. Hec, my 500mW green is easy to look at 50ft away.

Also when light hits a wall it does not reflect, concrete being a non reflective surface will instead absorb the light and spread it out.

If this was GLASS instead of a wall at 100ft away you would be screwed

So if you are worried about 100ft away, then no. No damage possible.
He was talking about a direct hit at 100ft, if I understand correctly.
Wolfman29 is offline   Reply With Quote
Old 10-13-2013, 09:54 PM #11
SKeeZ's Avatar
Class 2 Laser
 
Join Date: Sep 2013
Location: Boise, ID
Posts: 467
Rep Power: 452
SKeeZ has a reputation beyond reputeSKeeZ has a reputation beyond reputeSKeeZ has a reputation beyond reputeSKeeZ has a reputation beyond reputeSKeeZ has a reputation beyond reputeSKeeZ has a reputation beyond reputeSKeeZ has a reputation beyond reputeSKeeZ has a reputation beyond reputeSKeeZ has a reputation beyond reputeSKeeZ has a reputation beyond reputeSKeeZ has a reputation beyond repute
SKeeZ SKeeZ is offline
Class 2 Laser
SKeeZ's Avatar
 
Join Date: Sep 2013
Location: Boise, ID
Posts: 467
Rep Power: 452
SKeeZ has a reputation beyond reputeSKeeZ has a reputation beyond reputeSKeeZ has a reputation beyond reputeSKeeZ has a reputation beyond reputeSKeeZ has a reputation beyond reputeSKeeZ has a reputation beyond reputeSKeeZ has a reputation beyond reputeSKeeZ has a reputation beyond reputeSKeeZ has a reputation beyond reputeSKeeZ has a reputation beyond reputeSKeeZ has a reputation beyond repute
Default Re: How the heck does it work?

Quote:
Originally Posted by Mrnewbie View Post
Ok, well we figure it not a good thing, but you won't be joining the land of the blind.
.83mw exposure...and all exposure to be avoided.

Next question, same senario 100mw,120" beam, 100ft.

This time its you..your pointing twards a wall 100ft away, throwing a pretty 120" RED or Blue laser at it.
So the laser is traveling 100ft to wall, then bounce back 100ft to your eyes. I would think the reflectivity of the wall would play a major part in this one..lets call it 50%.

Your not wearing any goggles.. your not looking directly at the laser, your looking at the bounce back from the wall.
How would this one work out? 100mn/120in=.83 .83 x50% = .415mw

I suspect no problems at all, but just kinda currious
it would be even less, .20525mW because the beam expands further while on its way back, to 240in. thus halving the power again.
__________________

405nm 60mW pen
445nm 2W build
532nm 5mW WL core
532nm 15mW pen

633nm 5mW (2X) 05-LHP-111 MG HeNe's
650nm 5mW alignment

MELLES GRIOT 05-LPM-830-065 (HeNe PSU)

SKeeZ is offline   Reply With Quote
Reply





Thread Tools
Display Modes

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 Off
Trackbacks are On
Pingbacks are On
Refbacks are On



























Privacy Policy | Advertising Disclaimer | Terms of Use


 


All times are GMT. The time now is 04:06 PM.


Powered by: vBulletin
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO
Privacy Policy | Advertising Disclaimer | Terms of Use
Copyright (C) 2017 Laser Pointer Forums, LLC