650nm reflection hazard?

[SMIDSY]

Hi I have a DIY 650nm red laser (will post pics at soem point0 outputting at ~100mW.

I also have a pair of WL OD2+ glasses (LT ~17%). I kn0w from previous posts that this is enough to protect from diffuse reflections and even possibly a direct exposure for 0.3s

What I want to know is how long can I look at the dot of the laser when it is focused into burning mode and reflecting of a match without it hurting my eyes?
i.e. diffuse reflections when the dot is a pin size?

Thanks in advance for any help!

 

[Amnizu]

If you're looking at the dot through goggles while burning, you'll be absolutely fine basically indefinitely.

 

[supernova]

Hi

I would error on the cautious side. If it was me, I would align the dot to your subject and then look away until its popped, lit, or whatever. Then again, I like to view stuff through my digicam on my pc monitor as I generally record stuff I am messing with for reviewing later. An easy setup is to just work behind a opaque cloth and position your cam and laptop/monitor so you can view the monitor and get the "feel" like everything is "in front" of you. If you try a few setups, I am sure you can become comfortable with a setup similar to mine. Goggles / glasses are designed to work, but I have a hard time thinking that they are good enough for repetitive usage with high power lasers. Yeah I know they say they are, but If not, I don't want to learn the hard way. Using a cam is cool for comparisons and reviewing later too.

SN

EDIT: Also if you have friends over, its nice to have a "make shift lab" of sorts so everyone can watch the monitor and there is no need for many pairs of protective eyewear. It is just to easy for folks to ask to see what you can do and hard to say no to peer pressure, If your set to show it on cam, they can all watch safely.

 

[SMIDSY]

cheers guys, however for once in a blue moon burning I'm ok?

I will set up the 'lab' that may just work- but I still want to know if Im safe for like 5 mins of looking at the buring thing!

 

[chido]

YES, YOU'LL BE SAFE. ;D

 

[SMIDSY]

cheers

Im really scared about damaging my eyes....

I appreciate the reassurance!
edit: what about longer exposures

 

[chido]

Damn, you really take precautions don't you ;D
Even if you were using a 500mW laser, the dot through the lasershades (which I've heard multiple times they're OD3) would look like a .5mW laser, you could stare at the dot for hours and it wouldn't even bother you.

I HOPE THAT CLEARS THINGS UP. ;D

 

[SMIDSY]

Better safe than sorry?

YES IT CLEARS IT UP!

I thought that focusing the beam woudl have an effect on how long you could look at them- I must have been mistaken. :

cheers for the responses that's very definitive! and they say OD 2+ on them...

 

[nikokapo]

Better safe than sorry?  

YES IT CLEARS IT UP!

I thought that focusing the beam woudl have an effect on how long you could look at them- I must have been mistaken.  :

cheers for the responses that's very definitive! and they say OD 2+ on them...

well, actually, focusing it to a near distance does make a difference.

take for example if u point ur laser to a building one block away,

the divergence will make ur dot bigger and in consequence, the remaining power that "creates" the dot (because you will lose some power on the way) is allocated through a bigger dot and not focused into an extremely small one.

i hope i make my point

 

[SMIDSY]

[quote author=SMIDSY link=1205184242/0#7 date=1205269776]Better safe than sorry?  

YES IT CLEARS IT UP!

I thought that focusing the beam woudl have an effect on how long you could look at them- I must have been mistaken.  :

cheers for the responses that's very definitive! and they say OD 2+ on them...

well, actually, focusing it to a near distance does make a difference.

take for example if u point ur laser to a building one block away,

the divergence will make ur dot bigger and in consequence, the remaining power that "creates" the dot (because you will lose some power on the way) is allocated through a bigger dot and not focused into an extremely small one.

i hope i make my point [/quote]


erm.... :-? I know about all the power and focus and stuff... but...

so Im still safe for repeated exposures of 5mins with OD 2 glasses even though the laser is focused around 30cm away at the size of a nail head?

 

[chido]

YES, I've heard that they're OD3, but even if you say they have OD2 on them it's still safe, you'd need to have a 500mW laser to view a dot which would appear to be 5mW. BTW, where does it say they're OD2, I have the same goggles.

 

[Amnizu]

Once again, no matter what, as long as you're not focusing the dot into your eye, you'll be fine. If you've got goggles on and you spend 5 or 10 minutes looking at the focused dot while lighting matches or what have you, it would take 20 or 30 years of exposure to do any measurable, significant, or appreciable damage at all.

 

[SMIDSY]

Once again, no matter what, as long as you're not focusing the dot into your eye, you'll be fine. If you've got goggles on and you spend 5 or 10 minutes looking at the focused dot while lighting matches or what have you, it would take 20 or 30 years of exposure to do any measurable, significant, or appreciable damage at all.

LOL really! ;D
no matter how focused the dot is?! :

LOL ROFL that's hilarious... I can imagine me sitting there until I'm 40 waiting to go blind...

Cheers for that I appreciate it!

 

[SMIDSY]

YES, I've heard that they're OD3, but even if you say they have OD2 on them it's still safe, you'd need to have a 500mW laser to view a dot which would appear to be 5mW. BTW, where does it say they're OD2, I have the same goggles.

It says on the lens of mine:
"190-380 OD5+ 630-650nm OD 2+"

 

[chido]

Are you sure you have WL lasershades, mine don't say anything. Here are two pics of the ones I got from Xarylx:

 

[pseudonomen137]

[quote author=Amnizu link=1205184242/0#11 date=1205362608]Once again, no matter what, as long as you're not focusing the dot into your eye, you'll be fine. If you've got goggles on and you spend 5 or 10 minutes looking at the focused dot while lighting matches or what have you, it would take 20 or 30 years of exposure to do any measurable, significant, or appreciable damage at all.

LOL really!  ;D
no matter how focused the dot is?!  :

LOL ROFL that's hilarious... I can imagine me sitting there until I'm 40 waiting to go blind...  

Cheers for that I appreciate it!   [/quote]

Not through the goggles. Don't try shining a laser into your eye though as that power can damage the dyes in the goggles and ultimately just burn right through them. OD 2 goggles will cut the power down to 1% of its original, saving you most of the danger, but you still gotta exercise good judgement!

As for focusing into your eye, one thing to remember is that your eye already is a tool made for focusing. If you focused a laser onto the surface of your eye, you might damage your cornea, but in terms of your retina, your eye's lens will completely change the path of that beam and it wouldn't be even remotely focused when it hits your eye. However, if your eyes are naturally focusing at the distance where your laser also achieves its focus, you're lens is actually going to work to focus that light perfectly onto your retina - something to seriously worry about if you aren't using goggles.