Duration of afterimages?

[electros]

Your right, you make your own decisions, and you can take your own risks. From your original post, however, it sounded like you didn't know the risk you had took at the time. I know you wouldn't be looking at the spot if you knew it could blind you, and I'm not saying it would. But I have a lot of reason to come to that logic.

In your original post you did ask for info on afterimage duration, and I am sorry if I completely ignored this at first. Still though, it seemed you were wanting safety advise as you were mentioning your circumstances rather than just plain out asking about after images.

I still back up what I said as I do believe I stand correct and think it needed to be said, maybe not in the same tone, but still needed. You could damage your eyes looking at the spot without glasses. With any higher powered laser for that matter, but 1W makes it much more probable.
Also, I believe I have now answered your question about afterimages in my case.

Hope your eyes get right soon.

You cant blind yourself looking at a diffused reflection, but I understood it can cause damage. The damage is extremely minimal and does not impact my life at all. I have to be actively looking for it in most cases, and from what I understand this sort of damage you adapt to and never notice it all unless you specifically look for it. It has made me respect the laser a lot more, I don't even use it with a termination point anywhere close to me anymore. I've pretty much decided to just use it in the sky (after checking for planes) or with lens effects (The effect kits are in my g2 orders >.<)

I knew diffused posed a hazard, I even posted that on gizmodo out of concern for other people. It seems weird to me that the damage from a diffused would be a "Spot" as its diffused and not focused to a spot. It is why I think it is more likely an after image from looking at the dot, not damage. to describe this would basically be a floater. We all have them, except this one stays in a specific spot. You don't tend to notice floaters, and when you do its not a big issue.

 

[hugo999999]

You cant blind yourself looking at a diffused reflection, but I understood it can cause damage. The damage is extremely minimal and does not impact my life at all. I have to be actively looking for it in most cases, and from what I understand this sort of damage you adapt to and never notice it all unless you specifically look for it. It has made me respect the laser a lot more, I don't even use it with a termination point anywhere close to me anymore. I've pretty much decided to just use it in the sky (after checking for planes) or with lens effects (The effect kits are in my g2 orders >.<)

I knew diffused posed a hazard, I even posted that on gizmodo out of concern for other people. It seems weird to me that the damage from a diffused would be a "Spot" as its diffused and not focused to a spot. It is why I think it is more likely an after image from looking at the dot, not damage. to describe this would basically be a floater. We all have them, except this one stays in a specific spot. You don't tend to notice floaters, and when you do its not a big issue.

that sounds like eye damage to me. once i went to a doctor and he asked if the floaters moved, if they didn't it was a burn in the eye, if they did they were simply eye tissue broken off (floaters).

 

[Seoul_lasers]

Ok, well I am going just set the record straight on this one.

1) 440-450nm is dangerous for reasons for PCE (photochemical effect) as has been discussed already.

2) The diodes in question emit over 1W at full power, even with 1/10 reflection that's over 100mW to your eyes which can and will cause damage or blindness.

3) Bright blue light even at lower mW outputs can trigger migranes, and can cause eye focussing problems.

4) Viewing a spot that is not reflecting may overwhelm the optic nerve and cause you to have after images. But from literature out there says that this will ,most likely be temporary. Still it is not a smart idea given the potential for a major disaster causing blindness.

 

[Pontiacg5]

You cant blind yourself looking at a diffused reflection, but I understood it can cause damage. The damage is extremely minimal and does not impact my life at all. I have to be actively looking for it in most cases, and from what I understand this sort of damage you adapt to and never notice it all unless you specifically look for it. It has made me respect the laser a lot more, I don't even use it with a termination point anywhere close to me anymore. I've pretty much decided to just use it in the sky (after checking for planes) or with lens effects (The effect kits are in my g2 orders >.<)

I knew diffused posed a hazard, I even posted that on gizmodo out of concern for other people. It seems weird to me that the damage from a diffused would be a "Spot" as its diffused and not focused to a spot. It is why I think it is more likely an after image from looking at the dot, not damage. to describe this would basically be a floater. We all have them, except this one stays in a specific spot. You don't tend to notice floaters, and when you do its not a big issue.

You just don't get it do you? A diffused reflection off of a 1W laser IS enough to blind you. I never get afterimages from looking at my 125mW green, and I never got afterimages from ~200mW of 445 light.
Afterimages are the cones in your eye screaming that they are being overloaded, Its defiantly not a good thing...

 

[Seoul_lasers]

You just don't get it do you? A diffused reflection off of a 1W laser IS enough to blind you. I never get afterimages from looking at my 125mW green, and I never got afterimages from ~200mW of 445 light.
Afterimages are the cones in your eye screaming that they are being overloaded, Its defiantly not a good thing...

I'll agree with you, but on top of the power output we need to factor the PCE of this particular laser, this can cause additional side-effects.

I did happen to experience the dot from this laser without goggles because I couldn't see the
alignment with the goggles on properly as it was too dim. Just viewing it for 2 seconds gave me after images and a massive headache. The images cleared up in about 1hr.
Now I leave a light on so that I can see the alignment and the beam properly with the glasses on.
BTW, I am a very safety oriented person.

 

[Coherent Light]

Anyone have a clue as to what an unfocused 445nm diode operating at minimum threshold would do to one's eye....No I did not look into one of My diodes during this condition!!! Just wondering the potential as many peeps are building their 1st Lasers using this diode. IMHO I am not certain that anyone should jump into the home built arena with this particular diode.

Coherent:

 

[erdabyz]

Oh c'mon, around 80% of information coming to your body enters through the eyes and you only have two. Isn't that a good reason to care about them?

I have my 445 set to 350mA right now until inductors arrive for high powered driver and my routine is:

-Certified ARG goggles on
-Laser on
-Aim it to a spot where you can see the beam but not the spot
-Hold it in place and goggles off
-Admire the glorious beam
-Goggles on
-Aim it to a matte black suface some meters away
-Goggles off and admire the glorious blue spot for some seconds
-Goggles on and laser off

 

[CrazyMonkey]

I am not sure what you mean by longest after image.
I am sure the answer is forever. I have never had this problem
myself, I hope I never do. If you want to see a beam, then you
need to terminate it. Something really black that will not be destroyed.
Even then, there is still a risk. (black may not be black enough).
Here is info from Wikipedia: Beam dump.

 

[millirad]

Erdabyz, that sounds like some reasonable advice. On another note, how's the serrano in your part of town?

 

[LSRFAQ]

Electros, please read post 103 in "A plea for eye safety" sticky in the 445 nm thread.

If I'm working with a 1 watt visible blue spot on the wall assuming diffuse scattering, I'm going to be three meters or more away for daily exposure and instead finding a way of shielding the glare from that spot.

OSHA sets limits for exposure per unit area vs time, and so does ANSI Z136. I'm going to set up my environment to be below class IIA or worse case IIIA, but not the .95 mW or 4.95 mW limits, I'm going to look up the power per unit area at the pupil limit, which will be less. For skin its something less then 320 microwatts per square centimeter for a 8 hour day exposed to the laser.

But the only way I can truely find that out is to measure the scatter with a power meter at the location of my eyeball. I need to know the area of the detector, too, so I can figure the power density.

To put it other terms, if your feeling pain or have afterimages, your too damn close to the scatterer. Distance is your friend, and exposure goes down as the square of the distance, so if your at 1 unit back and you get x exposure, at 2 units you get 1/4 of what x was a 1 unit. At 4 units you get 1/16th and so forth, assuming a true diffuse scatterer. Those don't always exist.


And yes, with a class IV laser, or a high power IIIB laser you can certainly cause severe eye damage from a diffuse reflection. That eye damage can be cumulative and not instantly apparent. If its in the peripheral vision, which detects motion, its not much of a exaggeration to say, "You may not know you have damage, untill the truck hits you when you cross the street"

Its not fun to wake up in the morning and not be able to focus on the text in a book. Think about it and back off on your exposure.

Current experimental silicon retinas have a resolution of 30 by 30 and have only worked in abut 50% of the patients they were implanted in. In other words, the technology to fix your retina if damaged does not exist yet.

Since this is a scattering case and not a direct beam case, your risking both eyes. The pain is a warning, heed it.

Steve

 

[jupiter8]

If you look directly at the sun without eye protection how many mW of energy do you think your retina is assaulted with? I'd be curious to know...

Answered my own question - according to wikipedia typical sunlight contains 120 watts of light energy per meter2.

That's equates to 0.00012W/mm2 or 0.12mW/mm2

I guess the average pupil is around 4mm or so, the area of a 4mm pupil is 12.56mm2

That means a measly 1.5mW of light energy enters the eye looking directly at the sun...

I think my sums are right, and the moral of the story is, treat your lasers with respect!

 

[AdamCaudill]

That means a measly 1.5mW of light energy enters the eye looking directly at the sun...

That really puts it into perspective, kinda scary if you think about it.

Not many people realize just how much power that cheap 50mW pen has, much less 1W of blue - that's the reason I don't let anybody handle my lasers. It's just too risky for people that haven't done the research to understand what's really going on.

 

[electros]

Just thought I'd update you guys. I did suffer some damage but they are floaters, not stationary spots. Random onset of floaters can be an early sign of more serious complications, but 99.9% they are not (Actual statistics I found.. these are for old age related floaters, cant find info on laser caused). if you get them checked out early, and have a more serious condition developing (Retinal detachment) it is a quick fix with laser surgery at this stage. I dont think the floaters themselves are very treatable, but they can diminish over time.


I am going to the eye doctor today to make sure there isnt anything more serious happening. The arctic really scares me now though, Us on the forum are the minority.. and I actually knew the risk, yet still did something stupid without thinking (I am beating myself up for it). The majority of people going through gizmodo and such don't know the risk, and I gaurantee the first thing they will do is take it out, turn it on, point at the wall and look at dot, and suffer the same damage I did... or god forbid point it at something like a window and catch a real reflection.

the fact that it has a rectangular beam, and isnt a very visible color make it seem a lot less dangerous to your mind. but do not underestimate this thing..

I see this and wicked lasers marketing of such a device to the general public as a huge issue for laser enthusiasts, and of course for the public in general.

 

[erdabyz]

Erdabyz, that sounds like some reasonable advice. On another note, how's the serrano in your part of town?

Oh well, I'm in Madrid and we don't have "dehesas" where black pigs spend their lives exercising and eating acorn here.

So serrano ham produced in Madrid and surroundigs isn't the best of Spain. But we're pretty close to Salamanca and Extremadura and being the capital of Spain we can have highest quality ham at reasonable prices (somewhere aroud 50-60€/kilo (around 600€/piece) for "pata negras").

There are two or three places here in Madrid called "The ham museum" that are some sort of restaurants where you can admire and taste all the piggy gloriousness that Spain produces.

BTW, Is it legal to export ham to the US? I could sell some slices via LPF if it were legal... or even trade them for laser diodes!

 

[ShaOwned]

No one can answer this question because no one in their right mind looks at the dot of a 1W 445nm laser without goggles.

 

[Rafa]

Oh well, I'm in Madrid and we don't have "dehesas" where black pigs spend their lives exercising and eating acorn here.

So serrano ham produced in Madrid and surroundigs isn't the best of Spain. But we're pretty close to Salamanca and Extremadura and being the capital of Spain we can have highest quality ham at reasonable prices (somewhere aroud 50-60€/kilo (around 600€/piece) for "pata negras").

There are two or three places here in Madrid called "The ham museum" that are some sort of restaurants where you can admire and taste all the piggy gloriousness that Spain produces.

BTW, Is it legal to export ham to the US? I could sell some slices via LPF if it were legal... or even trade them for laser diodes!

Hell yeah, lets export some ham :crackup:

Does someone want to give me its argon for a "Pata negra"?