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Safety Goggles for looking at the beam? (Not the dot or dot reflection)

Architect23

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All the safety information I've found, refers to looking directly at the laser beam dot, shone on an object or reflected back at you. At what point in mW (for 445nm), are safety glasses required (if at all) when looking at the beam in the night sky?

I have a 1.6W 445nm laser on the way and am wondering if it is safe for me to admire the beam at night (without safety goggles), when (safely) shining the laser off into the distance?
 
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paul1598419

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Looking at the beam in the night sky is not dangerous at any power I am aware of. Certainly not a 1.6 watt 445nm laser. Guide stars are 589nm yellow lasers that are in the the tens of watts and are much more visible mW for mW than any 445nm laser. You can watch them to your heart's delight without harm.
 

Snecho

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As Paul said, there is no harm whatsoever to look at a beam with an infinite endpoint
 

nzoomed

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Thanks for asking this question, I was about to ask the same question.
Im in the process if building my own 2W laser with an M140 diode.
Im still waiting for my goggles arrive so i can test the jolly thing.

At what point does looking at the dot become dangerous with such a laser?
If i pointed on a tree or hill for example? Im assuming that an object, providing its not a reflective material such as glass, metal, etc would be safe enough to point at a given distance, whether that be 20M, 100M etc?
 

paul1598419

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To get 2 watts out of that diode takes a short focal length single element lens. Might get close with a G8, but they still tend to diverge quickly, so it wouldn't be a small spot at 100 meters. That said, it is only specular reflections that are dangerous. I have looked at the spot from a 3 watt 445nm laser at 8 feet without goggles many times with no damage to my retinas. These diffused reflections act like a point source of light and decrease in intensity proportional to the square of the distance you are away from it.
 

nzoomed

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To get 2 watts out of that diode takes a short focal length single element lens. Might get close with a G8, but they still tend to diverge quickly, so it wouldn't be a small spot at 100 meters. That said, it is only specular reflections that are dangerous. I have looked at the spot from a 3 watt 445nm laser at 8 feet without goggles many times with no damage to my retinas. These diffused reflections act like a point source of light and decrease in intensity proportional to the square of the distance you are away from it.
OK well thats good to know, as I was quite scared about testing this unit lol
Obviously I still want to be careful.
Is it true that while wearing goggles, you are not supposed to actually be able to see any of the beam or the dot if they are of decent quality?
 

hakzaw1

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no glasses needed.
For safe viewing glasses are NEEDED- when view from in front or many reflections...- from the side, like night sky viewing you are safe.
Can you add your location into your personal profile?? Did you make an intro?? if not put your location in the title of your intro (placed in the welcome section)--that way you may get greets from members nearby. ALL members who own LPMs will gladly meter your lasers free anytime. One way to meet many is to attend a LEM- via those meets I have met >100 members, their families and friends who also attend the LEM---and they attend free.

feel free to PM me if I can help--hak
 

nzoomed

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no glasses needed.
For safe viewing glasses are NEEDED- when view from in front or many reflections...- from the side, like night sky viewing you are safe.
Can you add your location into your personal profile?? Did you make an intro?? if not put your location in the title of your intro (placed in the welcome section)--that way you may get greets from members nearby. ALL members who own LPMs will gladly meter your lasers free anytime. One way to meet many is to attend a LEM- via those meets I have met >100 members, their families and friends who also attend the LEM---and they attend free.

feel free to PM me if I can help--hak
Thanks,
I will update it shortly, for the record, im all the way down under in New Zealand.
Im new to building lasers, figured out its easier and cheaper to make them rather than buy them online, not to mention that most lasers on ebay are poor quality, not to mention 1mW limit ebay imposes, you have no idea what you are buying lol
 

paul1598419

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That limit may be because of where you live. Doesn't New Zealand have limits similar to Australia? The 301 and 303 532nm laser pointers are often 80 mW. They are also ~$6.00USD with free shipping.
 

nzoomed

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That limit may be because of where you live. Doesn't New Zealand have limits similar to Australia? The 301 and 303 532nm laser pointers are often 80 mW. They are also ~$6.00USD with free shipping.
New Zealand imposed the limit to 1mW.
I never realised many of those lasers on ebay were that powerful though.
In saying that, many show photos of it igniting a match in the thumbnail image.
I messaged the seller once about this and they told me that Ebays policy was no lasers more powerful than 1mW were permitted, and that their lasers were actually more powerful lol

I guess this is how many of these incorrectly labelled lasers get through customs, as you need a permit to import the higher powered ones (anything over 1mW lol), not that they have much time to check all parcels entering the country.

The thing that is more of a concern is if those lasers do indeed ignite a match or pop balloons, then they are quite dangerous and obviously have no IR filter installed. I believe 50mW is the minimum power capable of burning stuff or at least melting plastic bags.
Although it varies wildly depending on how much IR the laser produces.
 

paul1598419

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The only way a 80 mW laser can burn is to focus the beam down to a fraction of a mm about an inch or two away from the aperture. That increases the power density of the profile to a much higher level. This same laser will never burn anything at a few feet or longer distance. The IR component is typically only ~20% of the total power and it follows the same path as the visible beam.
 




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