These are what I’m going to trust with my only pair of eyes:
OD7+ at 405nM which is overkill, but overkill is good. Relatively high transmission of visible light.
The enclosure is better than nothing, but the fact that it has gaps of any size means that an unlucky bounce can put a fair amount of power into your eye. This is NOT acceptable in any laser lab, or to me.
I’ve been working with high power lasers on and off for over 10 years, and I’ve had no incidents.
There are various eyewear choices on Ebay and Amazon, but this is one place where I need some level of trust in the vendor. If Thorlabs says it’s 7+, it’s SEVEN PLUS. Somehow I don’t get enough comfort out of “Fred’s discount laser safety and adult novelties store” brand.
The above document is worth a serious read. TLDR version: These are to protect you from ACCIDENTAL exposure. “Eye-protectors are only intended to give protection against accidental radiation; both the limiting values and the ratability tests are based on a maximum period of 5s.”
I didn’t cheap out on the SM350, or any other aspect of this project, and I am not cheaping out on the only real protection between me and that laser.
I got my from Laser Safety Industries and I like them very much as well - OD5+ with 50% VLT, quite similar.
OD7 is more than required - bigger is not necessarily better. Once you are below 1mW at the eye you’re fully protected. The minimum OD would be 4.0 for the 10W laser, 3.2 for the 1.6W laser.
You are not wrong, I get different results indicating OD5 is minimum, possibly we are using different beam diameter values? I choose to err on the side of safety.
Since the beam is not collimated, one could argue that no protection is needed at a significant distance, calculated by max power intercepted by the area of a fully blown pupil (9mm worst case) and the beamspread, but it is possible (Highly unlikely) that whatever the beam is hitting could result in focusing the laser at my eye. But we shouldn’t be working on the basis of “you’ll probably be fine”.
Given that I can’t control the target as a reflector, I’m not comfortable assigning any divergence to it.
Back when Wicked Lasers came out with their 1W blue, I saw some morons claiming that the eyewear didn’t provide any protection because the beam of the laser would eventually melt through the lenses of the eyewear, as some were eager to demonstrate… Agghhh…
I did some estimates of the 1.6W based on the measured spot size, although I was being conservative on the high divergence size to find the closest possible safe NOHD, would need to estimate the other way to find the most conservative minimum divergence for the purpose of eye protection.
If someone has one it would be awesome to post some of the numbers like focal length and spot size - I’m still not sure I believe the posted spot size values, I feel like they are too large.
Haha there is something to be said for that. Maybe shut it off though rather than standing motionless until it melts through lmao. That guy should probably be wearing a lead lined face shield to be safe.
