Greetings,
I obtained a blue laser about a year ago from someone who doesn't know anything about it, and I'm just getting around to trying it out. This is my first laser and I'm being very careful because I've read about how dangerous lasers are (in particular blue ones). Not wanting to risk eye injury, I purchased some safety glasses that have a very high OD of 7+ in the blue region. Here is a link to the glasses I purchased:
https://www.thorlabs.com/thorproduct.cfm?partnumber=LG3
The lenses of the glasses have the following information laser-printed at the top of the lenses:
180-532nm OD 7+ 48%VLT
180-315 D LB7 + IR LB4 >315-532 DIRM LB6 NOIR CE
The laser is a 3W 450nm focusable laser from China. It runs off of a 12VDC power supply and it has an input that is labeled "TTL".
The glasses arrived yesterday and I proceeded to turn on the laser for the first time. I set up a frequency generator to drive it with a 5 kHz PWM signal at a low duty cycle. I found the laser turns on at about 0.3% duty cycle. I briefly set it to a high duty cycle and it easily burned a piece of paper. It works, so nothing to complain about there. But being a newbie, I don't have the experience to know what I should be able to see through those safety glasses. I am thinking that I shouldn't be able to see anything in the blue spectrum. Blue colors on my computer monitor are completely blocked out by the glasses. But when I observe the laser on a piece of white paper at the lowest intensity and very poorly focused I can see it through the glasses. Is this normal with glasses that have a relatively high VLT? At low intensity and poorly focused, I viewed it on the paper without the glasses and it is indeed blue. Is it a feature of some lasers to output some light in other spectrum ranges so that you can see the laser while wearing safety glasses? Or do you think this laser is defective?
The light isn't uncomfortable to view through the glasses, and there isn't any persistence when I close my eyes. I expect to see some light when it burns things, but should I be able to see it when the power is very low?
I am attaching a picture of the laser and the power supply. If anyone has any information about it, please let me know.
Thank you very much in advance,
Greg