Laser and laser glasses testing and interesting results

[OpenTrackRacer]

Just thought I'd share some testing I did tonight with a few pairs of safety glasses and two different green lasers.

I'm testing using a ThorLabs benchtop power meter with photodiode sensor.

I have a green laser pointer that I got years ago. Fairly bright but never tested before. I also have a green laser pointer that my father-in-law just bought on-line. It seemed really bright to me so I decided to do some testing.

I have some HDE or HDE clone glasses that I just got with an eBay 1W 450nm laser and a pair of Uvex SCT-Orange glasses (which are not rated or certified as laser safety glasses but have been tested to perform well).

I got some interesting results...

Old pointer:

25mW raw - 103pW with Uvex glasses - 46pW with HDE glasses

Father-in-Law's pointer:

205mW raw - 150mW with Uvex glasses - 115mW with HDE glasses

I found this rather interesting. Both the HDE and the Uvex glasses seem to do well at 532nm with the 25mW laser (note those values through the glasses are pico Watts). However the 200mW (!!!) laser is another story. The result has me wondering if that laser is putting out a ton of IR or the glasses simply can't cope at that power level. It seems like it would be an awful lot of IR but...

Going to do more testing but I thought I'd share and get everyone's thoughts as well.

 

[GSS]

How do you see them blocking by eye? When advertising safety glasses they usually rate the blue green glasses from something like 400nm to 540nm which puts the green lasers 532nm right at the border. Knowledged members I think mentioned say the higher OD protection what ever might be is the medium off this rating. I know Uvex and HDE's never give numbers just say for blue and green laser's.
What do you see with your blue 1W?

 

[CurtisOliver]

IR leakage would most likely be the cause of the power difference. The other pointer obviously has a IR filter.
Plus at those low power powers you recorded the goggles would have to have a OD of around 9 at 532nm which is very high as the googles are cutting the power by over a 1,000,000,000x. OD 10+ for the specified wavelength? :thinking:
Assuming a beam diameter of 3mm that would put the lux at around ~0.01lx. (Calculated at 555nm standard)
Was your room less than 0.01 lux when you made the measurement, if not how did you get a reading if the illumination was less than the surrounding environment?
Something doesn't seem right with the measurements somehow.

 

[OpenTrackRacer]

The room was not dark. The low readings on the 25mW laser could be affected by that. I'll have to do some more testing. Is it really possible that the 200mW laser is putting out 50mW of green and 105mW of IR? It seemed like a lot to me but theoretically it's possible I guess.

As for the dot, it's very dim on the surface of both types of glasses. I have to check the blue again but I believe it was the same. No visible dot makes it past the glasses on any of them. I haven't tested power with the blue laser yet because it's more powerful than the detector. I need to get a ND filter first.

 

[Benm]

It's entirely possible for a 532 dpss to leak that much IR, which can be both at 1064 and at 808 nm.

It should be fairly obvious when looking at the beam shining through the goggles (sitting on a table etc) though: The visible green beam would be invisible or very much dimmer after the goggles, the IR stuff you cannot see so there should be no visible difference for that.

Using a photodiode sensor presents a problem though: those can be quite sensitive to IR light compared to visible depending on the type, so the power measurement is not accurate at all when calibrated for 532.