Laser Safety

[gandalfthegrey]

Thanks for the clarification. The Laser wasn't cheap, but I think I got quite a good deal from a reputable company. I think it was £1200 sterling pre-used.

[White-Light]

New prices are here:

http://www.laserknowhow.co.uk/laser-...how=180&page=1

It's been a while since there's been an NRG test on here.

However, they used to be considered a good budget option based on the one tested.

Top end lasers are brands such as Kvant, RGB Laser Systems and some others. However they also have top end price tags.

[gandalfthegrey]

I will say this for them. The Laser arrived broken, they took it back and fixed it and took care of the shipping costs. Yes, the red isn't great... But all in all, for what I paid, it seems like a pretty good Laser, and they took care of me.

[gandalfthegrey]

I will say this for them. The Laser arrived broken, they took it back and fixed it and took care of the shipping costs. But yes, the red isn't great... But all in all, for what I paid, it seems like a pretty good Laser, and they took care of me. Still no definitive answer as to if a scan fail device was fitted. I guess not...

[gandalfthegrey]

Ok, thanks again for all the input, this is where I'm at. Please see attachments.

Attached are 3 analyses - the 2.5 W at 2 mrad (just treating them all the wavelengths as the same). Then one that looks at a 1 millisecond slice of the beam at the full 2.5 watts (0.0025 J), still at 2 mrad divergence. Finally, a version that is a 1 millisecond slice of 200 mW (0.0002 J) at 5 mrad divergence, which brings the hazard range down to 10 meters.

We go from 177 meters for full power, 1/4 second exposure (not scanning) to 88 meters when the exposure time is 1 millisecond, to a final result of 200 mW at 5 mrad divergence (and 1 millisecond) for a 10 meter hazard range.

If the power of the laser is 200 mW and the beam divergence is 5 mrad, the beam should be about 5 cm across (at 10 meters), and the irradiance is about 10 mW/cm^2 (which is the MPE for 1 millisecond). So normal scanning will reduce the time of exposure to 1 millisecond or less.

If you can have 35 meters or so, you can work with pretty much full power (2.5 W), provided the beam is still at 5 mRad divergence (beam is at 17.5 cm across).

Provided input from Greg Makhov

[norty303]

Great, so get yourself a Pangolin PASS system so you can ensure max exposure time is 1ms and a lens so you can diverge the beam suitably and you're away by the sounds of it.

[gandalfthegrey]

Thanks again everyone. I've got quite a lot from this thread. I think the correct answer to my question is to buy a Kvant ClubMax 3000 with all it safety features & Pangolin SafetyScan lenses.

[JStewart]

There are some good points mentioned in this thread. I’d like to add one more thing for the benefit of anyone that comes across these posts, and has an interest in audience scanning.

For audience scanning there is no one simple easy answer that ‘fixes’ everything, making the exposure below the exposure limits. Effective audience scanning requires a multi-disciplined approach.

Calculation will get you so far. Software can be used to determine and check theoretical exposure levels, and provide more detail, to help reinforce the safety case. Scanning output emissions monitoring with something robust like PASS will address another part of the problem. (Keep in mind that PASS does not make all laser shows automatically safe, it has to be correctly implemented, and be set to the appropriate limits; which when done properly, can be very effective). Safety Scan lenses help solve another problem. But in addition to all these parts of the solution, an understanding of the applicable limits is necessary.

Ultimately there is a need to verify the actual exposure. This needs to be done to prove to yourself and others that the exposure is behaving as intended. It’s therefore almost essential that the user have some form of calibrated measuring device. This could be something as straightforward as a Coherent LaserCheck pen, as long as the user knows how this can be used to measure the intended output, keeping in mind the limitations and pitfalls. But with a low-cost basic device, it is doable for sure. Some means of checking the exposure duration, and the point at which this gets limited is a very good idea too.

I’m not saying all of this to put people off the idea. But simply to highlight the point that there is no single quick easy fix to making sure the levels are always below the limits if you want to have effective audience scanning. With a bit of care and effort, it is achievable though.

James

[hakzaw1]

subbing this excellent thread-TY to all who took the time to help--

[gandalfthegrey]

Hi all, I don't want to drag this thread out but want to resolve the safety issues raised and just want to mention I have got a positive result from Laser Know How Ltd (NRG), they have offered to do a part exchange or fit a scan fail device.

@norty303. You mentioned the red diode in the Laser I have not being great at 1000mW 650nm. What about for the replacement:

Power
1000mW - 500mW - 1500mW
Wave Length
R: 638nm G: 532nm B: 445nm
Beam Specifications:
3*4mm aperture,1.2mrad

With a shutter

Many Thanks