Hi Marcus,
Thanks for writing to us, and for paying such close attention to our writings. That article that appeared in The Laserist magazine was written very long ago, but still has great information. However, my general recommendations are as follows:
1. Generate a completely non-moving and unmodulated beam (not terribly easy with FB4, since we *really* try to keep things safe and apply modulation when needed). This may require you to turn on the lasers someway-somehow that does not involve the FB4.
2. Through lensing and also adjusting the maximum laser power (probably operating at below 100% -- i.e. below 5V modulation level), make sure the *irradiance* at the closest point of audience access does not exceed 10mW per square centimeter.
One way of doing this would be to create a 7mm aperture (for example, sheet of metal with a 7mm hole in it), project your non-moving beam toward (and through) that hole, and make sure a regular old laser power meter (located on the other side of that hole) reads no greater than 5mW.
It's a little secret (although sometimes discussed by me and John O'Hagan) that 5mW into a 7mm round aperture is roughly equivalent to 10mW per square centimeter.
(As a review of laser classes: Class 3R is nothing more than "5 times Class 1". Since Class 1 is 1mW, Class 3R is 5mW into the 7mm round aperture.)
The real challenge is finding a laser power meter that will measure in the milliwatts, but Thorlabs actually has a few, including one that can measure white light in the milliwatts.
3. Once you've accomplished points 1 and 2 above, you are *pretty much* home free, and the reason why you are is because you will have created a scenario where the laser projector puts out what is effectively Class 3R light levels. Therefore any scan fail on top of that would improve things even further.
So -- as a general recommendation, adjust FB4 scan guard to the point where it does not "cut up" (i.e. start interfering with) *normal* show content such as sheets, fans, tunnels, etc.
Note that the use of SafetyScan lenses along with FB4 would surely be better than nothing, and we would solute you for doing your part to keep laser shows safe. But it's still not as good as PASS, because PASS plays a more active role in laser show safety, and has an electronic design that includes redundant circuits. So PASS is still the gold standard for touring shows and mission-critical situations.
Best regards,
William Benner