I never said that, however venues have their license granted based on certain activities happening in the venue, 'pyro and special effects' being the coverall that lasers fall into. If they do not have provision for these activities on their license then they are required to apply on an individual basis. If they do have provision for these activities there will usually be some fairly clear specs about what can and cannot happen and how.
So you as an operator do not have to have a license, but you may be required to work to particular standards, and prove modes of operation when you do go into those venues. As I said, venue managers are often ignorant of these facts, which is why its not as much of an issue as it perhaps should be.
Since the publication of HSG95 and the Green Book, many local licensing authorities have used the recommendations in those publications as the basis for granting entertainments licenses to venues.
as long as the scanners are scanning it will not do any damge to your eyes IF the scanners do fail they are are linked to blanking relay which will turn off the diode with in about 0000.2 sec
Safe crowd scanning is all about safe MPE, and not about whether they are scanning or not, some patterns are safer than others, but as its so difficult to actually measure any particular pattern its very hard to prove what the output is. speed of scan is also less relevant as although it may be moving quicker, it is also passing over the eye more frequently. A static spot or a corner that is 'hot' will carry far higher levels than the middle of a line, so another variable to consider
Not seen the feedback blanking advertised on too many cheaper chinese lasers, as they often use galvos without feedback option. I agree though, the chinese are really pushing the market on, CNI, Laserwave, Lasever amongst others are all actively engaged in user testing to improve the product.
The link at the bottom of the page makes special mention of scan fail detection devices, and that if a projector doesn't have one it shouldn't be considered for crowd scanning
ther's no such thing as a trained operator and 500mw isn't that bright. Ive had my 1.8w laser in clubs that hold 500 people before and guess what no one was hurt and everybody could still see at the end of the night.
http://www.laservisuals.com/training.htm
I think that your anecdotal evidence as to injury may be just that. The fact that nobody actually got hurt is not proof that it may still not be a hazardous practise. There is evidence to suggest that people do not notice damage if it is not directly in the centre point of vision, and that the brain tends to 'fill in the gaps' so that damage is not so noticeable anyway (although still very much there)
I would disagree that 500mW is not that big, its cwertainly big enough to punch holes very quickly through tape at range, and do the whole lighting matches trick.
Again, there is first hand evidence from people with display laser injuries that happened with lasers of 200mW and under.
Here's a somewhat dated explanation of some of the facts and myths as represented by Nulight, which explained the a decade ago. It comments on the HSG95 documents and the fact that licensing authorities will be working to the guidelines in the future.
http://www.nu-light.co.uk/lasers/lfactsandmyths.htm
Also, North Devon's EHO website as an example states the following in relation to laser use: The one in red is often the kicker, if you cannot demonstrate the calculation of safe MPE at every position then the crowd scanning is a no-no
Class 3B & 4 Laser Products (eg. used for display purposes)
- The operator of the laser system should provide the proprietor/employer etc. with sufficient information to demonstrate it can be used safely.
- Minimisation of the emission of invisible and visible radiation.
- All equipment to be rigidly mounted.
- Use of non-flammable beam stops.
- Supervision by competent person.
- Control against unauthorised use.
- Demarcation of laser display areas.
- Secure and appropriate siting of laser control console.
- Emergency cut-off.
- Laser radiation exposure levels to be determined in advance at all appropriate positions.
- Marking of area boundaries.
- Precautions in setting up and aligning laser systems.
- Functional checks prior to public operation.