Info on scan fail systems

[Lynx]

Hi Bill

Thank you once again for you very open an informative comments.


Quote Bill
You have to increase the divergence period (unless you want to use 5 milliwat lasers). This might seem controversial to some, but not to the people who really know what the hell they are doing. James, back me up here...

I can also back you up on this & I am sure James would also, but it is also important to understand the power density will be reduced with an increase in divergence. The resulting power density will also depend on the initial power, even if we do use a 1W CW laser at 10mr, 2 mm dia we are still looking at approx. 22m NOHD for a single beam exposure. Therefore even if the beam is diverged my view is that it cannot be practical to use more than a 500mW projector for audience scanning purposes unless you spend serious money to obtain a system like PASS.

I for one do not wish to have the HPA (Health Protection Agency) cross examining myself in a court if things were to go wrong, purely because I had not covered even the basics of laser safety !!.

I do agree it would be a good project for hobbyists to create a simple scan fail project, but count me out as I would not wish to be the one who put forward a circuit only to find myself in court trying to say it was not me my lord ?? they built it !!

My ideas on audience scanning involves some ideas put forward by Greg Makhov & John Tyrer, but I certainly wold not make them public without external independent evaluation.

I have also in the past, offered and even given advice free and open to members of PL and UKLM, the offer still stands if anyone is interested in a safety workshop type event at the next meeting.
I am also willing to offer a day or two at our office in Durham for up to 10 people to show how to create a safer display, and debate audience scanning FREE as this is not only in my own interest, but also to protect the industry.


Regards


Kevin

[Jem]

I am also willing to offer a day or two at our office in Durham for up to 10 people to show how to create a safer display, and debate audience scanning FREE as this is not only in my own interest, but also to protect the industry.

Nice one Kevin, Count me in!, i'm always willling to learn

Just let me know a time and date.

Jem

[Pangolin]

Hi Jem,

Thanks for the comments. Regarding a trip to UK for me, I am sure it will happen sooner or later. It's just that up until now, the UKLM have always conflicted with other travel in my schedule.

And regarding me and James getting together at a meeting, that would be nice. We have worked together within ILDA, and on private matters. I consider us to be buddies and laser colleagues. But I can say that James certainly knows everything that I do for laser safety, and no doubt more. I do think I bring a kind of fresh perspective, or approach a problem from a different angle. I guess my point is, if you have a meeting in UK and James is present but I am not, that shouldn't be considered a deficit!

@Lynx, yes, in a medium size room, you definitely don't need more than 500mW to do audience scanning. In a small room, really 250mW is more than enough. You don't get up until the 1 watt range until you have a larger venue.

And when I mentioned a kind of "open source" scan fail circuit, what I am talking about is that people on PL basically collectively contribute, and then collectively benefit. But, as an "open source" project, there is no owner, and thus, nobody to sue (at least theoretically)... For my own part in this, I will not, for example, put forth a circuit diagram. But as others do, I will be glad to comment on what I would think are the weeknesses and strengths.

And also, this is really an idea only for a hobbyist-level project. Basically, to prevent the moms and daughters from having an accidental overexposure during a garage-type show. True professionals (and I lump anyone getting paid for doing a laser show in this category) will need a more substantial safety system than this "open source" idea, and should be able to afford it. Note I am not talking about people affording PASS, because we try hard NOT to sell that one .

Bill

[Banthai]

Bill said

Heck, at a PL meeting in Florida, we borrowed somebody's eyeglasses and taped them in front of the projector

haha ... want safe audience scanning ....Should have gone to specsavers


ok does not translate across the pond ... ( its a TV ad )

Should have gone to eyeglass world not the same ring for us brits

all the best ... Karl

PS ... HI Kev .... hope you are ok buddy ...

[aijii]

Dave and I toyed around with velocity sensing and feedback/ilda signal comparison circuits a while back. We got it _almost_ working, in that some ILDA images had hotspots removed from them. We couldn't get predictable results from it accross our range of laser effects.. but we aren't electronics super geniuses either.

I'll chat to dave about it... but we may put our work into the puiblic domain for others to toy with and make better, obviously washing our hands of any responsibility etc etc...

[Lasermad]

Really enjoying this disscusion here !

Post 18 by adam should be summarised slightly and made a sticky ... and then printed out and stuffed down the throat of every mobile DJ around the world .......... it seems a good summary as to why very few people *anywhere* can do audiance scanning with an audit trail strong enough to protect themselves , and their audiance.

Its seem YES a lot can be done to ease ones own consiounce , and lot can be done to make yourself feel you have done the best within your own abiliites to minimise risk ..but i think the debate here and other debates around PL in the past have proven to cover yourself in court is pretty much outwith the abilities of the majority in terms of finances and ability .....so it simply should not be done for a paid public gig if you value your future financial prosperity.

I attended the laser visuals course an it was enjoyable day out with a lot of info , and a healthy pack / reminder / guidance book to take away and its fantastic to see james and kev here passing on so much useful info ..... if i had one criticism or advice to james to improve the course .... although i do understand you are trying to cover lot of bases for your mixed group of attendees .......... is it would have been great to see the theory turned into reality with a bit of practicality ....... IE/ Look heres a safe projector ..look theres the interlock ! thats the scanfail installed there .....and hey lets turn it on a look at some safe frames ...lets debate /discuss about how we can audiance scan in THIS room safely and do the calculations and look over this equipment thats used to measure the power etc......... all of this was discussed it for me would have been more user friendly to try a practical excercise with a real projector ..... however even with this i currently beleive doing the audit trail paperwork AND ACTUALLY BE ABLE TO DEFEND IT to audiance scan would only really be practical on VERY well paid job and with lot more knowledge and equipment that i can currently afford ..so no audiance scanning for me for a very long while !

Anyways great thread

PAUL

[Jem]

Hi Jem,

Thanks for the comments. Regarding a trip to UK for me, I am sure it will happen sooner or later. It's just that up until now, the UKLM have always conflicted with other travel in my schedule.

And regarding me and James getting together at a meeting, that would be nice. We have worked together within ILDA, and on private matters. I consider us to be buddies and laser colleagues. But I can say that James certainly knows everything that I do for laser safety, and no doubt more. I do think I bring a kind of fresh perspective, or approach a problem from a different angle. I guess my point is, if you have a meeting in UK and James is present but I am not, that shouldn't be considered a deficit!

Hi Bill

We don't want you over here just for discussing the safety points... I have no doubt that James is quite capable (although two heads are always better than one)

I was more thinking along the lines of scanner tuning / Pangolin software tutorials / giving us loads of helpful hints and tips etc... and just to meet you in person as you seem a real nice helpful guy and i'd like to buy you a pint

Cheers

Jem

[buffo]

Really pleased to see this thread continue like this. Lots of great information!

Bill - one quick question: I thought ILDA was working on a "laserist training certification" standard of some sort. I seem to remember Aaron Bacs talking about it at FLEM Mark II back in March. (Or maybe it was Clandestiny - I forget...)

Anyway, the gist of it was that they had developed two knowledge standards that could be covered in a 1 day or a 3 day seminar. It covered simple things like CDRH requirements, basic laser safety, and so on. I think the 3 day class actually got into some MPE calculations.?.

What ever happened to this project? Did they release it? Is it still being developed? Because it sounds like a *really* good idea, particularly for the growing body of hobbyists here on PL.

Adam

[Pangolin]

Hi Adam,

That's something that is still under development as far as I know. Please contact Patrick about it, at ILDA.

Bill

[greenalien]

Mr Lynx

From the British Standards website :

If you manufacture or import a product which falls within the scope of one or more of the New Approach Directives and wish to place your product on the market in any of the members states of the European Economic Area (EEA), then you must apply CE marking to your product against the essential requirements of all these applicable directives.

you have a duty to ensure that your public or any other person is not exposed to any unnecessary risk

Absolutely. But having CE marking on a laser is no guarantee that it's being used safely!