Lasers and Audience Scanning MPE Calculations / Risks

[Alsone]

Hi,

I was just wondering how everybody addressed this issue as I've rapidly been getting the opinion from around the web that mobile discos / home users just risk it and I want to use my laser safely!

There are lots of mobile disco users on Youtube who show lasers scanning the sudience including one I asked recently about MPE to which he replied "Its OK because this laser uses Galvos not stepping motors" - something that means nothing as exposure time to class IIIA to cause eye damage is less than the time taken to blink and damage can't be felt and may be accumulative months / years and unoticed at first. Yet the company whose laser he users (he actually uses 2 at once!) - Prolight Ares II - said to me in an email about MPE data - "Sorry but the UK Environmental health people will not allow our lasers to scan the audience. we only sell them on the understanding that they are used as per the details in the instruction manual, (you can download it from our website).!" The manual warns of the need to calculate MPE!!!

Personally, I'm interested in buying a Purelight Tri-Beam Laser 260ms for home parties / BBQ's which I know comes highly recommended.

Like all lasers over 5mw, (the odd few fat beams aside) its Class IIIa which means that direct exposure can burn skin and or cause blindness.

Therefore in order to audience scan safely it's necessary to calculate the MPE (Maximum Permissible Exposure) and ensure that all the patterns used fall below the MPE levels.

However, the British Standard Document BS/EN 60825-1 which sets out MPE calculations costs a whopping £168+ VAT and even then the calculations are extremely complex and thus prone to user error, espcially from anyone not a qualified laserist. Laser assessment software is expensive and MPE power meters cost in the high hundreds.

So In was wondering, how does everyone address the MPE issue - is it just ignored or does anyone know of a cheap way of getting a reliable assessment.

Also, why don't manufacturers produce MPE data for their lasers for pre-programmed patterns?

It would seem sensible that for lasers like the excellent Prolight which is used for mobile disco / home use, manufacturers are in the best position to produce a data table on the basis of a minimum distance of 2 metres (which would effectively cover all common home use / mobile disco / pub applications) and which would then ensure safe usuage by all these groups and provide a useful selling point for the lasers - could be labelled "safe for audience scanning within the limits specified in the enclosed MPE table".

So how do people on here address MPE and anyone else think manufactureres should provide some standard data?

[soundtracker]

Hi,

I was just wondering how everybody addressed this issue as I've rapidly been getting the opinion from around the web that mobile discos / home users just risk it and I want to use my laser safely!

There are lots of mobile disco users on Youtube who show lasers scanning the sudience including one I asked recently about MPE to which he replied "Its OK because this laser uses Galvos not stepping motors" - something that means nothing as exposure time to class IIIA to cause eye damage is less than the time taken to blink and damage can't be felt and may be accumulative months / years and unoticed at first. Yet the company whose laser he users (he actually uses 2 at once!) - Prolight Ares II - said to me in an email about MPE data - "Sorry but the UK Environmental health people will not allow our lasers to scan the audience. we only sell them on the understanding that they are used as per the details in the instruction manual, (you can download it from our website).!" The manual warns of the need to calculate MPE!!!

Personally, I'm interested in buying a Purelight Tri-Beam Laser 260ms for home parties / BBQ's which I know comes highly recommended.

Like all lasers over 5mw, (the odd few fat beams aside) its Class IIIa which means that direct exposure can burn skin and or cause blindness.

Therefore in order to audience scan safely it's necessary to calculate the MPE (Maximum Permissible Exposure) and ensure that all the patterns used fall below the MPE levels.

However, the British Standard Document BS/EN 60825-1 which sets out MPE calculations costs a whopping £168+ VAT and even then the calculations are extremely complex and thus prone to user error, espcially from anyone not a qualified laserist. Laser assessment software is expensive and MPE power meters cost in the high hundreds.

So In was wondering, how does everyone address the MPE issue - is it just ignored or does anyone know of a cheap way of getting a reliable assessment.

Also, why don't manufacturers produce MPE data for their lasers for pre-programmed patterns?

It would seem sensible that for lasers like the excellent Prolight which is used for mobile disco / home use, manufacturers are in the best position to produce a data table on the basis of a minimum distance of 2 metres (which would effectively cover all common home use / mobile disco / pub applications) and which would then ensure safe usuage by all these groups and provide a useful selling point for the lasers - could be labelled "safe for audience scanning within the limits specified in the enclosed MPE table".

So how do people on here address MPE and anyone else think manufactureres should provide some standard data?

Hello, and welcome!

[Alsone]

Hi Soundtracker

[soundtracker]

Hi Soundtracker

Its customary on here to go to the Newbie section and introduce yourself. If you do this, you'll find people more willing to "come out to play" I won't comment on the laser thing, coz I know bog all about them!:)

[Solitaire Events Ltd]

So how do people on here address MPE and anyone else think manufactureres should provide some standard data?

I looked into this when I bought a couple of Prolight Nebulas.

I emailed Prolight and they told me to read the instruction manual.

I asked on another forum and got a laser 'expert' telling me not to worry as the beams were split too much.

I asked ProLaser UK on here and didn't get an answer that helped me either.

[Alsone]

Its customary on here to go to the Newbie section and introduce yourself. If you do this, you'll find people more willing to "come out to play" I won't comment on the laser thing, coz I know bog all about them!:)

Thanks - now completed.


I looked into this when I bought a couple of Prolight Nebulas.

I emailed Prolight and they told me to read the instruction manual.

I asked on another forum and got a laser 'expert' telling me not to worry as the beams were split too much.

I asked ProLaser UK on here and didn't get an answer that helped me either.

Its a pity no-one is taking care of this for us Solitaire.

The 1st time there's proven damage, its likely to spell the end of audience scanning for good and yet thats the very thing that makes lasers so much fun.

Its already totally banned in the US as I understand it.

The "expert" you mention has obviously little knowledge on the subject as even a split beam can in theory cause damage (not that I claim to be an expert either I might add) - what matters is the amount of energy transferred into the eye and only a check on MPE can reveal that. There are a lot of factors which is why MPE calculations are so complex but so important.

Thats why I believe that in the case of lasers, falling into the home use / mobile disco / pub price bracket - say less than £1,000, with built in pre-set patterns, the manufacturers should test these and produce a table showing which patterns are safe from a typical closest ever likely distance - 2m as this then gives a basis for home / disco / pub use. Its not hard for anyone to mount a laser so that no-one gets closer than that.

There's no reason why in respect of any patterns found unsafe from that distance, the manual couldn't say that for uses other than those in the test data, MPE calculations should be made thus leaving it open for other patterns to be used in different circumstances.

However it seems that at the moment everyone is left to take a chance as there is no way for anyone without a lot of money to verify the safety or otherwise of a laser effect for themself.

[DazzyD]

Although I confess to knowing nowt about lasers, it's good to see that people are taking the health and safety of everyone concerned very seriously indeed.

I remember a while ago someone posting comments about using strobe lighting for excessive lengths of time and believing that was ok. In fact, I think he ended up by saying "It's my disco and I don't care about anyone else so I'll keep on doing it!" (or words to that effect!).

Mind you, there was a post by Richard Veal (I think) regarding the safe distances for using lasers. Just been to look for it. Find it here (post #57):

http://www.mobilediscodirectory.co.uk/forums/showthread.php?t=11838&page=6&highlight=charlie+brown

This means little to me cos I don't use lasers (yet) but it may help you.

[Alsone]

Thanks for the link Dazzy,

Its nice to see that I'm not the only one concerned about safety.

I think Richard was wrong in his initial post though.

The safety drawing he's posted is the correct one for displays which are aerial only but is incorrect in several ways;

1. The correct minimum height as I understand it is 3m not 2.5m - this alone isn't achieveable in many rooms.

2. 2.5m refers to the minimum distance the beams must remain away from public access areas to the side of the display above ground level such as balconies

3. The 3 metre height specified is not the height of the actual projector, but it refers to the height of the laser effect. Therefore having the laser projector
positioned at 3m height and aimed directly down is not what the guidance is
saying.

Its saying NO beams should go below the 3m height.

Please note this is paraphrased from the a KAM laser user guide which can be viewed here: http://www.kam.co.uk/products/lighting/docs/KAM-Class3BLaserEffectUserGuide.pdf

Which I believe in turn repeats the guidance in the British Standards.

That represents some of the guidance for non audience scanning.

My understanding is the only way to safely scan an audience is with an MPE calculation for each pattern used to ensure the irradience level doesn't exceed the MPE exposure limit, only then can you be confident that you're not causing eye damage.

A class 3B laser by its very definition is capable of burning skin and causing blindness / eye damage faster than the eye can physically blink. Also, damage may go unoticed initially as there are no pain receptors in the back of the eye and its possible to burn holes in the periphery of the retina thereby causing damage that might no be immediately noticed. There is no treatment for laser damage as it literally burns a hole in the back of the eye!

Hence the reason for my initial quetsion on how everybody deals with audience scanning and if there's any cheap way of getting an MPE assessment of a laser set up.