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Thread: Safety- double-checking some details

  1. #1
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    Question Safety- double-checking some details

    Original post below, I didn't want to create a new thread for the same topic. So I'm reusing this thread. We were always told t'was good to recycle

    I'm still filling out paperwork for an event that I don't know whether will go ahead or not, but I'm having to do it anyway. Now, what I'm posting here is stuff that I've gathered from research (both FDA/CDRH documents and stuff on the ILDA site). I figured that posting it up here for some of the more experienced members to peer-review would be a good idea. So, this is either going to be more or less accurate, or I'm going to be eaten alive. I don't know.

    So, I've looked over what *could* go wrong, assuming worst case scenarios with no precautions in place:


    • Accidental exposure of audience to laser radiation above Class 1 levels through deliberate projection and scanning (such as audience scanning)
    • Accidental exposure of audience to laser radiation above Class 1 levels through accidental projection and scanning (equipment is inadvertently moved)
    • Accidental exposure of audience to laser radiation above Class 1 levels through access to beam termination surfaces or projection area.
    • Accidental exposure of audience to laser radiation above Class 1 levels through deliberate audience means. (such as jumping into laser beams)
    • Reflection hazards from surroundings and beam termination surface
    • Reflection hazards from objects deliberately placed into beam paths
    • Unauthorised usage of equipment resulting in inadvertent audience exposure to laser radiation above Class 1 levels
    • Equipment failure resulting in inadvertent audience exposure to laser radiation above Class 1 levels (during galvanometer failure or power loss)
    • Inadvertent access to restricted areas containing beam paths resulting in accidental exposure above Class 1 levels
    • Inability to terminate laser emission in a potentially hazardous scenario

    Now, what follows is an incoherent mess of dot-points, regarding each section. This is far from the finished version- everything here is simply in note form. I've broken the hazards up and addressed them section-by-section. Once again, apologies if it's hard to read.

    1. Beam paths and Beam Termination

    First of all, the beam path diagrams:



    (LOP is lighting operator)



    The beam [b]is projected onto the biobox at times, but it gets nowhere near the window of the biobox. The crew inside will actually need to lean out of said window (which isn't physically possible) in order to be exposed to any laser radiation.

    In those pictures, you'll see three points (A, B and C). Power density measurements for these three points will be given once the projector specifications have been finalised. However, these three points represent the three points required- A at the entry point to the audience, B at the exit point, and C at the beam termination surface.

    The beam termination area will be off-limits to everyone, except those already in the biobox. All crew in the biobox will be know about the projection, and there will be no projections on the stairs leading from the box.

    The beam termination area is also separated from the audience by a distance of 10 metres. As stated before, nobody will be allowed in this area in-between. There are no reflective materials of any kind on the beam termination surface capable of generating any specular reflections. At this distance, the power density from looking into a ceiling-mounted PAR64 is greater than the diffuse scattering from the surface.

    The DJ has also been told to use the stairs next to him, instead of cutting straight across the beam path.

    2. Operator and other people-stuff.

    I'll be personally running the laser, as well as lighting.

    I will be next to the laser at all times. The laser will not be run unless I'm there, on-stage. From my vantage point, I will also have a full view of all beam coverage areas.

    There will be someone supervising the entrance to the beam termination area and biobox to prevent anyone from getting in back there and accidently exposing themselves.

    No other laser devices apart from the projector will be in use that night. This includes any pointers brought in by audience members.

    3. Scan angles

    Three levels of scan angle enforcemnt:

    1. First level through software
    2. Second level through the mounting of the galvanometers themselves (the Y galvo will be moved to scan higher)
    3. Third level through a set of barn doors attached to the aperture, making it physically impossible for the beam to reach outside the limits set by said barn doors.

    4. Interlocks and Emergency stop.

    There will be a keylock on the projector. Lasers cannot power up unless key is inserted, even if power is connected.

    There will also be a secondary attenuator (constant-duty solenoid and beamdump). This attenuator will be connected to the galvo sub-circuit, so if power is lost to the galvos, then the attenuator closes too. (perhaps the world's most primitive scan-fail?)

    The switch to open and close this attenuator will be next to the aperture. This switch is illuminated, and will also serve as an emission indicator.

    Emergency stop will be in the form of one of those big red push-button thingys. This will be in-line with the projector, and on the operator's table at all times. This will hard-cut power to all circuitry within the projector when pressed. There are also multiple of these emergency stop devices in the hall itself, both on-stage and at ground level.



    Original post below line:
    _____________________________________

    Hey all,

    I come from 'the other forum', but recently I'm putting a projector together, and will be using it for a few shows. I'm clearing up the safety info first as I need to get some paperwork pushed through.


    The details of the projector have been fleshed out, but I will post a thread with its' specs to confirm I'm doing everything right.


    But first- something more important than the details about the projector-safety. I've talked with
    Things about it, and he's been a great help, but I just want to check on a few more details.

    The projector itself is a 1.6W RGB (650-1W, 445-300+mW, 532-300mW), and is running through a 40kpps Spacelas scan set. All three lasers will be analog modulated.


    Firstly, there'll be no audience scanning. Although it does seem obvious, I just wanted to make it clear that's definitely off the list.


    Secondly, the beam will not come lower than 1.5 metres above head level at all times. This will be enforced with projector placement and an aluminium sheet as an aperture.


    Thirdly, the beam will be terminated on a wall that will be out of visual sight. The back part of the venue will be blocked off using an opaque temporary wall, with the end result being the beam spots on the wall will be out of direct sight of everyone on the floor.


    The venue is 40m long, and the projector will be located on a stage (and on a mount) 3m above ground level.


    There will be an emergency stop switch in line with the projector power, and a manual aperture which can be activated with a toggle switch (and when power is lost to the scan set).


    There will be nobody else on my half of the stage, and the projector will not be operating unless I am within reach of both the computer and the projector itself.


    In Australia we don't need variances, but I'm triple-checking to make sure everything is safe.


    Is there anything I should be aware of?


    Cheers,


    Andrew
    Last edited by goninanbl00d; 01-02-2011 at 18:12.

  2. #2
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    Thumbs up Sounds good to me!

    It looks like you've done your homework.

    So long as you are always within reach of that kill switch, you should be fine. Be on the lookout for "audience unruliness" though. That is, anything that happens when people get drunk (or high) and come up with creative ways to put their bodies (or eyes) into the beams. Things like standing on tables, standing on shoulders, or climbing up the poles that hold the balcony up... (I've seen it done!)

    But from a safety standpoint, it sounds like you've got all the bases covered. Well done. Take some pictures of the show and let us know how it goes!

    Adam

  3. #3
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    Quote Originally Posted by buffo View Post
    It looks like you've done your homework.

    So long as you are always within reach of that kill switch, you should be fine. Be on the lookout for "audience unruliness" though. That is, anything that happens when people get drunk (or high) and come up with creative ways to put their bodies (or eyes) into the beams. Things like standing on tables, standing on shoulders, or climbing up the poles that hold the balcony up... (I've seen it done!)

    But from a safety standpoint, it sounds like you've got all the bases covered. Well done. Take some pictures of the show and let us know how it goes!

    Adam
    Yeah, I did a fair bit of reading beforehand. Much better get it right than wrong.

    It's for a school event with <30 people, and with adequate supervision, too. Not much chance of drunkenness or people getting high. (Well, I'd hope so)

    It'll just be me and the DJ on stage, and I'll be in my own little corner.

    I also forgot to add the projector will have a keylock on it, which cuts power to the lasers (but not to the galvos).

    Also, I may have logistical issues getting the movable walls in place, and beam termination may need to take place on a white wall.

    Less than ideal, yes, but it may just be safe. I I know there are calculations for maximum safe distance for diffuse viewing, but I don't have formulas or know what to do with them.

    Meanwhile, going by some data:

    Red: 127mm beam diameter at 40m, 6.2mW/cm2 3mRad divergence, 7mm beam diameter at aperture

    Green: Assuming 2mRad divergence and 1.5mm beam diameter, 81.5mm beam diameter at 40m, 4.516mW/cm2

    Blue: Assuming 1.5mRad on SA and 5mRad on FA (O-Like glass lens), and 5mm beam diameter at exit, 65mm x 205mm beam diameter at 40m, 2.62mW/cm2 (going by 350mW, may be increased for color balance)

    I will try to get somewhere to terminate the beam, but if that doesn't work out, the beams may have to be terminated on the wall.

    Either way, the back half of the hall will be fenced off, and there'll be at least 15m between the nearest person and the wall.

  4. #4
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    Quote Originally Posted by goninanbl00d View Post
    Meanwhile, going by some data:

    Red: 127mm beam diameter at 40m, 6.2mW/cm2 3mRad divergence, 7mm beam diameter at aperture

    Green: Assuming 2mRad divergence and 1.5mm beam diameter, 81.5mm beam diameter at 40m, 4.516mW/cm2

    Blue: Assuming 1.5mRad on SA and 5mRad on FA (O-Like glass lens), and 5mm beam diameter at exit, 65mm x 205mm beam diameter at 40m, 2.62mW/cm2 (going by 350mW, may be increased for color balance)

    I will try to get somewhere to terminate the beam, but if that doesn't work out, the beams may have to be terminated on the wall.

    Either way, the back half of the hall will be fenced off, and there'll be at least 15m between the nearest person and the wall.

    Based on the above specs audience scanning will be at MPE levels with a fast scanning device, good designed frames (no pencil beam.), etc

    Attached table can be of interest for you.
    Attached Thumbnails Attached Thumbnails MPE..JPG  


  5. #5
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    Quote Originally Posted by mccarrot View Post
    Based on the above specs audience scanning will be at MPE levels with a fast scanning device, good designed frames (no pencil beam.), etc

    Attached table can be of interest for you.
    Well, it's good to know at 40m I theoretically can audience-scan. I'm still worried about beam termination, though.

    In no way is the beam going to be even near the audience at any point. It's a cheap projector that I put together, and I certainly don't trust my work enough.

    Thanks for your and buffo's help.

  6. #6
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    Double post and necro-bump. I think that calls for a public hanging by the Janitor, no?

    Anyway, instead of creating a new thread, I've added everything I've got so far into the first post.

    Apologies if it's hard to read, it's all in note form (nowhere near finished).

  7. #7
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    That is very comprihensive regarding the direct laser hazard

    I may be stating the obvious and you might have covered this in a seperate section but I always cover the other hazards too: Electrical hazards to yourself and third parties, mechanical hazards like trip hazrds from cables, sharp edges, projectors falling, you falling during setup etc and hazards from the fog/haze, including a section on maintaining the fog/haze machine to your relevent government standard to prevent nasties being emitted or the machine catching fire.

    Ian
    http://img62.imageshack.us/img62/3985/laser.gif

    Doc's website

    The Health and Safety Act 1971

    Recklessly interfering with Darwinís natural selection process, thereby extending the life cycle of dim-witted ignorami; thus perpetuating and magnifying the danger to us all, by enabling them to breed and walk amongst us, our children and loved ones.





  8. #8
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    Quote Originally Posted by Doc View Post
    That is very comprihensive regarding the direct laser hazard

    I may be stating the obvious and you might have covered this in a seperate section but I always cover the other hazards too: Electrical hazards to yourself and third parties, mechanical hazards like trip hazrds from cables, sharp edges, projectors falling, you falling during setup etc and hazards from the fog/haze, including a section on maintaining the fog/haze machine to your relevent government standard to prevent nasties being emitted or the machine catching fire.

    Ian
    Oh, I'd forgotten about those.

    I had a section for fire safety, but I didn't have anything about OH&S. I'm adding that in now, nor did I remember that foggers get *hot* and are another fire ris.

    Thanks for the heads-up.


    Cheers,

    Andrew

  9. #9
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    'Big red push button thingy'

    or 'mushroom switch' or latching emergency stop switch.

    You might also mention that the laser can't re start simply be resetting the kill switch.
    http://img62.imageshack.us/img62/3985/laser.gif

    Doc's website

    The Health and Safety Act 1971

    Recklessly interfering with Darwinís natural selection process, thereby extending the life cycle of dim-witted ignorami; thus perpetuating and magnifying the danger to us all, by enabling them to breed and walk amongst us, our children and loved ones.





  10. #10
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    Quote Originally Posted by Doc View Post
    'Big red push button thingy'

    or 'mushroom switch' or latching emergency stop switch.

    You might also mention that the laser can't re start simply be resetting the kill switch.
    Ahh, so they do have a name.

    I've seen them referred to simply as "latching emergency stop switches" in catalogs, so I guess that's what I'm gonna go with in the paperwork.

    Also, the relay circuitry may be added as a part of the emergency stop, there's more than enough room in the box to do so. It'd be it's own sub-circuit running from 12V, but this can happen later.

    I'll be there the whole time, and if power is lost to the projector, that'd either mean that the whole venue's lost power, or that I've tripped the power.

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