Wood and Tin foil

[laserLips]

I have decided to make a case form wood as the metal one I have is to small.
Obviously some light will hit the inside of the case form maybe a dichro reflection. It may egnite at some point which wouldnt be very amusing.
If I covered the insides with tin foil, would that stop the posibility?

What about crumpling it all up so the surface is uneven, then the beam might split up into different directions and not be so strong.

Cheers,
graham

[VJ AIWAZ]

use blackwrap its like thick black tinfoil

http://www.videosmith.com/shop/index...roducts_id=114

[stanwax]

The power being lost is unlikley to ignite wood but its a good precaution to take. What you need is not something shiny - like tin foil - especially if it bounces the beam in an unwanted or uncontrolled direction - but rather something dull that has enough mass to dissipate the energy that it will be absorbing. For what you need a piece of black anodised aluminium of 3mm thick would do or a small steel plate 1 mm thick preferably painted black - somthing which wont burn but will absorb the heat/energy

Rob

[laserLips]

OK cool cheers


...

[mliptack]

Just to support the above post, blackwrap is great for stray light, and it's readily available at theatrical supply stores. Graham where are you located? If youre in the states I would be more than happy to send some to you, I dont have much... but it would give you an idea....

[laserLips]

That's really kind Mliptack but unfortunately I'm in London, UK.

I'll see if that company deliver to UK and how much. If it's not too bad then I'll grab myself a roll of that and line the inside with it.

Is it sticky? What would I use to pin it down, glue?, Staples (not shiny ones obvioulsy)
Graham

[VJ AIWAZ]

http://cgi.ebay.co.uk/New-Black-Wrap...QQcmdZViewItem

[laserLips]

Nice one thanks :0)

[mliptack]

It's not sticky unfortunately. Its made to cover light leak from theatrical lights, so adhesives wouldn't hold when the light is on. If you haven't built the case yet you might consider folding the blackwrap into the seams of the wood before you nail it together. I think that would make a pretty clean looking finished product. The other problem with using other adhesives is they would have to be made for high temp. The blackwrap will convert almost all of the light energy into heat, so the adhesive would cook pretty fast...

Putting the blackwrap in the seams would be a good option since it would create a bit of a air gap between the wood and the blackwrap. That way you are less likely to start burning the wood. If I have any time at work tonight I'll throw together an experiment with it (although I wouldnt be able to use a laser since I dont have it here but I will use a pretty intense concentrated light source, we've got plenty of those!)

[stanwax]

I dont think this is going to be a problem - even with glue. The light that is likley to hit it will be loss from the dichros and if that is enough to burn wood even if it is staright on to it then he needs to throw away the dichros and get some ones that work!

With a bit of luck even with several hundred milliwatts the losses will be only a few 10's of mW max - like I say if its more than this there is a different problem.

Rob