Re: Re: "Laser beam" deterrent

["Wayne" <wayne@xxxxxxx>]

I must admit - I've always like the idea of setting up a laser bouncing
aroung the garden (its a rectanguler jobbie) off mirrors and the like in a
criss-cross(?) pattern... Then when theres a bit of foggy weather you'll
get
that 'high security out of hollywood' effect :)

Using the dry ice idea sounds cool too! - although I could just imaging
getting up to the kids pointing out all the dead cats that have suffocated
the night before!!

Nothings perfect!

Wayne :-)


----- Original Message -----
From: "Keith Doxey" <ukha@xxxxxxx>
To: <ukha_d@xxxxxxx>
Sent: Tuesday, October 14, 2003 10:46 PM
Subject: RE: [ukha_d] Re: "Laser beam" deterrent


> -----Original Message-----
> From: Ian Tresman [mailto:ian@xxxxxxx]
>
> > The only way to see WHERE it's going is to suspend (*) something
in
> > the way and watch light reflected off it. This typically breaks
the
> > coherence, so you can see the impact from a wide viewing angle.
> >
> > A smoke machine is indeed good for this purpose :-)
>
>
> I'm a bit worried about the chemicals used in smoke machines... so
> maybe I'll try this with one of those ultrasonic water
"mist/fogger"
> machines.
>
> I only want people to see the laser for its deterrent effect.
>

There are three ways to get a smoke/fog effect.

Modern Way - ultrasonic mist machines but they increase the humidity in the
air because it is filled with microscopic water droplets

Most common way - fluid based smoke machine - uses an oil based smoke fluid
usually scented to obscure the smell of oil. Can set off smoke alarms and
can leave an oily film over time.

Oldest method - Dry Ice plunged into boiling water - creates a blanket of
fog that hugs the floor like real fog. Only two slight drawbacks.
1. Touch the dry ice and you fingers tend to drop off
2. Become immersed in the fog and you suffocate because it is pure carbon
dioxide.
It does have a couple of plus points though - disappears without a trace -
will silently eliminate burglars who try to slide under the laser beams.

As a safer alternative to lasers, if it is purely for effect, how about
ultra-bright LED's focused through a lens to simulate a laser. If fitted in
a chrome tube it could create a fairly tight beam. Not as tight as a laser
but the average burgular wouldnt know the difference.
____________________________________________________
)
LED                                            LENS )
____________________________________________________)


Keith

www.diyha.co.uk
www.kat5.tv



UKHA 2004: 15th and 16th May 2004

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