William,

There are two ways I can see you doing this.

#1: Use infared beams that bounce off of a reflector back to the source to
produce an alarm when the beam is broke. You can pick these up at Radio
Shack for around $50 or so... These have good points and bad points. Good
point is they are already built, bad point is they won't bounce around on
mirrors.

#2: Use a laser diode as the source and a circuit with a solar cell at the
destination. It would be a simple circuit to build containing a solar cell
(or a phototransitor), an opamp, and a relay. Basically the relay would be
latched when the beam hits the destination and release when the beam is
broke, causing an alarm or whatever you want it to do. The good point is
that it will bounce off of many mirrors and you could even see the beam :)
The bad point is someone would have to build the unit and make sure that
they are aligned as there is little room for movement like the infared beams
at radio shack have.

Hope this helps. Let me know if you want me to find the part #s at radio
shack or need more detail regarding the laser option.

-Harry

-----Original Message-----
From: Museum discussion list [mailto:[log in to unmask]]On
Behalf Of William Grewe-Mullins
Sent: Friday, November 23, 2001 7:33 AM
To: [log in to unmask]
Subject: Laser barriers


Date:    Thu, 22 Nov 2001 02:06:59 -0600
From:    Harry Aller <[log in to unmask]>
Subject: Re: Laser barriers

What is the distance between the source and destination???


I need to set up several small barriers, probably no further distance than
ten feet total, each, to protect uncovered sculptures, mosaics, etc...
I'd also like to protect some from 2 sides, and if possible use one sending
and one recieving unit for this, hopefully turning a corner with a mirror.
I have no Idea if any of this is practical, but I'd like to find out.
Wil

=========================================================
Important Subscriber Information:

The Museum-L FAQ file is located at
http://www.finalchapter.com/museum-l-faq/ . You may obtain detailed
information about the listserv commands by sending a one line e-mail message
to [log in to unmask] . The body of the message should read "help"
(without the quotes).

If you decide to leave Museum-L, please send a one line e-mail message to
[log in to unmask] . The body of the message should read "Signoff
Museum-L" (without the quotes).

=========================================================
Important Subscriber Information:

The Museum-L FAQ file is located at http://www.finalchapter.com/museum-l-faq/ . You may obtain detailed information about the listserv commands by sending a one line e-mail message to [log in to unmask] . The body of the message should read "help" (without the quotes).

If you decide to leave Museum-L, please send a one line e-mail message to [log in to unmask] . The body of the message should read "Signoff Museum-L" (without the quotes).