"Brian Reay" wrote in message
...

"Plod's Conscience" wrote in message
oups.com...
Played with it last night.

Powered as it is by AAA cells, it seems to have
a greater power, and a greater reserve of power, than
those laserpointers powered by watch batteries.

Given the relative size of AAA and "watch batteries", this is hardly
surprising.

Allowing for the lens that is used to produce the
straight line beam, the spot from the end was
easily picked out on a gravestone 1/4 mile away,
thus suggesting that a tight beam is being produced.


Laser's are coherent sources, the "ASER" stands for Amplification by
Stimulated Emission of Radiation- the crucial phenomena in the operation
of lasers and masers. The emitted photon is in phase with the stimulating
photon.

As these beasties come in a mounting that already
has facilities for screw fixing, perhaps there is
potential capability for optical communications?

Been done. UK record, as of a couple of years back at least, was something
like 75km. There is project in the latest RSGB handbook (if you are
interesed I'll look up the page, I noticed the article but haven't read
the detail).


Many years ago Practical Wireless had adesign for turning every ready
torches (the ones with the big 9v batteries) into a transmitter and receiver
by amplitude modulating the bulb.
It actually worked (over about 20 feet).