Trying to Find Class 1 Laser Diode

On Thu, 23 Jun 2011 21:48:49 -0700 (PDT), Patty <bonnypatty@gmail.com>
wrote:

On Jun 23, 8:17 pm, "k...@att.bizzzzzzzzzzzz"
k...@att.bizzzzzzzzzzzz> wrote:
On Thu, 23 Jun 2011 15:51:12 -0700 (PDT), Patty <bonnypa...@gmail.com> wrote:
I need to make a laser pointer for a profoundly disabled friend.  It
needs only to point 3 inches so I'm looking for a Class 1 laser diode
that will be safe for him despite his erratic movements.  Any help in
locating a Class 1 laser diode that would be appropriate would be
REALLY appreciated.

What color?

Thanks a lot for your response. Color isn't so important as long as
his pointer would still be easily visible when it hits an object
(plastic communication board because my fiend is aphasic) about 3
inches away.

Trish
Greetings Trish,

Green light is percieved by our eyes much better than red light.
Especially the red light typical of cheap laser pointers. So an
attenuated green laser of a much lower and safer energy can still be
seen while a red laser attenuated the same amount would be invisible.
However, cheap green laser pointers use a couple crystals to generate
green light from infra red light and one of these crystals (KTP) is
temperature sensitive. At too low a temperature the light output falls
off drastically. Low temp operation also extends the life of this
crystal. High temps from a constantly on laser will eventually degrade
the crystal. So I'm thinking that maybe operating a green laser with
less current will not only result in much lower energy output but will
enable the laser to be operated continuously without shortening its
life considerably. And be easier to see.
Eric