[Laser] laser pointer

[w.fritz at htp-tel.de]

Hello,
there are some further disadvantages in green DPSS Lasers.
The crystals for converting the frequency in visible green only work  
efficently in a small temperature range around 25 degrees Celsius.
So it would be necessary to keep the crystal temperature stable.
If not, the output may decrease rapidly with sinking or rising  
temperature. But even if you set up your equipment well, only around  
10%(maybe 15-20% in good cases) from the optical input power on 808nm  
IR will leave the laser as visible green. It would be much cheaper to  
take a high power red laser (DVD writer or similar) to reach the same  
visibility (5mW green ist as bright as 80mW red).
The other disadvantage is, the crystals only allow a narrow bandwidth.
For CW or voice communication it would be enough. But if you want to  
transport higher bandwidths (TV, Data), they are too slow. So green  
lasers are nice for shows and star pointing and so on, but not so good  
for communication via laser.
Vy 73
Wilfried, DJ1WF