[Laser] Depth of modulation for various lamp types

[F1AVYopto at aol.com]

Kerry 
Infrared  gives a better air transparency than the sodium yellow orange  
light. 
So very  under-powered classic thermal lamps could also work with a good  
modulation. 
Try  to mount a few lamps in serial mode so the lamps are just visible  red. 
At  this temperature the modulation depth could be better and the most of 
radiant  power in the infrared spectrum. 
A  very low cost infrared filter (colour slides developed without to be 
exposed)  could then reject all the other sodium light from the city  lights. 
73 Yves  F1AVY