[Laser] ARRL "coherent"

[Zack Widup]

On Thu, 10 Mar 2005, Karel Kulhavy wrote:

> > I would like to add a few comments on the issue of the ARRL recognizing  only 
> > transmissions from coherent sources.  It comes from one of  the general rules 
> 
> LED's are coherent - they have coherency length at least 100nm ;-) Does
> ARRL prescribe some minimum coherency length? And if yes, how much it
> is?
> 

I think coherency length was something unknown when the rule was made. 
Technology has advanced by leaps and strides, so I think it's time to 
redefine or change the rule.  

>From my recollections, the firt time I ever heard of a laser was around 
1959.  I remember ruby lasers being mentioned.  In the late 60's, gas 
lasers (small HeNe lasers) became cheap and popular.  By the early 70's, 
LED's came about and I think the solid-state lasers were developed 
slightly after the LED's.  I have 1967 and 1968 Allied Radio catalogs and 
a 1972 Lafayette Radio catalog that I just looked at.  None of them listed 
any LED's or solid-state lasers in those years.  But I recall seeing 
solid-state lasers appear shortly after that.  They were expensive! $600 
apiece. 

73, Zack W9SZ