On Friday, October 9, 2015 at 3:17:33 AM UTC-4, Mike S wrote:   
   > On 8/21/2015 3:50 PM, RichD wrote:   
   > > Lasers are useful for their low dispersion.   
   > >   
   > > What I wonder is, why are they necessary for the   
   > > most common applications?  e.g. bar codes, CD readers,   
   > > etc.   
   > >   
   > > My point is that collimated, non-coherent light   
   > > was developed long before the laser.  So what makes   
   > > a laser superior?   
   > >   
   > > --   
   > > Rich   
   >   
   > Knowing nothing about lasers I found this discussion interesting. On   
   > what may be a related note, does anyone know anything about the lasers   
   > used in the devices they try to find gravity waves with?   
      
   Well only from light reading.  Ligo (which is what I think you are talking   
   about.)   
   is now moving to advanced ligo. https://www.advancedligo.mit.edu/   
   (read away...)   
      
   It's a huge project, maybe a thousand scientists.   
      
   George H.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)