On Friday, August 21, 2015 at 9:25:53 PM UTC-4, Phil Hobbs wrote:   
   > On 8/21/2015 6:50 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.   
   >   
   > Sure, starlight for instance.  The problem with spatially incoherent   
   > sources such as LEDs and tungsten lamps is that in order to get a small   
   > focused spot, you have to trade away almost all of your light.   
   >   
      
   Yup, laser's get all the light going in the same direction.   
   Which is pretty cool when you think about it.   
   They are also (some of them) fairly efficient.   
      
   George H.   
   > Cheers   
   >   
   > Phil Hobbs   
   >   
   >   
   > So what makes   
   > > a laser superior?   
   > >   
   > > --   
   > > Rich   
   > >   
   >   
   >   
   > --   
   > Dr Philip C D Hobbs   
   > Principal Consultant   
   > ElectroOptical Innovations LLC   
   > Optics, Electro-optics, Photonics, Analog Electronics   
   >   
   > 160 North State Road #203   
   > Briarcliff Manor NY 10510   
   >   
   > hobbs at electrooptical dot net   
   > http://electrooptical.net   
      
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