From: daellis94@gmail.com   
      
   So, I'm hoping someone here knows enough about how lasers function to give me   
   some helpful pointers.     
      
   I'm doing some thinking on a science-fictional space warship that would   
   utilize a mix of rail-guns and missiles for ship-versus-ship engagements, and   
   rely on lasers for its missile defense needs.     
      
   I recently did a bit more in-depth reading on the ever-useful Atomic Rockets   
   website to try and get a sense for what I would want out of a laser used for   
   such applications.  My general idea is to use a phased-array, near-ultraviolet   
   laser (I settled on a    
   wavelength of around 250 nanometers, because why not) that would deliver   
   energy in a series of microsecond pulses at a rate of four pulses every   
   second.     
      
   My hope is to justify a laser that could deliver energy at a rate sufficient   
   to cause impulsive shock effects in steel at a range of 500 kilometers.  This   
   is partly a goal, and partly a starting base-line for my own calculations.  As   
   a base-line, I was    
   also thinking of average power consumption comparable to the ~5 megawatt   
   chemical oxygen-iodine laser used on the Air Force's YAL-1 prototype.     
      
   I calculated the power required to vaporize steel at a rate that would exceed   
   the velocity of sound in steel, and tried to work back from there using Atomic   
   Rockets's laser equations, treating the phased-array laser as a unitary laser   
   system with a 2.5-   
   meter lens.     
      
   If I take the energy of a one-second beam at 5 megawatts and divide it into   
   fourths, and take each of those four pulses and compress it into a one   
   microsecond period of time, the energy delivery of a diffraction-limited laser   
   would appear to require only    
   a little over 3 megawatts (average beam power, this is, not peak pulse power),   
   but adjusting the numbers to account for a beam with an arbitrary quality of   
   3, the average power needed was between 28 and 29 megawatts.     
      
   Now, working out how much beam power is more than I want to provide is easy   
   enough.  I simply have no real basis for knowing or understanding what kind of   
   beam quality makes sense for a laser of a particular power, size, etc.  I also   
   don't know how to    
   relate the quality of phased-array beam to that of a conventional beam in any   
   reasonably believable terms.     
      
   Another problem is that I have no idea whether I am understanding pulsed   
   lasers correctly.  Is compressing a fourth of a second of energy into a   
   microsecond pulse even something a designer would have the freedom to do?  Do   
   pulsed lasers work like that?     
      
   Hopefully there is someone here that understands lasers better than I do.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)