XPost: sci.electronics.design   
   From: the_obamunist@whitehouse.gov   
      
   "Jim Thompson"  wrote in   
   message news:flv9q69p4kj3glv8q5v230vgjvgnfv0ke0@4ax.com...   
   > On Tue, 12 Apr 2011 20:11:25 -0400, Phil Hobbs   
   >  wrote:   
   >   
   > [snip]   
   >>>   
   >>   
   >>Mechanical streak cameras are surprisingly fast--you spin a polygon on   
   >>an air bearing (or a magnetic bearing in a vacuum) and look at the   
   >>scanned beam from some distance.  You can do 12 facets x 100k rpm x 10m   
   >>~ 2500 km/s. (*) Nanoseconds are _easy_.  They did stuff like that back   
   >>in the 40s and 50s for bomb development.   
   >>   
   >>Cheers   
   >>   
   >>Phil Hobbs   
   >>   
   >>(*) There's an additional factor of 4 pi in there--2 pi for the angular   
   >>velocity and another 2 for the law of reflection (the beam scans twice   
   >>as fast as the polygon turns).   
   >   
   > Yep.  My first job as a technician in MIT Building 20 was designing   
   > and building a dual 400W amplifier to drive a two-phase motor for a   
   > smear camera at 30K RPM   
   >   
   >                                        ...Jim Thompson   
      
      
   That would have been no small task back then. Now they are less than $100.   
      
      
   tm   
      
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