XPost: sci.electronics.design   
   From: pcdhSpamMeSenseless@electrooptical.net   
      
   On 12/20/2013 10:06 PM, josephkk wrote:   
   > On Wed, 18 Dec 2013 23:09:40 -0500, Phil Hobbs   
   >  wrote:   
   >   
   >> On 12/18/2013 8:56 PM, dcaster@krl.org wrote:   
   >>> On Friday, December 13, 2013 8:06:44 PM UTC-5, Phil Hobbs wrote:   
   >>>> Hi, all,   
   >>>   
   >>>   
   >>> Have you considered using a low pressure sodium vapour lamp for the   
   >>> yellow light?   
   >>>   
   >>> Lots of problems in that approach,but you do get a lot of light per   
   >>> watt. From Wiki   
   >>>   
   >>> "Another unique property of LPS lamps is that, unlike other lamp   
   >>> types, they do not decline in lumen output with age. As an example,   
   >>> mercury vapor HID lamps become very dull towards the end of their   
   >>> lives, to the point of being ineffective, while continuing to consume   
   >>> full rated electrical use. LPS lamps, however, do increase energy   
   >>> usage slightly (about 10%) towards their end of life, which is   
   >>> generally around 18,000 hours for modern lamps."   
   >>>   
   >>> Dan   
   >>>   
   >>   
   >> Thanks.  The sodium lines are at 589 nm, which won't work in my   
   >> application.  I really need 578 and 598 nm.  If I could do it at 590,   
   >> there are a ton of bright LEDs there as well.   
   >>   
   >> Cheers   
   >>   
   >> Phil Hobbs   
   >   
   > Unfortunately both wavelength distances are beyond convenient thermal   
   > pulling distance if i understand correctly.  Plus, it could be hard to   
   > regulate target wavelength well.  Maybe a diffraction grating trick would   
   > help.   
   >   
   > Keep on thimkimg.    >?-)   
   >   
      
   The current best guess is either a good white LED or the very greenest   
   among the high-efficiency yellow ones, shining through a 3-5 nm wide   
   interference filter.   
      
   Cheers   
      
   Phil Hobbs   
      
   --   
   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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