From: pcdhSpamMeSenseless@electrooptical.net   
      
   On 11/22/20 3:51 AM, Daniel Tamisier wrote:   
   > Hello,   
   >   
   > I am a beginner with laser. I found an old  Omnichrome HeCd  laser Series   
   39X, model 439XL Class 3b date sept 87. The power supply is model 100. For me   
   it doesn't lase. I have only a very pale violet light at the output of the   
   tube...   
   > The tube lights but after 5 minutes;  the light around the tube is blue.   
   Owing to what I read in the manual (not complete...) it is not normal. The   
   voltages measured on the banana plug at the rear of the tube are good. The   
   counter on the small pcb in    
   the tube box shows more than 3000 hours (not very good).   
   > My questions:   
   > Does this laser output a visible light or only an uv light ? there is no   
   label about the lambda on the tube.   
   > In the bore, the light is very intensive but stop before the end of the   
   tube, is it normal? (obstruction by precipitation of cadmium ???)   
   > I know general electronics but I am a novice with laser!   
   > Thanks for your help.   
   >   
   > Daniel from Paris France   
   >   
      
   +1 for Sam's FAQ.   
      
   I don't know that model, but I've used quite a few lasers from that era.   
      
   HeCd laser tubes are notorious for crudding up the Brewster windows.  If   
   the windows are visibly contaminated, the tube is probably toast.   
      
   Otherwise it might just need walking in.   
      
   Cheers   
      
   Phil Hobbs   
      
   --   
   Dr Philip C D Hobbs   
   Principal Consultant   
   ElectroOptical Innovations LLC / Hobbs ElectroOptics   
   Optics, Electro-optics, Photonics, Analog Electronics   
   Briarcliff Manor NY 10510   
      
   http://electrooptical.net   
   http://hobbs-eo.com   
      
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