From: torty5737@gmail.com   
      
   On Wednesday, 8 February 2023 at 15:41:42 UTC, HoloLab wrote:   
   > > On Thursday, October 24, 2002 at 11:01:10 AM UTC+2, BS wrote:    
   > > If you need high frequency locking, I suggest you actually lock your   
   fringes    
   > > around a fixed frequency, not around a fixed position. For instance,    
   > > introduce a 100Hz movement into one of the mirrors of your setup via a   
   piezo    
   > > and correct this movement with a second mirror of the setup (also on a    
   > > piezo). The advantage here is that because your mirrors are already    
   > > vibrating at a 'high' frequency (but out of phase so as to cancel their    
   > > movements), you get a much higher bandwith in the correction of random   
   phase    
   > > shift errors...   
      
   I'm possibly being thick here, and my hands on holography experience is   
   decades out of date, but I'm struggling to find an intuitive understanding for   
   why vibrating the mirror is better vis-a-vis random phase shifts: surely half   
   the time the mirror is    
   travelling in the wrong direction, so first you have to stop it, and then move   
   it to the right place but you have now less time to do so (owing to time spent   
   halting it)...   
      
   Maybe if the vibration was mains-electricity related (motors, etc.) it would   
   make more sense?   
      
   Thanks   
      
   Henry   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)