[HN Gopher] LaserTweezer - Optical Trap
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       LaserTweezer - Optical Trap
        
       Author : o4c
       Score  : 73 points
       Date   : 2025-10-26 08:03 UTC (14 hours ago)
        
 (HTM) web link (www.gaudi.ch)
 (TXT) w3m dump (www.gaudi.ch)
        
       | ChrisMarshallNY wrote:
       | That's pretty cool!
       | 
       | One of the nice things about hanging here, is seeing posts like
       | this.
       | 
       | Of course, I suspect that I'll never have a use for this, myself.
        
       | dvh wrote:
       | I just used L272M today (I'm experimenting with sinusoidal
       | stepper drivers). It's a dip8 1A dual opamp, commonly used as
       | motor driver. Quite unobtainium these days. Lcsc only have L272D
       | version which is soic16. I got mine as a fake (but functional)
       | "black top" from AliExpress.
        
         | amelius wrote:
         | It's an obsolete part. It should not be difficult to find
         | substitutes for power opamps. Unless you're stuck with one
         | particular footprint of course.
        
       | tonetegeatinst wrote:
       | I have always seen manipulation at this scale done via
       | micromanipulators (wire bonder or inside of a vacuum chamber)
       | 
       | When you need precision movement, the alternative to
       | micromanipulation is using a XY stage like ASML uses.
       | 
       | XY let's you hold an object like a wafer or part, and move it
       | around in certain planes while not moving in others. XY and even
       | XYZ stages are not uncommon in vacuum chambers where parts need
       | moved but repeatability is key.
        
       | dr_coffee wrote:
       | Amazing that this can be achieved at such a low cost. The DVD
       | optical pickup is truly a marvel of engineering, incorporating
       | fairly complicated optics into such a small space. The focusing
       | lens additionally has a electromagnetically controlled suspension
       | system for adjusting the focus, so in theory you should be able
       | to achieve z positioning of the microspheres as well. It would be
       | great if the red dvd laser could be filtered out and the
       | microscopic fluctuations of the trapped particle could be imaged
       | with the camera to estimate the trap stiffness.
       | 
       | A similar optical pickup made of optical components from newport
       | or thorlabs would run you a few thousand dollars, whereas these
       | dvd optical pickups can be had for $10-20.
       | 
       | Here is another great paper (and accompanying youtube video) that
       | shows optical trapping, atomic force microscopy, and even imaging
       | with a dvd optical pickup.
       | 
       | https://pubs.acs.org/doi/10.1021/acssensors.8b00340
       | 
       | https://www.youtube.com/watch?v=5bqujaldaCQ
        
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       (page generated 2025-10-26 23:01 UTC)