Argh

I spent the day using my final set-up to try and trap the polystyrene beads. No such luck. I don't think my laser is powerful enough. And of course, there are all those problems I explained in the post below. I did come across one very strange thing during my first attempt at trapping. I was scrolling along the taper looking for beads and I came across two very large spheres stuck onto the side of the taper. I thought they were bubbles at first so I lowered to objective onto them to burst or move them, but they stayed put. I tried moving them with a micropipette and they didn't move. Johnathan thought they were two microspheres but we couldn't see why they would end up in my water.
While I was making a new sample and fibred slide to see if these spheres were an optical effect, I broke the taper in half - and I never got a photo of them! So then I tried trapping with half tapers. I also had no luck with this. I tried to trap the beads with a looped section of the half taper (inspired by Yuqiang 'lassooing' a microsphere with his taper) but I couldn't focus on the loop as the objective kept pushing it around in the water.