Portable Optical Tweezers Kit
Chapter 6: Experiments
Rev B, February 15, 2022
Page 65
Focus Level Settings
Set the laser focus so that you see the sample beads clearly and sharply. By moving the
laser spot onto a bead using the servomotors and levers on the K-cube controllers, you
can trap a bead and move it to another location. If you are able to capture one of the beads,
you have found the correct focus level.
Please note that reflections of the laser may occur. In the camera image, these will appear
with varying diameter (small spots or larger shapes). These are not a sign of bad
adjustment and can be ignored.
At this point, if the trapped beads move out of the focal plane, it indicates that the focal
planes of the laser and camera system are not aligned. See Section 5.5, above, for details.
6.3. Arranging the Silica Beads
In order to get to know the optical tweezers better, try next to move as many beads as
possible to one location using the K-cube controllers as shown in Figure 50. These
controllers allow you to set different speeds. You can use this to your advantage when
releasing the beads.
If you experience
lagging
of
the
camera image, try to
reduce the frame
rate in the camera
settings.
Hint
With older or slightly
dried samples, one
can observe that
some beads no
longer move, but
instead "stick" in
place.
Beads as Viewed Through the Microscope
Summary of Contents for EDU-OT3
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