David Carberry (Bristol University) is visiting and giving the AMOP Physics seminar on Wednesday 22 February. David works on optical micromanipulation techniques and recently demonstrated a multi-point holographic optical tweezers controlled through an iPad. The abstract for his seminar is below:
Abstract: Non-spherical probe particles have a number of advantages over microspheres: rotational motion may be monitored and controlled, the trapping points may be removed from the probe’s tip, and the tip can be more accurately positioned than a microsphere of equivalent radius.
We demonstrate a range of non-spherical probes, and discuss how they may be tailored to specific applications. We consider how probe geometry affects the region of space the tip explores – the ‘tip thermal volume’, and the relaxation times of this motion1. By independently position-clamping translational and rotational modes in different ways, we are able to further control the shape of the tip thermal volume, and dramatically improve the position resolution of the probe, with no reduction in force sensitivity2.
Using holographic optical tweezers combined with stereomicroscopy, we can both control and track the motion of our non-spherical probes in all three dimensions. Finally, we demonstrate the use of our probes to image surfaces in 3D3, and measure force and torque interactions with biological specimens.
- S.H. Simpson and S. Hanna. ‘Thermal Motion of a holographically trapped SPM-like probe’. Nanotechnology, 20 395710 (2009)
- D.B. Phillips et al. ‘Position clamping of optically trapped microscopic non-spherical probes’. Optics Express, 19 20622 (2011)
- D.B. Phillips et al. ‘Surface imaging using holographic optical tweezers’. Nanotechnology, 22 285503 (2011)
