Friday, 20 August 2010

Radial Polarization Movie

We have been working on an interferometric method for high-efficiency synthesis of cylindrical vector beams.

These are the class of laser beams that are linearly polarized in a cylindrical basis, the most common examples being beams where the polarization is purely radial or purely azimuthal. 

The latest movie from this experiment is here and on our YouTube channel. In this movie you can see the characteristic 'donut' shape of the beam and the intensity transmission pattern through a polaroid which demonstrates the radial and azimuthal polarization states.  These beams have many applications in, for example, high-resolution miroscopy and optical  trapping.

Monday, 16 August 2010

Photonic Force Microscopy Book Chapter

Our book chapter on 'Photonic Force Microscopy: from femtonewton force sensing to ultra-sensitive spectroscopy' in the volume 'Scanning Probe Microscopy in Nanoscience and Nanotechnology' is published by Springer, and can be viewed on Google Books

Monday, 9 August 2010

Nuffield Bursary Update (3)

Throughout the course of her Nuffield Foundation project this summer Radhika Patel will be making updates of her progress on our blog.  Her third instalment is below. 

Radhika writes: We wanted to improve the optical tweezers setup I have been working on so this week we partly dismantled the microscope was in order to get a better look at what was inside. Having made some adjustments, Susan and I have returned to aligning the beams, trapping particles and calibrating the trap again. In addition to this, we have started the process of integrating some optical fibres into the setup. Part of the last week was spent learning how to cut and prepare the fibres for use in the setup and actually connectorising some of the fibres.

Phil, Marios and I attended Richard Berry's lecture on Single-molecule observations of turnover, co-operativity and mechanochemistry in a macromolecular complex. As this was the first talk I had attended related to optical tweezing, it was interesting to hear about some of its applications.

Thursday, 5 August 2010

Optical Binding Movie

We have been working on an experiment to demonstrate evanescent wave optical binding of microparticles.

The latest movie from this experiment is here and on our YouTube channel. In this movie you can see 1 micron diameter silica microparticles suspended in water above the surface of a glass prism.  The microparticles organise into 1D chains when exposed to the evanescent field of a laser beam reflected from the surface below.

Monday, 2 August 2010

UCL Optical Tweezers on YouTube

The UCL Optical Tweezers Group now has a YouTube channel at

We will be publishing movies from our experiments like the one shown here of an optically trapped microbubble, together with references to the relevant papers. You can subscribe to the channel by using the button below:
Subscribe to me on YouTube