Coherent Diffractive Imaging (CDI) has been widely developed to study nanostructures, such as nanocrystals and biological samples. With ability to provide a high resolution image in nanometre scale without the need of the optical lens, CDI has found a vast potential in many disciplines since this method overcomes the manufacturing limit of the x-ray optics. One of the short wavelength source is to use High Harmonic Generation (HHG) process, where the XUV radiation is generated by focusing a high intensity laser beam into the noble gas medium.

 

At Centre for Quantum and Optical Science of Swinburne University, a spatial resolution of ~ 45 nm for a small size (3.5 μm x 3.5 μm) and larger size (7 μm x 7 μm) sample images is demonstrated. A short exposure time of ~ 2 s can be achieved by using a focusing mirror with a narrow-bandwidth HHG source around 30 nm.

As a member of the project, I have conducted the CDI experiment and performed the image reconstruction.  I have written and developed a reconstruction program using Matlab, which takes into account the curvature of the focused HHG beam on the sample that no one has considered before. This curvature correction algorithm allows the sample to be placed at a closer distance near the focus point, which utilizes the high photon flux and hence reduces the exposure time.  The GPU computing (on NVIDIA Tesla K20) is also utilized in the reconstruction program, which boosts the speed 10x faster than conventional programs.

 

 

 The project was presented in the  Australian and New Zealand Conference on Optics and Photonics conference (best student talk award, Perth 2013)  and Computational Optical Sensing and Imaging conference (Hawaii 2014). The online version of the presentation is shown below:

 

 The work has been published to Journal of Applied Physics, see: http://dx.doi.org/10.1063/1.4900982