# Presentation: 170345

## Keith A. Nugent
ARC Centre of Excellence for Coherent X-ray Science & School of Physics
The University of Melbourne
Australia

***ARC Centre of Excellence for Coherent X-ray Science & School of Physics***
***The University of Melbourne***
***Australia***

**Opportunities for imaging with coherence**

## Outline of Talk

- What can we aim for in 2013?
- Introduction to CDI – brief
- Fresnel CDI (FCDI)
- Quantitative phase measurement
- Application to malaria-infected red blood cell
- Keyhole FCDI – imaging extended objects
- Application to technology problem
- Early 3D results
- Conclusions

## Approaches to Coherent Imaging

- Holography
- Recent work at BESSY
- Limited path to high resolution
- Phase-contrast
- Very extensively used
- Low resolution
- Ptychography
- SLS – Oliver Bunk
- Extended objects, high resolution?
- CDI
- Plane wave incident
- Isolated objects
- Curved incident wave

- 	To Image extended objects in three-dimensions with 5nm resolution

## Coherent imaging methods are being developed.

**Coherent imaging methods are being developed.**

- z

- Coherent Field

**Impose Measure Intensity, Keep Phase**

**Impose “support”**

**Guess Phase**

- Unique!

- Use prior knowledge of the incident wave to recover the “exit surface wave” leaving the object

## The World’s Easiest CDI Experiment

**Fourier**

**Fresnel**

**Fresnel**

**Fourier**

## Reconstruction of the Illuminating Field

**HM Quiney, AG Peele, Z Cai, D Paterson, KA Nugent, *****Nature Physics*****, **_**2**_**, 101-104 (2006)**

## X-Ray CDI

## Fresnel diffraction imaging

**GJ Williams, HM Quiney, BB Dahl, CQ Tran, KA Nugent, AG Peele, D Paterson, M de Jonge, *****Physical Review Letters*****, **_**97**_**, 025506 (2006****)**

## Quantitative Phase Measurement

- Average AFM height and reconstructed thickness for the four areas indicated in Fig 2(c).
**Region****	****AFM (nm)****	****FCDI (nm)****	**
**1****	**370 ± 8***	**360 ± 29**	**
**2****	**344 ± 7**	**377 ± 28**	**
**3****	**308 ± 15**	**297 ± 32**	**
**4****	**348 ± 12**	**321 ± 19**	**
- *Errors are estimated from the variance in the heights recovered within each region, as this includes intrinsic height variation the errors are therefore conservative.

- Clark, J.N., et al., *Quantitative phase measurement in coherent diffraction imaging.* Optics Express, 2008. **16**(5) 3342-3348.

- Use prior knowledge of the incident wave to recover the “exit surface wave” leaving the object

## What do we mean by “support”?

- Support is interpreted slightly differently here –the structure to be reconstructed is the coherent exit wave, including the illumination, not the scattering object itself.

## Optical Demonstration

- Diode Laser Beam

- Optical Test Chart

- CCD Camera

## Slide 14

## Independent Fresnel CDI images of a large object

**Independent Fresnel CDI images of a large object**

- Experimental data obtained using coherent visible light

## X-Ray CDI

## Have achieved a resolution of ~15nm!

**Have achieved a resolution of ~15nm!**

- B Abbey et al, “Keyhole Coherent Diffractive Imaging”, *Nature Physics*, _Published on the web March 9, 2008_

**Exceeds resolution of STXM with same optics, by a factor of ~4!**

## Images of a fuse-bay sample

## All of the conceptual and methodological pieces are in place for us to achieve 3D imaging of extended objects with 5nm spatial resolution

## Collaborators

**Harry Quiney (UM)**
**Andrew Peele (La Trobe)**
**Garth Williams (UM) **
**Lachlan Whitehead (UM)**
**Brian Abbey (UM)**
**Jesse Clark (La Trobe)**

**David Paterson (Australian Synchrotron)**
**Martin de Jonge (APS – Now AS)**
**Ian McNulty (APS)**
**Z Cai (APS)**
**Leann Tilley (La Trobe)**
**Eric Hanssen (La Trobe)**