Home ▻ Research sites▻Applied Optics▻AO Group▻People▻Dr Nicholas Devaney

Dr Nicholas Devaney

Lecturer (Physics)

ndevaney Contact Information
National University of Ireland, Galway
Phone: +353-91-495188 ext 5188
Fax: +353-91-495529
email: nicholas.devaney@nuigalway.ie

CAREER SUMMARY

Ph.D. (NUIG then UCG) 1989
Royal Greenwich Observatory:Research Associate 1989-1991
Observatoire de Meudon, Paris: Research Associate 1991-1992
Instituto de Astrofisica de Canarias: Support Astronomer 1993-1995
GRANTECAN, Instituto de Astrofisica de Canarias: Adaptive Optics Manager 1995-2005
National University of Ireland, Galway: Lecturer 2005-

TEACHING

PH351: Wave Optics

PH103: History of Astronomy

PH402: Medical Image Processing (part)

PH459: Applied Optics (part)

Course materials are available to students via the Blackboard e-learning system.

RESEARCH INTERESTS

My background is in Astronomical Imaging with high spatial resolution, mostly involving Adaptive Optics and Image Processing. My current work in this area concerns the detection of extrasolar planets in data obtained using adaptive optics. I am also interested in the application of adaptive optics and other techniques to the enhancement of microscopy. In addition, I am supervising projects on Image processing of medical images; specifically on the study of retinal disease using adaptive-optics retinal images and the optimal detection of lesions in mammography. Here are some more details on these projects. I am keen to hear from prospective graduate students with an interest in working in any of these areas.

In addition, I would be interested in discussing projects with potential Postdoctoral researchers.

Exoplanet Detection

 A large number of planets have been detected outside our solar system using indirect techniques (e.g. see here). Imaging of these exoplanets is extremely challenging given how close they are to their parent stars, and how much fainter. The brightness ratio with the parent star is of the order 10^-6 to 10^-9. Obtaining such images will require using large (or extremely large) telescopes, with practically perfect adaptive optics. Even so, residual speckle effects severely hamper our ability to unambiguously detect exoplanets. We have developed optimal techniques based on using knowledge of the data statistics. We have also developed a powerful inverse-problem approach applicable to multi-wavelength data. This exploits the fact that the position of residual speckles scales with wavelength, and this fact may be used to discriminate speckles from planets. We want to extend these approaches to future Extremely Large Telescopes.

 High-resolution retinal image processing

Adaptive optics is now used to provide images of the retina with unprecedented detail. Image processing can further enhance these images by selecting those images with the highest contrast, and precisely registering the images. We use a multi-resolution approach based on wavelets to carry out these tasks. We are also using wavelets to automatically detect photoreceptors (cones and rods) in the retinal images.

Enhancing microscopy using Adaptive Optics and Computational Imaging

Images obtained with microscopes may be blurred by aberrations introduced by the sample. Adaptive optics has been used recently to correct for these aberrations and provide clearer images. Alternatively, the aberrations can be measured and the correction applied in post-processing. We will be examining this possibility. We are also developing 3D microscopy based on plenoptic imaging; this technique allows several views of the sample to be obtained simultaneously. Subsequent image processing can be used to examine the sample from different perspectives or to focus at different depths in the sample.

Lesion detection in mammography

The sort of optimal detection techniques which we have developed for exoplanet images can be applied to many tasks; one example is the detection of lesions in mammographs. This is complicated by the fact that there are many different kinds of lesions, and the background tissue varies greatly between subjects.

RECENT PUBLICATIONS

1

Devaney, N., Thiebaut, E., 2011,"Inverse problem approach to the detection of exoplanets in multiwavelength data", OSA Technical Digest, APDP1,
2

Murphy, K., Burke, D., Devaney, N.,Dainty,C. 2010,"Experimental detection of optical vortices with a Shack-Hartmann wavefront sensor", Opt. Expr., 18, 15448-15460
3 Burke, D., Devaney, N. 2010," Enhanced faint companion photometry and astrometry using wavelength diversity", JOSA A, 27, 246-252
4 Burke, D., Gladsyz, S., D., Roberts, L.C., Devaney, N. Dainty, C. 2009," An improved technique for the astrometry and photometry of faint companions", PASP, 21, 767-777
5 Devaney, N., Goncharov, A., Dainty, C., 2008,"The chromatic effects of the atmosphere on astronomical adaptive optics", Applied Optics, 47, 1072-1081
6 Devaney, N., Coburn, D., Coleman, C., Dainty, C., Dalimier, E., Farrell, T., Mackey, D., Mackey, R.,2008, "Characterisation of MEMs mirrors for use in atmospheric and ocular wavefront correction", Proc. SPIE 6888-1
7 Caucci, L., Barrett, H.H., Devaney, N., Rodriguez, J.J.,2007, "Application fo the Hotelling and ideal observers to the detection and localization of exoplanets", JOSA, A.,24,B13-B24
8 Devaney, N., "Review of Astronomical Adaptive Optics", 2007, Proc. SPIE 6584
9 Goncharov, A. V., Devaney, N., Dainty, C., 2007, "Atmospheric Dispersion Compensation for extremely large telescopes", Optics Express, 15, 1534-1542
10 Barrett, H. Myers, K., Devaney, N., Dainty, C., 2006, "Objective assessment of Image Quality: IV. Application to Adaptive Optics", JOSA, A.,23,3080-3105
11 Canales, J.E. Oti, P.J. Valle, M.P. Cagigal, N. Devaney, 2006, "Reduction of the diffraction pattern in segmented apertures", Opt. Eng., 45, 098001
12 A.Goncharov, N. Devaney, S. Esposito, C. Dainty, 2006, "Experimental verification of the Virtual Wavefront Sensor concept", Proc. SPIE 6272
13 Barrett, H. Myers, K., Devaney, N., Dainty, C., 2006, "Task performance in astronomical adaptive optics", Proc. SPIE 6272
14 Schumacher, A, Devaney, N, 2006, "Phasing Segmented Mirrors using defocused images at visible wavelengths", Mon. Not. Royal. Astron. Soc, 366, 567-546
15 Devaney, N. et al., 2004, "Preliminary design and plans for the GTC adaptive optics system", Proc. SPIE, 5382, 431-439
16   Devaney, N., Schumacher, A., 2004, " Cophasing techniques for extremely large telescopes", Proc SPIE 5382, PP431-439
17 Femenia, B., Devaney, N., 2003, " Optimization with numerical simulations of the conjugate altitudes of deformable mirrors in an MCAO system", Astron. Astrophys., 404, pp1165-1176
18 Esposito, S., Devaney, N., 2003, "Cophasing of segmented mirrors using the pyramid sensor", Proc. SPIE, 5169, pp72-78
19 Schumacher, A, Devaney, N, Montoya, L, 2002 "Phasing Segmented mirrors: a modification of the Keck narrow band technique and its application to ELTs" , Applied Optics, 41, 1297-1307

CHAPTERS

"Adaptive Optics: Principles, Performance and Challenges",
Proceedings of the NATO Advanced Study Institute on Optics in Astrophysics,
Cargese, France, Sept. 2002, eds. R. Foy and F.C. Foy, Springer 2005

OTHER

I am a member of the Institute of Physics (http://www.iop.org), the International Astronomical Union (http://www.iau.org/) and OSA (http://www.osa.org).

I am on the National Committee of the IOP and the Optics group committee of the IOP