My primary research field is that of adaptive optics, a mechatronic system used to overcome the time-varying deleterious effect of the earth’s atmosphere on astronomical imaging. This system consists of a sensor, which measures the instantaneous wavefront distortion due to the atmosphere, an adaptive mirror that can be locally deformed by independent actuators, and a control law to calculate the optimal actuator commands from the wavefront sensor measurements and atmospheric and noise statistics. By correcting for the atmosphere with a deformable mirror, we can compensate for the blurring effect of the atmosphere. In particular, my research is intended to solve problems for the design of the next generation of telescopes, especially the European Extremely Large Telescope (EELT) currently being designed by the European Southern Observatory (ESO).
My secondary research field is in phase-contrast X-ray imaging (i.e. using the phase of the X-ray wavefront rather than the magnitude or absorption as is done for a conventional X-ray image). In particular, I am interested in the area of ptychography, which uses multiple overlapping X-ray diffraction images to reconstruct the sample through iterative phase retrieval algorithms. This research involves reconstructing ptychographic tomographic datasets measured at the European Synchrotron Radiation Facility (ESRF) and numerical simulations of reconstruction algorithms and optimization of physical parameters.
- Engler B., Le Louarn M., Verinaud C., Weddell S. and Clare R. (2022) A flip-flop modulation method used with a pyramid wavefront sensor to correct piston segmentation on ELTs. Journal of Astronomical Telescopes, Instruments, and Systems JATIS21114SSR.
- Pal S., Clare R., Lambert A. and Weddell S. (2021) Multiscale optimization of the geometric wavefront sensor. Applied Optics 60(25): 7536-7544. http://dx.doi.org/10.1364/AO.423536.
- Clare R., Weddell S. and Le Louarn M. (2020) Mitigation of truncation effects in elongated Shack-Hartmann laser guide star wavefront sensor images. Applied Optics 59: 6431-6442. http://dx.doi.org/10.1364/AO.394751.
- Zanette I., Clare R., Eastwood D., Venkata C., Pfeiffer F., Cloetens P. and Thibault P. (2020) Phase-Vortex Removal for Quantitative X-Ray Nanotomography with Near-Field Ptychography. Physical Review Applied 14(6) http://dx.doi.org/10.1103/PhysRevApplied.14.064078.
- Clare RM., Stockmar M., Dierolf M., Zanette I. and Pfeiffer F. (2015) Characterization of near-field ptychography. Optics Express 23(15): 19728-19742. http://dx.doi.org/10.1364/OE.23.019728.