future events

Simulated annealing of multiple-aperture telescopes

TYPEComputational science seminar
Speaker:Irina Paykin
Affiliation:Physics Department, Technion
Location:Lidow 620
Remark:MSc seminar: Supervisors: Drs Erez Ribak and Joan Adler. In Hebrew
Abstract:A model based on the crystal roughening transition is applied to solve the phasing of a multi-aperture telescope.
The quest for finer angular resolution in astronomy leads to larger apertures. But high resolution imaging from space telescopes is currently limited by launch vehicle constrains and system cost. The concept of segmented and multi-aperture systems has attracted more interest in the next generation of the space telescopes, because such systems have the advantage of low cost, light weight, and can reach the demanded angular resolution. A multi-aperture system can combine the light from smaller sub-apertures to capture a higher angular resolution image than is possible from any of the individual sub-apertures. In order to achieve high resolution image we have to phase the sub-apertures to within a fraction of the wavelength.
Relatively short optical wavelengths require high positioning accuracy for alignment of each sub-aperture.

This study concentrates on an approach for aligning multi-aperture optical systems by using information available only in the image plane itself, thereby correcting the image without any information on the wave-front. Previous theoretical work and simulations have shown that the optical problem can be mapped onto a model for crystal roughening that has served as a motivation to implement the simulated annealing algorithm in adaptive optical systems.

We present the first simulations which are carried out in tandem with a hardware realization of a simulated annealing algorithm by Dr. E.
Ribak and Lee Yacobi in a specially designed multi-aperture active optical system. The results of both simulations and laboratory experiments demonstrate the ability of the simulated annealing algorithm to correct a piston and tip/tilt errors. In addition we explored image restoration techniques, required for multi-aperture systems. We implemented and investigated several classic deconvolution algorithms, such as Wiener-Helstrom, Lucy-Richardson and blind deconvolution. Finally, we analyzed diffraction and aberration effects related to specific multi-aperture pupil configurations.