Research

Tue, Dec 29, 2015

Background

I work on breaking down the barriers to imaging at the very highest angular resolutions in astronomy. I use interferometric arrays of telescopes to yield images with an angular resolution more than one hundred times better than that of the Hubble Space Telescope.

Interferometry is subject to fundamental limitations due to the paucity of photons from astronomical sources and the perturbations to the optical phase introduced by the Earth’s atmosphere. My research uses a wide range of techniques to overcome these limitations and thereby probe astrophysical processes on scales which cannot be accessed by any other means.

Fundamentals of interferometry

I made the first interferometric image of the surface of a star (Buscher 1990) and the first interferometric measurement of the outer scale of optical turbulence (Buscher et al 1995).

The reconstruction of images in optical interferometry differs from that in radio interferometry in subtle but important ways. The International Astronomical Union sponsors an “Imaging Beauty Contest” to promote the development of algorithms optimised for optical interferometry, and the BSMEM software I developed (Buscher 1994) has won this competition 3 out of the 5 times it has been held.

My latest project is building an interferometric testbed for a new generation of near-infrared eAPD detectors offering sensitivities 5-10 times better than has been possible to date. The aim is to build the first high-quantum-efficiency photon-counting infrared array in the world which should enhance the sensitivity and speed of imaging of interferometers by more than an order of magnitude.

MROI

Much of my research over the last decade has been dedicated to the design and construction of the Magdalena Ridge Observatory Interferometer (MROI), a project to build the world’s most ambitious optical array. As System Architect for MROI, I developed the technical vision for the array and determined the optimum values for all the key technical parameters. As a result, the MROI will be able to image targets 10 times fainter than those accessible with any other interferometer, and it will be able to make images on timescales of hours instead of days (Buscher et al 2013).

I have overseen the inception of the collaboration between Cambridge and New Mexico Tech and the building of the technical team, developed the system-wide error budget and provided technical guidance to all the engineers developing MROI subsystems. I led the analysis of the requirements for the MROI delay line (Buscher et al 2006): this is the longest single-stage delay line in the world, able to provide 400 metres of variable optical delay with a jitter of less than 10 nanometres (Fisher et al 2010). I wrote the specifications for the telescopes for MROI which will provide a wavefront quality which exceeds that of any telescope of its size.