Out-Of-Focus (OOF) Holography

These pages are now out-of-date. Please consult: these pages. Thanks!

Take me straight to the results from JCMT , GBT.

Holography in this context refers to measurement of the surface of a telescope. In particular we are interested in how the surface shape deviates from the design shape, since any deviations will reduce the efficiency with which the telescope collects radiation. Out-Of-Focus (OOF) Holography is one of the ways of performing holographic measurements. It involves making observations of bright astronomical objects (e.g. planets) at a series of focus settings and then analysing this data (which is a classical "inverse problem") to obtain the shape of the surface.

Prof. R. Hills, Dr. J. Richer and me have been working on a OOF holography system primarily aimed at the SCUBA/JCMT set-up, but deliberately designed to be extensible enough to be used on a wide range of telescopes. Over the past year or so, we have accumulated and analysed a number of data sets. Details of the results can be found at the following pages:

• Recent OOF results
• Previous Results.

We have recently produced a short paper describing the technique and our results. It will be published electronically for the 2002 URSI General Assembly but is available bellow. There are also two documents which could be of interest, though both are severely out of date:

• Phase Retrieval Measurements of Antenna Surfaces Using Astronomical Sources, B. Nikolic, R. Hills, J. Richer in Proceedings of the General Assembly of U.R.S.I. , 2002. Download: pdf
• My project write-up (12+ months out of date)
• OOF Holography Users manual