As an upgrade to the AAOmega IFU, we may implement an integral
field spectropolarimetry observing mode. This will be achieved by incorporating
a Wollaston prism polarization analyser in the fore optics as shown in
the figure below. The Wollaston prism (3) separates the input beam into
the two orthogonal polarization states which then form two images on the
integral field unit (5). In spectropolarimetry mode the IFU field of view
will be approximately 11 x 11 arc seconds squared (half the normal field
of view). Spectral resolution will remain unchanged.
|
| An optical design simulation (Zemax) of the SPIRAL fore optics. Lens 1 is situated at the telescope focus. Lens 2 is the magnification lens. 3 is a Wollaston prism. Lens 4 is a field lens providing a telecentric beam. 5 is the microlens array. The green and blue rays represent the two polarization states. |
Polarization modulation will be provided by the rotating half-wave or quarter-wave plates located in the AAT's existing Cassegrain Acquisition & Guidance unit.