What is the instruments spatial resolution?
The spatial resolution of IFIRS is determined by the combined performance of the telescope and instrument optics. This yields: • 150 nm rms wave front error • Strehl ratio of 0.8 at 2 µm • IFIRS is diffraction limited at 2 µm with a FWHM ~ 0.052″ for an 8m primary. The IFIRS wave front error budget includes: • Design residuals • Fabrication errors • Alignment tolerances • Interferometer optics • Mechanical & thermal deformation The pixel sampling is: • Near-IR channel pixel size is 0.”0386 – Nyquist sampled at 3 µm • Mid-IR channel pixel size is 0.”0772 – Nyquist sampled at 6 µm. The choice of pixel scale is not final. Since diffraction limited images can be constructed from a set of dithered images we will probably choose to be undersampled. Lauer (PASP, 111, 227) has shown that the reconstructed image is an exact representation of the data set with no loss of resolution at the Nyquist scale. Undersampling is advantageous for projects that require large instantaneous field of view, e.
