Analysis of edge jumps in multi-wavelength phasing of segmented-mirror telescopes.

Interferometric methods for phasing the primary mirrors of segmented-mirror telescopes generally need to make measurements at multiple wavelengths in order to achieve suitably large edge height capture ranges. In the presence of measurement errors, such methods have the potential for grossly wrong measurements, so-called edge jumps. In this paper, we investigate the causes of edge jumps using the example of Thirty Meter Telescope (TMT) phasing.

Approach based on χ to phasing segmented-mirror telescopes using multiple wavelengths: data reduction, wavelength selection, capture range.

The design of extremely large segmented-mirror telescopes (ELTs) calls for their segments to be phased, and a number of different interferometric techniques have been proposed in the literature for this purpose. To achieve the required large capture ranges for ELTs (typically a few microns), most of these techniques use measurements at multiple wavelengths, similar to what is done in standard distance-measuring laser interferometry. In this paper, we present a -based framework not tied to a specific phasing technique to obtain intersegment edge heights from multiwavelength data.