Figure 13. Extra focal images obtained during an early engineering test set up. Excellent optical alignment and focus of the VATT optics may now be readily achieved using a Forbes image splitter and new "EF" analysis software obtained during the Kresge program. Analysis of this pair of images shows that all optical aberrations , expressed as Zernike coefficients, are suitably small, typically well under 100 nm. Work is in progress to provide the VATT with permanent real time extra focal image analysis (and real time wave front sensing from a second system as well) for automatic alignment of the optics and automatic guiding. The system will considerably reduce the present demand of observer's time and skills to get the most performance out of the telescope.

Photo credit: Dan McKenna and Matt Nelson