Active optics at UKIRT

The 3.8 m United Kingdom Infrared Telescope (UKIRT) has recently installed active control of the primary mirror figure, taking advantage of aspects of the original mirror design, which permits the correction of low order aberrations. In this paper, we present results from a campaign of all-sky wavefront sensing carried out UKIRT. As a result of the campaign, a lookup table is being used to correct for attitude dependent astigmatism, while fixed corrections are applied to trefoil and spherical aberrations. Coma is removed by secondary mirror alignment. A continuous, model based, correction of focus for thermal and elastic effects is also applied. Accurate focus is now maintained throughout an observing night.

[1]  R. Noll Zernike polynomials and atmospheric turbulence , 1976 .

[2]  Andreas Glindemann,et al.  Progress of the UKIRT Upgrades Program , 1997, Other Conferences.

[3]  Malcolm J. Northcott,et al.  Testing optical telescopes from defocused stellar images , 1994, Astronomical Telescopes and Instrumentation.

[4]  Ralf-Rainer Rohloff,et al.  Five-axis secondary system for UKIRT , 1994, Astronomical Telescopes and Instrumentation.