Two low power cylindrical lenses rotate independently in order to correct for mild astigmatism in the 3.6 meter primary mirror at the Canada France Hawaii Telescope. The astigmatism corrector locates each optic independently in rotational space using a single stepper motor.
Thinner than a pocket calculator, this device sits between two assemblies within the High Resolution camera.
The camera operates at the prime focus of the Canada France Hawaii Telescope. The design of the corrector was one of my contribtions to the HRCam instrument.
This image, the first to resolve Pluto and its moon Charon, is among many ground-breaking images made with HRCam, which was the world's first instrument to successfully apply adaptive optics technology in astrophysics.