Adaptive Optics; June 1994; Scientific American Magazine; by Hardy; 6 Page(s)

Atmospheric turbulence, which causes stars to twinkle and distant objects to shimmer, has frustrated astronomers ever since telescopes were invented. "The only Remedy is a most serene and quiet Air," wrote Sir Isaac Newton in 1704, "such as may perhaps be found on the tops of the highest Mountains above the grosser Clouds." Astronomers have followed this advice, which Newton offered in his Opticks, but even on the highest peaks atmospheric turbulence severely limits the power of big telescopes such as the 200-inch Hale telescope at Mount Palomar in California. The launch of the Hubble Space Telescope showed to what heights astronomers are willing to go to circumvent turbulence.

My colleagues and I at Litton Itek Optical Systems in Lexington, Mass., as well as workers at other institutions, have been pursuing another, earthbound, solution to the problem of atmospheric turbulence. Our approach, called adaptive optics, also has its roots in the development of space technology, but now, somewhat ironically, it is being applied to ground-based astronomical telescopes. Adaptive optics uses a deformable mirror or similar device to compensate, or correct, for the distortion of light caused by atmospheric turbulence. Adaptive optics technology is improving the ability of the next generation of earthbound telescopes to resolve fine detail and to detect extremely faint objects in the sky.