Parabolic mirrors to shed light on the Sun

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Optical Surfaces has delivered three high precision off-axis parabolic mirrors to the Big Bear Solar Observatory (BBSO) located in Big Bear Lake, California, that will form key focusing components in the adaptive optical system associated with BBSO's new 1.6 metre solar telescope.

Due for completion later in 2008, the new 1.6m aperture off-axis Gregorian solar telescope will be the world's largest telescope enabling precise studies of the physics of the Sun and observation of solar phenomena.

The new BBSO solar telescope (NST) benefits from adaptive optics, which will allow atmospheric seeing to be corrected to the diffraction limit, an advanced computer systems capable of supporting sophisticated instruments such as Fabry-Perot interferometers and improved observation at infrared wavelengths. The adaptive optics will allow the BBSO NST to image actual photospheric flux tubes, at about 100km resolution.

Nicolas Gorceix, BBSO optical designer, said: ‘Optical Surfaces was selected to produce the critical focusing mirrors for the adaptive optics due to its technical excellence, reasonable pricing and a proven record in supplying ultra-smooth optics to leading astronomical research groups around the world.’

Using proprietary production techniques, Optical Surfaces’ craftsmen were able to produce the required three ultra-smooth 150mm diameter parabolic mirrors with a surface accuracy of lambda/10 p-v and excellent surface quality of 20:10 scratch/dig. All mirrors, effective focal length (2,000mm), were given a protected silver coating offering peak performance from 0.39-1.6µm.