Overview
South African observatory turns to the UK for high precision optics ...
The South African Astrophysical Observatory (Cape Town, South Africa) has purchased a series of high precision optics from Optical Surfaces Ltd..
Optical Components
The optical components including an aspheric plate, concave spherical mirror, field flattener lens and fold flat form the key elements of a Schmidt camera system which will enable researchers to extend the capabilities of the observatory's 1.88 metre telescope which surveys most areas of infrared and optical astronomy.
The camera to be supplied to the South African Astrophysical Observatory (SAAO) is an f1.4 folded Schmidt design to be used with a grating spectrograph working from 330nm to 900nm.
Schmidt Camera System
Made from special grade Zerodur, the collimator mirror is a 137 mm-diameter aspheric plate designed to depart from spherical by 120 microns of which 42 microns is concentrated in the last 2.5 mm of the diameter. To produce this rapid change of slope and up turned edge required a detailed knowledge of the polishing profile of tools of various stiffnesses. Forming part of the Schmidt camera optics a 186mm diameter spherical mirror (300 mm radius) was manufactured also from Zerodur and surface finished to a uniform lambda/80 rms.
In addition, Optical Surfaces have supplied an off-axis plano-convex field flattener lens that sits in front of the CCD's and a specially shaped fold flat with a rectangular central hole to maximise light throughput and a cut-out to allow the cryostat tube to get as close to the focus as possible. Both these additional camera elements were manufactured from hi-grade silica, which offers excellent homogeneity and high optical throughput.
About Optical Surfaces Ltd.
Optical Surfaces Ltd., has been producing optical components and systems for more than 30 years and is now accepted as one of Europe's leading manufacturers of high-precision optics.
The main workshops and test facilities are deep underground in a series of tunnels excavated in solid chalk where temperature remains constant and vibration is practically non-existent.
With such stable conditions testing particularly with long path lengths become quantifiable and reliable. Working with these natural advantages is a highly skilled team of craftsmen with a commitment to excellence in both product quality and customer service.