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8 June 1995 High-resolution encoding using redundant edge detection
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Encoding the angular position of large telescopes is typically achieved through the use of friction driven rotary encoders, tape style encoders mounted on the circumference of each telescope axis or co-axially mounted high precision rotary encoders. These forms of encoding have very stringent mounting requirements, are expensive, adversely affected by contaminating particles and often difficult to retrofit to existing telescopes. The advent of long CCDs presents the opportunity to develop accurate position encoding for telescope control using digital image metrology. In this paper we present the design of a high precision non- contact encoding system which uses the detection of multiple redundant visual edge features to develop sub-pixel edge position measurements to a precision of 1/50th pixel. The method is described in detail and is validated with both simulation trials and experimental results from a testbed setup.
© (1995) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Leslie K. Saddlemyer and Gerard F. McLean "High-resolution encoding using redundant edge detection", Proc. SPIE 2479, Telescope Control Systems, (8 June 1995);

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