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Proceedings Paper

Passive ranging metrology with range sensitivity exceeding one part in 10,000
Author(s): Paul Atcheson
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Paper Abstract

Measurement of the distance to an object can be done in a number of ways based on system constraints such as minimum or maximum range, range accuracy, measurement update rate, and system power, with a considerable variation in resulting system complexity. Active approaches used in laser rangefinders yield submillimeter accuracy in laboratory or survey exercises while time-of- flight or flash LIDAR yields centimeter-scale range accuracy from mapping platforms in low Earth orbit. High ranging sensitivity, in excess of one part in 106, can be achieved, but generally requires fairly sophisticated control of the output pulse phase, shape, and energy, and also relies on fairly high speed pulse detection and processing. Passive approaches based purely on parallax imaging can determine distances to centimeter accuracies over moderate distances. The accuracy that can be achieved with this type of system is highly dependent on the overall SNR and the parallax angle, with a range sensitivity of one part in 1000 being typical for this approach. A low-cost passive range metrology system is described based on geometrical imaging with distance measurement sensitivity to better than one part in 10,000. The approach uses knowledge of the relationship between features on the target and the imaging parameters of the metrology camera, as in the parallax/centroid approach, but incorporates a specific target encoding that optimizes the performance. Results are presented using a standard machine vision camera in room ambient lighting conditions, showing a range sensitivity of 100 microns with a target-camera separation of 1200 mm.

Paper Details

Date Published: 3 September 2010
PDF: 11 pages
Proc. SPIE 7793, Optical System Alignment, Tolerancing, and Verification IV, 77930H (3 September 2010); doi: 10.1117/12.860933
Show Author Affiliations
Paul Atcheson, Ball Aerospace & Technologies Corp. (United States)

Published in SPIE Proceedings Vol. 7793:
Optical System Alignment, Tolerancing, and Verification IV
José Sasián; Richard N. Youngworth, Editor(s)

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