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Triaxial Optical Angular Measuring System

IP.com Disclosure Number: IPCOM000077896D
Original Publication Date: 1972-Oct-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 3 page(s) / 68K

Publishing Venue

IBM

Related People

Goetz, WE: AUTHOR [+3]

Abstract

The optical system of Fig. 1 measures and/or monitors the angular movement between two spaced objects, not shown, located at stations A and B, respectively, about the three mutually orthogonal reference axes x, y, z, i.e. the angular displacements of pitch, yaw, and roll. Briefly, the system consists of a collimator 1 at one location B and a receiver-detector-measuring apparatus 2 at the other location A. An artificial star field provided by reticle 3 is located in the focal plane of the collimator lens 4 via mirror 5. Reticle 3 is a linear array of a number, e.g. eleven, light-emitting diodes (LEDs). The star field is projected by lens 4 towards station A and is imaged in the focal plane of the receiving optics 6' via the parabolic primary mirror 7, spherical secondary mirror 8 and lens 6.

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Triaxial Optical Angular Measuring System

The optical system of Fig. 1 measures and/or monitors the angular movement between two spaced objects, not shown, located at stations A and B, respectively, about the three mutually orthogonal reference axes x, y, z, i.e. the angular displacements of pitch, yaw, and roll. Briefly, the system consists of a collimator 1 at one location B and a receiver-detector-measuring apparatus 2 at the other location A. An artificial star field provided by reticle 3 is located in the focal plane of the collimator lens 4 via mirror 5. Reticle 3 is a linear array of a number, e.g. eleven, light-emitting diodes (LEDs). The star field is projected by lens 4 towards station A and is imaged in the focal plane of the receiving optics 6' via the parabolic primary mirror 7, spherical secondary mirror 8 and lens 6. The position of the stars in the image plane of lens 6 is sensed by reticles 9, which pass through this plane and are located on the rotating drum 10. Motor 11 drives drum 10. Housing 12 houses suitable detector and amplifier circuitry, not shown. Motor 11 and housing 12 are stationary.

Referring to Fig. 2, a single star 13 in the center of the star image field 14 is used to measure pitch and yaw. Two groups 15, 16 of the stars, which are located symmetrically about the center star 13, are used to measure roll. The distance between an initial position of the particular reticle 9 passing through the focal plane of optics 6, as determined by an appropriate timing signal during the drum revolution cycle, and the position when vertical slit 17 crosses the single star (13) image is a proportional measure of yaw. The distance between where the vertical slit 17 and the slanted slit 18, which is at a known angle (e.g. 30 degrees) to slit 17, cross the image of the single star 13 is a proportional measure of pitch. The respective crossings of the two short slits 19, 20 with the respective images of the two stars from the groups 15, 16, respectively, are used to determine roll. The two detected stars of each group are separated by a small known angle, e.g. 1 degrees. The distance between these two crossing points is a proportional measure of roll.

All of the measurements are taken by a single movement of a reticle 9 across the star field. The rotating reticles 9 provide a very high-data...