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Alignment Cube with One Diffractive FaceAn enhanced alignment cube has been invented for use in a confined setting (e.g., a cryogenic chamber) in which optical access may be limited to a single line of sight. Whereas traditional alignment-cube practice entails the use of two theodolites aimed along two lines of sight, the enhanced alignment cube yields complete alignment information through use of a single theodolite aimed along a single line of sight. Typically, an alignment cube is placed in contact with a datum surface or other reference feature on a scientific instrument during assembly or testing of the instrument. The alignment cube is then used in measuring a small angular deviation of the feature from a precise required orientation. Commonly, the deviation is expressed in terms of rotations (Rx,Ry,Rz) of the cube about the corresponding Cartesian axes (x,y,z). In traditional practice, in order to measure all three rotations, it is necessary to use two theodolites aimed at two orthogonal faces of the alignment cube, as shown in the upper part of the figure. To be able to perform such a measurement, one needs optical access to these two faces. In the case of an alignment cube inside a cryogenic chamber or other enclosed space, the optical-access requirement translates to a requirement for two windows located along the corresponding two orthogonal lines of sight into the chamber. In a typical application, it is difficult or impossible to provide two windows. The present enhanced version of the alignment cube makes it possible to measure all three rotations by use of a single line of sight, thereby obviating a second window.
Document ID
Document Type
Other - NASA Tech Brief
Ohl, Raymond G.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Sampler, Henry P.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Strojny, Carl R.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Hagopian, John G.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
McMann, Joseph C.
(ManTech International Corp. Fairfax, VA, United States)
Date Acquired
August 25, 2013
Publication Date
December 1, 2006
Publication Information
Publication: NASA Tech Briefs, December 2006
Subject Category
Man/System Technology And Life Support
Report/Patent Number
Distribution Limits
Public Use Permitted.
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