JPL Technical Report Server

Error modeling of multi-baseline optical truss, part II : application to SIM metrology truss field dependent error

Show simple item record Zhang, Liwei Dennis Milman, Mark Korechoff, Robert 2008-04-23T17:12:35Z 2008-04-23T17:12:35Z 2004-08-02
dc.identifier.citation SPIE 49th Annual Meeting : International Symposium on Optical Science and Technology, Denver, Colorado, August 2 - 6, 2004. en_US
dc.identifier.clearanceno 04-2047
dc.description.abstract The current design of the Space Interferometry Mission (SIM) employs a 19 laser-metrology-beam system (also called L19 external metrology truss) to monitor changes of distances between the fiducials of the flight system's multiple baselines. The function of the external metrology truss is to aid in the determination of the time-variations of the interferometer baseline. The largest contributor to truss error occurs in SIM wide-angle observations when the articulation of the siderostat mirrors (in order to gather starlight from different sky coordinates) brings to light systematic errors due to offsets at levels of instrument components (which include comer cube retro-reflectors, etc.). This error is labeled external metrology wide-angle field-dependent error. Physics-based model of field-dependent error at single metrology gauge level is developed and linearly propagated to errors in interferometer delay. In this manner delay error sensitivity to various error parameters or their combination can be studied using eigenvalue/eigenvector analysis. Also validation of physics-based field-dependent model on SIM testbed lends support to the present approach. As a first example, dihedral error model is developed for the comer cubes (CC) attached to the siderostat mirrors. Then the delay errors due to this effect can be characterized using the eigenvectors of composite CC dihedral error. The essence of the linear error model is contained in an error-mapping matrix. A corresponding Zernike component matrix approach is developed in parallel, first for convenience of describing the RMS of errors across the field-of-regard (FOR), and second for convenience of combining with additional models. Average and worst case residual errors are computed when various orders of field-dependent terms are removed from the delay error. Results of the residual errors are important in arriving at external metrology system component requirements. Double CCs with ideally co-incident vertices reside with the siderostat. The non-common vertex error (NCVE) is treated as a second example. Finally combination of models, and various other errors are discussed. en_US
dc.description.sponsorship NASA/JPL en_US
dc.language.iso en_US en_US
dc.publisher Pasadena, CA : Jet Propulsion Laboratory, National Aeronautics and Space Administration, 2004. en_US
dc.subject modeling en_US
dc.subject interferometer en_US
dc.subject metrology en_US
dc.subject comer cube retro-reflector en_US
dc.subject instrument systematic error en_US
dc.title Error modeling of multi-baseline optical truss, part II : application to SIM metrology truss field dependent error en_US
dc.type Preprint en_US

Files in this item

This item appears in the following Collection(s)

Show simple item record



My Account