Analysis methodology for a piezoelectric-driven optical tracker for ground-based interferometry

James H. Clark, F E Penado

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Citations (Scopus)

Abstract

We present our analysis methodology for a 20.3 cm prototype optical tracker to determine why instabilities occur below 50 Hz and suggest improvements. The Navy Precision Optical Interferometer makes use of six small optical telescope stations spaced along a Y-array to synthesize an equivalent single larger telescope. Piezoelectric-driven optical trackers steer 12.5 cm output beams from each station to an optics laboratory up to 700 m distant. A percentage of this starlight is split off and used in a closed-loop feedback to update the pointing of the telescope and steering of the tracker. Steering stabilizes atmospheric induced beam trajectory deviations, required for fringe generation. Because of closedloop feedback, we require all fundamental frequencies to be at least 3 times the desired operational frequency, or 150 Hz. These trackers are modified commercial aluminum gimbal mounts with flex-pivot axles and very small damping ratio. Steering is tip/tilt mirror rotation by push-only actuators and a return spring. It is critical contact be maintained between actuator, mirror mount and return spring. From our dynamic analysis, the 122 N return spring is 2.9 times that required, and has a natural frequency equal to 238 Hz. The range of steering, 140 microradian, is double that required and the 0.077 microradian precision is 2.6 times that required. The natural frequency of the tracker is 66 Hz and the tuned closed-loop operational frequency is only 22 Hz. We conclude the low fundamental frequency of the mount limits its performance below 50 Hz and stiffening the structure is required.

Original languageEnglish (US)
Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
PublisherSPIE
Volume9195
ISBN (Print)9781628412222
DOIs
StatePublished - 2014
EventOptical System Alignment, Tolerancing, and Verification VIII - San Diego, United States
Duration: Aug 17 2014Aug 18 2014

Other

OtherOptical System Alignment, Tolerancing, and Verification VIII
CountryUnited States
CitySan Diego
Period8/17/148/18/14

Fingerprint

Interferometry
interferometry
methodology
Telescope
Fundamental Frequency
Methodology
telescopes
Natural Frequency
Telescopes
Closed-loop
resonant frequencies
Actuator
Natural frequencies
Mirror
Mirrors
Actuators
stations
actuators
Optical telescopes
mirrors

Keywords

  • Frequency response
  • NPOI
  • Optical interferometry
  • Optical tracker
  • Piezoelectric actuator

ASJC Scopus subject areas

  • Applied Mathematics
  • Computer Science Applications
  • Electrical and Electronic Engineering
  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

Cite this

Clark, J. H., & Penado, F. E. (2014). Analysis methodology for a piezoelectric-driven optical tracker for ground-based interferometry. In Proceedings of SPIE - The International Society for Optical Engineering (Vol. 9195). [91950A] SPIE. https://doi.org/10.1117/12.2062490

Analysis methodology for a piezoelectric-driven optical tracker for ground-based interferometry. / Clark, James H.; Penado, F E.

Proceedings of SPIE - The International Society for Optical Engineering. Vol. 9195 SPIE, 2014. 91950A.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Clark, JH & Penado, FE 2014, Analysis methodology for a piezoelectric-driven optical tracker for ground-based interferometry. in Proceedings of SPIE - The International Society for Optical Engineering. vol. 9195, 91950A, SPIE, Optical System Alignment, Tolerancing, and Verification VIII, San Diego, United States, 8/17/14. https://doi.org/10.1117/12.2062490
Clark JH, Penado FE. Analysis methodology for a piezoelectric-driven optical tracker for ground-based interferometry. In Proceedings of SPIE - The International Society for Optical Engineering. Vol. 9195. SPIE. 2014. 91950A https://doi.org/10.1117/12.2062490
Clark, James H. ; Penado, F E. / Analysis methodology for a piezoelectric-driven optical tracker for ground-based interferometry. Proceedings of SPIE - The International Society for Optical Engineering. Vol. 9195 SPIE, 2014.
@inproceedings{1983bc92c25644c29af9f875fdfac987,
title = "Analysis methodology for a piezoelectric-driven optical tracker for ground-based interferometry",
abstract = "We present our analysis methodology for a 20.3 cm prototype optical tracker to determine why instabilities occur below 50 Hz and suggest improvements. The Navy Precision Optical Interferometer makes use of six small optical telescope stations spaced along a Y-array to synthesize an equivalent single larger telescope. Piezoelectric-driven optical trackers steer 12.5 cm output beams from each station to an optics laboratory up to 700 m distant. A percentage of this starlight is split off and used in a closed-loop feedback to update the pointing of the telescope and steering of the tracker. Steering stabilizes atmospheric induced beam trajectory deviations, required for fringe generation. Because of closedloop feedback, we require all fundamental frequencies to be at least 3 times the desired operational frequency, or 150 Hz. These trackers are modified commercial aluminum gimbal mounts with flex-pivot axles and very small damping ratio. Steering is tip/tilt mirror rotation by push-only actuators and a return spring. It is critical contact be maintained between actuator, mirror mount and return spring. From our dynamic analysis, the 122 N return spring is 2.9 times that required, and has a natural frequency equal to 238 Hz. The range of steering, 140 microradian, is double that required and the 0.077 microradian precision is 2.6 times that required. The natural frequency of the tracker is 66 Hz and the tuned closed-loop operational frequency is only 22 Hz. We conclude the low fundamental frequency of the mount limits its performance below 50 Hz and stiffening the structure is required.",
keywords = "Frequency response, NPOI, Optical interferometry, Optical tracker, Piezoelectric actuator",
author = "Clark, {James H.} and Penado, {F E}",
year = "2014",
doi = "10.1117/12.2062490",
language = "English (US)",
isbn = "9781628412222",
volume = "9195",
booktitle = "Proceedings of SPIE - The International Society for Optical Engineering",
publisher = "SPIE",

}

TY - GEN

T1 - Analysis methodology for a piezoelectric-driven optical tracker for ground-based interferometry

AU - Clark, James H.

AU - Penado, F E

PY - 2014

Y1 - 2014

N2 - We present our analysis methodology for a 20.3 cm prototype optical tracker to determine why instabilities occur below 50 Hz and suggest improvements. The Navy Precision Optical Interferometer makes use of six small optical telescope stations spaced along a Y-array to synthesize an equivalent single larger telescope. Piezoelectric-driven optical trackers steer 12.5 cm output beams from each station to an optics laboratory up to 700 m distant. A percentage of this starlight is split off and used in a closed-loop feedback to update the pointing of the telescope and steering of the tracker. Steering stabilizes atmospheric induced beam trajectory deviations, required for fringe generation. Because of closedloop feedback, we require all fundamental frequencies to be at least 3 times the desired operational frequency, or 150 Hz. These trackers are modified commercial aluminum gimbal mounts with flex-pivot axles and very small damping ratio. Steering is tip/tilt mirror rotation by push-only actuators and a return spring. It is critical contact be maintained between actuator, mirror mount and return spring. From our dynamic analysis, the 122 N return spring is 2.9 times that required, and has a natural frequency equal to 238 Hz. The range of steering, 140 microradian, is double that required and the 0.077 microradian precision is 2.6 times that required. The natural frequency of the tracker is 66 Hz and the tuned closed-loop operational frequency is only 22 Hz. We conclude the low fundamental frequency of the mount limits its performance below 50 Hz and stiffening the structure is required.

AB - We present our analysis methodology for a 20.3 cm prototype optical tracker to determine why instabilities occur below 50 Hz and suggest improvements. The Navy Precision Optical Interferometer makes use of six small optical telescope stations spaced along a Y-array to synthesize an equivalent single larger telescope. Piezoelectric-driven optical trackers steer 12.5 cm output beams from each station to an optics laboratory up to 700 m distant. A percentage of this starlight is split off and used in a closed-loop feedback to update the pointing of the telescope and steering of the tracker. Steering stabilizes atmospheric induced beam trajectory deviations, required for fringe generation. Because of closedloop feedback, we require all fundamental frequencies to be at least 3 times the desired operational frequency, or 150 Hz. These trackers are modified commercial aluminum gimbal mounts with flex-pivot axles and very small damping ratio. Steering is tip/tilt mirror rotation by push-only actuators and a return spring. It is critical contact be maintained between actuator, mirror mount and return spring. From our dynamic analysis, the 122 N return spring is 2.9 times that required, and has a natural frequency equal to 238 Hz. The range of steering, 140 microradian, is double that required and the 0.077 microradian precision is 2.6 times that required. The natural frequency of the tracker is 66 Hz and the tuned closed-loop operational frequency is only 22 Hz. We conclude the low fundamental frequency of the mount limits its performance below 50 Hz and stiffening the structure is required.

KW - Frequency response

KW - NPOI

KW - Optical interferometry

KW - Optical tracker

KW - Piezoelectric actuator

UR - http://www.scopus.com/inward/record.url?scp=84923106788&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84923106788&partnerID=8YFLogxK

U2 - 10.1117/12.2062490

DO - 10.1117/12.2062490

M3 - Conference contribution

SN - 9781628412222

VL - 9195

BT - Proceedings of SPIE - The International Society for Optical Engineering

PB - SPIE

ER -