Miniature instrument for the measurement of gap thickness using poly-chromatic interferometry

R. L. Johnson, J Roger P Angel, M. Lloyd-Hart, G. Z. Angeli

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

2 Citations (Scopus)

Abstract

An optical instrument for measuring the thickness of a thin gap or transparent film is presented. It will be used to calibrate the adaptive secondary mirror under development for the Steward Observatory 6.5 m Multiple Mirror Telescope. Capacitive sensors in the mirror assembly measure dynamically the thickness of the nominally 50 μm air gap between the deformable mirror and a glass reference body. The miniature interferometer has been developed to accurately determine the gap thickness so that the capacitive sensors may be calibrated. Interference fringes are produced by illuminating an air gap, which is between two reflective surfaces, with monochromatic plane waves and observing the reflected light. Intensity variations are measured as the wavelength of illumination is varied over an octave. The film thickness is determined by correlating the observed fringes with those modeled for different gaps. Absolute measurement to an accuracy of a small fraction of a wavelength is possible.

Original languageEnglish (US)
Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
PublisherSociety of Photo-Optical Instrumentation Engineers
Pages245-253
Number of pages9
Volume3762
StatePublished - 1999
EventProceedings of the 1999 Adaptive Optics Systems and Technology - Denver, CO, USA
Duration: Jul 21 1999Jul 22 1999

Other

OtherProceedings of the 1999 Adaptive Optics Systems and Technology
CityDenver, CO, USA
Period7/21/997/22/99

Fingerprint

Miniature instruments
Interferometry
interferometry
Mirrors
Capacitive sensors
mirrors
Optical instruments
Wavelength
Observatories
Air
Telescopes
Interferometers
deformable mirrors
sensors
air
octaves
Film thickness
wavelengths
Lighting
illuminating

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Condensed Matter Physics

Cite this

Johnson, R. L., Angel, J. R. P., Lloyd-Hart, M., & Angeli, G. Z. (1999). Miniature instrument for the measurement of gap thickness using poly-chromatic interferometry. In Proceedings of SPIE - The International Society for Optical Engineering (Vol. 3762, pp. 245-253). Society of Photo-Optical Instrumentation Engineers.

Miniature instrument for the measurement of gap thickness using poly-chromatic interferometry. / Johnson, R. L.; Angel, J Roger P; Lloyd-Hart, M.; Angeli, G. Z.

Proceedings of SPIE - The International Society for Optical Engineering. Vol. 3762 Society of Photo-Optical Instrumentation Engineers, 1999. p. 245-253.

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

Johnson, RL, Angel, JRP, Lloyd-Hart, M & Angeli, GZ 1999, Miniature instrument for the measurement of gap thickness using poly-chromatic interferometry. in Proceedings of SPIE - The International Society for Optical Engineering. vol. 3762, Society of Photo-Optical Instrumentation Engineers, pp. 245-253, Proceedings of the 1999 Adaptive Optics Systems and Technology, Denver, CO, USA, 7/21/99.
Johnson RL, Angel JRP, Lloyd-Hart M, Angeli GZ. Miniature instrument for the measurement of gap thickness using poly-chromatic interferometry. In Proceedings of SPIE - The International Society for Optical Engineering. Vol. 3762. Society of Photo-Optical Instrumentation Engineers. 1999. p. 245-253
Johnson, R. L. ; Angel, J Roger P ; Lloyd-Hart, M. ; Angeli, G. Z. / Miniature instrument for the measurement of gap thickness using poly-chromatic interferometry. Proceedings of SPIE - The International Society for Optical Engineering. Vol. 3762 Society of Photo-Optical Instrumentation Engineers, 1999. pp. 245-253
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