Abstract

Measuring the radial velocity of an object can be achieved by quantifying the Doppler shift of Fraunhofer lines. Measurements are typically made using high-resolution conventional spectroscopy, in which the Doppler shift is calculated numerically on a computer. An alternative technique includes cross-correlation spectroscopy, which performs an optical correlation of the incident spectrum against a reference spectrum embedded in the instrument. Many existing correlation spectrometers leverage a chrome mask and obtain a single beam measurement, making the sensors more sensitive to atmospheric turbulence without moving parts. In this paper, we present a static dual-beam polarization-based technique for acquiring cross-correlation spectra that is insensitive to atmospheric turbulence and contains no moving parts. The instrument is based on acquiring light both inside and outside of the solar Fraunhofer lines using a twisted nematic liquid-crystal spatial light modulator. Correlation spectra can be calculated as a ratio of these two components. A model of the dual-beam cross-correlation spectrometer is presented and subsequently validated with experimental observations of Venus. Radial velocity accuracies, as calculated against reference ephemerides, yielded an absolute error less than 0.24%.

© 2019 Optical Society of America

Fiber Fabry–Perot astrophotonic correlation spectroscopy for remote gas identification and radial velocity measurements

Ross Cheriton, Adam Densmore, Suresh Sivanandam, Ernst de Mooij, Pavel Cheben, Dan-Xia Xu, Jens H. Schmid, and Siegfried Janz
Appl. Opt. 60(32) 10252-10263 (2021)

Determination of velocity gradients with scattered light cross-correlation measurements

C. Keveloh and W. Staude
Appl. Opt. 22(2) 333-338 (1983)

Dual Fabry-Perot spectrometer measurements of daytime thermospheric temperature and wind velocity: data analysis procedures

T. D. Cocks
Appl. Opt. 22(5) 726-732 (1983)

Dual-beam incoherent cross-correlation spectroscopy

K.-Q. Xia, Y.-B. Xin, and P. Tong
J. Opt. Soc. Am. A 12(7) 1571-1578 (1995)

Atmospheric coherence time measurement by four-aperture DIMM defocus velocity technique

M. Panahi, R. Shomali, M. Mollabashi, and Saifollah Rasouli
Appl. Opt. 58(31) 8673-8679 (2019)