Instrument function of the Fabry-Perot spectrometer

Wilksch, Philip A.

doi:10.1364/ao.24.001502

Cited by 33 publications

(14 citation statements)

References 37 publications

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“…The laser operates at a fixed wavelength and the spectral scanning has thus been performed by changing the wavelength position of the interferometer transmission profile through incremental increases in the plate spacing. In this way, as we increased the interferometer spacing and moved the transmission profile past the laser emission peak from the blue to the red, the interferometer profile was sequentially sampled from longer to shorter wavelengths (Wilksch 1985).…”

Section: Data Descriptionmentioning

confidence: 99%

Characterization of Fabry-Perot interferometers and multi-etalon transmission profiles

Reardon¹,

Cavallini²

2008

A&A

115

109

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Aims. Properly characterizing Fabry-Perot interferometers (FPI) is essential for determining their effective properties and evaluating the performance of the astronomical instruments in which they are employed. Furthermore, in two-dimensional spectrographs where multiple FPI are used in series, the actual distribution of plate separation errors will be crucial for determining the resulting transmission profiles. We describe techniques that address these issues utilizing the FPI of IBIS, a solar bidimensional spectrometer installed at the Dunn Solar Telescope. Methods. A frequency-stabilized He-Ne laser was used in three different optical layouts to measure the spatially-resolved transmission of the FPI. Analyzing the shape and wavelength shift of the observed profiles allows the characteristics of the cavity errors and the interferometer coating to be determined. Results. We have measured the spatial distribution of the large-scale plate defects, which shows a steep radial trend, as well as the magnitude of the small-scale microroughness. We also extracted the effective reflectivity and absorption of the coating at the laser line wavelength for both interferometers. Conclusions. These techniques, which are generally applicable to any Fabry-Perot interferometer, provide the necessary information for calculating the overall instrumental profile for any illuminated area of the interferometer plates. Accurate knowledge of the spectral transmission profile is important, in particular when using inversion techniques or in comparing observations with simulated data.

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Section: Data Descriptionmentioning

confidence: 99%

Characterization of Fabry-Perot interferometers and multi-etalon transmission profiles

Reardon¹,

Cavallini²

2008

A&A

115

109

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“…The laser is assumed to have zero instrinsic line-width compared to the resolving power of the FPS; hence, the laser profile is taken as a measure of the intrinsic broadening of the instrument. This is termed the instrument function (see Wilksch, 1985, for a detailed discussion of this).…”

Section: The Fabry-perot Spectrometermentioning

confidence: 99%

Mesospheric temperatures from observations of the hydroxyl (6–2) emission above Davis, Antarctica: A comparison of rotational and Doppler measurements

et al. 2001

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Abstract. We present observations of the hydroxyl (6-2) airglow lines from ∼87 km altitude obtained at Davis station, Antarctica, in the austral winter of 1999. Nine nights of observations were made of the P-branch near λ840 nm with a Czerny-Turner scanning spectrometer (CTS); at the same time, high-resolution Fabry-Perot Spectrometer (FPS) spectra were collected of the Q 1 (1) doublet at λ834 nm. Rotational temperatures were determined from the CTS observations, while Doppler temperatures were derived from the line-widths of the FPS Q 1 (1) spectra. Absolute temperatures determined by these methods are uncertain by ∼2 and ∼20 K, respectively. For the comparison we set the value of the reflective finesse of the FPS at λ834 nm so the mean FPS temperature from one night of simultaneous data was equal to that from the CTS, and then looked at the measured variations in each data set for the other eight nights. Both instruments show the upper mesosphere temperature to vary in a similar manner to within the observational errors of the measurements, implying an equivalence of the rotational and Doppler temperatures. We believe that this is the first published simultaneous, same-site, comparison of rotational and Doppler temperatures from the OH emission.

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“…Each exposure yields a separate spectrum for each of the allocated zones. Each spectrum is a vector of samples of the emission's spectral distribution, convolved with the spectrometer's instrument function [Wilksch, 1985], and spans a wavelength interval equal to one free spectral range of the Fabry-Perot etaIon.…”

Section: Raw Data and Initial Analysismentioning

confidence: 99%

Spatial structure in the thermospheric horizontal wind above Poker Flat, Alaska, during solar minimum

Conde¹,

Smith²

1998

J. Geophys. Res.

120

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Abstract. A new all-sky imaging, wavelength scanning Fabry-Perot spectrometer was used to record high-resolution (R ___ 200,000) spectra of the A630 nm thermospheric optical emission above Poker Flat, Alaska. These spectra were used to derive spatially resolved maps of the horizontal wind vector at approximately 250 km altitude. We describe the procedure used to infer vector winds from hue-of-sight Doppler shifts, along with its limitations. We present the time evolution of the vector wind fields obtained from this method for 6 nights of observation. Five of the 6 nights contained periods when we inferred the existence of significant curvature, divergence or shear in the thermospheric wind across our instrument 's 001000 km diameter field of view. The sixth night exhibited little spatial structure and is shown for comparison. We compare these results with a "generic" solar minimum winter time run of the National Center for Atmospheric Research's Thermosphere, Ionosphere, and Electrodynamics General Circulation Model. While agreement was good at the start and end of the night, considerable differences were found in the late evening and midnight sectors. Some possible origins for these discrepancies are proposed. In particular, we suggest that the F region horizontal wind may be deflected by upwelling vertical winds, which are in turn driven by E region heating in the auroral zone. We note that both the instrument used and our high-latitude implementation of the analysis procedure are new experimental techniques. Thus the data presented here should be regarded as prehminary and, if possible, be vahdated by comparison with results from other techniques.

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Instrument function of the Fabry-Perot spectrometer

Cited by 33 publications

References 37 publications

Characterization of Fabry-Perot interferometers and multi-etalon transmission profiles

Characterization of Fabry-Perot interferometers and multi-etalon transmission profiles

Mesospheric temperatures from observations of the hydroxyl (6–2) emission above Davis, Antarctica: A comparison of rotational and Doppler measurements

Spatial structure in the thermospheric horizontal wind above Poker Flat, Alaska, during solar minimum

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