Measurements of half-widths of spectral lines by means of a Fabry-Perot interferometer with photoelectric recording

1959 ◽  
Vol 2 (10) ◽  
pp. 756-760 ◽  
Author(s):  
Yu. P. Efremov
Keyword(s):  
Spectral Lines ◽  
Photoelectric Recording ◽  
Fabry Perot

The Use of Fabry-Perot Filters for Spectral Scanning

1969 ◽  
Vol 1 (6) ◽  
pp. 293-294
Author(s):  
M. D. Waterworth
Keyword(s):  
Stellar Atmospheres ◽  
Spectral Lines ◽  
Resolving Power ◽  
Doppler Broadening ◽  
Collisional Broadening ◽  
Fabry Perot

In designing a stellar spectrograph, it is pointless to exceed the resolving power necessary to obtain all the information from the spectrum of a star. This is limited mainly by atomic thermal motions, giving rise to the Doppler broadening of spectral lines, by turbulence and rotation of the stellar atmospheres in which the lines are formed, and by collisional broadening.

scholarly journals Messung der Ionentemperatur mit Hilfe des thermischen Doppler-Effekts an einer Wasserstoff-Lichtbogenentladung

1970 ◽  
Vol 25 (4) ◽  
pp. 473-481 ◽  
Author(s):  
D. Ludwig ◽  
J. Raeder
Keyword(s):  
Doppler Effect ◽  
Axial Magnetic Field ◽  
Transmission Band ◽  
Interference Filter ◽  
Half Width ◽  
Spectral Lines ◽  
Ion Temperature ◽  
Strong Reduction ◽  
Radial Profiles ◽  
Fabry Perot

AbstractThe radial ion temperature distribution in a 2600 amp hydrogen arc in a 30 kG axial magnetic field was measured spectroscopically with a Fabry-Perot interferometer by evaluating the half width of Doppler broadened carbon lines. As the admixture of methane had to be low, in order to prevent a strong reduction of the temperature on the axis, the intensities of the C III and C IV lines were relatively weak. Consequently an interference filter with narrow transmission band width was used instead of a spectrograph in front of the F.-P.-interferometer. The broadening of the spectral lines, which were used for measurement, was caused mainly by the thermal Doppler effect. The rotation of the plasma and the macroscopical Doppler effect resulting therefrom did not disturb the measurements. The ion temperature, which was found to be 1.4 × 105 °K on the axis, was determined from the half width of the profiles of a C III spectral line. Since the discharge was observed side-on, the measured integrated values were reduced to radial profiles by using appropriate inversion formulae.

scholarly journals Continuous Hue-Based Self-Calibration of a Smartphone Spectrometer Applied to Optical Fiber Fabry-Perot Sensor Interrogation

Sensors ◽  
2020 ◽  
Vol 20 (21) ◽  
pp. 6304
Author(s):  
Aleksandr Markvart ◽  
Leonid Liokumovich ◽  
Iurii Medvedev ◽  
Nikolai Ushakov
Keyword(s):  
Optical Fiber ◽  
Optical Path Difference ◽  
Path Difference ◽  
Spectral Lines ◽  
Light Sources ◽  
Temperature Drift ◽  
Self Calibration ◽  
Fabry Perot ◽  
Wavelength Scale ◽  
Calibration Approach

Smartphone-based optical spectrometers allow the development of a new generation of portable and cost-effective optical sensing solutions that can be easily integrated into sensor networks. However, most commonly the spectral calibration relies on the external reference light sources which have known narrow spectral lines. Such calibration must be repeated each time the fiber and diffraction grating holders are removed from the smartphone and reattached. Moreover, the spectrometer wavelength scale can drift during the measurement because of the smartphone temperature fluctuations. The present work reports on a novel spectral self-calibration approach, based on the correspondence between the light wavelength and the hue features of the spectrum measured using a color RGB camera. These features are caused by the nonuniformity of camera RGB filters’ responses and their finite overlap, which is a typical situation for RGB cameras. Thus, the wavelength scale should be externally calibrated only once for each smartphone spectrometer and can further be continuously verified and corrected using the proposed self-calibration approach. An ability of the plug-and play operation and the temperature drift elimination of the smartphone spectrometer was experimentally demonstrated. Conducted experiments involved interrogation of optical fiber Fabry-Perot interferometric sensor and demonstrated a nanometer-level optical path difference resolution.

Registration of Low Intenstity Spectral Lines with Fabry Perot Interferometer by Photon Counting Method

1980 ◽  
Vol 13 (6) ◽  
pp. 407-417 ◽  
Author(s):  
L. Dunchev ◽  
A. Petrakiev ◽  
S. Z. Mohamad ◽  
I. Mandjukov
Keyword(s):  
Photon Counting ◽  
Spectral Lines ◽  
Counting Method ◽  
Fabry Perot ◽  
Photon Counting Method

The McDonald Observatory High Precision Radial Velocity Spectrometer

1984 ◽  
Vol 88 ◽  
pp. 109-120
Author(s):  
William D. Cochran ◽  
Brenda W. Young
Keyword(s):  
Radial Velocity ◽  
Large Mass ◽  
Spectral Lines ◽  
Stellar Spectrum ◽  
Stellar Oscillations ◽  
Doppler Shifts ◽  
Calibration Methods ◽  
Fabry Perot ◽  
Fixed Reference ◽  
Low Amplitude

AbstractWe are developing a prototype instrument for McDonald Observatory designed to measure stellar radial velocity variations to a precision of a few meters per second. The instrument will be used to study low amplitude stellar oscillations, to search for binary stellar systems with large mass ratios, and possibly to search for extra-solar planetary systems. A fixed gap Fabry-Perot etalon, used in reflection, imposes a set of fixed reference absorption lines on the stellar spectrum before it enters the McDonald Observatory 2.7m coudé spectrograph. The spectrum, covering 1500 Å at 0.13 Å resolution, is recorded on a set of eight Reticon arrays, placed end-to-end. Doppler shifts of the stellar spectral lines with respect to the fixed Fabry-Perot orders are measured by cross-correlation techniques. Calibration methods have been developed to measure any long-term drifts within the system.

scholarly journals Quantifying Resolving Power in Astronomical Spectra

2013 ◽  
Vol 30 ◽  
Author(s):  
J. Gordon Robertson
Keyword(s):  
Spectral Line ◽  
Spatial Dimension ◽  
Spectral Lines ◽  
Resolving Power ◽  
Noise Power ◽  
Line Spread Function ◽  
Fabry Perot ◽  
Lorentzian Profile ◽  
Multi Mode ◽  
Line Spread

AbstractThe spectral resolving power R = λ/δλ is a key property of any spectrograph, but its definition is vague because the ‘smallest resolvable wavelength difference’ δλ does not have a consistent definition. Often, the FWHM is used, but this is not consistent when comparing the resolution of instruments with different forms of spectral line-spread function. Here, two methods for calculating resolving power on a consistent scale are given. The first method is based on the principle that two spectral lines are just resolved when the mutual disturbance in fitting the fluxes of the lines reaches a threshold (here equal to that of sinc2 profiles at the Rayleigh criterion). The second criterion assumes that two spectrographs have equal resolving powers if the wavelength error in fitting a narrow spectral line is the same in each case (given equal signal flux and noise power). The two criteria give similar results and give rise to scaling factors that can be applied to bring resolving power calculated using the FWHM on to a consistent scale. The differences among commonly encountered line-spread functions are substantial, with a Lorentzian profile (as produced by an imaging Fabry–Perot interferometer) being a factor of two worse than the boxy profile from a projected circle (as produced by integration across the spatial dimension of a multi-mode fibre) when both have the same FWHM. The projected circle has a larger FWHM than its true resolution, so using FWHM to characterise the resolution of a spectrograph which is fed by multi-mode fibres significantly underestimates its true resolving power if it has small aberrations and a well-sampled profile.

scholarly journals Astro-comb: revolutionizing precision spectroscopy in astrophysics

2008 ◽  
Vol 4 (S253) ◽  
pp. 499-501
Author(s):  
Claire E. Cramer ◽  
Chih-Hao Li ◽  
Andrew J. Benedick ◽  
Alexander G. Glenday ◽  
Franz X. Kärtner ◽  
...  
Keyword(s):  
Doppler Shift ◽  
Extrasolar Planets ◽  
Frequency Comb ◽  
Laser Frequency ◽  
Spectral Lines ◽  
Resolving Power ◽  
Long Term Stability ◽  
Fabry Perot ◽  
Line Spacing ◽  
Wide Line

AbstractSearches for extrasolar planets using the periodic Doppler shift of stellar spectral lines have recently achieved a precision better than 60cm/s. To find a 1-Earth mass planet in an Earth-like orbit, a precision of 5cm/s is necessary. The combination of a laser frequency comb with a Fabry-Perot filtering cavity has been suggested as a promising approach to achieve such Doppler shift resolution via improved spectrograph wavelength calibration. Here we report the fabrication of such a filtered laser comb with up to 40 GHz (~1 Angstrom) line spacing, generated from a 1 GHz repetition-rate source, without compromising long-term stability, reproducibility or spectral resolution. This wide-line-spacing comb (astro-comb) is well matched to the resolving power of high-resolution astrophysical spectrographs. The astrocomb should allow a precision as high as 1cm/s in astronomical readial velocity measurements.

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