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Comparison of digital photography and spectrometry for evaluating colour perception in humans and other trichromatic species. Behav Ecol Sociobiol 2021. [DOI: 10.1007/s00265-021-03071-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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2
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Ďurian M, Sámel M, Matejčík Š. Step-scan Michelson Fourier-transform spectrometer for optical emission spectroscopy in UV-VIS spectral range. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:033102. [PMID: 32259943 DOI: 10.1063/1.5119206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 02/13/2020] [Indexed: 06/11/2023]
Abstract
We present the design, construction, and first spectra of a step-scan Michelson Fourier-transform spectrometer for optical emission spectroscopy in the UV-VIS spectral range. The mirror motion mechanism is based on a long-travel piezo-based linear translation stage with built-in position feedback. The step-scan arrangement allows for signal integration, making the instrument suitable for measurements of less intensive radiation sources and for the photon-counting technique. The spectrometer consists of two coupled Michelson interferometers, one for the spectrometer itself and the other to provide positional reference for the mirror stepping mechanism using interference fringes of a stabilized 635 nm laser diode. Using interpolation of the laser interferogram and taking advantage of the translation stage precision in linear-piezo mode, the mechanism is capable of performing 79 nm steps, which puts the Nyquist wavelength at ∼320 nm. The spectrometer was tested by measuring the spectra of HgAr cold-cathode fluorescent lamp and electron-induced fluorescence of ambient air. Two different detectors were used, an amplified photodiode detector and a photomultiplier tube module in photon counting mode. The highest achieved experimental spectral resolving power was ∼4000 using 1 mm of total mirror travel and the highest achieved noise-free dynamic range was 103. Test results show that the instrument is suitable for use with moderate-to-low intensity signal sources such as small gas discharges and spectroscopic measurements at astronomical telescopes.
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Affiliation(s)
- Michal Ďurian
- Department of Experimental Physics, Faculty of Mathematics, Physics and Informatics, Comenius University, Mlynska dolina, 842 48 Bratislava, Slovak Republic
| | - Matúš Sámel
- Department of Experimental Physics, Faculty of Mathematics, Physics and Informatics, Comenius University, Mlynska dolina, 842 48 Bratislava, Slovak Republic
| | - Štefan Matejčík
- Department of Experimental Physics, Faculty of Mathematics, Physics and Informatics, Comenius University, Mlynska dolina, 842 48 Bratislava, Slovak Republic
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Oriana A, Réhault J, Preda F, Polli D, Cerullo G. Scanning Fourier transform spectrometer in the visible range based on birefringent wedges. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2016; 33:1415-1420. [PMID: 27409701 DOI: 10.1364/josaa.33.001415] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We introduce a spectrometer capable of measuring sample absorption spectra in the visible regime, based on a time-domain scanning Fourier transform (FT) approach. While infrared FT spectrometers typically employ a Michelson interferometer to create the two delayed light replicas, the proposed apparatus exploits a compact common-mode passive interferometer that relies on the use of birefringent wedges. This ensures excellent path-length stability (∼λ/300) and accuracy, with no need for active feedback or beam tracking. We demonstrate the robustness of the technique measuring the transmission spectrum of a colored bandpass filter over one octave of bandwidth and compare the results with those obtained with a commercial spectrophotometer.
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Luu J, Willard B. Highly folded 5 m Fourier transform spectrometer for spaceborne wind lidar. APPLIED OPTICS 2015; 54:6190-6198. [PMID: 26193393 DOI: 10.1364/ao.54.006190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We have designed and built a prototype Fourier transform spectrometer intended for a wind lidar system. The significant characteristics of this design include (1) an optical layout that folds a maximum optical path difference of 5.8 m to fit into a 1.2 m cavity, (2) two confocal parabolas to compensate for beam diffraction over the entire path length, and (3) a photon-counting detector for high sensitivity. The optical path difference is measured with a reference beam produced by the heterodyne technique. The reference beam is collinear with the data beam, and accounts for all mechanical vibrations along the optical path.
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Wang S, Li KF, Pongetti TJ, Sander SP, Yung YL, Liang MC, Livesey NJ, Santee ML, Harder JW, Snow M, Mills FP. Midlatitude atmospheric OH response to the most recent 11-y solar cycle. Proc Natl Acad Sci U S A 2013; 110:2023-8. [PMID: 23341617 PMCID: PMC3568342 DOI: 10.1073/pnas.1117790110] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The hydroxyl radical (OH) plays an important role in middle atmospheric photochemistry, particularly in ozone (O(3)) chemistry. Because it is mainly produced through photolysis and has a short chemical lifetime, OH is expected to show rapid responses to solar forcing [e.g., the 11-y solar cycle (SC)], resulting in variabilities in related middle atmospheric O(3) chemistry. Here, we present an effort to investigate such OH variability using long-term observations (from space and the surface) and model simulations. Ground-based measurements and data from the Microwave Limb Sounder on the National Aeronautics and Space Administration's Aura satellite suggest an ∼7-10% decrease in OH column abundance from solar maximum to solar minimum that is highly correlated with changes in total solar irradiance, solar Mg-II index, and Lyman-α index during SC 23. However, model simulations using a commonly accepted solar UV variability parameterization give much smaller OH variability (∼3%). Although this discrepancy could result partially from the limitations in our current understanding of middle atmospheric chemistry, recently published solar spectral irradiance data from the Solar Radiation and Climate Experiment suggest a solar UV variability that is much larger than previously believed. With a solar forcing derived from the Solar Radiation and Climate Experiment data, modeled OH variability (∼6-7%) agrees much better with observations. Model simulations reveal the detailed chemical mechanisms, suggesting that such OH variability and the corresponding catalytic chemistry may dominate the O(3) SC signal in the upper stratosphere. Continuing measurements through SC 24 are required to understand this OH variability and its impacts on O(3) further.
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Affiliation(s)
- Shuhui Wang
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA.
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Equations for solar tracking. SENSORS 2012; 12:4074-90. [PMID: 22666019 PMCID: PMC3355400 DOI: 10.3390/s120404074] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/09/2012] [Revised: 03/16/2012] [Accepted: 03/16/2012] [Indexed: 11/16/2022]
Abstract
Direct sunlight absorption by trace gases can be used to quantify them and investigate atmospheric chemistry. In such experiments, the main optical apparatus is often a grating or a Fourier transform spectrometer. A solar tracker based on motorized rotating mirrors is commonly used to direct the light along the spectrometer axis, correcting for the apparent rotation of the Sun. Calculating the Sun azimuth and altitude for a given time and location can be achieved with high accuracy but different sources of angular offsets appear in practice when positioning the mirrors. A feedback on the motors, using a light position sensor close to the spectrometer, is almost always needed. This paper aims to gather the main geometrical formulas necessary for the use of a widely used kind of solar tracker, based on two 45° mirrors in altazimuthal set-up with a light sensor on the spectrometer, and to illustrate them with a tracker developed by our group for atmospheric research.
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Wang S, Pongetti TJ, Sander SP, Spinei E, Mount GH, Cede A, Herman J. Direct Sun measurements of NO2column abundances from Table Mountain, California: Intercomparison of low- and high-resolution spectrometers. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2009jd013503] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Wang X, Chan RKY, Cheng ASK. Near UV-near IR Fourier transform spectrometer using the beam-folding position-tracking method based on retroreflectors. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2008; 79:123108. [PMID: 19123546 DOI: 10.1063/1.3046281] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
A near UV-near IR Fourier transform spectrometer based on a beam-folding position-tracking method realized by using retroreflectors is reported. The use of retroreflectors maintains all beams in the beam-fold arrangement in parallel with the incident beams. The beam-folding interferometer used for position tracking is arranged to have optical path symmetry with the measurement interferometer in the zero path difference position of the measurement interferometer, and the vertex of the movable retroreflector in the measurement interferometer is arranged very close to the midpoint of the vertices of two movable retroreflectors in the position-tracking interferometer. These measures keep the equivalent optical axis of the position-tracking interferometer well in line with that of the measurement interferometer even with translational misalignments. Therefore, the change in the optical path difference of the position-tracking interferometer is always synchronous to that of the measurement interferometer during the scanning process. That is, the position-tracking error can be suppressed to very small values during a scan. We have demonstrated a UV-near IR Fourier transform spectrometer with a standard quality ball-bearing translation stage achieving a resolution close to the theoretical resolution of approximately 0.28 cm(-1) at the He-Ne laser wavelength when the scan distance reaches the travel distance of over 2 cm. This was achieved without the need for elaborate optics, sophisticated detecting electronics, and high-precision servomotion control.
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Affiliation(s)
- Xuzhu Wang
- Department of Electronic Engineering, Ocean University of China, Qingdao 266100, People's Republic of China
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Cheung R, Li KF, Wang S, Pongetti TJ, Cageao RP, Sander SP, Yung YL. Atmospheric hydroxyl radical (OH) abundances from ground-based ultraviolet solar spectra: an improved retrieval method. APPLIED OPTICS 2008; 47:6277-6284. [PMID: 19023394 DOI: 10.1364/ao.47.006277] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The Fourier Transform Ultraviolet Spectrometer (FTUVS) instrument has recorded a long-term data record of the atmospheric column abundance of the hydroxyl radical (OH) using the technique of high resolution solar absorption spectroscopy. We report new efforts in improving the precision of the OH measurements in order to better model the diurnal, seasonal, and interannual variability of odd hydrogen (HO(x)) chemistry in the stratosphere, which, in turn, will improve our understanding of ozone chemistry and its long-term changes. Until the present, the retrieval method has used a single strong OH absorption line P(1)(1) in the near-ultraviolet at 32,341 cm(-1). We describe a new method that uses an average based on spectral fits to multiple lines weighted by line strength and fitting precision. We have also made a number of improvements in the ability to fit a model to the spectral feature, which substantially reduces the scatter in the measurements of OH abundances.
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Affiliation(s)
- Ross Cheung
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA.
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Pickett HM, Drouin BJ, Canty T, Salawitch RJ, Fuller RA, Perun VS, Livesey NJ, Waters JW, Stachnik RA, Sander SP, Traub WA, Jucks KW, Minschwaner K. Validation of Aura Microwave Limb Sounder OH and HO2measurements. ACTA ACUST UNITED AC 2008. [DOI: 10.1029/2007jd008775] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Celarier EA, Brinksma EJ, Gleason JF, Veefkind JP, Cede A, Herman JR, Ionov D, Goutail F, Pommereau JP, Lambert JC, van Roozendael M, Pinardi G, Wittrock F, Schönhardt A, Richter A, Ibrahim OW, Wagner T, Bojkov B, Mount G, Spinei E, Chen CM, Pongetti TJ, Sander SP, Bucsela EJ, Wenig MO, Swart DPJ, Volten H, Kroon M, Levelt PF. Validation of Ozone Monitoring Instrument nitrogen dioxide columns. ACTA ACUST UNITED AC 2008. [DOI: 10.1029/2007jd008908] [Citation(s) in RCA: 164] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Chan RKY, Lim PK, Wang X, Chan MH. Fourier transform ultraviolet-visible spectrometer based on a beam-folding technique. OPTICS LETTERS 2006; 31:903-5. [PMID: 16599206 DOI: 10.1364/ol.31.000903] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
A beam-folding technique in optical interferometry, where the number of beam folds used can be very large, is reported. This technique can be used as a low-cost position-tracking method in a Fourier transform spectrometer (FTS) to cover the broad spectral range from UV to IR. The main advantage gained is the simple position-tracking algorithm used in sampling the interferogram. We have developed a UV-visible FTS, whose wavelength coverage is limited only by the optical elements (350 nm(-1) microm with off-the-shelf components). Preliminary results show that it can achieve a resolution of approximately 4 cm(-1) even with a ball-bearing translation stage.
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Affiliation(s)
- Robert K Y Chan
- Department of Physics, Hong Kong Baptist University, 224 Waterloo Road, Hong Kong, China.
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Gattinger RL, Degenstein DA, Llewellyn EJ. Optical Spectrograph and Infra-Red Imaging System (OSIRIS) observations of mesospheric OH A2Σ+-X2Π 0-0 and 1-1 band resonance emissions. ACTA ACUST UNITED AC 2006. [DOI: 10.1029/2005jd006369] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Abstract
AbstractVolcanic gas and aerosol surveillance yield important insights into magmatic, hydrothermal, and atmospheric processes. A range of optical sensing and sampling techniques has been applied to measurements of the composition and fluxes of volcanic emissions. In particular, the 30-year worldwide volcanological service record of the Correlation Spectrometer (COSPEC) illustrates the point that robust, reliable, straightforward optical techniques are of tremendous interest to the volcano observatory and research community. This chapter reviews the field, in particular the newer and more versatile instruments capable of augmenting or superseding COSPEC, with the aim of stimulating their rapid adoption by the volcanological community. It focuses on sensors that can be operated from the ground, since they generally offer the most flexibility and sensitivity. The success of COSPEC underlines the point, however, that such devices should be comparatively cheap, and easy to use and maintain, if they are to be widely used.
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Affiliation(s)
- A. J. S. McGonigle
- Department of Geography, University of Cambridge
Downing Place, Cambridge CB2 3EN, UK
| | - C. Oppenheimer
- Department of Geography, University of Cambridge
Downing Place, Cambridge CB2 3EN, UK
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