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Metzger NK, Spesyvtsev R, Bruce GD, Miller B, Maker GT, Malcolm G, Mazilu M, Dholakia K. Harnessing speckle for a sub-femtometre resolved broadband wavemeter and laser stabilization. Nat Commun 2017; 8:15610. [PMID: 28580938 PMCID: PMC5465361 DOI: 10.1038/ncomms15610] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2016] [Accepted: 04/12/2017] [Indexed: 11/09/2022] Open
Abstract
The accurate determination and control of the wavelength of light is fundamental to many fields of science. Speckle patterns resulting from the interference of multiple reflections in disordered media are well-known to scramble the information content of light by complex but linear processes. However, these patterns are, in fact, exceptionally rich in information about the illuminating source. We use a fibre-coupled integrating sphere to generate wavelength-dependent speckle patterns, in combination with algorithms based on the transmission matrix method and principal component analysis, to realize a broadband and sensitive wavemeter. We demonstrate sub-femtometre wavelength resolution at a centre wavelength of 780 nm, and a broad calibrated measurement range from 488 to 1,064 nm. This compares favourably to the performance of conventional wavemeters. Using this speckle wavemeter as part of a feedback loop, we stabilize a 780 nm diode laser to achieve a linewidth better than 1 MHz.
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Affiliation(s)
| | - Roman Spesyvtsev
- SUPA, School of Physics and Astronomy, University of St Andrews, Scotland KY16 9SS, UK
| | - Graham D. Bruce
- SUPA, School of Physics and Astronomy, University of St Andrews, Scotland KY16 9SS, UK
| | - Bill Miller
- M Squared Lasers Ltd, Venture Building, 1 Kelvin Campus, West of Scotland Science Park, Glasgow G20 0SP, UK
| | - Gareth T. Maker
- M Squared Lasers Ltd, Venture Building, 1 Kelvin Campus, West of Scotland Science Park, Glasgow G20 0SP, UK
| | - Graeme Malcolm
- M Squared Lasers Ltd, Venture Building, 1 Kelvin Campus, West of Scotland Science Park, Glasgow G20 0SP, UK
| | - Michael Mazilu
- SUPA, School of Physics and Astronomy, University of St Andrews, Scotland KY16 9SS, UK
| | - Kishan Dholakia
- SUPA, School of Physics and Astronomy, University of St Andrews, Scotland KY16 9SS, UK
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Ferrero A, Perales E, Rabal AM, Campos J, Martínez-Verdú FM, Chorro E, Pons A. Color representation and interpretation of special effect coatings. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2014; 31:436-447. [PMID: 24562043 DOI: 10.1364/josaa.31.000436] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A representation of the color gamut of special effect coatings is proposed and shown for six different samples, whose colors were calculated from spectral bidirectional reflectance distribution function (BRDF) measurements at different geometries. The most important characteristic of the proposed representation is that it allows a straightforward understanding of the color shift to be done both in terms of conventional irradiation and viewing angles and in terms of flake-based parameters. A different line was proposed to assess the color shift of special effect coatings on a*,b*-diagrams: the absorption line. Similar to interference and aspecular lines (constant aspecular and irradiation angles, respectively), an absorption line is the locus of calculated color coordinates from measurement geometries with a fixed bistatic angle. The advantages of using the absorption lines to characterize the contributions to the spectral BRDF of the scattering at the absorption pigments and the reflection at interference pigments for different geometries are shown.
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Ferrero A, Rabal A, Campos J, Martínez-Verdú F, Chorro E, Perales E, Pons A, Hernanz ML. Spectral BRDF-based determination of proper measurement geometries to characterize color shift of special effect coatings. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2013; 30:206-214. [PMID: 23456055 DOI: 10.1364/josaa.30.000206] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
A reduced set of measurement geometries allows the spectral reflectance of special effect coatings to be predicted for any other geometry. A physical model based on flake-related parameters has been used to determine nonredundant measurement geometries for the complete description of the spectral bidirectional reflectance distribution function (BRDF). The analysis of experimental spectral BRDF was carried out by means of principal component analysis. From this analysis, a set of nine measurement geometries was proposed to characterize special effect coatings. It was shown that, for two different special effect coatings, these geometries provide a good prediction of their complete color shift.
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Affiliation(s)
- Alejandro Ferrero
- Instituto de Óptica, Consejo Superior de Investigaciones Científicas (CSIC), Madrid 28006, Spain.
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Ceolato R, Riviere N, Hespel L. Reflectances from a supercontinuum laser-based instrument: hyperspectral, polarimetric and angular measurements. OPTICS EXPRESS 2012; 20:29413-29425. [PMID: 23388769 DOI: 10.1364/oe.20.029413] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Recent developments of active hyperspectral systems require optical characterization of man-made materials for instrument calibration. This work presents an original supercontinuum laser-based instrument designed by Onera, The French Aerospace Lab, for fast hyperspectral polarimetric and angular reflectances measurements. The spectral range is from 480 nm to 1000 nm with a 1 nm spectral resolution. Different polarization configurations are made possible in whole spectrum. This paper reviews the design and the calibration of the instrument. Hyper-spectral polarimetric and angular reflectances are measured for reference and man-made materials such as paint coatings. Physical properties of reflectances as positivity, energy conservation and Helmholtz reciprocity are retrieved from measurements.
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Affiliation(s)
- Romain Ceolato
- Onera, The French Aerospace Lab - FR31000 Toulouse, France
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Ferrero A, Rabal AM, Campos J, Pons A, Hernanz ML. Spectral and geometrical variation of the bidirectional reflectance distribution function of diffuse reflectance standards. APPLIED OPTICS 2012; 51:8535-8540. [PMID: 23262591 DOI: 10.1364/ao.51.008535] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Accepted: 11/11/2012] [Indexed: 06/01/2023]
Abstract
A study on the variation of the spectral bidirectional reflectance distribution function (BRDF) of four diffuse reflectance standards (matte ceramic, BaSO(4), Spectralon, and white Russian opal glass) is accomplished through this work. Spectral BRDF measurements were carried out and, using principal components analysis, its spectral and geometrical variation respect to a reference geometry was assessed from the experimental data. Several descriptors were defined in order to compare the spectral BRDF variation of the four materials.
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Affiliation(s)
- Alejandro Ferrero
- Instituto de Óptica, Consejo Superior de Investigaciones Científicas, Madrid, Spain.
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Ferrero A, Rabal AM, Campos J, Pons A, Hernanz ML. Variables separation of the spectral BRDF for better understanding color variation in special effect pigment coatings. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2012; 29:842-847. [PMID: 22673411 DOI: 10.1364/josaa.29.000842] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
A type of representation of the spectral bidirectional reflectance distribution function (BRDF) is proposed that distinctly separates the spectral variable (wavelength) from the geometrical variables (spherical coordinates of the irradiation and viewing directions). Principal components analysis (PCA) is used in order to decompose the spectral BRDF in decorrelated spectral components, and the weight that they have at every geometrical configuration of irradiation/viewing is established. This method was applied to the spectral BRDF measurement of a special effect pigment sample, and four principal components with relevant variance were identified. These four components are enough to reproduce the great diversity of spectral reflectances observed at different geometrical configurations. Since this representation is able to separate spectral and geometrical variables, it facilitates the interpretation of the color variation of special effect pigments coatings versus the geometrical configuration of irradiation/viewing.
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Affiliation(s)
- Alejandro Ferrero
- Instituto de Óptica, Consejo Superior de Investigaciones Científicas, Madrid, Spain.
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