This paper is oriented towards comparison of measurement methods for iodine absorption cells quality evaluation. Traditionally used method of laser induced fluorescence with evaluation of Stern-Volmer coefficients and method of... more
This paper is oriented towards comparison of measurement methods for iodine absorption cells quality evaluation. Traditionally used method of laser induced fluorescence with evaluation of Stern-Volmer coefficients and method of measurement of absolute frequency shifts of hyperfine spectras have several limitations and sensitivity limits. Due to this reason an alternative technique of hyperfine spectra linewidth measurement is proposed and summarization of all methods advantages and drawbacks are described.
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We propose a technique based on a transmission grating placed in front of an imaging system (e.g. a telescope) mounted on a frame that can be rotated around the optical axis. The grating creates, for each point of the source image (e.g. a... more
We propose a technique based on a transmission grating placed in front of an imaging system (e.g. a telescope) mounted on a frame that can be rotated around the optical axis. The grating creates, for each point of the source image (e.g. a star), at the focal plane, an image composed by the undistorted image of the star plus symmetrical dispersion images of several diffraction orders. The grating is rotated and several images are captured for different angular positions of the same. By analyzing the different images obtained for a different grating angle, it is possible to build the hyperspectral cube. The advantages of this method is its simplicity, extreme compactness and low cost making it suitable both for amateur astronomy and low budget science laboratory. We will present preliminary experimental results along with a discussion about the achievable spectral and spatial resolution and photon collection efficiency as a function of different type of gratings and of the number of t...
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ABSTRACT We have validated the laser-induced fluorescence technique to measure the quality of iodine cells whose transitions are used as a reference in laser standards for the realization of the definition of the metre. In this technique,... more
ABSTRACT We have validated the laser-induced fluorescence technique to measure the quality of iodine cells whose transitions are used as a reference in laser standards for the realization of the definition of the metre. In this technique, the change in induced fluorescence is measured for different values of iodine pressure in the cell: for an iodine cell contaminated with foreign gases the fluorescence is more sensitive to iodine pressure changes than for a pure one due to collisional quenching of the excited states. We have measured the fluorescence parameter Ko for a total of 96 iodine cells, and for each cell we correlated Ko with the measured absolute frequency when the cell is inserted into laser standards at wavelengths 515 nm, 532 nm and 633 nm. We observed that the distribution of the quality of the produced iodine cells has a large dispersion and we believe that this also significantly affects the frequency distribution of the iodine-based laser standards that are used to realize the definition of the metre.
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The aim of this work is to demonstrate the potential of a novel method, based on optical spectroscopy, as a primary method for quantitative gas analysis. The interest of this technique stays in the possibility to realize sensors, even... more
The aim of this work is to demonstrate the potential of a novel method, based on optical spectroscopy, as a primary method for quantitative gas analysis. The interest of this technique stays in the possibility to realize sensors, even very compact, that guarantee also to the in-...
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The extreme resolution provided by laser interferometers can be exploited for improving the measurement of Earth’s gravity field from space. Here we describe the concept of a Next Generation Gravity Mission based on this optical metrology... more
The extreme resolution provided by laser interferometers can be exploited for improving the measurement of Earth’s gravity field from space. Here we describe the concept of a Next Generation Gravity Mission based on this optical metrology and some of the ongoing developments on the key technologies, carried out in preparation of an operational mission.
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This work is oriented to comparison of methods for iodine absorption cells quality evaluation. Optical frequency references based on molecular iodine represent one of the most used references for stabilizion of laser standards working at... more
This work is oriented to comparison of methods for iodine absorption cells quality evaluation. Optical frequency references based on molecular iodine represent one of the most used references for stabilizion of laser standards working at visible spectral range. Unfortunately iodine is a media with very high sensitivity to contamination so the chemical purity of iodine cells must be preciselly controlled. Traditional methods for iodine absorption cells quality checking have several difficulties and disadvantages, these problems complicate their common using in labs. Due to this reason we propose an alternative method of spectral linewidths measurement, which overcomes these difficulties of traditionally used approaches and which serves as a tool for iodine cells quality evaluation. In this work we present the results of comparison of two laser induced fluorescence setups (with and without the compensation for the laser source spectral mode-hops) with proposed method of selected hyperfine transition linewidth measurements and we discuss advantages and limitations of these methods for practical using.
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A CO/sub 2/ laser has been frequency stabilized to an OsO/sub 4/ transition with a control bandwidth of 10 kHz. The obtained spectral purity of the laser is 100 Hz. The realization of very accurate frequency standards and experiments of... more
A CO/sub 2/ laser has been frequency stabilized to an OsO/sub 4/ transition with a control bandwidth of 10 kHz. The obtained spectral purity of the laser is 100 Hz. The realization of very accurate frequency standards and experiments of high resolution spectroscopy in the 10 /spl mu/m region are made possible by this source.
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Absolute frequency measurement at the International Bureau of Weights and Measures of an iodine-stabilized Nd:YAG laser with λ ≈ 532 nm is reported. The reference laser system Nd:YAG-C stabilized to the a10 component in the R(56) 32-0... more
Absolute frequency measurement at the International Bureau of Weights and Measures of an iodine-stabilized Nd:YAG laser with λ ≈ 532 nm is reported. The reference laser system Nd:YAG-C stabilized to the a10 component in the R(56) 32-0 line was measured using an optical femtosecond comb set-up. The frequency found was 563 260 223 510.4 kHz with a standard uncertainty of uc = 0.2 kHz. A simplified scheme was used in which the absolute frequency measurements were made possible while controlling only the repetition rate of the comb; this reduces the control of the frequency comb to a one-dimensional problem.
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In this paper we present a technique for the determination of the linestrength of SF 6 and OsO 4 transitions that occur in coincidence with the CO 2 laser lines at 10 mum. The absorption coefficient is measured at different gas pressure... more
In this paper we present a technique for the determination of the linestrength of SF 6 and OsO 4 transitions that occur in coincidence with the CO 2 laser lines at 10 mum. The absorption coefficient is measured at different gas pressure in the cell using an experimental set-up formed by ...
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... Ramiz Hamid, Ersoy Sahin, Mehmet Celik ... Lett., Vol. 85, No. 18, pp. 3797-3800, 2000. [4] M. Erin, I. Malinovsky, A. Titov, A. Chartier and J. M. Chartier, " Comparison between the He-Ne laser wavelength standards at 633 nm... more
... Ramiz Hamid, Ersoy Sahin, Mehmet Celik ... Lett., Vol. 85, No. 18, pp. 3797-3800, 2000. [4] M. Erin, I. Malinovsky, A. Titov, A. Chartier and J. M. Chartier, " Comparison between the He-Ne laser wavelength standards at 633 nm from the UME and the BIPM ", Metrologia, vol. 32, pp. ...
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In this work is presented the design and the preliminary promising experimental results obtained by our new two-way time-of-flight telemeter. The system is based on the evaluation of the phase delay of the returning optical pulses train... more
In this work is presented the design and the preliminary promising experimental results obtained by our new two-way time-of-flight telemeter. The system is based on the evaluation of the phase delay of the returning optical pulses train with respect to the outgoing one, generated from a femtosecond laser. The main idea is to expand the phase difference time delay measured with the adoption of a heterodyne method, beating at high harmonic, till 10 GHz, applied symmetrically to the two channels. It is expected that micrometer absolute accuracies and better repeatability can be obtained in this way than in simple time of flight telemetry.
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ABSTRACT The absolute optical frequency of a 633 nm, I2-stabilized He-Ne laser system is measured with a femtosecond laser frequency comb. Results over a three-year period using chain- and comb-based measurements yield an operating... more
ABSTRACT The absolute optical frequency of a 633 nm, I2-stabilized He-Ne laser system is measured with a femtosecond laser frequency comb. Results over a three-year period using chain- and comb-based measurements yield an operating frequency of ff = (473 612 353 602 850 ± 570) Hz for the INMS 3 laser stabilized to the f or a16 component of the 11-5 R(127) transition in 127I2 at the operating conditions specified for the realization of the recommended value of this radiation. The frequency of the NRC INMS 2 laser system has recently been measured with combs at NRC and BIPM and was shown to be reproducible to better than 600 Hz (1 × 10-12) after transport. These results indicate the high level of reproducibility attainable by such widely used optical frequency standards.
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Page 1. 10−12 level reproducibility of an iodine-stabilized HeNe laser endorsed by absolute frequency measurements in the BIPM and UME This article has been downloaded from IOPscience. Please scroll down to see the full text article.... more
Page 1. 10−12 level reproducibility of an iodine-stabilized HeNe laser endorsed by absolute frequency measurements in the BIPM and UME This article has been downloaded from IOPscience. Please scroll down to see the full text article. 2006 Metrologia 43 106 ...
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Page 1. Direct measurement of the absolute frequency of the international reference laser BIPM4 This article has been downloaded from IOPscience. Please scroll down to see the full text article. 2004 Metrologia 41 65... more
Page 1. Direct measurement of the absolute frequency of the international reference laser BIPM4 This article has been downloaded from IOPscience. Please scroll down to see the full text article. 2004 Metrologia 41 65 (http://iopscience.iop.org/0026-1394/41/1/009) ...
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A model for the comprehensive analysis of uncertainty in measurement by the ultraviolet photometric method for the determination of ozone concentration in air is presented. The practical evaluation of uncertainty is carried out on a... more
A model for the comprehensive analysis of uncertainty in measurement by the ultraviolet photometric method for the determination of ozone concentration in air is presented. The practical evaluation of uncertainty is carried out on a commercial photometer analysing the systematic effects and the associated uncertainty of each input quantity. The combined standard uncertainty is given. The analysis is applicable to
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We present the preliminary results of a hyperspectral imaging camera in the near medium infrared region (1.5 μm–5 μm) of the electromagnetic spectrum. This region is important to undertake remote sensing by detecting pollutants released... more
We present the preliminary results of a hyperspectral imaging camera in the near medium infrared region (1.5 μm–5 μm) of the electromagnetic spectrum. This region is important to undertake remote sensing by detecting pollutants released by industrial plants, or methane gas leaked by pipes, or even to study the efficiency and the gases produced by combustion reactions. The hyperspectral camera is based on a Fabry-Perot interferometer.
Effective interaction and accumulation of nanoparticles (NPs) within tumor cells is crucial for NP-assisted diagnostic and therapeutic biomedical applications. In this context, the shape and size features of NPs can severely influence the... more
Effective interaction and accumulation of nanoparticles (NPs) within tumor cells is crucial for NP-assisted diagnostic and therapeutic biomedical applications. In this context, the shape and size features of NPs can severely influence the strength of adhesion between NPs and cell and the NP internalization mechanisms. This study proved the ability of the PT45 and A549 tumor cells to uptake and retain magnetic Au-coated Ni80Fe20 nanodisks (NDs) prepared by means of a bottom–up self-assembling nanolithography technique assisted by polystyrene nanospheres. The chosen geometrical parameters, i.e., diameter (≈650 nm) and thickness (≈30 nm), give rise to magnetic domain patterns arranged in vortex state at the magnetic remanence. PT45 and A549 cell lines were cultured in the presence of different concentrations of Au-coated Ni80Fe20 nanodisks, and their biocompatibility was evaluated by viability and proliferation tests. Electron microscopy techniques and a combined CARS (Coherent Anti-st...
A possible technique to measure absolute distances is presented. It is based on a Michelson interferometer where two tuneable lasers are superposed to create a very short synthetic wavelength. By exploiting relative and absolute... more
A possible technique to measure absolute distances is presented. It is based on a Michelson interferometer where two tuneable lasers are superposed to create a very short synthetic wavelength. By exploiting relative and absolute interferometry theories merged together in a demonstrator experiment we have shown the possibility of absolute distance measurements with sub-fringe resolution.
This paper presents the design and breadboarding of the proof of concept demonstrator for the so called retro-reflector interferometer scheme in off-axis configuration for the ‘Next Generation Gravity Mission’ (NGGM) studied at the... more
This paper presents the design and breadboarding of the proof of concept demonstrator for the so called retro-reflector interferometer scheme in off-axis configuration for the ‘Next Generation Gravity Mission’ (NGGM) studied at the European Space Agency (ESA). This configuration can offer benefits in terms of overall satellite configuration compared to the transponder scheme, which is currently flying on board of GRACE-FO. However, it relies on very low received laser signal levels due to the fact that the laser light is travelling about 100 km from the master satellite to the remote satellite and is reflected back to the master satellite by a retro-reflector. In comparison to the transponder scheme, where the signal is amplified on the remote satellite using a laser, which is optically phase locked to the laser signal of the master spacecraft, this reflection does not amplify the signal. Thus, even with higher emitted laser power, instead of some nanowatt, only a few picowatt are a...
We discuss the relation between atomic clocks and gravity from two perspectives: gravity potential measurements for optical clock comparisons and contributions to international timescales and, conversely, the measurement of gravity... more
We discuss the relation between atomic clocks and gravity from two perspectives: gravity potential measurements for optical clock comparisons and contributions to international timescales and, conversely, the measurement of gravity potential differences using optical clocks. © 2019 The Author(s)
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A homodyne interferometer based on a spatially separated concentric laser beams has been realized at INRIM. The spatial separation, based on the use of a truncated corner cube, allows to avoid polarization mixing, while the coaxial... more
A homodyne interferometer based on a spatially separated concentric laser beams has been realized at INRIM. The spatial separation, based on the use of a truncated corner cube, allows to avoid polarization mixing, while the coaxial configuration allows to cancel common mode effects. The non linearity of the instrument is expected to be of the order or few picometers allowing its use for very critical applications at the nano-scale. The experimental set up and the preliminary results will be presented. Interferometry, Nanometrology, Non-linearity, Picometer
The conservation of artworks requires a profound knowledge about pictorial materials, their chemical and physical properties and their interaction and/or degradation processes. For this reason, pictorial materials databases are widely... more
The conservation of artworks requires a profound knowledge about pictorial materials, their chemical and physical properties and their interaction and/or degradation processes. For this reason, pictorial materials databases are widely used to study and investigate cultural heritage. At Centre for Conservation and Restoration La Venaria Reale, we prepared a set of about 1200 mock-ups with 173 different pigments and/or dyes, used across all the historical times or as products for conservation, four binders, two varnishes and four different materials for underdrawings. In collaboration with the Laboratorio Analisi Scientifiche of Regione Autonoma Valle d’Aosta, the National Institute of Metrological Research and the Department of Architecture and Design of the Polytechnic of Turin, we created a scientific database that is now available online (http://www.centrorestaurovenaria.it/en/areas/diagnostic/pictorial-materials-database) designed as a tool for heritage science and conservation. Here, we present a focus on materials for pictorial retouching where the hyperspectral imaging application, conducted with a prototype of new technology, allowed to provide a list of pigments that could be more suitable for conservation treatments and pictorial retouching. Then we present the case study of the industrial painting Notte Barbara (1962) by Pinot Gallizio where the use of the database including modern and contemporary art materials showed to be very useful and where the fibre optics reflectance spectroscopy technique was decisive for pigment identification purpose. Later in this research, the mock-ups will be exploited to study degradation processes, e.g., the lightfastness, or the possible formation of interaction products, e.g., metal carboxylates.
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The absorption cells represent an unique tool for the laser frequency stabilization. They serve as irreplaceable optical frequency references in realization of high-stable laser standards and laser sources for different brands of optical... more
The absorption cells represent an unique tool for the laser frequency stabilization. They serve as irreplaceable optical frequency references in realization of high-stable laser standards and laser sources for different brands of optical measurements, including the most precise frequency and dimensional measurement systems. One of the most often used absorption media covering visible and near IR spectral range is molecular iodine. It offers rich atlas of very strong and narrow spectral transitions which allow realization of laser systems with ultimate frequency stabilities in or below 10-14 order level. One of the most often disccussed disadvantage of the iodine cells is iodine’s corrosivity and sensitivity to presence of foreign substances. The impurities react with absorption media and cause spectral shifts of absorption spectra, spectral broadening of the transitions and decrease achievable signal-to-noise ratio of the detected spectra. All of these unwanted effects directly influence frequency stability of the realized laser standard and due to this fact, the quality of iodine cells must be precisely controlled. We present a comparison of traditionally used method of laser induced fluorescence (LIF) with novel technique based on hyperfine transitions linewidths measurement. The results summarize advantages and drawbacks of these techniques and give a recommendation for their practical usage.
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This article deals with the evaluation of the chemical purity of iodine-filled absorption cells and the optical frequency references used for the frequency locking of laser standards. We summarize the recent trends and progress in... more
This article deals with the evaluation of the chemical purity of iodine-filled absorption cells and the optical frequency references used for the frequency locking of laser standards. We summarize the recent trends and progress in absorption cell technology and we focus on methods for iodine cell purity testing. We compare two independent experimental systems based on the laser-induced fluorescence method, showing an improvement of measurement uncertainty by introducing a compensation system reducing unwanted influences. We show the advantages of this technique, which is relatively simple and does not require extensive hardware equipment. As an alternative to the traditionally used methods we propose an approach of hyperfine transitions' spectral linewidth measurement. The key characteristic of this method is demonstrated on a set of testing iodine cells. The relationship between laser-induced fluorescence and transition linewidth methods will be presented as well as a summary o...