The measurement and monitoring of radiation dose delivered in patient tissues is a critical aspect in radiation therapy. Various dosimeters have proven effective in measuring radiations at low doses. However, there is a growing demand for new dosimeters based on small, non-invasive and high resolution devices. Here we report on a miniature dosimeter based on an optical fiber cavity. We demonstrate an ultimate detection limit of 160 mGy with an effective interaction region of 6 x 10-4 mm3. Due to its reliability, compactness and biomedical dose level sensitivity, our system shows itself suitable for applications in radiation therapy dosimetry.
We present a beam shaping method using deformable mirrors without using a target beam shape.
The key to the method is the use of an image-based metric on the quality of beam with respect to
the desired attributes of the super-Gaussian output beam. This technique iteratively adjusts the
deformable mirror shape to minimize the metric measured using a charge-coupled device camera.
Since the algorithm does not use a target beam for the optimization, it produces the resulting
super-Gaussian beam geometry consistent with the constraints imposed by the limited stroke and
the finite number of actuators of the deformable mirror.
KEYWORDS: Adaptive optics, Interferometers, Digital signal processing, Deformable mirrors, Actuators, Interference (communication), Transmission electron microscopy, Astronomy, High power lasers, Wavefronts
We present the results of an Adaptive Optics prototype system used to test the feasibility of active control for corrections of geometrical aberrations of gravitational wave interferometers input laser beam. It is shown that the efficiency of the system in correcting fluctuations extends up to 80 Hz unity gain frequency and that the upper limit of reintroduced noise is within gravitational wave interferometers requirements.
We present a study and preliminary experimental results on the possibility of using an adaptive optics system for reduction of geometrical fluctuations of input laser beam in long baseline interferometric detectors of gravitational waves. Presently used completely passive systems are expected to reduce fluctuations only at a level that, due to coupling of geometrical fluctuations with interferometer asymmetries, impose requirements on interferometer operation which are at the limit of present technology. Active pre-stabilization could reduce fluctuations and relax these requirements, allowing a safer and more robust interferometer operation on the planned time-scale of years of continuous data acquisition. The system and the methodologies we have developed are going to be adapted to the Mode Cleaner of the IDGW-3P, a prototype of three-meter suspended Michelson Interferometer expressely developed for Seismic Noise measurement, now becoming operational in Napoli.
In this paper we briefly discuss the possibility to use Adaptive Optics in long baseline interferometric gravitational wave detectors. Analisys is carried out to demonstrate the usefulness of Adaptive Optics as a method to integrate double-mode-cleaner systems, presently used or foreseen in the next generation detectors as systems for the reduction of geometrical fluctuations of input laser beam. Finally a prototype of (AO) system for the control of geometrical fluctuations in a laser beam, based on the interferometric detection of phase front, is presented. By comparison with the usual Shack-Hartmann based AO system, we show that this technique is of particular interest when high sensitivity and high band-pass are required for correction of small perturbations like, for instance, the control of the input beam of gravitational waves interferometric detectors.
Fausto Acernese, Paolo Amico, N. Arnaud, Saverio Avino, D. Babusci, Regis Barille, Fabrizio Barone, L. Barsotti, M. Barsuglia, F. Beauville, M. Bizouard, C. Boccara, Francois Bondu, L. Bosi, C. Bradaschia, S. Braccini, Alain Brillet, V. Brisson, L. Brocco, Damir Buskulic, G. Calamai, Enrico Calloni, E. Campagna, F. Cavalier, G. Cella, Eric Chassande-Mottin, Frederic Cleva, T. Cokelaer, J.-P. Coulon, Elena Cuoco, Vincenzino Dattilo, M. Davier, Rosario De Rosa, Luciano Di Fiore, A. Di Virgilio, B. Dujardin, Antonio Eleuteri, Daniel Enard, I. Ferrante, F. Fidecaro, I. Fiori, Raffaele Flaminio, J.-D. Fournier, S. Frasca, Franco Frasconi, Andreas Freise, Luca Gammaitoni, Alberto Gennai, Adalberto Giazotto, Gianfranco Giordano, Lara Giordano, G. Guidi, H. Heitmann, P. Hello, P. Heusse, L. Holloway, S. Kreckelbergh, Paolo La Penna, Vincent Loriette, Magali Loupias, G. Losurdo, Jean-Marie Mackowski, E. Majorana, Catherine Man, E. Marchetti, Frederique Marion, Fabrizio Martelli, Alain Masserot, Louis Massonnet, Massimo Mazzoni, Leopoldo Milano, J. Moreau, F. Moreau, Nazario Morgado, F. Mornet, Benoit Mours, J. Pacheco, A. Pai, C. Palomba, Federico Paoletti, Silvio Pardi, R. Passaquieti, D. Passuello, B. Perniola, Laurent Pinard, R. Poggiani, Michele Punturo, P. Puppo, Ketevan Qipiani, J. Ramonet, P. Rapagnani, V. Reita, Alban Remillieux, F. Ricci, Iolanda Ricciardi, Guido Russo, Salvatore Solimeno, Ruagero Stanga, E. Tournefier, F. Travasso, Herve Trinquet, Didier Verkindt, Flavio Vetrano, Oliver Veziant, A. Vicere, J.-Y. Vinet, H. Vocca, Michel Yvert
The French-Italian interferometric gravitational wave detector VIRGO is currently being commissioned. Its principal instrument is a Michelson interferometer with 3 km long optical cavities in the arms and a power-recycling mirror. This paper gives an overview of the present status of the system. We report on the presently attained sensitivity and the system’s performance during the recent commissioning runs.
In this paper we discuss an Adaptive Optics (AO) system for the control of geometrical fluctuations in a laser beam based on the interferometric detection of phase front. By comparison with the usual Shack-Hartmann based AO system, we show that this technique is of particular interest when high sensitivity and high band-pass are required for correction of small perturbations like, for instance, the control of the input beam of gravitational waves interferometric detectors. The good results obtained allow us to decide for its application within the mode cleaner system of the 3m prototype optical interferometer on gravitational wave detection (IDGW-3P) developed for R&D and operational in Napoli.
We present an Adaptive Optics (AO) system for the control of geometrical fluctuations in a laser beam based on the interferometric detection of phase front. By comparison with the usual Shack-Hartmann based AO system, we show that this technique is of particular interest when high sensitivity and high band-pass are required for correction of small perturbations like, for instance, the control of the input beam of gravitational waves interferometric detectors.
We present a study and preliminary experimental results on the possibility of using an adaptive optics system for reduction of geometrical fluctuations of input laser beam in long baseline interferometric detectors of gravitational waves. Presently used completely passive systems are expected to reduce fluctuations only at a level that, due to coupling of geometrical fluctuations with interferometer asymmetries, impose requirements on interferometer operation which are at the limit of present technology. Active pre-stabilization could reduce fluctuations and relax these requirements, allowing a safer and more robust interferometer operation on the planned time-scale of years of continue data acquisition.
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