Remote Laboratory System: A Model Proposal and Implementation on X-Ray Laboratory Machines

This work presents the development and implementation of a remote X-ray laboratory, located at CNR – ISM, Rome, Italy. The remote laboratory model is based on a innovative, flexible and scalable modular architecture which makes it easier to update, expand or deal with problems. The developed system, accessible for control only to authenticated users, provides a remote control of the laboratory equipment, a real time visual feedback of the machinery and the opportunity to retrieve and make a preliminary analysis of stored data. These features offer the possibility to researchers of carrying out real research experiments remotely, avoid the exposure to ionizing radiation produced by the X-Ray equipment. The system also provides the opportunity of carrying out experiments programmatically, optimizing the use of available machine time and providing the possibility of running experiments in special environment-dependent conditions. Eventually, the system allows researchers located outside of laboratory site to run experiments in a collaborative way

Model predictive control for laser beam shaping

peer reviewedAdaptive Optics (AO) is a technique used to mitigate the effect of the atmosphere in the resolution of scientific images. The performance of an adaptive optics system strongly depends on the quality of the laser beam projected to the sky in terms of amplitude and phase. Currently, cumbersome procedures are carried out to optimize the laser beam. This paper presents the performance of a Model Predictive Controller (MPC) to adjust the quality of the laser in a system of two deformable mirrors. The Results shows that the MPC effectively corrects the amplitude and phase of the laser beam using deformable mirrors with about 140 actuators and a separation between mirrors z = 3 [m]

A method to deconvolve stellar rotational velocities II

Aims. Knowing the distribution of stellar rotational velocities is essential for understanding stellar evolution. Because we measure the projected rotational speed v sin i, we need to solve an ill-posed problem given by a Fredholm integral of the first kind to recover the “true” rotational velocity distribution. Methods. After discretization of the Fredholm integral we apply the Tikhonov regularization method to obtain directly the probability distribution function for stellar rotational velocities. We propose a simple and straightforward procedure to determine the Tikhonov parameter. We applied Monte Carlo simulations to prove that the Tikhonov method is a consistent estimator and asymptotically unbiased. Results. This method is applied to a sample of cluster stars. We obtain confidence intervals using a bootstrap method. Our results are in close agreement with those obtained using the Lucy method for recovering the probability density distribution of rotational velocities. Furthermore, Lucy estimation lies inside our confidence interval. Conclusions. Tikhonov regularization is a highly robust method that deconvolves the rotational velocity probability density function from a sample of v sin i data directly without the need for any convergence criteria

Beam shaping for laser-based adaptive optics in astronomy

International audienceThe availability and performance of laser-based adaptive optics (AO) systems are strongly dependent on the power and quality of the laser beam before being projected to the sky. Frequent and time-consuming alignment procedures are usually required in the laser systems with free-space optics to optimize the beam. Despite these procedures, significant distortions of the laser beam have been observed during the first two years of operation of the Gemini South multi-conjugate adaptive optics system (GeMS). A beam shaping concept with two deformable mirrors is investigated in order to provide automated optimization of the laser quality for astronomical AO. This study aims at demonstrating the correction of quasi-static aberrations of the laser, in both amplitude and phase, testing a prototype of this two-deformable mirror concept on GeMS. The paper presents the results of the preparatory study before the experimental phase. An algorithm to control amplitude and phase correction, based on phase retrieval techniques, is presented with a novel unwrapping method. Its performance is assessed via numerical simulations, using aberrations measured at GeMS as reference. The results predict effective amplitude and phase correction of the laser distortions with about 120 actuators per mirror and a separation of 1.4 m between the mirrors. The spot size is estimated to be reduced by up to 15% thanks to the correction. In terms of AO noise level, this has the same benefit as increasing the photon flux by 40%