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LUCA DI CECILIA


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Pubblicazioni

2018 - IOT-Based Measurement System for Wine Industry [Relazione in Atti di Convegno]
Masetti, Gianluca; Marazzi, Francesco; Di Cecilia, Luca; Rovati, Luigi
abstract

An IoT-based measurement system designed to monitor wine fermentation during vinification process is presented. The system consists in a network of sensorized buoys, placed inside the tanks where fermentation occurs, and access points used to share the data to a cloud web platform. The access to the collected data is performed by an intuitive web interface. The system architecture could provide multiple services for the farmers and winemakers, such as vinification monitoring, but also market oriented services (e.g.Traceability of the product). Preliminary experimental results demonstrated the capability of the system in measuring the wine pH, liquid level and temperature in a 24 hours interval with low uncertainty, along with the possibility to upload data on a website.


2018 - Imaging the human iris: a hyperspectral approach [Abstract in Rivista]
Di Cecilia, L; Marazzi, F; Rovati, L
abstract

Purpose: Hyperspectral (HS) imaging is a promising optical technique that allows the detection of both spatial and spectral information in a single data acquisition. Here we investigate the capability of a prototype HS instrument to measure the iris spectral reflectance in vivo. Moreover, we evaluate the intra- and inter-session repeatability of quantitative HS measurements of the human iris. Methods: Eight healthy volunteers (all males, average age 27 ± 2 years) participated in the study. Irises colors were classified using the grading system of Franssen et al [Grading of Iris Color with an Extended Photographic Reference Set, J Optom 2008; 1:36-40]. Each HS acquisition (duration: 4125 ms) consists of 22 images (HS cube) captured between 480 – 900 nm, in 20nm intervals. Each acquisition was repeated 6 times. The instrument was calibrated using a NIST white reflectance standard, to ensure quantitative and repeatable measurements. Reflectance was analyzed across the 22 spectral bands in an annular region of interest concentric to the pupil. Repeatability was assessed from images captured in 3 sessions, at the same exposure time, with realignment of the iris and refocusing between each session. Results: Inter-subject variability was highest at short wavelengths (Fig. 1) and reflectance exhibited opposite trends in the visible and near infrared. This might be the result of melanin scattering. The influence of water absorption is detected above 850 nm. Repeatability was highest for lighter irises and for wavelengths from 520 to 900 nm. In that range, the coefficient of repeatability (95% of confidence interval) for measurements between sessions was ±10% and ±5% for dark and light irises, respectively. The within-session repeatability was ±7.5% and ±4%, respectively. Conclusions: Automated in vivo HS imaging of the human iris appears to be reliable and reproducible. This technique could potentially be exploited for monitoring iris pigmentation changes with time induced by prostaglandin analogues. In addition, the iris spectral reflectance could be correlated with the development of certain ocular pathologies.


2017 - A hyperspectral imaging system for the evaluation of the human iris spectral reflectance [Relazione in Atti di Convegno]
DI CECILIA, Luca; Marazzi, Francesco; Rovati, Luigi
abstract

According to previous studies, the measurement of the human iris pigmentation can be exploited to detect certain eye pathological conditions in their early stage. In this paper, we propose an instrument and a method to perform hyperspectral quantitative measurements of the iris spectral reflectance. The system is based on a simple imaging setup, which includes a monochrome camera mounted on a standard ophthalmic microscope movement controller, a monochromator, and a flashing LED-based slit lamp. To assure quantitative measurements, the system is properly calibrated against a NIST reflectance standard. Iris reflectance images can be obtained in the spectral range 495-795 nm with a resolution of 25 nm. Each image consists of 1280 x 1024 pixels having a spatial resolution of 18 μm. Reflectance spectra can be calculated both from discrete areas of the iris and as the average of the whole iris surface. Preliminary results suggest that hyperspectral imaging of the iris can provide much more morphological and spectral information with respect to conventional qualitative colorimetric methods.


2017 - An improved imaging system for hyperspectral analysis of the human iris [Relazione in Atti di Convegno]
Di Cecilia, Luca; Marazzi, Francesco; Rovati, Luigi
abstract

We have developed an instrument and a method to perform in vivo hyperspectral imaging of the human iris in order to quantitatively measure its spectral reflectance. Understanding age-related changes in the reflectance properties of the iris is important for multiple aspects of vision research. The images are acquired in the spectral range 450-810nm from three healthy volunteers. The spectral resolution is equal to 30nm, while each image of 1024×768 pixels has a spatial resolution of 22.5μm. The instrument appears suitable for measuring iris pigmentation changes over time. These measurements could offer new diagnostic possibilities in ophthalmology.


2017 - An improved optical scheme for self-mixing low-coherence flowmeters [Relazione in Atti di Convegno]
DI CECILIA, Luca; Rovati, Luigi; Cattini, Stefano
abstract

In this paper we present a fiber-based low-coherence self-mixing interferometer exploiting a single-arm approach to measure the flow in a pipe. The main advantages of the proposed system are the flexibility offered by fiber-connected optical head, a greater ease of alignment, the rejection of “common-mode” vibrations, and greater stability. Thanks to the use of a low-coherence source, the proposed system investigates the velocity of the scattering particles owing only in a fixed and well defined region located close to the duct wall itself. The reported experimental results demonstrate that in laminar flow regime the developed system is able to determine the flow and it is quite robust to variation in the scatterers concentration. Increasing the scatterers concentration of about 24 times, the sensitivity S has reduced of less than 30%. © (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.


2017 - Hyperspectral imaging of the human iris [Relazione in Atti di Convegno]
Di Cecilia, Luca; Marazzi, Francesco; Rovati, Luigi
abstract

We describe an optical system and a method for measuring the human iris spectral reflectance in vivo by hyperspectral imaging analysis. It is important to monitor age-related changes in the reflectance properties of the iris as they are a prognostic factor for several eye pathologies. In this paper, we report the outcomes of our most recent research, resulting from the improvement of our imaging system. In particular, a custom tunable light source was developed: the images are now acquired in the spectral range 440-900 nm. With this system, we are able to obtain a spectral resolution of 20nm, while each image of 2048 x 1536 pixels has a spatial resolution of 10.7 μm. The results suggest that the instrument could be exploited for measuring iris pigmentation changes over time. These measurements could provide new diagnostic capabilities in ophthalmology. Further studies are required to determine the measurements' repeatability and to develop a spectral library for results evaluation and to detect differences among subsequent screenings of the same subject.


2016 - Single-arm Self-mixing Superluminescent Diode Interferometer for Flow Measurements [Articolo su rivista]
DI CECILIA, Luca; Cattini, Stefano; Giovanardi, Fabio; Rovati, Luigi
abstract

Laser-diode self-mixing interferometry is a noncontact technique widely used both in industries and laboratories. In this paper we propose to extend the self-mixing approach to low-coherence sources such as superluminescent diodes. In particular, we present a fiber-based common-path interferometer exploiting a single mode pigtailed super-luminescent diode. The developed measuring system has been demonstrated to be able to directly measure the flow in pipes. To the best of our knowledge, it is the first time that flow measurements have been performed by a single-arm self-mixing pigtailed super-luminescent-diode. The measuring system exploits the Doppler interference pattern produced by the light back-reflected from the inner facet of the pipe wall and the light back-diffused by the moving particles. Then, the use of a low-coherence source allows to measure the velocity of the scattering particles in a fixed and well defined region located close to the pipe wall, thus providing good robustness to variations of scatterers concentration and allowing to easily estimate the flow under the laminar flow assumption. Experimental results demonstrated a high linearity (Pearson coefficient of about 99%) and sensitivity of about 16.62±1.1 cm−3, with flows ranging from 1 cm3/s to 15 cm3/s and scatterers volume concentration ranging from 0.015% to 0.36%.