Terahertz confocal microscopy with a quantum cascade laser source

The recent advances in generation, manipulation and detection of Terahertz (THz) radiation have been accompanied by a growing interest in the application of THz technologies to a wide range of fields spanning from imaging, remote sensing and security controls, to spectroscopy and biomedical science. An appealing reason for developing photonic techniques in this frequency range is the capability for THz rays to penetrate common packaging materials (paper, plastic, wood, ceramics). The recent invention of quantum cascade lasers (QCL) emitting at THz frequencies is enabling a major step forward in THz imaging technologies thanks to the availability of a powerful, compact, solid-state, laser source. Once combined with bolometer array camera detectors, they have allowed the first systems for stand-off THz image acquisition operating in real time up to distances of more than twenty meters. On the other side, there are also great expectations for THz microscopy, especially as a potential diagnostic tool in quality inspection of various industrial productions or in molecular biology at the cell level. Yet, this research direction is just in its infancy, with most works focusing on near-field techniques. In the present thesis work, I focused instead on trying to transfer the principle of optical confocal microscopy to the THz, by implementing the first confocal imaging system based on a QCL, in this case emitting at ~ 3 THz. The confocal spatial filtering can sensibly reduce the depth of field of the microscope, as well as improve its resolution and contrast, making it very useful for inspection of close-by surfaces, where different planes have to be clearly distinguished, or where a depth information is crucial. The use of a QCL source required various preparatory tests and measurements, to assess the emission beam quality and to choose the best option for the spatial filter. In order to reduce the emitting area and improving the profile regularity, hollow metallic waveguide couplers and pinholes were examined. The waveguides were also fully characterized in terms of propagation and coupling losses to QCLs in different configurations, proving that very low-loss modes can be efficiently excited, an interesting result for the future development of THz endoscopes. The definitive confocal setup was finally assembled and characterized in terms of lateral and axial resolution and several images of test objects were collected in order to show the excellent performance of the instrument realized

A. S. MAKARENKO’S HERITAGE AND RE-EDUCATION OF PRISONERS WITHIN THE PARADIGM OF ITALIAN CONSTITUTION

В статье характеризируется опыт работы президента Международной Макаренковской ассоциации на должности преподавателя-волонтера в двух итальянских тюрьмах и то, как он анализирует возможность перевоспитывать заключенных в парадигме итальянской конституции. Кроме того, соавторы обращают большое внимание на сходство нескольких статей итальянской Конституции, посвященных образованию и воспитанию, с некоторыми теоретическими установками А. С. Макаренко и Л. В. ВыготскогоIn the article is studied the professional experience of the president of International Makarenko Association as volunteer – teacher in two Italian jails and how he studies the possibility to re-educate prisoners in the paradigm of Italian Constitution. Moreover, coauthors pay particular attention to the analogies of some articles of Italian Constitution dedicated to education and upbringing with theoretical setups of A. S. Makarenko and L. V. Vygotsk

Linestrength ratio spectroscopy as a new primary thermometer for redefined Kelvin dissemination

Experimental methods for primary thermometry, after Kelvin unit redefinition on May 2019, become based on a known value of the Boltzmann constant rather than by measuring temperature with respect to a reference point. In this frame, we propose Linestrength Ratio Thermometry (LRT) as a candidate method for primary thermometry in the 9-700 K temperature range. Temperature accuracies at the ppm level are prospected for LRT applied to optical transitions of the CO molecule in the range 80-700 K and of a rare-earth-doped crystal in the 9-100 K one. Future implementations of this technique can contribute to measure the calibration- discrepancies in the ITS-90 metrological scale of thermodynamic temperature which can have a measurable impact in applications ranging from fundamental-physics to meteorology and climatology

A combined Remote Sensing and GIS-based method for Local Climate Zone mapping using PRISMA and Sentinel-2 imagery

In the last decade, several methods have been developed for Local Climate Zone (LCZ) mapping, encompassing Remote Sensing and Geographic Information Systems (GIS) −based procedures. Combined approaches have also been proposed to compensate for intrinsic limitations that characterized their separate application. Recent work has disclosed the potential of hyperspectral satellite imagery for improving LCZ identification. However, the use of hyperspectral data for LCZ mapping is yet to be fully unfolded. A combined Remote Sensing and GIS-based method for LCZ mapping is proposed to exploit the integration of hyperspectral PRISMA and multispectral Sentinel-2 images with ancillary urban canopy parameter layers. Random Forest algorithm is applied to the feature sets to obtain the LCZ classification. The method is tested on the Metropolitan City of Milan (Italy), for the period from February to August 2023. A spectral separability analysis is carried out to investigate the improvement in LCZ identification using PRISMA in comparison to Sentinel-2 data, as well as improvements in LCZ spectral separability on PRISMA pan-sharpened images. The resulting maps’ quality is evaluated by extracting accuracy metrics and performing inter-comparisons with maps computed from the LCZ Generator benchmark tool. Inter-comparisons yield promising results with a mean Overall Accuracy increase of 16% using PRISMA for each LCZ class. Furthermore, we find that PRISMA improves the detection of LCZs compared to Sentinel-2, with a mean Overall Accuracy increase of 5%, in line with the higher spectral separability of PRISMA spectral signatures computed on the training samples

QGIS AND OPEN DATA CUBE APPLICATIONS FOR LOCAL CLIMATE ZONES ANALYSIS LEVERAGING PRISMA HYPERSPECTRAL SATELLITE DATA

Climate change poses a significant threat to humans and biodiversity, impacting various aspects of livelihoods, infrastructure, and ecosystems. Understanding climate change and its interaction with the environment is crucial for achieving Sustainable Development Goals. Local Climate Zones (LCZ) play a key role in comprehending climate change by categorizing urban areas also based on their thermal characteristics. This study presents prototype open-source software tools developed to integrate ground and satellite data for LCZ analysis in the Metropolitan City of Milan (Northern Italy). These tools consist of a QGIS plugin to access and preprocess ground-based meteorological sensor data and a client-server platform, based on the Open Data Cube and Docker technologies, for the exploitation of multispectral and hyperspectral satellite data in LCZ mapping and analysis. The tools’ architecture, data retrieval methods, and analysis capabilities are described in detail. The QGIS plugin facilitates the access and preprocessing of ground-based sensor data within the user-friendly QGIS environment. The platform enables seamless ground-sensor and satellite data management and analysis, using Jupyter Notebooks as an interface to support programmatic operations on the data. The proposed tools provide a framework for studying climate change and its local impacts on urban environments, with the potential of empowering users to effectively analyze and mitigate its effects

MAPPING LOCAL CLIMATE ZONES WITH MULTIPLE GEODATA AND THE OPEN DATA CUBE: INSIGHTS OF DOMAIN USER REQUIREMENTS AND OUTLOOKS OF THE LCZ-ODC PROJECT

Rapid urbanization and climate change are intensifying the urban heat island (UHI) phenomenon across cities worldwide. There is a pressing need to implement evidence-based mitigation and adaptation strategies as well as to develop tools for effectively measuring the impact of such actions on UHI patterns. In this context, the Local Climate Zone (LCZ) concept is a well-established classification system commonly used for the assessment of UHI. With this in mind, we present here the LCZ-ODC project aiming to develop a methodology for LCZ mapping in the Metropolitan City of Milan (northern Italy) by leveraging multiple geospatial data and cutting-edge software tools, including the Open Data Cube (ODC). A key aim of the project is to develop user-oriented solutions facilitating the exploitation of the generated LCZ maps for different application tasks. In this paper, we first present a brief overview of the methodologies and data sources used in the literature for LCZ mapping. Then, we introduce the LCZ-ODC project, with a focus on the end-user requirements which were gathered through a questionnaire distributed to a sample of potential stakeholders. The primary objective of the survey was to collect insights and consolidate requirements related to the key features of LCZ maps that will be produced within the project. The outcomes of the survey play a pivotal role in guiding the project’s development phase, ensuring that the project outputs will effectively address the identified end-user needs

Retrieval of phase relation and emission profile of quantum cascade laser frequency combs

The major development recently undergone by quantum cascade lasers has effectively extended frequency comb emission to longer-wavelength spectral regions, i.e. the mid and far infrared. Unlike classical pulsed frequency combs, their mode-locking mechanism relies on four-wave mixing nonlinear processes, with a temporal intensity profile different from conventional short-pulses trains. Measuring the absolute phase pattern of the modes in these combs enables a thorough characterization of the onset of mode-locking in absence of short-pulses emission, as well as of the coherence properties. Here, by combining dual-comb multi-heterodyne detection with Fourier-transform analysis, we show how to simultaneously acquire and monitor over a wide range of timescales the phase pattern of a generic frequency comb. The technique is applied to characterize a mid-infrared and a terahertz quantum cascade laser frequency comb, conclusively proving the high degree of coherence and the remarkable long-term stability of these sources. Moreover, the technique allows also the reconstruction of electric field, intensity profile and instantaneous frequency of the emission.Comment: 20 pages. Submitted to Nature Photonic