Search results for "laser"

Ohjattavan virtalähteen suunnittelu suuritehoiselle diodilaserille

2008

Revealing lattice disorder, oxygen incorporation and pore formation in laser induced two-photon oxidized graphene

2019

Laser induced two-photon oxidation has proven to be a reliable method to pattern and control the level of oxidation of single layer graphene, which in turn allows the development of graphene-based electronic and optoelectronic devices with an all-optical method. Here we provide a full structural and chemical description of modifications of air-suspended graphene during the oxidation process. By using different laser irradiation doses, we were able to show via transmission electron microscopy, electron energy loss spectroscopy, electron diffraction and Raman spectroscopy how graphene develops from its pristine form up to a completely oxidized, porous and amorphous carbon layer. Furthermore, …

Laserspektroskopia mineraalianalytiikassa : nopeasti ja tehokkaasti monipuolista informaatiota mineraaleista

2022

Laserspektroskopiset menetelmät ovat nopeita ja tehokkaita mineraalitutkimuksen keinoja, koska analyysi voidaan tehdä suoraan näytteen pinnalta ja jopa metrien päästä kohteesta. Nykyteknologian ansiosta laserspektroskopian laitteistoja voidaan lisäksi miniatyrisoida, ja siten ne soveltuvat etämittauksiin esimerkiksi maastossa, linjastolla tai kaivoksessa (in situ). Tässä artikkelissa esitellään laserindusoitu plasmaspektroskopia (LIBS), laser-indusoitu luminesenssispektroskopia ja Raman-spektroskopia, joilla saadaan näytteistä toisiaan täydentävää informaatiota (Romppanen 2021). Tunnetuimmat esimerkit laserspektroskopian soveltuvuudesta mineraalianalytiikassa löytyvät Marsista, sillä planee…

Molekyylien linjautuminen laserkentässä

2009

Laser developments and high resolution resonance ionization spectroscopy of actinide elements

2014

Towards in-jet resonance ionization spectroscopy : An injection-locked Titanium:Sapphire laser system for the PALIS-facility

2018

This article presents a pulsed narrowband injection-locked Titanium:Sapphire laser aimed for high-resolution in-jet resonance ionization spectroscopy at the SLOWRI/PALIS at RIKEN. The laser has been integrated into the PALIS laser laboratory enabling it to be utilized with the existing broadband Titanium:Sapphire and dye lasers. The seed efficiency has been evaluated to be close to unity over the master laser wavelength range ∼ 753 to 791 nm, and the slope efficiency, namely the ratio of the pump power to the output power, was determined to be ∼ 30 % at 780 nm. A two-step ionization scheme with 386.4016 nm first step and 286.731 nm second step into an autoionizing state was developed for re…

Rilievi e indagini diagnostiche non distruttive per l’individuazione delle cripte - La Cattedrale di Ragusa

2014

I diversi operatori, che si occupano di Beni Storici e Culturali, si avvalgono sempre più spesso delle soluzioni tecnologiche avanzate offerte dalla moderna Geomatica, facendo ricorso ad integrazioni delle sue discipline, per meglio studiare, indagare e monitorare un bene di interesse storico. Oggi si tentano nuove integrazioni con altre discipline che, tradizionalmente, non riguardano il campo del rilievo propriamente detto. Questo è, ad esempio, il caso dello studio condotto sulla Cattedrale di San Giovanni a Ragusa, nel quale si è partiti dal rilievo laser scanning di una porzione della chiesa e del suo pregiatissimo pavimento, sotto il quale secondo uno schizzo dei primi anni del XIX se…

Testing the shape-similarity hypothesis between particle-size distribution and water retention for Sicilian soils

2012

Application of the Arya and Paris (AP) model to estimate the soil water retention curve requires a detailed description of the particlesize distribution (PSD) but limited experimental PSD data are generally determined by the conventional sieve-hydrometer (SH) method. Detailed PSDs can be obtained by fitting a continuous model to SH data or performing measurements by the laser diffraction (LD) method. The AP model was applied to 40 Sicilian soils for which the PSD was measured by both the SH and LD methods. The scale factor was set equal to 1.38 (procedure AP1) or estimated by a logistical model with parameters gathered from literature (procedure AP2). For both SH and LD data, procedure AP2 …

TESTING THE GRAIN-SIZE DISTRIBUTION DETERMINED BY LASER DIFFRACTOMETRY FOR SICILIAN SOILS

2012

In this paper the soil grain-size distribution determined by Laser Diffraction method (LDM) is tested using the Sieve-Hydrometer method (SHM) applied for 747 soil samples representing a different texture classification, sampled in Sicily. 005_Di_Stefano(599)_39 28-12-2011 15:01 Pagina 45 The analysis showed that the sand content measured by SHM can be assumed equal to the one determined by LDM. An underestimation of the clay fraction measured by LDM was obtained with respect to the SHM and a set of equations useful to refer laser diffraction measurements to SHM was calibrated using the measurements carried out for 635 soil samples. Finally, the proposed equations were tested using independe…

RPAS AND TLS TECNIQUES FOR ARCHAEOLOGICAL SURVEY: THE CASE STUDY OF THE ARCHAEOLOGICAL SITE OF ERACLEA MINOA (ITALY)

2018

Abstract. Digital documentation and 3D modelling of archaeological sites are important for understanding, definition and recognition of the values of the sites and of the archaeological finds. The most part of archaeological sites are outdoor location, but a cover to preserve the ruins protects often parts of the sites. The possibility to acquire data with different techniques and merge them by using a single reference system allows creating multi-parties models in which 3D representations of the individual objects can be inserted. The paper presents the results of a recent study carried out by Geomatics Laboratory of University of Palermo for the digital documentation and 3D modelling of E…