Sökning: "Low level laser"

Visar resultat 1 - 5 av 101 avhandlingar innehållade orden Low level laser.

1. 1. Nonlinear optical techniques for ultrafast laser diagnostics : Development of femtosecond LIF, LIGS, CARS and backward lasing

   Författare :Maria Ruchkina; Förbränningsfysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; laser diagnostics; femtosecond laser; nonlinear interactions; ultrafast spectroscopy; multi-photon excitation; laser-induced fluorescence; rotational coherent anti-Stokes Raman spectroscopy; laser-induced grating spectroscopy; lasing; backward lasing technique; Fysicumarkivet A:2021:Ruchkina;

   Sammanfattning : The thesis work concerns development and application of four versatile nonlinear optical techniques, based on exploiting ultrashort laser pulses, for diagnostic purposes in gases and flames. The four techniques, all laser-based, are two-photon laser-induced fluorescence (TPLIF), hybrid femtosecond/nanosecond (fs/ns) rotational coherent anti-Stokes Raman scattering (fs/ns RCARS), fs-laser-induced grating spectroscopy (fs-LIGS), and backward lasing. LÄS MER

3. 2. Ground Object Recognition using Laser Radar Data : Geometric Fitting, Performance Analysis, and Applications

   Författare :Christna Grönwall; Fredrik Gustafsson; Kalle Åström; Linköpings universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Laser radar; object detection; object recognition; performance; least squares; ICP; Cramér-Rao; Signal processing; Signalbehandling;

   Sammanfattning : This thesis concerns detection and recognition of ground object using data from laser radar systems. Typical ground objects are vehicles and land mines. For these objects, the orientation and articulation are unknown. The objects are placed in natural or urban areas where the background is unstructured and complex. LÄS MER

4. 3. Optical Properties of Low Dimensional Semiconductor Materials

   Författare :Tiantian Han; Ying Fu; Per-Olof Holtz; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Semiconductor; Low dimensional; optics; Physics; Fysik;

   Sammanfattning : This dissertation presents a serial study on optical properties of different semiconductor materials. Three main types of studies are addressed: The role of doping levels of N and Al atoms in the room-temperature photoluminescence (PL) of 4H-SiC films for optoelectronic applications; the use of a basic Monte Carlo method combined with probability calculations of the time-dependent Schroedinger equation to manifest multi-photon absorption and emission of II-VI compound quantum dots (QDs) for bioimaging; a theoretical quantum chemistry approach to study of structure and optical properties of InGaAsN and GaAs clusters for laser technology applications. LÄS MER

5. 4. Stainless steels fabricated by laser melting : Scaled-down structural hierarchies and microstructural heterogeneities

   Författare :Kamran Saeidi; Zhijian Shen; Xiaoxu Huang; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Selective laser melting; Stainless steel; Structural hierarchies; Microstructure heterogeneity; Mechanical properties; Materials Chemistry; materialkemi;

   Sammanfattning : Additive manufacturing is revolutionizing the way of production and use of materials. The clear tendency for shifting from mass production to individual production of net-shape components has encouraged using selective laser melting (SLM) or electron beam melting (EBM). LÄS MER

7. 5. Development of Structural Steels for Powder Bed Fusion - Laser Beam

   Författare :William Hearn; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; tensile properties; in situ tempering; process development; martensite; additive manufacturing; cold cracking; low-alloy steel; structural steel; powder bed fusion – laser beam; carbon steel;

   Sammanfattning : Over the past decade, powder bed fusion – laser beam (PBF-LB) has attracted noticeable attention from both academia and industry. However, there remains a scarcity of approved material for the process, as fewer than 40 alloys are commercially available. LÄS MER