Enhanced 2D-image upconversion using solid-state lasers

Based on enhanced upconversion, we demonstrate a highly efficient method for converting a full image from one part of the electromagnetic spectrum into a new desired wavelength region. By illuminating a metal transmission mask with a 765 nm Gaussian beam to create an image and subsequently focusing the image inside a nonlinear PPKTP crystal located in the high intra-cavity field of a 1342 nm solid-state Nd:YVO4 laser, an upconverted image at 488 nm is generated. We have experimentally achieved an upconversion efficiency of 40% under CW conditions. The proposed technique can be further adapted for high efficiency mid-infrared image upconversion where direct and fast detection is difficult or impossible to perform with existing detector technologies

Incoherent optical frequency domain reflectometry for distributed thermal sensing

This thesis reports the main results from an investigation of a fibre-optic distributed temperature sensor based on spontaneous Raman scattering. The technique used for spatial resolving is the incoherent optical frequency domain reflectometry, where a pump laser is sine-modulated with a stepwise increasing frequency, after which the inverse Fourier transform is applied to the signal from the backscattered light. This technique is compared with the more conventional optical time domain reflectometry, where a short pulse is sent through the fibre, and the location of the scattering section is determined by the time difference from the emission to the detection of light. A temperature sensor with a range of 2-4km comprising a step-index multi-mode fibre and a high-power 980nm pump laser existed prior to the start of the PhD study. In this study, a sensor range of approximately 10km, and a spatial resolution of order 1m is strived to be achieved. These demands are attempted to be reached by employing a low-loss telecom-grade transmission single-mode fibre or an alternative fibre as the sensing fibre, and a pump laser operating in the low-loss region of silica. An analysis of the optical module comprising a pump laser, optical filters, optical fibre and photo-detectors are presented. Limitations, trade-offs and optimisation processes are described for setups having different specifications with respect to range, resolution and accuracy. The analysis is conducted using computer simulation programs developed and implemented in Matlab. The computer model is calibrated and tested, and describes the entire system with high precision. Noise analysis and digital processing of the detected signal are discussed as well. An equation describing the standard deviation of the measured temperature is derived for the device, and shows the dependency of the accuracy on measurement time, resolution, range, attenuation and detector parameters. Temperature measurements on 7.8km low-loss graded-index multi-mode fibre and 14km standard single-mode fibre with a spatial resolution varying from 0.5m to 6m are given as representative examples of the achieved accuracy (0.5 degrees C to 5 degrees C) and range, with measurement time of a few minutes. Measurements on 25km were conducted as well to demonstrate this possibility; with a short measurement time it was not possible to obtain a reasonable accuracy though. In addition to the Raman based temperature sensor, a quasi-distributed fibre-optic temperature and strain sensor based on an array of fibre Bragg gratings interrogated by a tuneable laser is also developed and analysed. This type of fibre-sensor is particularly suitable for strain monitoring on large concrete constructions such as bridges. The sensor is built and tested in a field trial on a bridge, and the estimated accuracy of around 2 mu times epsilon is achieved

Tietomallinnus kiinteistöjohtamisen apuna

Building information modelling has established its position as a new process in design and construction industries. The promising results from the design and construction phases have awaken the interest of the owners, too. While the pilot projects in using building information model assisted real estate management have already been started, the actual benefits of the new management tools are still vague for the majority. The common generalization that has been made in the real estate management is to limit the use of building information models to the mere maintenance tasks. This thesis specifies the broader opportunities that the change to the building information management can bring to the owners. Until now the requirements for modelling have been made for each construction project and the deliverables have also varied from project to another. Now that the BIM requirement collection "Yleiset tietomallivaatimukset 2012" is released the deliverables as well as the modelling processes are likely to be standardized among the actors in the construction industry. However, from owner's viewpoint the current situation is far from optimal as the information content of the models is adequate for constructing the building but not for managing and operating it. The deeper perspective to the requirements and needed information content is provided. The problems with the information exchange between the building life cycle phases and challenges in storing the information are also discussed shortly. Especially the commissioning phase and its related documents are investigated and the recommendations are given. In addition, the effect that the change to the building information modelling assisted management has is evaluated and the model based process and its requirements are roughly described.Rakennuksen tietomallinnus on viime aikoina yleistynyt suunnittelussa ja rakentamisessa. Näillä aloilla saavutetut lupaavat tulokset ovat saaneet myös kiinteistönomistajat vakuuttumaan prosessimuutoksen tarpeellisuudesta. Tietomallien hyödyntämisestä kiinteistöjohtamisessa on jo tehty pilottihankkeita, mutta kokonaiskuva saavutettavissa olevista hyödyistä on monilta osin ollut puutteellinen. Tavallisesti tietomallien käyttökelpoisuutta tarkasteltaessa on rajoituttu yksinomaan sovelluksiin huoltokirjassa ja ylläpitotöihin. Tässä työssä kiinteistöjohtamista käsitellään kokonaisvaltaisemmin huomioiden myös muut tehtävät, joihin tietomallia ja sen sisältämää yksityiskohtaista tietoa voidaan hyödyntää. Toistaiseksi tietomallinnettavat rakennushankkeet on käsitelty yksittäisinä ja yhteiset ohjeet muun muassa suunnittelijoiden toimittamia tietomalleja varten ovat puuttuneet. Tämä on johtanut siihen, että tietomallien laadun ja sisällön laajuuden vaihtelu projektien välillä on ollut suurta. Hiljattain julkaistu "Yleiset tietomallivaatimukset 2012" määrittelee osaltaan toimitettavien tietomallien sisältöä ja laatua ja yhtenäistää samalla eri toimijoiden käytäntöjä. Kiinteistönomistajien kannalta nykyisenkaltaisten tietomallien ja niiden tietosisältöjen standardisointi ei kuitenkaan ole riittävää, koska nykyisistä tietomalleista edelleen puuttuu kiinteistöjohtamisen kannalta olennaista tietoa. Työssä otetaan kantaa myös tietomallien sisältövaatimuksiin kiinteistöjohtamisen näkökulmasta. Tietomallien ja niihin liittyvän tiedon siirtäminen eteenpäin rakennushankkeen elinkaaren aikana sekä tietojen säilyttäminen liittyvät olennaisesti tietomallinnusprosessiin. Työssä keskitytään erityisesti rakennuksen käyttöönottovaiheeseen liittyviin tiedonsiirtohaasteisiin. Lisäksi tietomallinnettavan rakennushankkeen prosessi ja sen asettamat uudet vaatimukset kiinteistönomistajataholle esitellään pääpiirteissään