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Colloidal semiconductor quantum dots (QDs) have gained substantial interest as adjustable, bright and spectrally tunable fluorophores in the past decades. Besides their in-depth analyses in the scientific community, first industrial applications as color conversion and color enrichment materials were implemented. However, stability and processability are essential for their successful use in these and further applications. Methods to embed QDs into oxides or polymers can only partially solve this challenge. Recently, our group introduced the embedding of QDs into ionic salts, which holds several advantages in comparison to polymer or oxide-based counterparts. Both gas permeability and environmental-related degradation processes are negligible, making these composites an almost perfect choice of material. To evaluate this new class of QD-salt mixed crystals, a thorough understanding of the formation procedure and the final composites is needed. The present work is focused on embedding both aqueous-based and oil-based metal-chalcogenide QDs into several ionic salts and the investigations of their optical and chemical properties upon incorporation into the mixed crystals. QDs with well-known, reproducible and high-quality synthetic protocols are chosen as emissive species. CdTe QDs were incorporated into NaCl as host matrix by using the straightforward "classical" method. The resulting mixed crystals of various shapes and beautiful colors preserve the strong luminescence of the incorporated QDs. Besides NaCl, also borax and other salts are used as host matrices. Mercaptopropionic acid stabilized CdTe QDs can easily be co-crystallized with NaCl, while thioglycolic acid as stabilizing agent results in only weakly emitting powder-like mixed crystals. This challenge was overcome by adjusting the pH, the amount of free stabilizer and the type of salt used, demonstrating the reproducible incorporation of highest-quality CdTe QDs capped with thioglycolic acid into NaCl and KCl salt crystals. A disadvantage of the "classical" mixed crystallization procedure was its long duration which prevents a straightforward transfer of the protocol to less stable QD colloids, e.g., initially oil-based, ligand exchanged QDs. To address this challenge, the "Liquid-liquid-diffusion-assisted-crystallization" (LLDC) method is introduced. By applying the LLDC, a substantially accelerated ionic crystallization of the QDs is shown, reducing the crystallization time needed by one order of magnitude. This fast process opens the field of incorporating ligand-exchanged Cd-free QDs into NaCl matrices. To overcome the need for a ligand exchange, the LLDC can also be extended towards a two-step approach. In this modified version, the seed-mediated LLDC provides for the first time the ability to incorporate oil-based QDs directly into ionic matrices without a prior phase transfer. The ionic salts appear to be very tight matrices, ensuring the protection of the QDs from the environment. As one of the main results, these matrices provide extraordinary high photo- and chemical stability. It is further demonstrated with absolute measurements of photoluminescence quantum yields (PL-QYs), that the PL-QYs of aqueous CdTe QDs can be considerably increased upon incorporation into a salt matrix by applying the "classical" crystallization procedure. The achievable PL enhancement factors depend strongly on the PL-QYs of the parent QDs and can be described by the change of the dielectric surrounding as well as the passivation of the QD surface. Studies on CdSe/ZnS in NaCl and CdTe in borax showed a crystal-induced PL-QY increase below the values expected for the respective change of the refractive index, supporting the derived hypothesis of surface defect curing by a CdClx formation as one main factor for PL-QY enhancement. The mixed crystals developed in this work show a high suitability as color conversion materials regarding both their stability and spectral tunability. First proof-of-concept devices provide promising results. However, a combination of the highest figures of merit at the same time is intended. This ambitious goal is reached by implementing a model-experimental feedback approach which ensures the desired high optical performance of the used emitters throughout all intermediate steps. Based on the approach, a white LED combining an incandescent-like warm white with an exceptional high color rendering index and a luminous efficacy of radiation is prepared. It is the first time that a combination of this highly related figures of merit could be reached using QD-based color converters. Furthermore, the idea of embedding QDs into ionic matrices gained considerable interest in the scientific community, resulting in various publications of other research groups based on the results presented here. In summary, the present work provides a profound understanding how this new class of QD-salt mixed crystal composites can be efficiently prepared. Applying the different crystallization methods and by changing the matrix material, mixed crystals emitting from blue to the near infrared region of the electromagnetic spectrum can be fabricated using both Cd-containing and Cd-free QDs. The resulting composites show extraordinary optical properties, combining the QDs spectral tunability with the rigid and tight ionic matrix of the salt. Finally, their utilization as a color conversion material resulted in a high-quality white LED that, for the first time, combines an incandescent-like hue with outstanding optical efficacy and color rendering properties. Besides that, the mixed crystals offer huge potential in other high-quality applications which apply photonic and optoelectronic components.

No presente trabalho é apresentada uma nova abordagem para medida de potenciais em altos níveis de tensão que utilizam sensores eletro-ópticos Pockels. Também descreve a aplicação da técnica de interferometria de luz branca em sistemas de alta tensão por fibras ópticas. Neste sistema a informação é codificada no espectro da luz, permitindo assim que a medida seja independente da potência óptica transmitida pelo link de fibras ópticas. Um protótipo foi construído e testado sob excitação de tensão a.c. até 20 kV em 60 Hz mostrando boa resposta e demonstrando a viabilidade deste método. / A new approach to perform measurement of potentials in high voltage levels using electrooptical Pockels sensors is presented here. This work describes an application of the White Light Interferometry technique to a high voltage optical fiber measurement system. In this system the information is encoded in the spectrum of the light, allowing the measurement to be independent of the optical power transmitted by the optical fiber link. A prototype was built and tested under excitation of a.c. voltages up to 20 kV in 60 Hz showing good response and demonstrating the feasibility of this method.

Background: At the time of diagnosis, approximately 75% of all bladder cancers are Non-Muscle Invasive Bladder Cancers (NMIBC) - the standard treatment for these cancers is a Transurethral Resection of the Bladder Tumour (TURBT). Although, the vast majority of these cancers are not life-threatening, they have a high risk of recurrence (and progression, particularly in higher risk NMIBC), despite the use of adjuvant intravesical chemotherapy. Consequently, patients are kept on long term cystoscopic surveillance with endoscopic removal if recurrences are detected - this impacts on patients' quality of life and contributes to the high cost for the healthcare provider. Aims: The fundamental aim of this series of clinical studies, spanning 12 years, was to identify and implement, means of improving the efficiency in both processing and operating on patients with NMIBC to not only reduce recurrence, but also to reduce the duration of follow up and repeat operations. It was an evolutionary process where the findings in the preceding studies formed the basis of the subsequent one - while the aim of the individual studies were different, there was a clear link to the essential principles, thus forming a coherent collection of studies. Methods and results: The project was carried out in 3 phases (with 2 or 3 main studies in each phase, augmented by 1 to 2 linked studies - making the entire submission for PhD by publications a series of 12 studies, to date): Phase 1 (5 studies in this phase): The aim was to demonstrate the natural history of non-invasive bladder cancer and identify sub-categories of patients who could be discharged from surveillance at 5 years. This was initially achieved by evaluating a prospectively maintained cohort of non-invasive bladder cancer patients diagnosed between 1978 and 1984 at the Western General Hospital, Edinburgh. This study identified the importance of the recurrence rate at the first follow up cystoscopy (RRFFC) as an essential prognostic marker. This finding was further validated using 2 separate cohorts from a different Centre (the Royal Infirmary, Edinburgh) managed in the 80s and the 90s, respectively. The data confirmed that over the decades, recurrence patterns do change, possibly as a result of differing techniques and improvements in optics and instruments; however, what remained the same was the prognostic value of the RRFFC. Phase 2 (3 studies in this phase): The early recurrence was deemed to be the result of missed and tumours left behind at the initial TURBT, i.e. a marker of quality. However, RRFFC was only known 3 months after the initial surgery. Since the RRFFC was such an important prognostic factor, the aim of this phase was to determine the surgical factors contributing to the quality of TURBT and subsequently implement changes to the principles in carrying out the surgery to improve this quality. This was achieved by prospective collection of information regarding all patients undergoing TURBT for new bladder cancers, recording the tumour features, surgeon experience, if the resection was deemed to have been complete or not, and the pathological results. We identified that the detrusor muscle in the resected specimen and the experience of the surgeon were independent determinants of TURBT quality. This finding was validated in a further study using cohorts from another time period and another Centre - this allowed me to develop the concept of Good Quality White Light TURBT (GQWLTURBT) as the benchmark for the white light TURBT. Phase 3 (4 studies in this phase): Photodynamic Diagnosis assisted TURBT (PDDTURBT) was demonstrated in randomised controlled trials as a technique that reduces the recurrences in NMIBC. In the absence of evidence with this technique in the 'real life' setting nor comparisons with standardised, benchmarked white light TURBT technique, we performed a prospective controlled study comparing PDD-TURBT and GQ-WLTURBT, evaluating early and delayed recurrence rates in 2 separate studies. I also performed a multicentre UK study on the outcomes with PDD-TURBT and collaborated with other experts in Europe in producing a review article around Photodynamic Diagnosis and the cost effectiveness of this technique. Summary: This coherent series of studies has contributed to knowledge in bladder cancer surgery by, among others: (a) mapping the individual patient natural history of non-invasive bladder cancer; (b) confirming the importance of early recurrence as a strong prognostic indicator; (c) identifying predictors of this early recurrence and the quality of TURBT; (d) introducing the concept of the benchmark Good Quality White Light TURBT and (e) demonstrating the benefits of photodynamic diagnosis within a 'real life' setting.

No presente trabalho é apresentada uma nova abordagem para medida de potenciais em altos níveis de tensão que utilizam sensores eletro-ópticos Pockels. Também descreve a aplicação da técnica de interferometria de luz branca em sistemas de alta tensão por fibras ópticas. Neste sistema a informação é codificada no espectro da luz, permitindo assim que a medida seja independente da potência óptica transmitida pelo link de fibras ópticas. Um protótipo foi construído e testado sob excitação de tensão a.c. até 20 kV em 60 Hz mostrando boa resposta e demonstrando a viabilidade deste método. / A new approach to perform measurement of potentials in high voltage levels using electrooptical Pockels sensors is presented here. This work describes an application of the White Light Interferometry technique to a high voltage optical fiber measurement system. In this system the information is encoded in the spectrum of the light, allowing the measurement to be independent of the optical power transmitted by the optical fiber link. A prototype was built and tested under excitation of a.c. voltages up to 20 kV in 60 Hz showing good response and demonstrating the feasibility of this method.

Im Rahmen der vorliegenden Arbeit ist es erstmals gelungen, mit einem ps-Pumplaser (10 ps) Weißlicht mit einer spektralen Breite von mehr als einer optischen Oktave in einer mikrostrukturierten Faser (MSF) bei einer Pumpwellenlänge von 1064 nm zu generieren. Es ließ sich, abgesehen von nichtkonvertierten Resten der Pumpstrahlung, ein unstrukturiertes und zeitlich stabiles Weißlichtspektrum von 700 nm bis 1650 nm generieren. Die maximale Ausgangsleistung dieser Weißlichtstrahlung betrug 3,1 W. Es konnten sehr gute Einkoppeleffizienzen von maximal 62 % erzielt werden. Die an der Weißlichterzeugung beteiligten dispersiven und nichtlinear optischen Effekte, wie z.B. Selbstphasenmodulation, Vierwellenmischung, Modulationsinstabilitäten oder Solitoneneffekte, werden detailliert theoretisch untersucht und erläutert. Die Arbeit beinhaltet ebenfalls eine umfangreiche Beschreibung der Wirkungsweise und Eigenschaften von mikrostrukturierten Fasern mit einem festen Faserkern. Aufgrund der großen Variationsvielfalt des mikrostrukturierten Fasermantels und der damit verbundenen Wellenleitereigenschaften ergeben sich, insbesondere für die Anwendung in der nichtlinearen Optik, eine Reihe von interessanten Eigenschaften. Es wurden insgesamt vier verschiedene mikrostrukturierte Fasern experimentell untersucht. Für die Interpretation der experimentellen Ergebnisse ist die Pulsausbreitung der ps-Pumppulse in einer dispersiven, nichtlinear optischen Faser anhand der verallgemeinerten nichtlinearen Schrödinger-Gleichung berechnet worden. Durch einen Vergleich der Berechnungen mit den Messdaten ließen sich verstärkte Modulationsinstabilitäten und verschiedene Solitoneneffekte als hauptsächlich für die Weißlichterzeugung bei ps-Anregungspulsen verantwortlich identifizieren. Auf der Basis der durchgeführten Untersuchungen wurde in Kooperation mit der Fa. Jenoptik Laser, Optik, Systeme GmbH eine kompakte und leistungsstarke Weißlichtquelle entwickelt. Diese wurde erfolgreich in einer Kohärenztomographiemessung (Optical Coherence Tomography - OCT) getestet: Es konnte in ex vivo-Untersuchungen gezeigt werden, dass sich mit dieser ps-Weißlichtquelle eine hohe Eindringtiefe von ca. 400 µm in die Netzhaut eines Affen erreichen lässt. / With the present work it succeeded for the first time to generate white-light with a spectral width of more than an optical octave in a microstructured fiber (MSF) with a pump wavelength of 1064 nm and ps-pump pulses (10 ps). Apart from non-converted remainders of the pumping radiation, an unstructured and temporally stable white-light spectrum from 700 nm to 1650 nm could be generated. The maximum output power of this white-light radiation amounted to 3.1 W. Very good coupling efficiencies of max. 62 % could be obtained. At the white light generation different dispersive and nonlinear optical effects took part, e.g. self-phase modulation, four-wave mixing, modulation instabilities and soliton effects. These processes are theoretically examined and described in detail. Likewise the work contained an extensive description of the principle of operation and characteristics of microstructured fibers with a solid fiber core. Due to the large variation variety of the microstructured fiber cladding and the associated wave-guiding characteristics arise, in particular for application in the nonlinear optics, a set of interesting properties. Altogether four different microstructured fibers were experimentally examined. For the interpretation of the experimental results the pulse propagation of ps-pump pulses in a dispersive, nonlinear optical fiber was computed on the basis of the generalized nonlinear Schroedinger equation. By a comparison of the calculation results with the measuring data amplified modulation instabilities and different soliton effects could be identified as main responsible for the white light generation with ps-pump pulses. With respect to the accomplished experimental and theoretical investigations in co-operation with the company Jenoptik laser, optics, systems GmbH a compact and high-performance white-light source was developed. This broadband light source was tested successfully in an optical coherence tomography measurement (OCT): It could be shown in ex vivo investigations that with this white-light source high penetration depths of approx. 400 µm into the retina of a monkey could be achieved.

Poly-p-phenylenebenzazoles (PBXs) are heterocyclic aromatic rigid-rod liquid-crystalline polymers with fully conjugated backbone having excellent thermo-oxidative, as well as dimensional stabilities. PBXs are considered to be multifunctional polymers of superior mechanical tenacity, non-linear optical response, and electrical properties. The fully conjugated PBX polymers are deemed to have excellent opto-electronic properties. In the last decade, molecular light emitting diodes (LEDs) have been investigated intensively for having distinct advantages as an advanced opto-electronic technology. This dissertation leads to rigid-rod polymer thin-films and mono-layer devices fabricated from acidic solutions. Photoluminescence (PL) spectra for poly-p-phenylenebenzobisthiazole (PBT) freestanding film were measured over a temperature range of 67 K to 300 K showing distinct electron-phonon interaction. Using an Mg cathode, the mono-layer PBT LEDs displayed a diodic electric response with a threshold voltage as low as 1 V. A blue shift in the maximum emission wavelength of the electroluminescence (EL) spectra was also observed with increasing electrical injection energy. For the multi-layer LEDs based on PBT using the same electrodes, the p-type/n-type bi-layer structure showing the most enhanced EL emission, and the tri-layer heterojunction had the least threshold voltage using the same electrodes. Our results indicated that the heterojunction architecture could be applied to balance charge carriers for increasing EL intensity. Meanwhile, the investigation also revealed the advantage in using the extra PBT layer for increasing both EL emission intensity and injection efficiency by lowering its threshold voltage. Two schemes for making uniaxial freestanding films and LED devices for polarized optical absorption and emission were processed from uniaxial poly-p-phenylenebenzobisoxazole (PBO) fiber. The PL of the uniaxial PBO films demonstrated an emission intensity ratio I¡ü/I¡æas high as 5. Anisotropically processed mono-layered PBO LED showed a markedly decreased threshold voltage from 7 V of the isotropic PBO device to 5 V. The polarization effects in optical absorption, PL and EL emissions were acquired and correlated with the uniaxial orientation of the rigid-rod PBO polymer. The molecular modification investigated the opto-electronic properties of poly-2,2'-m-phenylene-5,5'-bibenzimidazole (Pbi) with PBT physical blends, and monolithic 6F-PBO-OH-co-6F-PBO-di(OC10H21) copolymers. Partially conjugated polymer Pbi and fully conjugated polymer PBT were mixed for luminescence study. Their absorption spectra showed superposition of individual absorption response indicating no inter-molecular energy transfer. However, the PL and the EL emission demonstrated a blue shift with increasing Pbi content. This was attributed to the rigid-rod configuration or the aggregation of PBT perturbed by mixing with coil-like Pbi. It was recognized that the backbone of the fully conjugated rigid-rod PBT was collinear having more charge delocalization than that of not fully conjugated coil-like Pbi. The diode threshold voltage of the physical blends varied from 4 V to 14 V with decreasing PBT content. Another molecular modification was changing the composition of 6F-PBO copolymers. Their PL emission exhibited excellent chromatic tuning range from green to blue emission. The Commission Internationale de l¡¦Eclairage (C. I. E.) coordinates of the copolymer EL emission were from (0.25, 0.53) to (0.24, 0.31) covering a wide visible range and demonstrating a white light emission. Atomic substitution of the rigid-rod polymers was utilized to examine individual atomic contribution for luminescence emission. The hydrogen bond effect for PBO-OH and PBO was evidenced in a major Stoke¡¦s shift to a longer wavelength because of protonic transfer on the excited state. Elemental electronegativities affected the delocalization of the £k electron leading to a blue shift in absorption spectra as shown in case of PBO and PBT. The PBO molecule was more collinear and co-planar, providing more charge delocalization than PBT. However the absorption edge of the PBT was about 30 nm higher than that of PBO. This suggested that the electronegativities affected the molecular delocalization. Using the solid-state physics with pseudofunction (PSF) calculation, there was good match between absorption spectra and calculated excitation energies for the rigid-rod polymer systems.

In this work, measurements and simulations were used to investigate the effects of grinding wheel topography on the geometric aspects of the grinding process. Since existing methods for measuring the grinding wheels were either not accurate enough or could only measure a small portion of a grinding wheel, a novel grinding wheel measurement system was developed. This system consists of a white light chromatic sensor, a custom designed positioning system and software. The resulting wheel scanning system was capable of measuring an entire grinding wheel with micron level accuracy. The system was used to investigate the effects of fine, medium and course dressing on grinding wheel surface topology and the resulting workpiece surface. New techniques were also developed to simulate metal removal in grinding. The simulation software consisted of a stochastic wheel model, dressing model and metal removal model. The resulting software could determine the uncut chip thickness, contact length for every cutting edge on a grinding wheel as well as the resulting surface roughness of the grinding wheel. The simulation was validated by comparing the wheel model used in the simulation to grinding wheel measurements and by comparing the simulated surface finish to the measured surface finish. There was excellent agreement between the predicted and experimentally measured surface topology of the workpiece. The results suggested that only 22 to 30% of the cutting edges exposed on the grinding wheel are active and that the average grinding chip is as much as 10 times thicker and 5 times shorter than would be produced by a grinding wheel with a regular arrangement of cutting edges as assumed by existing analytical approaches.

This thesis is specialized on composition of workplace for experiments flowing from optical interferometry. Here are described laboratory exercise servant for demonstration basic principles of interferometry. In more details is described method measurement of height profile objects with method white light interferometry.

Content is focused on fluorescence lifetime imaging techniques. Fluorescence lifetime is computed from data acquired with using of Leica TCS SP8X confocal microscope sequential scanning. Algorithms and software for the computation, imaging and analysis of fluorescence lifetime is presented. Software is allowing both 2D and 3D imaging of fluorescence lifetime. Techniques are used for fluorescence lifetime imaging of mesenchymal cells and fibroblasts tainted with SPIO-Rhodamin complex.