Shading devices are frequently used to control solar gain through windows. Solar optical properties are very important in the energy analysis of windows. Transmittance, absorptance and reflectance are required to quantify solar heat gain through complex fenestration systems, which consist of combinations of glazing and shading layers. In this research the solar transmittance of a sheer blind was measured using a Broad Area Illuminating Integrating Sphere (BAI-IS). More specifically, the spectral directional-hemispherical transmittance was measured in the wavelength range of 0.4 µm to 2.0 µm. A “sheer blind” consists of soft fabric vanes, similar to a venetian blind, suspended between two vertical layers of sheer fabric. This arrangement is popular because it is attractive and it has potential application for daylighting. The vertical sheer fabric reduces the solar intensity and diffuses incident radiation; generally reducing solar gain and producing soft, natural illumination. The fabric vanes control the amount of light entering the room. Shading devices such as venetian blinds, sheer blinds and drapes have spatially non-uniform and light scattering surfaces. Hence, measurement error occurs if the solar optical properties are measured by traditional narrow-beam measurement techniques typically used in commercial spectrophotometers. To reduce this error, a BAI-IS is recommended. The BAI-IS apparatus consists of a 20-inch diameter integrating sphere, sample mounting system, monochromator, radiant source, lock-in-amplifier, photo sensor, optical chopper and various auxiliary devices. In order to improve reliability of the measurement the BAI-IS has recently been upgraded by replacing most of the key control and measurement equipment. The refurbishment of the BAI-IS apparatus was successful. The directionalhemispherical transmittance of a sheer blind from BAI-IS measurement was found to agree well with an analytical model.

Shading devices are frequently used to control solar gain through windows. Solar optical properties are very important in the energy analysis of windows. Transmittance, absorptance and reflectance are required to quantify solar heat gain through complex fenestration systems, which consist of combinations of glazing and shading layers. In this research the solar transmittance of a sheer blind was measured using a Broad Area Illuminating Integrating Sphere (BAI-IS). More specifically, the spectral directional-hemispherical transmittance was measured in the wavelength range of 0.4 µm to 2.0 µm. A “sheer blind” consists of soft fabric vanes, similar to a venetian blind, suspended between two vertical layers of sheer fabric. This arrangement is popular because it is attractive and it has potential application for daylighting. The vertical sheer fabric reduces the solar intensity and diffuses incident radiation; generally reducing solar gain and producing soft, natural illumination. The fabric vanes control the amount of light entering the room. Shading devices such as venetian blinds, sheer blinds and drapes have spatially non-uniform and light scattering surfaces. Hence, measurement error occurs if the solar optical properties are measured by traditional narrow-beam measurement techniques typically used in commercial spectrophotometers. To reduce this error, a BAI-IS is recommended. The BAI-IS apparatus consists of a 20-inch diameter integrating sphere, sample mounting system, monochromator, radiant source, lock-in-amplifier, photo sensor, optical chopper and various auxiliary devices. In order to improve reliability of the measurement the BAI-IS has recently been upgraded by replacing most of the key control and measurement equipment. The refurbishment of the BAI-IS apparatus was successful. The directionalhemispherical transmittance of a sheer blind from BAI-IS measurement was found to agree well with an analytical model.

Proper functioning of instruments requires precise calibration and routine quality assurance. In a clinical setting, this is achieved through the use of phantoms, which mimic the physical characteristics of tissues. Polyvinyl alcohol (PVA), a non-toxic, water-soluble polymer is well-suited for use as clinical phantom material. Through successive freezing and thawing, solutions of PVA in water can be solidified into rigid cryogels (PVA-C). The number of freeze-thaw cycles affects the properties of the material, including its optical characteristics. A double integrating sphere system was used in conjunction with the Inverse Adding Doubling (IAD) algorithm to characterize the optical properties of thin slab samples. The setup was evaluated using liquid phantoms. Liquid emulsion and food colouring were used to impart scattering and absorbing properties in the range characteristic of human tissue. Measured values of normalized reflectances and transmittances were entered into IAD, and a set of optical properties (μ′s,μa,g) retrieved. The reduced scattering coefficient was found to increase linearly with increasing lipid concentration, while a consistent overestimation of the absorption coefficient was observed. Measurements of PVA cryogels revealed a linear increase in the reduced scattering coefficient with an increasing number of freeze-thaw cycles up to five cycles. Scattering was also observed to increase with concentration up to PVA concentrations of 15%, and to spontaneously increase during the lifetime of the slab samples. These findings suggest it is possible to tune the optical scattering of PVA-C via different purely physical mechanisms. / Thesis / Master of Science (MSc)

<p> An integrating sphere system has been developed to study the optical properties of biological tissues non-invasively, over a broad spectral range with the ultimate goal of quantifying erythema resulting from external beam radiotherapy. An empirical model was defined to calculate the absorption coefficient, μa, from the normalized integrating sphere signal, R *, and the reduced scattering coefficient, μ's As erythema is associated with an increase in the apparent concentration of oxygenated haemoglobin in the skin, the potential of the technique in quantifying erythema was assessed using measurements made in homogenous tissue simulating phantoms containing whole horse blood. After system validation in this simple model, a two-layer model was investigated. Whole blood from a horse was added to the bottom layer, while the top layer was fixed at an optical thickness simulating the epidermis. Reflectance measurements were made through the top layer while the bottom layer was deoxygenated using yeast. The retrieved concentrations of oxy- and deoxygenated haemoglobin were used to calculate the total haemoglobin concentration and the haemoglobin oxygen saturation. Errors in estimating the total haemoglobin concentration ranged from 3-12%; decreasing as a broadband absorber was added to the top layer. Preliminary in vivo measurements were also performed on areas of erythema induced by a topical anesthetic. For regions of erythema there was an increase in the apparent haemoglobin oxygenation which correlates to values of the erythema index calculated from the definition established by Dawson et al. These results demonstrate that the apparent haemoglobin oxygenation has the potential to be used as a surrogate in quantifying erythema. </p> / Thesis / Doctor of Philosophy (PhD)

abstract: This thesis mainly focuses on the study of quantum efficiency (QE) and its measurement, especially for nanowires (NWs). First, a brief introduction of nano-technology and nanowire is given to describe my initial research interest. Next various fundamental kinds of recombination mechanisms are described; both for radiative and non-radiative processes. This is an introduction for defining the internal quantum efficiency (IQE). A relative IQE measurement method is shown following that. Then it comes to the major part of the thesis discussing a procedure of quantum efficiency measurement using photoluminescence (PL) method and an integrating sphere, which has not been much applied to nanowires (NWs). In fact this is a convenient and useful approach for evaluating the quality of NWs since it considers not only the PL emission but also the absorption of NWs. The process is well illustrated and performed with both wavelength-dependent and power-dependent measurements. The measured PLQE is in the range of 0.3% ~ 5.4%. During the measurement, a phenomenon called photodegradation is observed and examined by a set of power-dependence measurements. This effect can be a factor for underestimating the PLQE and a procedure is introduced during the sample preparation process which managed to reduce this effect for some degree. / Dissertation/Thesis / M.S. Electrical Engineering 2012

No description available.

Successful integration of daylighting systems requires the ability to predict their performance for given climates. In this dissertation, a bottom-up approach is applied to evaluate the optical performance of a selection of daylighting systems. The evaluations are based on the optical properties of the included materials, and part of the dissertation focuses on developing new optical characterization methods. The work on characterization techniques uses an integrating sphere method to characterize the transmittance of light scattering samples more accurately. The method's principle is to reduce the discrepancy in light distribution between the reference and the sample scans by using an entry port beam diffuser. For samples exhibiting distinct light scattering patterns, the benefits of improved uniformity outweigh the errors introduced by the diffusing material. The method is applicable to any integrating sphere instrument, and its simplicity makes it suitable for standard measurements. In addition to normal-hemispherical properties, many daylighting applications require knowledge of the system's spatial light distribution. This dissertation presents a method combining experimental techniques and ray tracing simulations to assess the light distribution from a Venetian blind system. The method indicates that ray tracing based on simplified optical data is inadequate to predict the light distribution for slat materials exhibiting both specular and diffuse properties. Ray tracing is a promising complement to experimental methods used to characterize light guiding or light redirecting systems. Here, spectrophotometric measurements of a scaled mirror light pipe validate a ray tracing model. The model shows excellent agreement with experimental results for both direct and diffuse incident light. The spectral evaluation shows no dramatic color changes for the transmitted light. The ray tracing model is used to evaluate four daylighting systems for a selection of Swedish locations. The percentage of occupied time when the studied systems achieve full design illuminance is relatively low, but the systems provide a valuable contribution to the required illuminance. Additionally, this dissertation provides an overview of available energy efficient windows and illustrates the importance of including the solar energy transmittance when evaluating window energy performance. Overall, this dissertation presents optical characterization techniques for improved performance evaluations of daylighting systems.

<p>Single junction silicon photovoltaic cells (SJSPVCs) are unable to transform all the energy in the solar spectrum into electricity, due to the broad nature of the solar spectrum and the limits imposed by a single bandgap. Furthermore, high surface recombination velocity reduces the SJSPVC external quantum efficiency response, particularly to ultraviolet photons. It is the goal of spectral engineering to optimize the light that is incident on the cell, by down-shifting high energy photons to lower energies, for example, to improve the performance of photovoltaic cells.</p> <p>This thesis represents a study into the luminescence of ion implanted films, involving silicon nanocrystals (Si-NCs) and rare-earth ions in fused silica or silicon nitride. Quantum efficiency measurements taken with an integrating sphere were used to characterize some of the samples. Other photoluminescence (PL) characterization work was carried out with a single-wavelength laser and a collection lens normal to the sample. Variable angle spectroscopic ellipsometry (VASE) was used to estimate the optical constants of the implanted films. In secondary work, Rutherford backscattering spectrometry, time-dependent PL, infrared-PL measurements, and electrical conductivity measurements were used to characterize select samples.</p> <p>It was found that the conversion efficiency of Si-NCs in fused silica was about 1% – too low to be useful according to modeled results. However, considerable variation in the peak wavelength of the Si-NC PL was obtained, depending on the peak concentration of implanted silicon. Si-NC-type PL was also produced by low-energy implantation of oxygen into a Czochralski silicon wafer.</p> <p>Oxygen was also implanted into films of cerium-doped high-purity silicon nitride, and it was shown that the photoluminescence from these films is largely dependent on the level of oxygen doping. The internal conversion efficiency of a cerium-doped fused silica sample was found to approach 20%, which indicates that this is a promising avenue for future research.</p> <p>Finally, energy transfer was demonstrated between Si-NCs and erbium ions. The lifetime of the erbium PL appears to increase with increasing implanted silicon fluence.</p> / Master of Applied Science (MASc)

<p>The determination of the optical properties of biological tissue is an important issue in laser medicine. The optical properties define the tissue´s absorption and scattering behaviour, and can be expressed by quantities such as the albedo, the optical thickness and the anisotropy coefficient. During this project, a measurement system for the determination of the optical properties was built up. The system consists of a double integrating sphere set-up to perform the necessary reflection and transmission measurements, and a computer algorithm to calculate the optical properties from the measured data. This algorithm is called Inverse Adding Doubling method, and is based on a one-dimensional transport model. First measurements were conducted with the system, including measurements with phantom media (Intralipid-ink solutions) and with cartilage samples taken from the human knee joint. This work also includes an investigation about the preparation of tissue samples for optical measurements.</p>

In the fight to reduce carbon emissions, it is easy to see the necessity of reducing energy consumption. Buildings consume a large amount of energy, and have significant potential for energy savings. One tool for realising these potential savings is building simulation. To be able to use building simulation, accurate models for windows are needed. The models include individual layer models, to determine the solar and longwave radiative behaviours, as well as whole-system models to determine heat flows through the various layers of fenestration systems. This thesis looks at both kinds of models for incorporating windows into building simulations. A new network whole-system model is implemented, and integrated into the California Simulation Engine building simulation software. This model is also used as the calculation engine for a stand-alone rating tool. Additionally, a measurement technique used to measure off-normal solar properties of drapery materials, as part of developing shading layer models, is investigated using a Monte Carlo simulation. The network model uses a very general resistance network, allowing heat transfer between any two layers in a complex fenestration system (CFS), whether they are adjacent or not, between any layer and the indoor or outdoor side, or between the indoor and outdoor sides, although this last case is unlikely. Convective and radiative heat transfer are treated using the same format, resulting in increased stability. This general resistance network is used to calculate indices of merit for the CFS using numerical experiments. This approach requires fewer iterations to solve than previous solution methods, and is more flexible. The off-normal measurement technique which was investigated used a sample holder inserted into an integrating sphere. This is a non-standard way of using an integrating sphere, and early analyses did not provide conclusive information as to the effect of the sample holder. A Monte Carlo analysis confirmed the amount of beam attenuation as being 20% for the sample holder used in the experiments. Also con firmed was the effectiveness of dual-beam integrating spheres in correcting for the presence of a sample holder. The stand-alone rating tool which uses the general network framework, incorporates an easy-to-use visual interface. This tool models multiple types of shading layers with no restrictions on how they are combined. Users can easily change any one layer to see the effects of different arrangements. Users may specify any combination of indoor and outdoor ambient and mean radiant temperatures, insolation, and beam/diffuse split.