Spelling suggestions: "subject:"nanoelektronikk og fotonik"" "subject:"nanoelektronik og fotonik""
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Skin effects and UV dosimetry of climate therapy in patients with psoriasisBartosova, Veronika January 2010 (has links)
<p>Sun exposure and climate therapy is an effective treatment for psoriasis. However, even though this treatment gives the patients relief from their discomforting symptoms, it has some potentially dangerous side effects such as an increased risk of skin cancer and premature skin aging. A prospective field study plans to follow the patients undergoing the climate therapy. During this study the UV dose to each patient will be monitored by personal dosimeters worn by the patients. Furthermore the patients' skin spectra acquired by the means of optical spectroscopy will be obtained daily. Both psoriatic skin a unaffected skin will be observed. These data will be used to assess the skin changes which take place during the psoriasis treatment. This project is focused on developing an automatic algorithm for handling bulk spectrometric measurements data and to propose ways of numerically evaluating the skin spectra. These numerical values will be later used to compare the daily patients' spectra and monitor progress of the treatment. An inverse model based on a lookup table and successive iteration was proposed in this project. The model matches the diffuse skin reflectance spectra modeled with a diffuse skin model with the measured patients skin spectra. The measured skin spectra are then defined by the diffuse skin model input parameters which were found by the inverse model. These parameters are oxygenation, blood volume and melanin absorption coefficient. Additionally four indexes were proposed to supplement the parameters found by the inverse model, namely the erythema index, melanin index, hemoglobin index and oxygenation index. Measurements of several skin spectra including psoriatic plaques spectra were carried out and used to test the inverse fitting model performance. The proposed model proved to match the measured spectra in an acceptable form employable for distinguishing between different measured spectra. The highest deviation is at the ends of the spectra due to the use of a constant value of scattering coefficient and additional parameters not directly relevant to sun exposure, hence not considered by the model. The proposed parameters together with the indexes proved to be a viable means of evaluating the healing in the psoriatic plaques as well as determining the changes caused by the sun in normal skin.</p>
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Investigation of methods for speckle contrast reductionWelde, Kristine January 2010 (has links)
<p>Speckle arises when coherent light is reflected from a rough screen and observed by an intensity detector with a finite aperture. Because speckle causes serious image degradation when lasers are used as light sources in e.g. projectors, methods for reducing the speckle contrast need to be developed. Different speckle contrast reduction methods are investigated in this thesis, such as a rotating diffuser and a sinusoidal rotating grating. In addition, speckle simulations with the optical system design software ZEMAX has been explored. A setup consisting of a 4-f imaging system with a rotating diffuser in the Fourier plane was developed in order to decide whether or not it is advantageous to perform speckle reduction in the Fourier plane. Hence, measurement series were performed with the rotating diffuser placed at different positions in the 4-f imaging system for comparison. Measurement series were executed both with an empty object plane and with a lens in it to spread the light in the Fourier plane. Placing a rotating diffuser in the Fourier plane does not appear to be effective for speckle contrast reduction. The last setup investigated was a transmissive spatial light modulator (SLM) placed in the beam path. Sinusoidal rotating gratings created by means of gray levels, to simulate a potential modulator based on a deformable polymer layer, were implemented on the SLM. The gratings were rotated around their centers, and in a spiral in order to reduce the speckle contrast. For the first method the modulator speckle contrast was 34% for N = 18 averaged images, and for the second method it was 31% for N = 36 averaged images, both with a grating period of 4 pixels. Due to the drawbacks of the SLM optimal results were not achieved, but the SLM is useful for a proof-of-concept. Further measurements should be performed for this promising, novel method based on a true sinusoidal grating.</p>
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Security of quantum key distribution sourceSimonsen, Eivind Sjøtun January 2010 (has links)
<p>Cryptography has begun its journey into the field of quantum information theory. Classical cryptography has shown weaknesses, which may be exploited in the future, either by development in mathematics, or by quantum computers. Quantum key distribution (QKD) is a promising path for cryptography to enable secure communication in the future. Although the theory of QKD promises absolute security, the reality is that current quantum crypto systems have flaws in them, as perfect devices have proven impossible to build. However, this can be taken into account in security proofs to ensure security, even with flaws. Security loopholes in QKD systems are being discovered as development progresses. Nevertheless, the system being built at NTNU is intended to address them all, creating a totally secure system. During this thesis, work was continued assembling the interferometer which is the basis for encoding qubits. It was fully connected on an optical table, and interference was obtained. Concerning theoretical work, calculations for a photon source specific parameter was carried out. It consisted of expanding previous framework and applying the results in both an established security proof, and a recent generalization of this proof. Two source effects were in focus, the lasers random phase and its fluctuating pulse intensity. Where analytical derivation was no longer possible, Matlab was used for numerical calculations. Under the conditions of the framework and proofs this thesis lies on, randomized phase turned out to have a negligible improvement over the case of non-random phase. Fluctuating amplitude showed a larger effect, reducing system performance. The input parameters were extreme, thus in a realistic situation it should not affect system performance significantly. However, these fluctuations must be taken into account when proving system security.</p>
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Støyreduksjon av hyperspektrale bilder / Noise reduction of hyperspectral imagesFjerdingen, Sverre January 2010 (has links)
<p>Støyreduksjon har blitt utført på hyperspektrale bilder i både spektral retning og romlige retninger. Algoritmene som har blitt benyttet for å oppnå støyreduksjon er Principal Component Analysis (PCA), Maximum Noise Fraction (MNF) og wavelet-transform. MNF-algoritmen har blitt kjørt med mange forskjellige støyestimatorer for å bestemme hvilke av disse som gir høye signal-støy-forhold. Å utføre støyestimatet i fourierrommet har også blitt undersøkt. Dette ga gode resultater når man benyttet fasedifferansen med nærliggende piksler som estimator for hyperspektrale bilder tatt under hvitt lys. Ble derimot kilden endret til en 355nm laserkilde fikk man langt dårligere resultater. Det er bare Haar-transformen som har blitt brukt til wavelet-transformasjon. Haar-transformen ga dårlig støydempning i både spektral retning og romlige retninger. Algoritmene PCA og MNF fungerer bra til støyreduksjon. I spektral retning er det liten forskjell mellom PCA og de ulike støyestimatene som er brukt under MNF. Ser man derimot på det romlige planet finner en større forskjeller mellom dem. Dette gjelder spesielt for spektralbånd med lav intensitet og mye støy. Her gir PCA bedre støydempning enn MNF. Støyreduksjonen ved PCA og MNF kommer som en direkte følge av å begrense antallet prinsipalkomponenter under tilbaketransformasjonen. Hvor grensen bør settes for hvilke prinsipalkomponenter som skal bevares, ble også vurdert. Når lyskildeforholdene for de hyperspektrale bildene blir sammenlignet er grensen valgt slik at 99,25% av det opprinnelige signalet blir bevart. Spekteret til hyperspektrale bilder tatt under hvitt lys har høy intensitet for lange bølgelengder, og lav intensitet ved korte bølgelengder. Endres derimot lyskilden til en 355nm laserkilde får man lav intensitet for lange bølgelengder og høy intensitet for korte.</p>
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Subthreshold Potential Modeling of FinFET and QuadFETNilsen, Dag-Martin January 2009 (has links)
<p>A precise subthreshold potential model for the Quadruple FET (QuadFET) is presented in this thesis. The attempt of modeling the FinFET ("Fin" FET) in the same way failed, but the procedure of the attempt will still be presented in this thesis, and a conclusion of why this modeling did not work is given. For the QuadFET, an analytical solution of the inter-electrode potential distribution of the double-gate MOSFET (DG MOSFET) is used by performing a simple geometric scaling transformation. This is done with a high degree of precision due to structural similarities between the QuadFET and DG MOSFET, accounting for the dierence in gate control of the two devices. A parabolic approximation is then used to model the the cut-plane in the middle of the device, perpendicular to the electron ow from source to drain, of the QuadFET. The resulting analytical solution agrees very well with numerical simulations. For the FinFET, the same analytical solution of the DG MOSFET is used directly in the ground plane of the device, assuming that the electric elds going through the ground plane, into the thick substrate, is negligible. Conformal mapping is then used in the same plane as modeled in the QuadFET, that is the plane in the middle of the device, perpendicular to the electron ow from source to drain, resulting in an analytical solution of the FinFET. Since the potential curvature in the source-drain direction was neglected when making the three dimensional problem of the FinFET to a two dimensional one, the modeling failed. However, an attempt of modeling the transistor has been tested, the electrostatics of the device is better known, and a new way of modeling the device is briey discussed.</p>
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Skin effects and UV dosimetry of climate therapy in patients with psoriasisBartosova, Veronika January 2010 (has links)
Sun exposure and climate therapy is an effective treatment for psoriasis. However, even though this treatment gives the patients relief from their discomforting symptoms, it has some potentially dangerous side effects such as an increased risk of skin cancer and premature skin aging. A prospective field study plans to follow the patients undergoing the climate therapy. During this study the UV dose to each patient will be monitored by personal dosimeters worn by the patients. Furthermore the patients' skin spectra acquired by the means of optical spectroscopy will be obtained daily. Both psoriatic skin a unaffected skin will be observed. These data will be used to assess the skin changes which take place during the psoriasis treatment. This project is focused on developing an automatic algorithm for handling bulk spectrometric measurements data and to propose ways of numerically evaluating the skin spectra. These numerical values will be later used to compare the daily patients' spectra and monitor progress of the treatment. An inverse model based on a lookup table and successive iteration was proposed in this project. The model matches the diffuse skin reflectance spectra modeled with a diffuse skin model with the measured patients skin spectra. The measured skin spectra are then defined by the diffuse skin model input parameters which were found by the inverse model. These parameters are oxygenation, blood volume and melanin absorption coefficient. Additionally four indexes were proposed to supplement the parameters found by the inverse model, namely the erythema index, melanin index, hemoglobin index and oxygenation index. Measurements of several skin spectra including psoriatic plaques spectra were carried out and used to test the inverse fitting model performance. The proposed model proved to match the measured spectra in an acceptable form employable for distinguishing between different measured spectra. The highest deviation is at the ends of the spectra due to the use of a constant value of scattering coefficient and additional parameters not directly relevant to sun exposure, hence not considered by the model. The proposed parameters together with the indexes proved to be a viable means of evaluating the healing in the psoriatic plaques as well as determining the changes caused by the sun in normal skin.
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Subthreshold Potential Modeling of FinFET and QuadFETNilsen, Dag-Martin January 2009 (has links)
A precise subthreshold potential model for the Quadruple FET (QuadFET) is presented in this thesis. The attempt of modeling the FinFET ("Fin" FET) in the same way failed, but the procedure of the attempt will still be presented in this thesis, and a conclusion of why this modeling did not work is given. For the QuadFET, an analytical solution of the inter-electrode potential distribution of the double-gate MOSFET (DG MOSFET) is used by performing a simple geometric scaling transformation. This is done with a high degree of precision due to structural similarities between the QuadFET and DG MOSFET, accounting for the dierence in gate control of the two devices. A parabolic approximation is then used to model the the cut-plane in the middle of the device, perpendicular to the electron ow from source to drain, of the QuadFET. The resulting analytical solution agrees very well with numerical simulations. For the FinFET, the same analytical solution of the DG MOSFET is used directly in the ground plane of the device, assuming that the electric elds going through the ground plane, into the thick substrate, is negligible. Conformal mapping is then used in the same plane as modeled in the QuadFET, that is the plane in the middle of the device, perpendicular to the electron ow from source to drain, resulting in an analytical solution of the FinFET. Since the potential curvature in the source-drain direction was neglected when making the three dimensional problem of the FinFET to a two dimensional one, the modeling failed. However, an attempt of modeling the transistor has been tested, the electrostatics of the device is better known, and a new way of modeling the device is briey discussed.
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Investigation of methods for speckle contrast reductionWelde, Kristine January 2010 (has links)
Speckle arises when coherent light is reflected from a rough screen and observed by an intensity detector with a finite aperture. Because speckle causes serious image degradation when lasers are used as light sources in e.g. projectors, methods for reducing the speckle contrast need to be developed. Different speckle contrast reduction methods are investigated in this thesis, such as a rotating diffuser and a sinusoidal rotating grating. In addition, speckle simulations with the optical system design software ZEMAX has been explored. A setup consisting of a 4-f imaging system with a rotating diffuser in the Fourier plane was developed in order to decide whether or not it is advantageous to perform speckle reduction in the Fourier plane. Hence, measurement series were performed with the rotating diffuser placed at different positions in the 4-f imaging system for comparison. Measurement series were executed both with an empty object plane and with a lens in it to spread the light in the Fourier plane. Placing a rotating diffuser in the Fourier plane does not appear to be effective for speckle contrast reduction. The last setup investigated was a transmissive spatial light modulator (SLM) placed in the beam path. Sinusoidal rotating gratings created by means of gray levels, to simulate a potential modulator based on a deformable polymer layer, were implemented on the SLM. The gratings were rotated around their centers, and in a spiral in order to reduce the speckle contrast. For the first method the modulator speckle contrast was 34% for N = 18 averaged images, and for the second method it was 31% for N = 36 averaged images, both with a grating period of 4 pixels. Due to the drawbacks of the SLM optimal results were not achieved, but the SLM is useful for a proof-of-concept. Further measurements should be performed for this promising, novel method based on a true sinusoidal grating.
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Security of quantum key distribution sourceSimonsen, Eivind Sjøtun January 2010 (has links)
Cryptography has begun its journey into the field of quantum information theory. Classical cryptography has shown weaknesses, which may be exploited in the future, either by development in mathematics, or by quantum computers. Quantum key distribution (QKD) is a promising path for cryptography to enable secure communication in the future. Although the theory of QKD promises absolute security, the reality is that current quantum crypto systems have flaws in them, as perfect devices have proven impossible to build. However, this can be taken into account in security proofs to ensure security, even with flaws. Security loopholes in QKD systems are being discovered as development progresses. Nevertheless, the system being built at NTNU is intended to address them all, creating a totally secure system. During this thesis, work was continued assembling the interferometer which is the basis for encoding qubits. It was fully connected on an optical table, and interference was obtained. Concerning theoretical work, calculations for a photon source specific parameter was carried out. It consisted of expanding previous framework and applying the results in both an established security proof, and a recent generalization of this proof. Two source effects were in focus, the lasers random phase and its fluctuating pulse intensity. Where analytical derivation was no longer possible, Matlab was used for numerical calculations. Under the conditions of the framework and proofs this thesis lies on, randomized phase turned out to have a negligible improvement over the case of non-random phase. Fluctuating amplitude showed a larger effect, reducing system performance. The input parameters were extreme, thus in a realistic situation it should not affect system performance significantly. However, these fluctuations must be taken into account when proving system security.
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Støyreduksjon av hyperspektrale bilder / Noise reduction of hyperspectral imagesFjerdingen, Sverre January 2010 (has links)
Støyreduksjon har blitt utført på hyperspektrale bilder i både spektral retning og romlige retninger. Algoritmene som har blitt benyttet for å oppnå støyreduksjon er Principal Component Analysis (PCA), Maximum Noise Fraction (MNF) og wavelet-transform. MNF-algoritmen har blitt kjørt med mange forskjellige støyestimatorer for å bestemme hvilke av disse som gir høye signal-støy-forhold. Å utføre støyestimatet i fourierrommet har også blitt undersøkt. Dette ga gode resultater når man benyttet fasedifferansen med nærliggende piksler som estimator for hyperspektrale bilder tatt under hvitt lys. Ble derimot kilden endret til en 355nm laserkilde fikk man langt dårligere resultater. Det er bare Haar-transformen som har blitt brukt til wavelet-transformasjon. Haar-transformen ga dårlig støydempning i både spektral retning og romlige retninger. Algoritmene PCA og MNF fungerer bra til støyreduksjon. I spektral retning er det liten forskjell mellom PCA og de ulike støyestimatene som er brukt under MNF. Ser man derimot på det romlige planet finner en større forskjeller mellom dem. Dette gjelder spesielt for spektralbånd med lav intensitet og mye støy. Her gir PCA bedre støydempning enn MNF. Støyreduksjonen ved PCA og MNF kommer som en direkte følge av å begrense antallet prinsipalkomponenter under tilbaketransformasjonen. Hvor grensen bør settes for hvilke prinsipalkomponenter som skal bevares, ble også vurdert. Når lyskildeforholdene for de hyperspektrale bildene blir sammenlignet er grensen valgt slik at 99,25% av det opprinnelige signalet blir bevart. Spekteret til hyperspektrale bilder tatt under hvitt lys har høy intensitet for lange bølgelengder, og lav intensitet ved korte bølgelengder. Endres derimot lyskilden til en 355nm laserkilde får man lav intensitet for lange bølgelengder og høy intensitet for korte.
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