A thin film deposition system using ultrasonic atomization is designed and constructed. The coatings have been produced by pyrolysis using a solution of indium chloride in deionized water. Solution containing precursors is transported by carrying gas to the heated substrate where deposition is accomplished. In this study sample series obtained with of varying process parameters such as the flow rate of carrying gas, the tin concentration, and substrate temperature. The electrical properties of indium oxide thin film was improved using SnCl4¡E5H2O as a dopant. The effects of doping in crystalline, surface morphology, optical transmittance and electrical conductivity of the deposition thin films were examined and the best optimal percentage of doping for the transmittance and electrical properties were found. Weak diffraction peaks of crystalline indium oxide were observed in XRD pattern of the thin films deposition at 250¢J. The grains size of crystalline thin films grows with increasing substrate temperature. There is no change in XRD spectra between undoped and tin-doped indium oxide obtained with the same deposition temperature. The resistivity of thin films decreased greatly when dopant atom was added. The electrical resistivity of undoped indium oxide is ~10-2£[-cm, while that of ITO films reaches a minimum of 9.54¡Ñ10-4£[-cm when doping is in the range 2~ 6%.The UV-Visible spectra indicate that the optical transmittance of all films is between 75~88%. The transmittance was not strongly affected by doping concentration.

The lenses are important elements in optical imaging systems. However, lenses are liable to defects such as dusts and thus deteriorate their imaging quality. These kinds of imaging systems are investigated in this thesis .The polluted lens can be verified equivalent to a polluted random screen set against a clean lens .In our model ,the defects on random screen are assumed poisson-distribution ,overlapped and the transmittance effect of each defect is multiplicative .The autocorrelation function of screen is obtained by defects' density ,radius ,and transmittance. The evaluation of the optical transfer function for this imaging system can be achieved by the autocorrelation of the above random screen. This thesis includes computer simulation, experiments and comparison with other model and restoration method. The experiments are set up by the instruments including the video camera , capture card ,and personal computer. We may estimate the key parameters of our theoretical autocorrelation function by the real optical transfer function obtained from experiment. Accordingly, two methods are applied to image restoration in this thesis. One is to use the theoretical autocorrelation, the other is to use a second-order statistics of optical transfer function. The computation of second-order statistics involves a fourfold integration .By the help of changing variables and geometric analysis, we simplify the fourfold integration to double integration. Both of our methods are better for image restoration in RMS value than the method proposed by Tamas Daboczi

Glaucoma is a blinding disease characterized by damage to the optic nerve and often caused by an increase in the intra-ocular pressure. Glaucoma affects from 2% to 8% of the South African population, depending on race and age. Primary Open-angle Glaucoma (POAG) is found mostly in patients above the age of 40 years. POAG is more prevalent in black people, with the number of black persons contracting the disease double that of persons of European origin. In South Africa, the prevalence of blindness is estimated to be 0,6%, thus 240 000 out of a total of 40 million. Glaucoma is responsible for an estimated 20% of the total number of blind people, thus approximately 48 000. The treatment of glaucoma in Africa, and particularly in rural areas, presents many unresolved problems. Conventional conservative treatment with eye drops is difficult, due to the following reasons: -- Logistical problems of providing patients with a supply of medication. -- Appropriate use of drops requires education, together with a high degree of personal compliance. -- Cost of medical treatment. Patients require life-long treatment. Eye drops cost approximately R100,00 per person per month. Thus, over a ten-year period, the cost would be R12 000,00 per person and R576 million for the estimated 48 000 sufferers. Conventional surgery is not very effective, due to the following reasons: -- Scarring takes place at the surgical site. -- Can be performed only in main centres with microsurgical facilities and competent staff. -- Requires travelling expenses, not only for surgery, but also for periodical follow-up examinations. -- Surgical complications are not uncommon. Conventional laser surgery is not effective, for the following reasons: -- Can be performed only in main centres with laser surgery facilities and competent staff. -- Requires travelling expenses, not only for surgery, but also for periodical follow-up examinations. -- Complications of surgery are not uncommon. This dissertation describes an investigation concerning treatment of glaucoma, with specific reference to the use of optical energy sources. The spectral transmission of the human sclera is investigated. Alternative methods of sourcing optical energy to the ciliary processes are presented and compared. Results obtained can be summarized as follows: -- The spectral transmission of the sclera was measured. -- Trans-scleral transmission was measured to be very low (less than 5%). The result was confirmed by means of histological investigation, where high scleral absorption was found. -- Since no well-defined transmission window could be found, the application source need not be monochromatic. -- Results published in literature were found to be inconsistent. / Dissertation (MEng (Bio-engineering))--University of Pretoria, 2006. / Electrical, Electronic and Computer Engineering / unrestricted

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.

Blue-Phase liquid crystal display possesses potential to become next generation display technology because of its submillisecond response time, alignment-layer-free process and wide view angle. Intrinsically, BP only operates across a narrow temperature range due to the influence of intrinsic structural defects. Recently, the temperature range of BP has been successfully extended beyond 60K through the polymer-stabilized effect. Unfortunately, the structure of the polymer networks poses a number of problems, for instance, hysteresis effect, which degrades the accuracy of grayscale control, and residual birefringence, which decreases the contrast ratio of LCDs. This paper investigates the voltage-induced hysteresis and residual birefringence in the polymer-stabilized blue phase I and II, under various phase separation conditions and material ratio. Based on experiment result, the polymer network morphology, distribution and pure BP temperature can result in a variety of PSBP electro-optical properties. Hysteresis and residual transmittance free PSBP display could be achieved by choosing appropriated phase separation condition and material ratio. Key word¡Gblue phase¡Bmonomer¡Bhysteresis¡Bresidual transmittance

It¡¦s not easy to keep photographs clean in every day. A photograph is liable to be polluted by accumulating defects such as dusts, which can degrade the imaging quality. In the thesis, a method of image restoration is proposed for image polluted by multiplicative transmittance noise. The method is based on estimating the approximate autocorrelation function of the unpolluted image. This autocorrelation function is obtained by analyzing the relationship among the autocorrelation function for polluted image, unpolluted image and noise. Further more, the noisy image is restored by the property of the autocorrelation function. A polluted photograph in imaging system is modeled by a thin random screen against the original image. In this model, defects are Poisson-distribution and may be overlapped. Since transmittance effect of each defect is multiplicative, the transmittance of random screen is computed as a product of Poisson-distribution-centered random function. Then, the statistical autocorrelation function of random screen is accordingly computed. More specifically, we should rearrange image data as periodic signal to avoid insufficient data in computing the process autocorrelation function. The simulated polluted image is restored by the amplitude information from the estimated autocorrelation function of the original image. Simulating results is demonstrated that the RMS of the restored image computed with the polluted image is improved.

Diamond-Like Carbon (DLC) films have been deposited on ITO glass substrate. DLC thin film was electrodeposited at low DC potential using a mixture of acetic acid and DI water. The DLC film deposition parameters include DC potential, deposited temperature, the concentration of electrolyte were used to study the characteristics of DLC film measured by the Ellipsometer, XPS, SEM and Raman spectroscopy in detail. The Raman spectra shows two peaks located near 1358cm-1 and 1580cm-1 assigned as the characteristics peaks of DLC films. That is an evidence for DLC film deposited successfully on ITO glass. Scanning electron microscopy (SEM) can make insight into accurately the surface morphology and uniformity of DLC films so as used to grow the best quality of DLC films. From the variations of the I-t curve and the surface morphology observed by SEM, the properties of DLC film depend on a verity of growth parameters such as applied voltage, the concentration of electrolyte and deposition temperature. The shift of G-peak increase with the applied voltage, and the sp2/sp3 ratio of the content C1s decreases with the applied voltage. Finally, based on the I-t curve and results of SEM, XPS, Raman, and Ellipsometer for n, k coefficients measured, we obtain a deeply understanding for the growth conditions of DLC films and their surface morphology. We achieve the consistent results between various measurements. Finally, the optimizing growth of DLC film is to be studied and discussed in future

ITO is a wide band gap semiconductor material, its band gap is from 4.7 eV to 5.2 eV. Due to the low resistivity, high transmittance to visible light, great absorption to UV light, and high reflection to IR, ITO is wide used to photovoltatic application; such as anodic electrode of Liquid Crystal Display (LCD) and photovoltaic devices. In the thesis, samples are deposited with an ITO layer on color filter (CF) by magnetron sputtering. The conductivity of samples is measured by 4-probe measurement, and the transmittance is characterized by visible spectroscopy. In this work is heat treatment parameters of temperature and annealing time of ITO thin film know been studied, and found an optima condition. From the experiment results, an optima heat treatment condition is temperature of 200¢Jfor 40 minutes, which reveals lower resistivity and improved transmittance of ITO samples. And, it is less process time and lower treatment temperature to used condition for industry presently. The reducing time of heat treatment will increase 9.9 % production, and enhancing the properties of color filter. Depending on the results of this work, there is space to improve performance and reduce power for fabrication of color filter.

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