http://hdl.handle.net/2248/5842 Search the Channel search http://prints.iiap.res.in/simple-search http://hdl.handle.net/2248/5911 Title: Image processing for stellar objects<br/><br/>Authors: Arun Surya<br/><br/>Description: Thesis Supervisor Prof. S. K. Saha http://hdl.handle.net/2248/5902 Title: High altitude Balloon experiments<br/><br/>Authors: Sreejith, A. G<br/><br/>Abstract: We are beginning a program of high altitude balloon flights at the Indian Instituteof Astrophysics with the eventual goal of ultraviolet spectroscopy from high altitudeballoons. The primary purpose of these flights is to develop instrumentation for eventualuse in space but we also plan to investigate science problems in the upper atmosphereincluding spectroscopy of meteor flashes in the UV and of lightning. These will requireboth high speed and high dynamic range and we are developing the instrumentation forthe same.<br/><br/>Description: Thesis Supervisor Prof. Jayant Murthy http://hdl.handle.net/2248/5900 Title: Design Aspects of Stokes Polarimeter for Solar Observations<br/><br/>Authors: Sajal Kumar Dhara<br/><br/>Abstract: Measurement of line polarization is an essential step towards remote sensing of the solarmagnetic fields. The instrument used for measuring the polarization is known as polarimeter.Waveplate is one of the main parts of the polarimeter. Before using this element it isnecessary to characterize it for different required wavelengths because this component ishighly dependent on the wavelength of light. In the first phase of the project the availablePancharatnam half-waveplate was characterized for different wavelength range of light andthe measured retardation values were used to simulate the efficiency of the dual beamspectropolarimeter (Nagaraju et al., 2007).The dual beam spectropolarimeter is designed for l = 630nmand eight stagemodulation scheme is used for this polarimeter. In the second phase of the project, differenttypes of modulations schemes for polarimeter design was studied in the wavelength range of400nm to 700nm.<br/><br/>Description: Thesis Supervisor Prof. K. E. Rangarajan http://hdl.handle.net/2248/5887 Title: Wavefront Sensing of Extended sources<br/><br/>Authors: Satya Ranjan Behera<br/><br/>Abstract: Atmospheric turbulence is a major problem when imaging is done with the help ofoptical telescopes. Adaptive Optics has played a major role in compensating theturbulence to give a near diffraction-limited image. Our closest star, the Sun, is alsoaffected by earth’s atmosphere turbulence. Since it is observed in day time, the spatialresolution is limited by seeing, largely compared to night time observation.Scene-based wave-front sensing (SBWFS) is a technique that allows an arbitraryscene to be used for wave-front sensing with adaptive optics (AO) instead of thenormal point source. This makes AO feasible in a wide range of interesting scenarios.This report first presents the basic concepts and properties of SBWFS.Shack-Hartmann wavefront sensor is widely used for the measurement of phaseperturbations induced by turbulence. Such a wavefront sensor relies on themeasurement of the image displacements in the lenslet array focal plane. Differentalgorithms can be used to estimate this displacement. This report is dedicated to thecorrelation techniques which are well suited to extended sources. This techniqueresults in lower noise than that of other centroiding algorithms.<br/><br/>Description: Thesis Supervisor Dr. J. P Lancelot