This thesis presents a compact femtosecond laser amplifier design for optical preamplifiers and power amplifiers consist of theoretical perspective, simulations to analyze and optimize beam performance. The propagation through optical media is simulated for every optical component such as mirrors and nonlinear crystal separately and suggested realignment of these components required increasing amplifier performance. Finally Gaussian beam propagation and aberration compensation has been conducted.

The confocal laser-scanning microscope (CLSM), known simply as a confocal microscope, is an important instrument which allows us to observe an object or a surface in three-dimensions with confocal microcopy technique. The basic difference of confocal microscopy is detecting the in- focused light, while the out of focus light is blocked out by the help of a pinhole. By this optical dissection ability of confocal microcopy, CLSM provides the images of investigated object or the surface with higher resolution and contrast as against conventional microscopic systems. Various types of Laser Scanning confocal microscopes have been developed and due to its high resolution and contrast they have become an invaluable tool for investigations in many areas like biology and medicine. In addition to its wide range of use, confocal microscope can be used for detecting of possible defects on metal surfaces. In this thesis our goal was to develop the analytical and theoretical back ground necessary for the successful completion of a laser/optic system coupled to a fiber bundle waveguide based on confocal scanning principles to effectively image a non-uniform, metal surface with speed and precision in order to assess any surface damage. In addition to this analysis we demonstrate a working confocal microscopy set-up and investigate the factors which affect the image quality by the experiments conducted in METU (Middle East Technical University) Laser Laboratory

Today, riflescope systems are used widely, mostly by military forces. In this study, a riflescope working in the visible range (400-700 nm) will be designed. The riflescope will have 3 degrees field of view and maximum 15 cm total track. Total design length is limited to 15 cm because a short riflescope is more stabilized than a long one with respect to thermal instability and vibrational effects. Taken into account the cost factor, only two types of glasses will be used in the design. One of them is NBK7 a crown glass and the other is N-F2 a flint glass. Moreover, Schmidt-Pechan prism will be used to construct an erected image. The optical performance analysis of the design is also carried out for a production ready riflescope system.

Focal plane corrected Cassegrain type optical systems have been widely used in various fields. The axial alignment of complex optical systems is not easy and a practical alignment method is needed for such systems. Tilts, decenters and axial motion of elements or group of elements in the system are the typical alignment parameters. Interferometric measurement is an effective way to see the errors caused by the misalignment of each element in an optical system. In this thesis, alignment of a Cassegrain type telescope will be examined by using interferometric measurements and modulation transfer function simulations.

The construction of an optical experimental setup is the objective, to measure transmission coefficient of optical components used in plasma investigations. Thus, proper light source either with continuous or line radiation spectrum should be used. In addition, the detectors&rsquo / output signal is recorded on a PC based data recorder after being digitized by an analog to digital converter card.

This thesis explains low temperature operation of an InGaAs Avalanche Photo Diode (APD) cooled using thermoelectric coolers in order to utilize in the quantum cryptographic applications. A theoretical background for the equipment used in the experiment was provided. Circuitry and mechanics used for the low temperature operation were designed. Performance measures for APD were explained and experiment results were presented.

The group theory allows one to study different branches of physics using the same set of commutation relations. It is shown that a formulation of the polarization optics that depends on the representations of the Lorentz group is possible. The set of four Stokes parameters, which is a standard tool of polarization optics, can be used to form a four-vector that is physically unrelated but mathematically equivalent to the space-time four-vector of the special relativity. By using the Stokes parameters, it is also possible to generate four-by-four matrix representations of the ordinary optical filters that are traditionally represented with the two-by-two Jones matrices. These four-by-four matrices are treated as the entities of the Lorentz group. They are like the Lorentz transformations applicable to the four-dimensional polarization space. Besides, optical decoherence process can be formulated within the framework of the SO(3,2) de Sitter group. The connection between the classical and quantum mechanical descriptions of the polarization of light allows the extension of the Stokes parameters to the quantum domain. In this respect, the properties of the polarization of the two-photon system can also be studied within the framework of the Lorentz group.

In the last few years, interest in polymer optical fibers (POF) has increased because of their low cost, easy handling and good flexibility even at large diameters. Moreover, optical cables do not have the problem of electromagnetic interference, which gives, for instance, the problem of cross-talk in copper telephone cables. In the usage of current communication and computer systems the yield has gained a big importance and it has seen from studies that light scattering loss is the only loss, which cannot be eliminated entirely. Besides, this loss causes its attenuation loss intrinsically and determines the lower limit of loss in the POF. In this work, the importance and the dependencies of light scattering were studied, and calculations were done in order to find more appropriate polymer for using as core material of POFs. For this aim, a computer program that calculates the light scattering loss of several amorphous polymers and plots the graph of isotropic scattering loss versus isothermal compressibility and total attenuation loss versus wavelength was written.

Concentrating Photovoltaic systems are good candidates for low cost and clean electricity generation from solar energy. CPV means replacing much of the expensive semiconductor photovoltaic cells with the cheaper optics. Although the idea is simple, CPV systems have several problems inherent to their system design, such as module thickness, expensive PV cells and overheating. Light guide systems are good alternatives to classical CPV systems that can clear off most of the problems of those systems. In this thesis we explore a new light-guide based solar concentrator by optical design and simulations. It is shown that this solar concentrator can reach 1000x geometric concentration, 96.5% optical efficiency with a &plusmn / 1 degree acceptance angle. As a result of simulations, effectiveness of the horizontally staggered light guide solar concentrators is proved. A practical module study is carried on to improve the knowledge related to light guide CPV systems. The concentrator geometry is fabricated as a medium concentrator system with a geometric concentration of 45x and +-2 degrees acceptance angle. With the prototype level injection molding 74% optical efficiency is achieved and can be improved with a better mold manufacturing. A cost analyses is also performed with real manufacturing parameters and it is shown that grid parity can be achieved with this kind of light guide solar concentrators.

Two-dimensional thermal, mechanical and optical simulations are carried out to investigate the effect of Nd3+ concentration on thermal, mechanical and optical behavior of Nd:YAG ceramic laser materials under continuous wave laser operation. In the analyses, rods are pumped longitudinally with laser diodes, in three, six, nine and twelve fold structures. Rods having diameters of 3 and 6 mm are pumped with 808 nm and 885 nm sources separately having Nd+3 concentrations of 0.6, 1, 2, 3, 4 and 6 at. %. Total absorbed pump power are kept constant for all rods. Absorbed pump power distribution are obtained for each rod using ray tracing method and Beer&amp / #8217 / s Law. In the analysis, temperature dependent material properties are incorporated. Nonlinear numerical solutions of thermal and stress equations have been performed. Temperature and stress results are obtained to investigate the effect of Nd concentration on the optical properties of ceramic YAG laser material. Analysis results reveal that, increase in Nd3+ concentration of YAG ceramic laser material, decreases the temperature and stress developed during optical pumping. Rods pumped with 808 nm source have large temperature and stress values compared to 885 nm pumped ones. Optical path difference (OPD) of each ray passed trough the material is calculated using thermal and elastic strain results together with photo-elastic constants of Nd:YAG material. Focal length and depolarization of each rod is calculated numerically from OPD results. Focal length of each rod is found to increase, in contrary depolarization is found to decrease with increase in the dopant concentration.