Universiẗat, Diss., 2000--Dortmund. / Dateiformat: PDF.

Atom interferometers and gyroscopes are highly sensitive atom-optical devices which are capable to measure inertial, gravitational, electric, and magnetic fields and to sense rotations. Theoretically, the signal-to-noise ratio of atomic gyroscopes is about a hundred billion times more than that of their optical counterparts for the same particle flux and the enclosed area. Ultra cold atoms from a Bose-Einstein condensate (BEC) can easily be controlled and coherently manipulated on small chips by laser pulses. Atom-optical devices will therefore play a significant role in fundamental research, precision measurements, and navigation systems. In BEC-based atom interferometers, a BEC in a trap is split by using laser pulses, the split clouds are allowed to evolve, they are reflected, and then recombined by laser pulses to observe interference. The split clouds accumulate spatial phase because of the trap and the nonlinearity caused by atom-atom interactions. A velocity mismatch due to reflection laser pulses also introduces a phase gradient across each cloud. These factors contribute to spatial relative phase between the clouds at recombination, causing the loss of contrast of the interference fringes. The main objective of this dissertation is to study the dynamics of a split condensate in atom Michelson interferometers, investigate the effect of trap frequencies, nonlinearity, and the velocity mismatch on the contrast, and to obtain the best theoretical limit of performance in terms of the experimental parameters: trap frequencies, number of atoms, and the velocity imparted to the clouds by the splitting laser pulses.

Because the acoustic wave is capable of propagating at a long-distance in water, the hydrophone plays a key role in the underwater acoustic sensing all the time. The hydrophone based on fiber optic interferometry has an extremely high sensitivity and large dynamic range. In addition, the electrically passive, immunity to electromagnetic interference, and multiplexing properties of fiber optic sensor offer great advantages over traditional piezoelectric hydrophone. Due to the complete path-balance between the two counterpropagating waves, a Sagnac interferometric configuration can employ a low-coherent light source to reduce the cost. This configuration can easily route optical paths and replace sensor heads to compare with each other. But, the sensitivity varying with frequency and the polarization-induced signal fading problem make it unsuitable for applications in need of detecting correct amplitude of signals. The Michelson interferometric configuration with Farady rotator mirror (FRM) has a constant sensitivity and solves the polarization-induced signal fading problem. But, this configuration uses a high-coherent light source and expensive FRMs, and be difficult to route. In this paper, we use the polarization-insensitive Michelson fiber optic sensor to adjust the demodulation circuits we design. In this paper, we establish the interferometric hydrophones. The fiber optic coil of the sensor head is embedded with the special materials in order to acoustic impedance matching and waterproofing. We employ phase generated carrier demodulation technology to get the acoustic signal of interest from the output of the interferometer. In our experiment, the dual Sagnac configuration has a dynamic range of 23 dB and a sensitivity of -226 dB re V/1uPa, the Michelson configuration with FRMs has a dynamic range of 25 dB and a sensitivity of -204 dB re V/1uPa.

[Truncated abstract] This thesis presents the design, construction and operation of a new rotating mod- ern Michelson-Morley test of Lorentz invariance. The experiment measures the isotropy of the speed of light by comparing the frequencies of two orthogonally ori- ented cryogenic sapphire whispering gallery mode resonators. Putative violations of Lorentz invariance will manifest as periodic variations in the difference frequency between the two resonators, related to the changing orientation of the experiment with respect to a preferred cosmological frame. Actively rotating the experiment is advantageous for three reasons. Firstly, by careful selection of the rotation frequency in the laboratory we are able to sample the isotropy of the speed of light at a rate that coincides with the optimal frequency instabilities of the oscillators (18 seconds). Secondly, the statistics of this exper- iment are improved with respect to non-rotating (stationary) experiments, which rely on the motion of the Earth to sample the isotropy of the speed of light. This results from integrating over more periods of rotation per unit of time, compared to the sidereal rotation experienced by stationary experiments. ... Many noise sources and systematic disturbances have been characterized and the operation of the experiment optimized. Two frequencies are generated at 10 GHz with 226 kHz separation, exhibiting a fractional frequency instability of less than 2x10-14 from 5 to 500 seconds. Furthermore, the work includes a detailed analysis of the experiment within the Standard Model Extension and Robertson, Mansouri and Sexl frameworks. The sensitivity of the experiment to violations of Lorentz invariance has been derived in each of these frameworks, for both short data set and the complete full year analysis. The data has been analysed using two separate data analysis techniques, which were optimised for noise present in the data. We have operated the experiment over the course of more than one year, collect- ing data more than 30 percent of the time. By analysing over 1 year of data we were able to set the first independent limits on 8 parameters in the photon sector of the Standard Model Extension as low as 10-16 for Ke- and 10-12 for Ko+ parameters, improving upon previous non-rotating experiments by up to an order of magnitude. We have also set new a new limit on the isotropy parameter PMM = 9.4(8.1)x10-11 of the Robertson, Mansouri and Sexl framework, which is a factor of 25 improvement.

Art and optics are inseparable. Though seemingly opposite disciplines, the combination of art and optics has significantly impacted both culture and science as they are now known. As history has run its course, in the sciences, arts, and their fruitful combinations, optical aberrations have proved to be a problematic hindrance to progress. In an effort to eradicate aberrations the simple beauty of these aberrational forms has been labeled as undesirable and discarded. Here, rather than approach aberrations as erroneous, these beautiful forms are elevated to be the photographic subject in a new body of work, On the Bright Side. Though many recording methods could be utilized, this work was composed on classic, medium-format, photographic film using white-light, Michelson interferometry. The resulting images are both a representation of the true light rays that interacted on the distorted mirror surfaces (data) and the artist’s compositional eye for what parts of the interferogram are chosen and displayed. A detailed description of the captivating interdisciplinary procedure is documented and presented alongside the final artwork, CCD digital reference images, and deformable mirror contour maps. This alluring marriage between the arts and sciences opens up a heretofore minimally explored aspect of the inextricable art-optics connection. It additionally provides a fascinating new conversation on the importance of light and optics in photographic composition.

The interferometeric optical fiber sensor has high sensitivity for sound signal. This characteristic is used to design hydrophones. The sound pressure causes the optical fiber to change its shape. So as to induce phase difference between sensing and reference arms. Using the demodulation system, we can get the signal we want. In this thesis, we plan to analyze three different kinds of optic configurations, such as Michelson, compensating Mach-Zehnder, hybrid configuration of Mach-Zehnder and Sagnac interferometers. The mathematical methods are used to compare their characters. We also use software to simulate the relation among sensitivity, delay fiber and frequency character of the Sagnac interferometer. In our experiment, we use PGC modulation technology and compare the results with a standard hydrophone B&K 8103 for calibration. We also measure the dynamic range of proposed three interferometers. The measurement result of this paper is as following: Michelson and compensating type Mach-Zehnder interferometer dynamic range were about 24.90 dB and 13.98 dB, the acoustic signal sensitivity was -201.67 dB re V/1uPa and -205.97 dB re V/Pa, respectively. The dynamic range of the hybrid of Mach-Zehnder and Sagnac type interferometer was 33.67 dB and acoustic signal sensitivity was -212.47 dB re V/1uPa.

In this paper, the fesibility of using a Fiber Bragg Grating (FBG) as a sensing scheme to detect the underwater acoustic signals is analyzed. When a FBG is disturbed by an underwater sound, the wavelength of the FBG is changed. Therefore, the central spectrum of the reflected light is shifted according to the wavelength change of the FBG. This spectrum can be detected by an imbalanced two-arm interferometer. Its transfer function will be studied. Also, the polarization induced signal fading of those two-arm interferometers will be studied.

Techn. Universiẗat, Diss., 2002--Braunschweig.

In Michelson interferometry, many algorithms are used to detect the number of active laser sources at any given time. Conventional FFT-based non-parametric methods are widely used for this purpose. However, non-parametric methods are not the only possible option to distinguish the peaks in a spectrum, as these methods are not the most suitable methods for short data records and for closely spaced wavelengths. This thesis aims to provide solutions to these problems. It puts forward the use of parametric methods such as autoregressive methods and harmonic methods, and proposes two new algorithms to detect the closely spaced peaks for different scenarios of optical signals in wavemeters. Various parametric algorithms are studied, and their performances are compared with non-parametric algorithms for different criteria, e.g. absolute levels, frequency resolution, and accuracy of peak positions. Simulations are performed on synthetic signals produced from specifications provided by our sponsor, i.e., a wavemeter manufacturing company.

As specialized materials are developed for various applications, it becomes desirable to test them under adverse conditions, such as at elevated temperatures and in harsh environments. It is increasingly important that sensors be developed to meet the growing needs of research and industry. The ability of sapphire to withstand elevated temperatures and many chemically harsh environments has long been recognized. However, currently available sapphire fiber possesses poor optical quality and is not available with a cladding. It has found use in a variety of temperature sensors, but the investigation of sapphire-based strain and displacement sensors has been limited. The primary development of a white-light Michelson interferometer that utilizes a sapphire fiber sensing head is presented in this thesis. Development includes efforts to combat the poor optical quality of the sapphire fiber, minimize polarization mode fading, and preferentially excite the fundamental mode of the sapphire fiber. This thesis demonstrates the feasibility of fabricating a Michelson white-light interferometer capable of measuring displacements in environments ranging from room temperature to 800 degrees Celsius. The sensor developed in this work is capable of measuring displacements exceeding 6.4 millimeters at room temperature, and exceeding 1 millimeter at 800 degrees Celsius. This thesis also presents the application of this sensor to the alignment of a sapphire-fiber based Fabry-Perot sensor. This technique allows the Fabry-Perot sensor to be aligned so that usable fringes are always obtained. Alignment of the sapphire-fiber based Fabry-Perot sensors has been considered prohibitively difficult. / Master of Science