Laser interference fringe tomography (LIFT) is within the class of optical imaging devices designed for volumetric microscope applications. LIFT is a very simple and cost-effective three-dimensional imaging device which is able to reliably produce low-quality imagery. It measures the reflectivity as a function of depth within a sample and is capable of producing three-dimensional images from optically scattering surfaces. The first generation of this instrument is designed and prototyped for optical microscopy. With an imaging spot size of 42 μm and a 180 μm axial resolution kernel, LIFT is capable of producing one- and two- dimensional images of various samples up to 1.5 mm thickness. The prototype was built using commercial-off-the-shelf components and cost ~ $1,000. It is possible that with effort, this device can become a reliable, stable, low-quality volumetric imaging microscope to be readily available to the consumer market at a very affordable price. This document will present the optical design of LIFT along with the complete mathematical description of the instrument. The design trade-offs and choices of the instrument are discussed in detail and justified. The theoretical imaging capabilities of the instrument are tested and experimentally verified. Finally, some imaging results are presented and discussed.

Miniature microphones have numerous applications but often exhibit poor performance which can be attributed to the challenges associated with capacitive detection at small size scales. Optical detection methods are able to overcome some of these challenges although miniaturized integration of these optical systems has not yet been demonstrated. An optical interferometric detection scheme is presented and is implemented using micro-scale optoelectronic devices which are used primarily in fiber optic data transmission. Using basic diffraction theory, a model is developed and used to optimize the micro-optical system within a 1mm3 volume. Both omnidirectional and directional optical microphone designs are presented and a modular packaging architecture is assembled in order to test these devices. Results from the 2mm diameter omnidirectional optical microphone structure demonstrate a 26dBA noise floor. The biomimetic directional optical microphone, which has an equivalent port spacing of 1mm, demonstrates a noise floor of 34dBA. Additionally, these results demonstrate an array of two biomimetic directional optical microphones located on the same silicon chip and separated by less than 5mm. These results confirm the micro-optical detection method as an alternative to capacitive detection especially for miniaturized microphone applications and suggest that this method in its modular packaging architecture is competitive with industry leading measurement microphones.

The main aim of this study is to extending the holographic interferometry technique to measure the out-of-plane displacement of an object subjected to both temperature and displacement field. It is noted that both the out-of-plane displacement and the ambient temperature change can cause image fringes. Therefore, an auxiliary object is used to identify the fringe numbers caused by the ambient temperature change during the experiment. The warpage measurement of a PBGA package is used as an example. It can be shown that the proposed method works

The prevalence of concrete and cement-based materials in the civil infrastructure plus the risk of failure makes structural health monitoring an important issue in the understanding of the complete life cycle of civil structures. Correspondingly, the field of nondestructive evaluation (NDE) has been maturing and now concentrates on the detection of flaws and defects, as well as material damage in early stages of degradation. This defect detection is typically usually done by looking at the impulse response of the medium in question such as a cement-based material. The impulse response of a solid can be used to image a complex medium. Classically, the waveform is obtained by an active setup: an ultrasonic signal is generated at one location and recorded at another location. The waveform obtained from imaging can be used to quantitatively characterize the medium, for example by calculating the material's diffusivity coefficient or dissipation rate. In recent years, a different monitoring technique has been developed in seismology to measure the velocity of different kinds of waves, the Coda Wave Interferometry (CWI). In this CWI technique, the main focus is given to the late part of the recorded waveform, the coda. CWI is now successfully used in seismology and acoustics. In the current research, CWI is applied on concrete in different damage states to develop basic knowledge of the behavior of the wave velocity, and how it can be used to characterize cement-based materials. By comparing two impulse responses, the relative velocity change between the two impulse responses is used to characterize damage. Because of the stress-dependency of the velocity change, the calculations can also be used to directly calculate the Murnaghan's and Lam´e's coefficients. The newer technique of CWI is applied - the Stretching Technique (ST) [27]. The first goal of this research is to establish the viability of using CWI in cement-based materials. Next, we use the ST in the application of stress as we compress concrete samples for the detection of thermal damage, ASR-damage and mechanical softening.

Thesis (M.Sc. (Physics & Electronics)) - Rhodes University, 2008.

Thesis (M.S.M.E.)--University of South Florida, 2003. / Title from PDF of title page. Document formatted into pages; contains 87 pages. Includes bibliographical references.

This dissertation provides the first demonstration of scanning synthetic aperture radar (ScanSAR) advanced interferometry processing for measuring surface deformation. ScanSAR data are synthesized from ERS-1/2 stripmap SAR images over known deformation in Phoenix, Arizona. The strategy is to construct a burst pattern similar to Envisat ScanSAR data and to create a realistic variable-burst synchronization scenario in which any image pair has at least 50% burst overlap. The Small Baseline Subsets technique is applied to the synthesized data to demonstrate ScanSAR time series analysis for a scenario generally conducive for interferometry. The same processing approach is employed with the stripmap data to validate the results. The differences in ScanSAR and stripmap velocities have a mean and standard deviation of 0.02±0.02 cm/year. 96.3% and 99.1% of the velocity differences are within ±0.1 cm/year and ±0.2 cm/year, respectively. The RMS deviations between the ScanSAR and stripmap displacement estimates are 0.40±0.30 cm. 68.5% and 94.6% of the differences are within ±0.5 cm and ±1.0 cm, respectively. The Permanent Scatterer (PS) technique also is adapted and applied to the synthesized data to demonstrate the presence of PS in ScanSAR data. The atmospheric and nonlinear motion phase derived from a PS analysis of stripmap data are removed from the ScanSAR interferograms. Even for this idealized scenario, the final PS identification yields fewer ScanSAR PS (10 PS/km²) than the stripmap PS results (312 PS/km² or 15.6 PS/km² at the ScanSAR pixel resolution). Based on the calculated likelihood of finding multiple stripmap PS within a ScanSAR pixel, it is concluded that the ScanSAR single scatterer PS model is flawed. A model is introduced that considers multiple PS within a ScanSAR pixel. The search for two PS per pixel yields 120 PS/km². The ScanSAR and stripmap PS velocity differences mean is zero and standard deviation is 0.02 cm/year. However, while the differences between the ScanSAR and stripmap PS DEM error estimates are zero-mean, they have a 7-meter standard deviation. One possible explanation for this relatively large deviation is the differencing of the wrong ScanSAR and stripmap PS as the result of a misalignment between the ScanSAR and stripmap images. / text

Atomic polarizability plays an essential role in topics ranging from van der Waals interactions, state lifetimes, and indices of refraction, to next generation atomic clocks and atomic parity non-conservation experiments. Polarizability measurements, such as the ones described in this thesis, provide valuable input to these subjects and serve as benchmark tests for sophisticated atomic structure calculations. We measured the static polarizability of potassium and rubidium with record precision and 0.5% uncertainty using a Mach-Zehnder atom interferometer with an electric-field gradient. To support future precision measurements of polarizability, we developed a new atom beam velocity measurement technique called phase choppers. Using phase choppers, we demonstrated measurements of mean atom beam velocity with an uncertainty of 0.1%. We also developed a new way to probe atomic structure: a measurement of a zero-crossing of the dynamic polarizability of potassium, known as a magic-zero wavelength. We measured the first magic-zero wavelength of potassium with 1.5 pm uncertainty and established a new benchmark measurement for the ratio of the D1 and D2 line strengths. Finally, we propose the use of a resonant photoionization detector for measurements of strontium polarizability, and the use of contrast interferometry for measurements of alkali dimer tensor polarizabilities.

Measurement of the quality and performance of soft contact lenses is not new and is continually evolving as manufacturing methods develop and more complicated contact lenses become available. Qualification of soft contact lenses has not been a simple task since they are fundamentally difficult to measure. The shape of the lens is extremely sensitive to how the lens is supported and the material properties can change quickly with time. These lenses have been measured in several different ways, the most successful being non-contact optical methods that measure the lens while it is immersed in saline solution. All of these tests measure the lens in transmission and do not directly measure the surface structure of the lens. The reason for this is that the Fresnel reflectivity of the surface of a contact lens in saline solution is about 0.07%. Surface measurements have been performed in air, but not in saline. The lens needs to be measured in solution so that it can maintain its true shape. An interferometer is proposed, constructed, verified, and demonstrated to measure the aspheric low reflectivity surfaces of a contact lens while they are immersed in saline solution. The problem is extremely difficult and requires delicate balance between stray light mitigation, color correction, and polarization management. The resulting system implements reverse raytracing algorithms to correct for retrace errors so that highly aspheric, toric, and distorted contact lens surfaces can be measured. The interferometer is capable of measuring both surfaces from the same side of the contact lens as well as the lens thickness. These measurements along with the index of refraction of the lens material are enough build a complete 3D model of the lens. A simulated transmission test of the 3D model has been shown to match the real transmission test of the same lens to within 32nm RMS or 1/20th of a wave at the test wavelength.

Here it is demonstrated that nanofabricated structures can be used as electron optical elements in new types of electron interferometers. This enables novel investigations with electrons analogous to experiments in light and atom optics. Far field diffraction from a single nanograting is used to examine the force on a charge moving in close proximity to a surface. Near field diffraction from the nanograting is investigated in a Talbot interferometer. It is found that electron waves form replicas of the grating in free space, and these replicas can be de-magnified using illumination by a converging beam. An electron Lau interferometer has the same grating configuration as the Talbot interferometer, but uses spatially incoherent beams that give rise to drastically different interference behavior. A single optical theory is developed to efficiently model a variety of grating interferometers under a diverse set of illumination conditions, and it is used to understand the experiments described here. Applications for these new interferometers are discussed, as well as possible directions for future research.