Thesis (M.S. in M.E.)--School of Mechanical Engineering, Georgia Institute of Technology, 2004. Directed by Thomas R. Kurfess. / Includes bibliographical references (leaves 110-112).

Classical fabrication methods alone do not enable manufacturing of large flat mirrors that are much larger than 1 meter. This dissertation presents the development of enabling technologies for manufacturing large high performance flat mirrors and lays the foundation for manufacturing very large flat mirrors. The enabling fabrication and testing methods were developed during the manufacture of a 1.6 meter flat. The key advantage over classical methods is that our method is scalable to larger flat mirrors up to 8 m in diameter.Large tools were used during surface grinding and coarse polishing of the 1.6 m flat. During this stage, electronic levels provided efficient measurements on global surface changes in the mirror. The electronic levels measure surface inclination or slope very accurately. They measured slope changes across the mirror surface. From the slope information, we can obtain surface information. Over 2 m, the electronic levels can measure to 50 nm rms of low order aberrations that include power and astigmatism. The use of electronic levels for flatness measurements is analyzed in detail.Surface figuring was performed with smaller tools (size ranging from 15 cm to 40 cm in diameter). A radial stroker was developed and used to drive the smaller tools; the radial stroker provided variable tool stroke and rotation (up to 8 revolutions per minute). Polishing software, initially developed for stressed laps, enabled computer controlled polishing and was used to generate simulated removal profiles by optimizing tool stroke and dwell to reduce the high zones on the mirror surface. The resulting simulations from the polishing software were then applied to the real mirror. The scanning pentaprism and the 1 meter vibration insensitive Fizeau interferometer provided accurate and efficient surface testing to guide the remaining fabrication. The scanning pentaprism, another slope test, measured power to 9 nm rms over 2 meters. The Fizeau interferometer measured 1 meter subapertures and measured the 1.6 meter flat to 3 nm rms; the 1 meter reference flat was also calibrated to 3 nm rms. Both test systems are analyzed in detail. During surface figuring, the fabrication and testing were operated in a closed loop. The closed loop operation resulted in a rapid convergence of the mirror surface (11 nm rms power, and 6 nm rms surface irregularity). At present, the surface figure for the finished 1.6 m flat is state of the art for 2 meter class flat mirrors.

Thesis (Ph. D.)--Mechanical Engineering, Georgia Institute of Technology, 2007. / Committee Chair: King, William; Committee Member: Allen, Mark; Committee Member: Brand, Oliver; Committee Member: Glezer, Ari; Committee Member: Joshi, Yogendra.

Thesis (Ph. D.)--University of Washington, 1996. / Vita. Includes bibliographical references (p. [125]-135).

Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2004. / Dr. William P. King, Committee Member ; Dr. F. Levent Degertekin, Committee Member ; Dr. Thomas R. Kurfess, Committee Chair.

Thesis (Ph.D.) - University of St Andrews, October 2007.

The main aim of this work was the machining by hard turning of surfaces with optical surface quality. A numerical target had been set as a surface roughness Ra = 10nm. It has been shown that achieving roughness of that magnitude by hard turning is possible. Individual work pieces exhibited the desired surface properties for short lengths at a time, but it proved to be very difficult to achieve these surfaces consistently and over longer cuts. The factors influencing the surface roughness were identified as tool defects and machine vibration in addition to the standard cutting parameters and choice of cutting tool. A model of surface generation in hard turning has been developed and good correlation between simulated and experimentally determined surface roughnesses was achieved. By introducing a material partition equation which determines the proportional contribution of material removal mechanisms in the undeformed chip a comprehensive method for assessing the contributing factors in material removal was developed. While it has been shown that surfaces in hard turning are almost exclusively generated by chip removal and plastic deformation the developed model is versatile enough to include elastic deformation of the work piece. With the help of the model of surface generation in hard turning it has been possible to attribute magnitudes of the influencing factors with respect to the cutting parameters such as feed rate and tool corner radius, and the main disturbances - tool defects and machine vibration. From this conclusions were drawn on the requirements for machine tools and cutting tools, which will need to be realised to make ultra-precision hard turning of surfaces of optical quality a feasible manufacturing process.

Freeform optics provide excellent performance for a wide variety of applications. However, obtaining an accurate freeform surface measurement is highly challenging due to its large aspheric/freeform departure. It has been proven that SCOTS (Software Configurable Optical Test System), an advanced deflectometry system developed at the University of Arizona, can measure the departure of a freeform surface from the desired shape with nanometer accuracy. Here, a new data processing technique was used to measure a freeform surface without any prior knowledge of the shape of the surface. Knowing only the geometry of one point on the test surface, this method can take a blind measurement of a freeform surface and arrive at the true surface through iterative construction.

This article describes a pressure generation technique that has been applied to the task of calibrating hydraulic pressure transducers. The technique combines principles given by the Lorentz Force and Faraday's Law of Induction to generate a hydrostatic pressure within a cavity. The time history of this pressure is given by the device without reliance on a reference transducer or knowledge of: the local gravity; thermodynamic properties of the working fluid; or acceleration of the cavity. In this way, the Pascal can be defined by reference only to the standards of the Amp, the Volt, the Meter, and -- in the case of time varying pressure -- the Second. Using this technique, a prototype device has been developed using commonly available tooling and can generate pressures in the range of 0.1 to 600 Pa with relative errors of 1.5%. / Master of Science

2024 / This dissertation investigates the scientific practices involved in biodiversity conservation at the intersection of the philosophy of measurement, the philosophy of data, and the literature on values in science. With a focus on the epistemology, methods,and ontology of measuring biodiversity within the context of conservation science, it aims to develop a socially relevant and socially engaged philosophy of science. Chapter 1 challenges ”Biodiversity Skepticism,” which dismisses the usefulness of the concept of biodiversity due to the proliferation of heterogeneous, non covariant measurements. Instead, drawing from Norman M. Bradburn, Nancy L. Cartwright, and Jonathan Fuller’s model of the measurement process, I argue for understanding the pluralistic nature of conceptualizing complex measurands. In Chapter 2, I address the need for a proper justification of the claim that we are in a biodiversity crisis by analyzing the conceptual and data incommensurability between contemporary biodiversity and paleodiversity. Building on Carlos Santana’s ideas, I propose solutions for obtaining robust inferences about the status of environmental crises. Chapter 3 challenges the slogan implicitly endorsed in evidence-based conservation that ”the bigger the data, the bigger the evidence,” highlighting the complexity of turning data into evidence through an examination of the IUCN’s redlisting process. I contend that evidence relies on a complex infrastructure made of data communities and evidential standards, and undermine the facile equating of data with evidence. In Chapter 4, I counter the contention that performance metrics in conservation are value-neutral, using the philosophical framework of ”critical metrology.” This section exposes the fallacy of measurements’ inherent value neutrality and addresses the contribution of conservation science to ”scientific colonialism.” I also propose potential solutions for fostering an ethical and epistemically stronger conservation agenda. Chapter 5 concludes by going back to the measurement theory used to account for biodiversity measurement, and shows how this context reveals the ways in which Bradburn, Cartwright, and Fuller’s theory of measurement needs to be amended. It also sketches an adequacy-for-purpose view to evaluate measurements and elaborates on some implications of this view in relation to measurement validation and the irremediable value-ladeness of measurements. This dissertation offers novel philosophical insights into the theoretical and practical complexities of measuring biodiversity that is valuable to biodiversity scientists, offering a space for building actionable knowledge at the intersection of philosophy and conservation science. / 2027-02-07T00:00:00Z