Development of a flexible and modular metrology system for measuring complex surfaces

The demand for customised optical devices is increasing tremendously. Such optical devices do not employ traditional designs like planar, spherical, or even aspherical shapes. Instead, modern lenses exhibit free-form surfaces with a large variety of gradients in all directions. Highly accurate and repeatable measurement of such lens surfaces represents a considerable challenge; therefore there is a pressing need to both improve the metrology systems used in the optical industry and to develop new generations of high-performance metrology systems that employ innovative measurement techniques.Workshops need fast measurement solutions for the rough surfaces produced in the early stages of a lens typical production chain. The last steps produce very smooth surfaces, usually ideally suited to interferometers. However, interferometers are physically not suited to the measurement of strong aspheres or free-form shaped objects. Therefore, research was undertaken to investigate a metrology solution applicable to all common surface types and roughness grades at any stage of the production chain.This PhD research presents a novel approach for applying the principle of a spherical coordinate measurement machine (SCMM) to lens metrology. SCMMs require the precise and repeatable alignment of all axes. Therefore, research was performed to investigate a novel method for generic axes alignment without the need for external tools. This method, with the enhanced SCMM approach, was then combined with research into suitable multi-sensor measurement modes, in order to adequately address the needs of all stages in the production chain. Coordinate measurement machines are subject to the influence of errors. Therefore, research was conducted to develop a novel user-interface and a patented device to analyse and compensate for errors of the applied rotational axes and the 3D-Scale. The mathematical models presented, enable a simple transfer to other types of SCMMs. Also, the researched processes, software tools and mechatronic devices may be generically adopted to other machines applying rotational axes. Therefore, in addition to providing advanced capabilities for high-accuracy measurement of lenses with complex morphologies; the results of this research and the new approaches developed may be employed with SCMMs more generally, in a wide range of industrial sectors

The 29th Aerospace Mechanisms Symposium

The proceedings of the 29th Aerospace Mechanisms Symposium, which was hosted by NASA Johnson Space Center and held at the South Shore Harbour Conference Facility on May 17-19, 1995, are reported. Technological areas covered include actuators, aerospace mechanism applications for ground support equipment, lubricants, pointing mechanisms joints, bearings, release devices, booms, robotic mechanisms, and other mechanisms for spacecraft

Serial laser lithography for efficient manufacture of universal microstructures

The technique of microstructuring revolutionises all classical fields of engineering like electronics, optics and mechanics. In order to manufacture a microstructure in large quantities and at a reasonable price, master elements or masks will be formed that can be duplicated in a highly efficient process. Further development in technology leads, on the one hand, to further reduction of possible dimensions of structures down to the range of sub-nano technology and, on the other hand, to the development of more flexible systems in using more reasonably priced technologies for the structuring in the classical micrometre range, which in turn opens a much larger field of use. This study examines the use of serial laser lithography for efficient manufacture of universal microstructures. To facilitate this, a laser beam writer or so-called Laser Pattern Generator (LPG) was developed and described here as well as in a previous work[Samu96a]. The laser beam writer uses a precise positioning system for the movement of a substrate for material processing using a focussed laser beam. This system permits the production of structures with dimensions down to 0.5 μm which can be used in several application fields. This was systematically analysed for optimisation of the production process. Based on the achieved results, a computer-aided simulation system for process parameter determination and optimisation was developed that may be used in order to minimise the experimental effort in LPG manufacturing. The total production process and the individual optimising steps are illustrated by the manufacture of different microstructures. Because of the high reproducibility in manufacturing different structure types and, compared with other manufacturing methods, the low equipment and manufacturing effort, serial laser lithography is an efficient process for the microstructuring of universal microstructures down to the dimensions in the micrometre range

41st Aerospace Mechanisms Symposium

The proceedings of the 41st Aerospace Mechanisms Symposium are reported. JPL hosted the conference, which was held in Pasadena Hilton, Pasadena, California on May 16-18, 2012. Lockheed Martin Space Systems cosponsored the symposium. Technology areas covered include gimbals and positioning mechanisms, components such as hinges and motors, CubeSats, tribology, and Mars Science Laboratory mechanisms

The 20th Aerospace Mechanisms Symposium

Numerous topics related to aerospace mechanisms were discussed. Deployable structures, electromagnetic devices, tribology, hydraulic actuators, positioning mechanisms, electric motors, communication satellite instruments, redundancy, lubricants, bearings, space stations, rotating joints, and teleoperators are among the topics covered

39th Aerospace Mechanisms Symposium

The Aerospace Mechanisms Symposium (AMS) provides a unique forum for those active in the design, production, and use of aerospace mechanisms. A major focus is the reporting of problems and solutions associated with the development and flight certification of new mechanisms. Organized by the Mechanisms Education Association, NASA Marshall Space Flight Center (MSFC) and Lockheed Martin Space Systems Company (LMSSC) share the responsibility for hosting the AMS. Now in its 39th symposium, the AMS continues to be well attended, attracting participants from both the United States and abroad. The 39th AMS was held in Huntsville, Alabama, May 7-9, 2008. During these 3 days, 34 papers were presented. Topics included gimbals and positioning mechanisms, tribology, actuators, deployment mechanisms, release mechanisms, and sensors. Hardware displays during the supplier exhibit gave attendees an opportunity to meet with developers of current and future mechanism components

Precision Attitude Determination System (PADS) design and analysis. Two-axis gimbal star tracker

Development of the Precision Attitude Determination System (PADS) focused chiefly on the two-axis gimballed star tracker and electronics design improved from that of Precision Pointing Control System (PPCS), and application of the improved tracker for PADS at geosynchronous altitude. System design, system analysis, software design, and hardware design activities are reported. The system design encompasses the PADS configuration, system performance characteristics, component design summaries, and interface considerations. The PADS design and performance analysis includes error analysis, performance analysis via attitude determination simulation, and star tracker servo design analysis. The design of the star tracker and electronics are discussed. Sensor electronics schematics are included. A detailed characterization of the application software algorithms and computer requirements is provided

Vestibular Function Research (VFR) experiment. Phase B: Design definition study

The Vestibular Functions Research (VFR) Experiment was established to investigate the neurosensory and related physiological processes believed to be associated with the space flight nausea syndrome and to develop logical means for its prediction, prevention and treatment. The VFR Project consists of ground and spaceflight experimentation using frogs as specimens. The phase B Preliminary Design Study provided for the preliminary design of the experiment hardware, preparation of performance and hardware specification and a Phase C/D development plan, establishment of STS (Space Transportation System) interfaces and mission operations, and the study of a variety of hardware, experiment and mission options. The study consist of three major tasks: (1) mission mode trade-off; (2) conceptual design; and (3) preliminary design

12th International Conference on Vibrations in Rotating Machinery

Since 1976, the Vibrations in Rotating Machinery conferences have successfully brought industry and academia together to advance state-of-the-art research in dynamics of rotating machinery. 12th International Conference on Vibrations in Rotating Machinery contains contributions presented at the 12th edition of the conference, from industrial and academic experts from different countries. The book discusses the challenges in rotor-dynamics, rub, whirl, instability and more. The topics addressed include: - Active, smart vibration control - Rotor balancing, dynamics, and smart rotors - Bearings and seals - Noise vibration and harshness - Active and passive damping - Applications: wind turbines, steam turbines, gas turbines, compressors - Joints and couplings - Challenging performance boundaries of rotating machines - High power density machines - Electrical machines for aerospace - Management of extreme events - Active machines - Electric supercharging - Blades and bladed assemblies (forced response, flutter, mistuning) - Fault detection and condition monitoring - Rub, whirl and instability - Torsional vibration Providing the latest research and useful guidance, 12th International Conference on Vibrations in Rotating Machinery aims at those from industry or academia that are involved in transport, power, process, medical engineering, manufacturing or construction