Key Engineering Materials Vols. 381-382

Abstract: Nanotechnology can be defined as “the study, development and processing of materials, devices, and systems in which structure on a dimension of less than 100 nm is essential to obtain the required functional performance.” There are currently two very different approaches to nanotechnology, the first and more classical approach is commonly called engineering nanotechnology. This approach involves using classical deterministic mechanical and electrical engineering principles to build structures with tolerances at levels approaching a nanometer. The other approach, sometimes called molecular nanotechnology, is concerned with self-assembled machines and the like and is far more speculative. At UNC Charlotte’s Center for Precision Metrology we have been working in engineering nanotechnology for more than a decade. We started with molecular manipulation with scanning probe microscopes in the late 1980s [1] and have continued to develop new measurement systems [2], nano-machining systems [3,4], and nano-positioning devices. One of the largest challenges is precision motion control of macroscopic stages. Currently we have three stages under development or modification. The first is the Sub Atomic Measuring Machine (SAMM) [5] which is being modified to provide picometer resolution; the second is the Multi-Scale Alignment and Positioning System (MAPS) initially to be used for nanoimprinting; the third is an Ultra-Precision Vacuum Stage [6], which is the subject of another paper in this conference. This paper will discuss the first two systems.

Abstract: Metrology plays an important role in the development and commercialisation of micro and nanotechnology. For calibrating versatile micro- and nanoscale standards, a dimensional metrology instrument coupled with multi sensor heads including atomic force microscope (AFM), tactile stylus, laser focus sensor and assembled cantilever probes (ACPs) has been developed. Two kinds of ACPs are highlighted in the paper. One is fabricated by gluing a vertical AFM cantilever to a horizontal AFM cantilever using micro assembling techniques. It is applicable for direct and non-destructive measurements of sidewall surfaces. The other is an ACP ball probe designed for true 3D measurements of micro structures. It is realised by gluing a tungsten wire with a probing sphere ball, 40 ... 120 µm in diameter, to a horizontal AFM cantilever. The ACP ball probe has advantages such as small probing forces (<1µN) and high probing sensitivity. Some typical calibrations on micro and nano structures such as step height, grating and sphere calotte artefact are introduced.

Abstract: This paper presents the resent advances in our research on ultrahigh resolution laser confocal microscopy to further improve the accuracy of non-contact 3D measurement of micro-structural dimensions and profiles at the level of micron/nanometer with emphasis on ways and means to improve axial and lateral resolutions. A scan measuring technique based on differential confocal microscopy is developed using the difference in the distribution of the scanning spot on near and far confocal planes by keeping the detectors off-focus at equal distance before and after the conjugate image plane of the scanning spot. This differential confocal microscopic scan measuring technique can be used to double the measurement sensitivity and obviously expand the linear range to improve the axial resolution, and to locate the tracking zero point at the center of the linear range with the highest sensitivity to achieve the bipolar tracking properties. In addition, this new technique can be used to effectively suppress the light source intensity drift and detector electronic drift and noise to improve the S/N ratio. The differential confocal detection technique can be combined with the optical superresolving filtering technique to improve both lateral and axial resolutions, and the confocal detection technique based on micro optical arrays has a very promising potential application for improving of detection efficiency.

Abstract: The reliable determination of periodic micro structures on open surfaces as they exist on involute tooth flanks gain of increasing importance. They allow conclusions from the waviness of the gear surface to the wear and running noise in gears. With the aim of determining traceable wave structures, a method has been developed at the Physikalisch-Technische Bundesanstalt (PTB) in Braunschweig by which it is possible to model, realise and, especially, reliably evaluate wave-shaped structures on the flank surfaces of involute cylindrical gears.

Abstract: For functional properties such as gliding, sealing, assembling, adhering etc. the outer layer of the surface is the functional related surface. For the functional assessment of the surface this outer layer should be used as the reference for any functional characteristic. With the existing mean line system for the assessment of roughness and waviness, the standardized characteristics do not follow this logic. However there are valid historical reasons for the acceptance of the shortcomings of the mean line system. They are e.g. the alignment of the profile, the removal of form, the assumption of a sinusoidal structure of the waviness on the surface, and the distortion of the surface by the application of the mean line filtering process. To overcome these shortcomings morphological operations have been used to establish a new developed envelope system. In order to define new parameters to characterize and specify functional properties of surfaces, a common datum is necessary. The presented method for the alignment of datums is consistent with the algorithms used to establish datums and datum systems for workpieces, where the datum is established by the location of a tangent geometrical element such as a line, plane, cylinder etc. The orientation is usually derived by the application of the minimum zone algorithm. The benefit of the assessment of the functional properties of surfaces with morphological operations will be presented for two examples.

Abstract: This paper presents procedures and standards to test tactile and optical microsensors and micro-computed tomography (CT) systems. The tests are similar to the established tests for classical coordinate measuring machines and assess local and global sensor characteristics. For this purpose, adequate and miniaturized reference standards were manufactured, calibrated and tested. In addition, task-specific reference standards have been realized to determine special sensor characteristics such as the maximum slope angle measurable by optical sensors or specific errors of tactile-optical microprobes measuring deep microholes.

Abstract: This paper presents an efficient computation method to evaluate scattered light intensity distributions, generated by a nanostructured surface which is illuminated with a monochromatic laser beam of several millimeters in diameter. The new simulation approach based on a modified Huygens-Fresnel approximation enables to improve measuring methods without expensive and time consuming experiments. The qualitative verification of the model results in a roughness measuring principle based on double scattering of coherent light.