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Thomae D.,Carl Zeiss GmbH | Sandfuchs O.,Hamm-Lippstadt University of Applied Sciences | Brunner R.,Carl Zeiss GmbH
Journal of the Optical Society of America A: Optics and Image Science, and Vision | Year: 2015

The Talbot self-imaging effect of amplitude gratings is afflicted with aberrations that distort the self-image. This occurs especially if the grating period p is only a few times larger than the illumination wavelength λ. For example, for lithographic applications of the Talbot effect these aberrations lower the lateral writing resolution and should be minimized. Noponen found, however, some discrete ratios of p/λ in the interval of 2.0 < p/λ < 3 that are aberration-free. We generalize the definition of the Talbot distance to include oblique illumination and show how Noponen's discrete ratios can be shifted by it. In the second part, we look at ratios of p/λ larger than 3, so that there are more than five diffraction orders behind the grating. For this region we present a method to find ratios of p/λ with at least minimal aberrations and present some self-image examples that are of interest for lithographic purposes up to the range of p/λ ≈ 12. © 2015 Optical Society of America.

Spura C.,Hamm-Lippstadt University of Applied Sciences
Forschung im Ingenieurwesen/Engineering Research | Year: 2015

Gear couplings are essential machine elements and where used in many areas of the gear and transmission technology. The significant advantages of gear couplings are the transmission of high drive power and torque in a small space, and the compensation of an existing radial and/or angular displacement. For this compensation a geometrically complicated special gearing and the knowledge of the load distribution within the teeth is essential. To calculate the load distribution, the focal factor is the tooth stiffness and its dependence on various influencing variables. The following article shows the basic principles and the present knowledge of the tooth stiffness calculation for gear couplings and shows the application of the methods for calculating the contemporary practical use in the design phase of this machine element. © 2015, Springer-Verlag Berlin Heidelberg.

Thomae D.,Jena University of Applied Sciences | Maass J.,Carl Zeiss GmbH | Sandfuchs O.,Hamm-Lippstadt University of Applied Sciences | Gatto A.,Carl Zeiss GmbH | Brunner R.,Jena University of Applied Sciences
Applied Optics | Year: 2014

A flexible illumination system for Talbot lithography is presented, in which the Talbot mask is illuminated by discrete but variable incidence angles. Changing the illumination angle stepwise in combination with different exposure doses for different angles offers the possibility to generate periodic continuous surface relief structures. To demonstrate the capability of this approach, two exemplary micro-optical structures were manufactured. The first example isa blazed grating with a stepsize of 1.5 μm. The second element is a specific beam splitter with parabolic-shaped grating grooves. The quality of the manufacturing process is evaluated on the basis of the optical performance of the resulting micro-optical elements. © 2014 Optical Society of America.

Bittmann B.,Schrodinger | Haupert F.,Hamm-Lippstadt University of Applied Sciences | Schlarb A.K.,University of Kaiserslautern
Journal of Applied Polymer Science | Year: 2012

Nanocomposites gained more and more importance in the last few years because of their improved performance over the neat polymer matrix, that is, toughness and stiffness can be enhanced simultaneously by the addition of nanoparticles. However, the dispersion of these particles in the matrix remains a big challenge. In this study, two types of TiO 2 nanoparticles were dispersed in two different epoxy resins by means of ultrasound. The particle size development in dependence on the dispersion time was investigated by dynamic light scattering for the different material systems. Furthermore, the influence of the viscosity on the sonication process' efficiency was analyzed. The resulting nanocomposites were tested for fracture and Charpy toughness. SEM images revealed that the improved fracture toughness properties are correlated to a rougher fracture surface, whose formation dissipates more energy. © 2011 Wiley Periodicals, Inc.

Englert M.,Corporate Research and Development | Bittmann B.,University of Kaiserslautern | Haupert F.,Hamm-Lippstadt University of Applied Sciences | Schlarb A.K.,University of Kaiserslautern
Polymer Engineering and Science | Year: 2012

Thermosets reinforced with inorganic nanoparticles show numerous benefits over the unreinforced polymer. However, to achieve reinforcement the nanoparticles have to be well separated and distributed homogeneously within the matrix. In the present study the laboratory scale discontinuous ultrasonic dispersion process was scaled up to a continuous ultrasonic dispersion process of agglomerated nanoparticles in epoxy resin (EP). Exemplarily, the dispersion experiments were carried out for a 4-l suspension volume consisting of epoxy resin and 14 vol% TiO 2-nanoparticles was carried out as a function of the dispersion time and the amplitude of the ultrasonic cell. Following, nanocomposites were manufactured with particle contents of 2, 5, and 10 vol%. For the verification of the manufactured nanocomposites quality, particle sizes analysis and mechanical characterization were undertaken. The obtained results were compared with those of the discontinuous dispersion at laboratory scale. It has been found that comparable particle sizes and mechanical properties could be achieved, although, the volume of the suspension was 10 times higher as that one of the batchwise dispersion. © 2011 Society of Plastics Engineers.

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