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Biomedical subjects

Markus Testorf

Publications and source records attributed to Markus Testorf.

6 recordsLinked to original sources
PubMed2006

Photoconductive optically driven deformable membrane for spatial light modulator applications utilizing GaAs substrates.

The fabrication and characterization of an optically addressable deformable mirror for a spatial light modulator is described. Device operation utilizes an electrostatically driven pixellated aluminized polymeric membrane mirror supported above an optically controlled photoconductive GaAs substrate. A 5 microm thick grid of patterned photoresist supports the 2 microm thick aluminized Mylar membrane. A conductive ZnO layer is placed on the back side of the GaAs wafer. A standard Michelson interferometer is used to measure mirror deformation data as a function of illumination, applied voltage, and frequency. A simplified analysis of device operation is also presented.

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PubMed2006

Design of diffractive optical elements for the fractional Fourier transform domain: phase-space approach.

Phase-space optics is used to relate the problem of designing diffractive optical elements for any first-order optical system to the corresponding design problem in the Fraunhofer diffraction regime. This, in particular, provides a novel approach for the fractional Fourier transform domain. For fractional Fourier transforms of arbitrary order, the diffractive element is determined as the optimum design computed for a generic Fourier transform system, scaled and modulated with a parabolic lens function. The phase-space description also identifies critical system parameters that limit the performance and applicability of this method. Numerical simulations of paraxial wave propagation are used to validate the method.

Journal Article↗
PubMed2006

Designing Talbot array illuminators with phase-space optics.

The problem of designing Talbot array illuminators is revisited in the context of phase-space optics. It is shown that for Talbot array illuminators with optimum compression ratio the construction of phase-only grating profiles can be simplified significantly by using phase-space representations of optical signals. Based on the Wigner distribution function a graphical procedure is derived for obtaining the complete design of the array generator for a given compression ratio. The application of phase-space optics to other classes of Talbot array illuminators, and its use as part of numerical optimization algorithms, is considered as well.

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PubMed2006

Local-field enhancement in metal-dielectric nanocylinders with complex cross sections.

Numerical simulations are used to study the near-field properties of nanocylinders. Specific attention is given to surface-plasmon-polariton resonances and field localization in dielectric cylinders with partial metal coating. Conditions for observing local-field enhancement are investigated as well as the degrees of freedom that are available to customize the wavelength response of the nanosystem.

Journal Article↗
PubMed2004

Phase-space interpretation of deterministic phase retrieval.

Deterministic phase retrieval is reinterpreted in terms of phase-space optics. A novel derivation of the transport-of-intensity equation is presented based on the Wigner distribution function and the ambiguity function. The phase retrieval problem is formulated as estimating the local first-order moment of the Wigner function from intensity information. A comparison with phase-space tomography suggests a generalization of deterministic phase retrieval that provides larger flexibility for signal recovery. In addition, one particular numerical implementation of generalized deterministic phase retrieval is presented. Simulated intensity data are used to validate the method.

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