Wolfgang Prof. Dr. Ehrfeld

Grid polarizer for the visible spectral region

We report on the fabrication of a grid polarizer for the visible spectral region, based on metallic grids with periods below 100 nm. Theoretical calculations of the degree of polarization predict useful values for the visible region, if the period is in the range of 100 nm. The properties of the polarizer are shown to be strongly dependent on the optical constants of the metal and the substrate. For the fabrication of the grids, direct e-beam writing in combination with a dry etching process has been used. Metallic grids with 50 nm lines and a period of 100 nm were fabricated on a glass substrate. Measurements of the degree polarization were made at a wavelength of 670 nm. The results are compared to theoretical calculations made in the framework of a rigorous diffraction theory.

Mechatronic micro devices

Nowadays, novel trends can be observed in micro system technology: Micro systems more and more develop into stand-alone devices for multi-purpose applications, and they do not only comprise detector elements but really interact mechanically by micro actuators with their surroundings. A modular concept especially for high performance actuators which proved to be a main prerequisite for these developments is illustrated in the contribution. With dimensions of a few millimeters, piezo-driven valves and membrane pumps overcome fluid pressures of 1,000 hPa. Electromagnetic motors generate torques of 7 to 100 /spl mu/Nm which are multiplied by adapted micro gears. Gear motors serve as a key unit for high force micro positioning systems or micro gear pumps which are first examples for the device level. With the integration of electronics and optics the actuator performance can considerably be increased by establishing a feedback control and the systems become really micro mechatronic devices. Additionally, interface components like electrical and fiber-optical connectors with pitches as small as 250 /spl mu/m, special gears and miniaturized clamping structures enable the implementation of complex optical fiber networks, micro robots or chemical micro reactors from these mechatronic devices in a construction kit. A wide range of 3D-micro fabrication techniques, from design and simulation, micro spark erosion (/spl mu/-EDM) for the prototypes to mass technologies like LIGA including injection molding, allows a fast commercialization into micro product lines and will round the circle of the considerations on the mechatronic micro devices.