Spatial Light Modulator (SLM) technologies are well established in many application fields over the last decades. Addressing challenging operational conditions, a special class of high-speed SLMs has emerged over the past 20 years, namely Micromirror Array (MMA) devices. Fraunhofer IPMS MMA technology has enabled several ultraviolet photolithography applications at industrial scale. Given the fact that these devices are available for scientific testing, we proposed to explore for the first time their functionality and performance with respect to the space application requirements for the European framework cooperation. Previous studies strongly support this approach with the investigation of several SLM technologies for space instrumentation. In this study, the key parameters of an already available 256 x 256 pixel MMA device have been assessed and its performance has been evaluated under environmental constraints of a future space mission, in terms of temperature (from -40 °C to 80 °C), vacuum (< 10-5 mbar) and vibrations in X-, Y- and Z-axes, showing zero failure rate for the MMA device after all tests. These experimental findings, together with simulations results, confirm the robustness of the MMA technology, especially against temperature changes, and encourage further activities for the development of a space-customized spatial light modulator technology.
“CaliBend” proposes a direct diode laser approach for thermal assisted processing of steel sheets. Our module aims at enabling bending processes of high-strength steels (HSS) and with minimal bending radii without inducing damage to the metal part. In this work we present a laser source integrated on an industrial servo press for continuous die processing. The metal sheet is heated up locally by laser radiation before the bending stroke. By reaching power densities close to 40 W/mm2 , the bending line of the metal sheet reaches the hot forming temperature regime in under two seconds allowing a faultless while increasing the typically low forming limits of HSS.
We developed a novel 512 x 320 tip-tilt micro mirror array (MMA) together with the entire related technology platform, including mirror fabrication process, integrated CMOS address circuitry and external drive electronics. The MMA itself consists of 2axis-tip-tilt actuators at 48μm pixel size, allowing a continuous pure tip-tilt motion up to 3.5° in arbitrary directions, fully calibratable at standard deviations of better than 0.025°. The mirrors are realized within a 2-level architecture defined by three structural layers, two for hinge and reinforcement suspension and one for the overlying mirror. They are fabricated by surface-micromachining within a fully CMOS compatible process. MMA programming is accomplished by an underlying CMOS backplane supporting drive voltages up to 27V and frame rates up to 3.6kHz.
Based on the demand for a responsible use of natural resources and energy the need for lightweight materials is increasing. The most common materials for lightweight production are high and highest strength steel. These materials are difficult to machine using conventional sheet metal working processes because the high strength leads to a limited formability and high tool wear. The Fraunhofer IPT developed the laser-assisted sheet metal working. Selective laser based heating of the part directly before machining softens the material locally. Thus the quality of the following cut can be increased, for example for shearing 1.4310 the clear cut surface ratio can be increased from 20% up to 100% using a shearing gap of 10% of the sheet thickness. Because of the softening of the material and thus the increased formability, parts with a higher complexity can be produced. For example 1.4310 can be bent laser-assisted with a radius of 0.25 mm instead of 2-3 mm using the conventional process. For the first time spring steel can be embossed with conventional tools up to 50% of the sheet thickness. For the implementation in series production a modular system upgrade “hy-PRESS” has been developed to include laser and scanner technology into existing presses. For decoupling the sensitive optical elements of the machine vibrations an active-passive damping system has been developed. The combination of this new hybrid process and the system technology allows to produce parts of high strength steel with a high complexity and quality.
The present article discusses an optical concept for the characterization of diffractive micromirror arrays (MMAs) within
an extended wavelength range from the deep ultra-violet up to near-infrared. The task derives from the development of a
novel class of MMAs that will support programmable diffractive properties between 240 nm and 800 nm. The article
illustrates aspects of the achromatic system design that comprises the reflective beam homogenization with divergence
control and coherence management for an appropriate MMA illumination as well as the transfer of phase modulating
MMA patterns into intensity profiles for contrast imaging. Contrast measurements and grey scale imaging demonstrate
the operation of the characterization system and reflect the encouraging start of technology development for
multispectral, diffractive MMAs.
KEYWORDS: Mirrors, Actuators, Electronics, Metals, Micromirrors, Deep ultraviolet, Control systems, Near infrared, Reflectivity, Electron beam lithography
A new generation of micromirror arrays (MMAs) with torsional actuators is being developed within the European
research project MEMI in order to extend the usable spectral range of diffractive MMAs from deep ultraviolet into the
visible and near infrared. The MMAs have 256 x 256 pixels reaching deflections above 350 nm at a frame rate of 1 kHz,
which enables an operation in the target wavelength range between 240 nm and 800 nm. Customized driver electronics
facilitates computer controlled operation and simple integration of the MMA into various optical setups. Tests in the
visible wavelength range demonstrate the functionality and the high application potential of first MMA test samples.
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