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Der Übergang des hellen in den dunklen Bereich einer Scheinwerferlichtverteilung unterliegt gesetzlichen Auflagen. Bei Scheinwerfer-Projektionssystemen wird der Übergang durch eine streuende Struktur auf der Linsenfläche aufgeweicht. Bisher erfolgte die Auslegung manuell. Diese Arbeit befasst sich mit der Auslegung strukturierter Flächen unter Anwendung von genetischen Algorithmen. Die Anforderungen an die Hell- Dunkel-Grenze eines Scheinwerfers werden erläutert. Es werden Verfahren dargestellt, um CAD-Flächen mit einer streuenden Struktur zu überlagern. Damit die Auslegung strukturierter Linsenflächen durch Optimierungsalgorithmen ermöglicht werden konnte, musste die Zeit für eine lichttechnische Simulation der Fläche reduziert werden. Die verwendete Simulationsmethodik wird erklärt und erste Ergebnisse diskutiert.

The short-pulse source at the 1.5-GeV synchrotron light source DELTA, operated by the TU Dortmund University, enables the generation of sub-ps radiation pulses in the VUV regime based on coherent harmonic generation (CHG). As an upgrade, the employment of echo-enabled harmonic generation (EEHG) is planned which allows to produce shorter wavelengths. Recent developments and measurements regarding the twofold energy modulation required for EEHG are presented., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

At the 1.5-GeV synchrotron light source DELTA operated by the TU Dortmund University, ultrashort radiation pulses in the vacuum ultraviolet (VUV) and terahertz (THz) regime are routinely generated by the interaction of electron bunches with femtosecond laser pulses. A laser-induced energy modulation is converted into a density modulation (microbunching) by a magnetic chicane, leading to coherent emission at harmonics of the initial laser wavelength (coherent harmonic generation, CHG). Path length differences of the energy-modulated electrons along the magnetic lattice lead to a dip in the longitudinal charge distribution, which gives rise to the coherent emission of THz radiation. In first pump-probe photoemission experiments, the spatial and temporal overlap of laser pump and CHG probe pulse on the sample was demonstrated. Furthermore, the effect of two temporally separated seed pulses was studied in the VUV and (sub-)THz regime., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

Coherent THz pulses induced by a laser-electron interac- tion are routinely produced and observed at DELTA, a 1.5- GeV synchrotron light source operated by the TU Dortmund University. At a dedicated THz beamline, measurements using a Fourier-transform spectrometer have been performed between 1 THz and 7 THz. Recently, an ultrafast Schottky- diode detector and a novel polarizing Fourier-transform spec- trometer were installed, which enable turn-by-turn-resolved spectral measurements in the frequency range below 1 THz. The commissioning results of the new spectrometer and simulations are presented., Proceedings of the 7th Int. Particle Accelerator Conf., IPAC2016, Busan, Korea

At the 1.5-GeV synchrotron light source DELTA operated by the TU Dortmund University, ultrashort and coherent radiation pulses in the VUV and THz regime are routinely generated by the interaction of electron bunches with 45-fs laser pulses. A laser-induced modulation of the electron energy is converted into a density modulation (microbunching) by a magnetic chicane, giving rise to coherent emission at harmonics of the initial laser wavelength (coherent harmonic generation, CHG). As a first step towards active control of the shape and spectrum of CHG pulses, spectral studies were performed under variation of the chicane strength and the laser properties. The spectral phase of the laser pulses was controlled by tuning the compressor of the laser amplifier and was monitored using FROG (frequency-resolved optical gating). In this paper, monochromator scans as well as single-shot spectrograms of the CHG radiation are presented and compared to simulations of the laser-electron interaction and microbunching process. In addition, other results from the short-pulse facility as well as a future upgrade employing the echo-enabled harmonic generation (EEHG) scheme will be outlined., Proceedings of the 7th Int. Particle Accelerator Conf., IPAC2016, Busan, Korea