Beurteilung der Wellenfront von CO2-Lasern mittels phase retrival

Zu den bislang wenig untersuchten Aspekten der Strahlqualität an Bearbeitungslasern gehört die Vermessung der Wellenfront. Dies liegt an grundsätzlichen Schwierigkeiten bei der Anwendung interferometrischer Methoden im Hochleistungsbereich. Die Phasenverteilung ist jedoch neben der Intensitätsverteilung mitentscheidend für eine gute Fokusqualität. Sowohl durch den Laserresonator als auch durch das Strahlführungssystem können Wellenfrontdeformationen verursacht werden. Wir stellen ein robustes Verfahren vor, um aus Intensitätsmessungen Information über die Wellenfront zu gewinnen. Erste Ergebnisse, die mit dieser Methode an CO2-Lasern gewonnen wurden, werden vorgestellt und diskutiert

Diffractive optical elements for CO2 laser beam diagnostics

In laser machining great interest has been shown in diagnostic tools for on-line testing and correcting. We present here beam sampling mirrors, which are basically shallow gratings, and which can be applied to give an accurate sample of the original beam without deteriorating it. The method compares favourably with other techniques for beam diagnostics. First results using these elements are presented

A new way to measure partner burden in depression: construction, validation, and sensitivity to change of the partner burden in depression questionnaire

Depression occurs in an interpersonal dynamic and living with a depressed person can lead to a significant burden on the partner. Instruments measuring burden do not address couples and often measure caregiving for individuals with schizophrenic disorders. The partner burden in depression (PBD) questionnaire is a new instrument measuring PBD by asking individuals, (1) which symptoms they can observe in their depressed partners and (2) to which degree this burdens them. Hence, PBD combines measuring the awareness of observed depressive symptoms and the resulting burden. Additionally, it addresses aspects unique to couple relationships. Our German validation confirmed a one-factor model with 12 items. The PBD had good psychometric properties and was sensitive to change. Partner burden predicted self-reported depressive symptoms (PHQ-9) over time. PBD is short, easily applicable in research and practice and can add to the understanding of partner effects in depression

Avoided Crossing Patterns and Spectral Gaps of Surface Plasmon Modes in Gold Nano-Structures

The transmission of ultrashort (7 fs) broadband laser pulses through periodic gold nano-structures is studied. The distribution of the transmitted light intensity over wavelength and angle shows an efficient coupling of the incident p-polarized light to two counter-propagating surface plasmon (SP) modes. As a result of the mode interaction, the avoided crossing patterns exhibit energy and momentum gaps, which depend on the configuration of the nano-structure and the wavelength. Variations of the widths of the SP resonances and an abrupt change of the mode interaction in the vicinity of the avoided crossing region are observed. These features are explained by the model of two coupled modes and a coupling change due to switching from the high frequency dark mode to the low frequency bright mode for increasing wavelength of the excitation light. PACS numbers: 73.20.Mf, 42.70.Qs, 42.25.-p,Comment: 17 pages, 4 figure

Inszenierung von Wirklichkeit : 24h Berlin als besonderes Beispiel für dokumentarische Glaubwürdigkeit

nicht vorhande