Spontaneous Generation of Vortex Array Beams from a Thin-Slice Solid-State Laser with Wide-Aperture Laser-Diode Pumping

We studied complex lasing pattern formations in a thin-slice solid-state laser with wide-aperture laser-diode end-pumping. Radial and rectangular vortex arrays were found to be formed in a controlled fashion with symmetric and asymmetric pump beam profiles, respectively. Most of these vortices exhibited single-frequency oscillations arising from a spontaneous process of transverse mode locking of nearly degenerate modes assisted by the laser nonlinearity. Single-frequency rectangular array beams consisting of a large number of vortices, e.g., closely packed 36 or 46 vortex pixels, were generated, originating from Ince-Gaussian modes excited by the asymmetric pumping.Comment: 16 pages, 4 figure

Deprojection of luminosity functions of galaxies in the Coma cluster

We use a simple analytic model to deproject 2-d luminosity functions (LF) of galaxies in the Coma cluster measured by Beijersbergen et al. 2002. We demonstrate that the shapes of the LFs change after deprojection. It is therefore essential to correct LFs for projection effects. The deprojected LFs of the central area have best-fitting Schechter parameters of M^{*}_U=-18.31^{+0.08}_{-0.08} and \alpha_U=-1.27^{+0.018}_{-0.018}, M^{*}_B=-19.79^{+0.14}_{-0.15} and \alpha_B=-1.44^{+0.016}_{-0.016} and M^{*}_r=-21.77^{+0.20}_{-0.28} and \alpha_r=-1.27^{+0.012}_{-0.012}. The corrections are not significant enough to change the previously observed trend of increasing faint end slopes with increasing distance to the cluster center. The weighted U, B, and r band slopes of the deprojected LFs show a slightly weaker steepening with increasing projected cluster radius.Comment: Accepted for publication in A&A as a Research Not

Ray transfer matrix for a spiral phase plate

We present a ray transfer matrix for a spiral phase plate. Using this matrix, we determine the stability of an optical resonator made of two spiral phase plates, and trace stable ray orbits in the resonator. Our results should be relevant to laser physics, optical micromanipulation, quantum information and optomechanics.Comment: 5 pages, 3 figure

GRI: The Gamma-Ray Imager mission

With the INTEGRAL observatory, ESA has provided a unique tool to the astronomical community revealing hundreds of sources, new classes of objects, extraordinary views of antimatter annihilation in our Galaxy, and fingerprints of recent nucleosynthesis processes. While INTEGRAL provides the global overview over the soft gamma-ray sky, there is a growing need to perform deeper, more focused investigations of gamma-ray sources. In soft X-rays a comparable step was taken going from the Einstein and the EXOSAT satellites to the Chandra and XMM/Newton observatories. Technological advances in the past years in the domain of gamma-ray focusing using Laue diffraction have paved the way towards a new gamma-ray mission, providing major improvements regarding sensitivity and angular resolution. Such a future Gamma-Ray Imager will allow studies of particle acceleration processes and explosion physics in unprecedented detail, providing essential clues on the innermost nature of the most violent and most energetic processes in the Universe.Comment: 8 page

Measuring orbital angular momentum superpositions of light by mode transformation

We recently reported on a method for measuring orbital angular momentum (OAM) states of light based on the transformation of helically phased beams to tilted plane waves [Phys. Rev. Lett.105, 153601 (2010)]. Here we consider the performance of such a system for superpositions of OAM states by measuring the modal content of noninteger OAM states and beams produced by a Heaviside phase plate

Generation of high-order optical vortices using directly machined spiral phase mirrors

We report on the generation of high-order optical vortices by spiral phase mirrors. The phase mirrors are produced by direct machining with a diamond tool and are shown to produce high-quality optical vortices with topological charges ranging from 1 to 1000 at a wavelength of 532 nm. The direct machining technique is flexible and offers the promise of high-precision, large-diameter spiral phase mirrors that are compatible with high optical powers.Comment: 4 pages, 4 figure

The Adult Attachment Interview: coherence & validation in adolescents

The Adult Attachment Interview (AAI) was developed in the early 1980s to measure an adult’s attachment representation. Since then, it has been applied in more than 100 studies. This thesis aimed to shed light on some of the potentials and limitations of the AAI. We found that coherence, which is an important concept in attachment interviews, is not defined similarly by attachment experts, linguists, and non-experts. Therefore, it seems that a measure for coherence cannot make the AAI more easily accessible for non-attachment experts. Secondly, we showed that the attachment representations of adopted adolescents were related (1) to their own autonomy behaviors and mothers’ relatedness behaviors during a discussion task, (2) to the adolescents’ emotional investment in others, and (3) to the adolescents’ perceived support from others. Intelligence and perceived temperament were not associated with the adolescents’ attachment representation. These results support the validity of the AAI when assessed with (adopted) adolescents. Finally, we revealed that the AAI differentiates between adolescents with divergent physiological responses (interbeat interval reactivity) to attachment relevant situations: dismissing adolescents showed less physiological reactivity during the AAI than secure adolescents, while they appeared to be more stressed during a discussion task with their mothers.LEI Universiteit LeidenFSW - Gezinsopvoeding - Ou