Compact 20-pass thin-disk amplifier insensitive to thermal lensing

We present a multi-pass amplifier which passively compensates for distortions of the spherical phase front occurring in the active medium. The design is based on the Fourier transform propagation which makes the output beam parameters insensitive to variation of thermal lens effects in the active medium. The realized system allows for 20 reflections on the active medium and delivers a small signal gain of 30 with M$^2$ = 1.16. Its novel geometry combining Fourier transform propagations with 4f-imaging stages as well as a compact array of adjustable mirrors allows for a layout with a footprint of 400 mm x 1000 mm.Comment: 7 pages, 6 figure

Study of structure and antireflective properties of LaF3/HfO2/SiO2 and LaF3/HfO2/MgF2 trilayers for UV applications

Abstract The aim of this paper is to study antireflective properties of the tree-layer systems LaF3/HfO2/SiO2 and LaF3/HfO2/MgF2 deposited on heated optical glass substrates. The films were evaporated by the use two deposition techniques. In first method oxide films were prepared by means of e-gun evaporation in vacuum of 5 × 10−5 mbar in the presence of oxygen. The second was used for the deposition of fluoride films. They were obtained by means of thermal source evaporation. Simulation of reflectance was performed for 1M2H1L (Quarter Wavelength Optical Thickness) film stack on an optical quartz glass with the refractive index n = 1.46. The layer thickness was optimized to achieve the lowest light scattering from glass surface covered with dioxide and fluoride films. The values of the interface roughness were determined through atomic force microscopy measurements. The essence of performed calculation was to find minimum reflectance of light in wide ultraviolet region. The spectral dispersion of the refractive index needed for calculations was determined from ellipsometric measurements using the spectroscopic ellipsometer M2000. Additionally, the total reflectance measurements in integrating sphere coupled with Perkin Elmer 900 spectrophotometer were performed. These investigations allowed to determine the influence of such film features like surface and interface roughness on light scattering

CENP-meta, an Essential Kinetochore Kinesin Required for the Maintenance of Metaphase Chromosome Alignment in Drosophila

CENP-meta has been identified as an essential, kinesin-like motor protein in Drosophila. The 257-kD CENP-meta protein is most similar to the vertebrate kinetochore-associated kinesin-like protein CENP-E, and like CENP-E, is shown to be a component of centromeric/kinetochore regions of Drosophila chromosomes. However, unlike CENP-E, which leaves the centromere/kinetochore region at the end of anaphase A, the CENP-meta protein remains associated with the centromeric/kinetochore region of the chromosome during all stages of the Drosophila cell cycle. P-element–mediated disruption of the CENP-meta gene leads to late larval/pupal stage lethality with incomplete chromosome alignment at metaphase. Complete removal of CENP-meta from the female germline leads to lethality in early embryos resulting from defects in metaphase chromosome alignment. Real-time imaging of these mutants with GFP-labeled chromosomes demonstrates that CENP-meta is required for the maintenance of chromosomes at the metaphase plate, demonstrating that the functions required to establish and maintain chromosome congression have distinguishable requirements

Dithieno[2,3-d;2',3'-d]benzo[2,1-b;3,4-b']dithiophene: a novel building-block for a planar copolymer

A planar heteroacene building block, dithieno[2,3-d;2′,3′-d′]benzo[1,2-b;3,4-b′]dithiophene (DTmBDT), is reported via a facile synthetic procedure.</p