Orbital angular momentum carrying light beams are usedfor optical trapping and manipulation. This emerging trend provides new challenges involving device miniaturization for improved performance and ...enhanced functionality at the microscale. Here we discus a new fabrication method based on combining the additive 3D structuring capability laser photopolymerization and the substractive sub-wavelength resolution patterning of focused ion beam lithography to produce micro-optical elements capable of compound functionality. As a case in point of this approach binary spiral zone pattern based high numerical aperture micro-lenses capable of generating topological charge carrying tightly focused vortex beams in a single wavefront transformation step are presented. The devices were modelled using finite-difference time-domain simulations, and the theoretical predictions were verified by optically characterizing the propagation properties of light transmitted through the fabricated structures. The resulting devices had focal lengths close to the predicted values of f = 18 µm and f = 13 µm as well as topological charge ℓ dependent vortex focal spot sizes of ~ 1:3 µm and ~ 2:0 µm for ℓ = 1 and ℓ = 2 respectively.
The active galactic nucleus PG 1553+113 was observed by the MAGIC telescope in July 2006 during a multiwavelength campaign, in which telescopes in the optical, X-ray, and very high energies ...participated. Although the MAGIC data were affected by strong atmospheric absorption (calima), they were analyzed after applying a correction. In 8.5 h, a signal was detected with a significance of 5.0σ. The integral flux above 150 GeV was $(2.6\pm0.9)\times 10^{-7}~{\rm ph\,s^{-1}\,m^{-2}}$. By fitting the differential energy spectrum with a power law, a spectral index of $-4.1\pm0.3$ was obtained.
The nearby dwarf spheroidal galaxy Draco, with its high mass to light ratio, is one of the most auspicious targets for indirect dark matter (DM) searches. Annihilation of hypothetical DM particles ...can result in high-energy -rays, e.g., from neutralino annihilation in the supersymmetric framework. A search for a possible DM signal originating from Draco was performed with the MAGIC telescope during 2007. Analysis of the data results in a flux upper limit (2 capital sigma ) of image photons cm super(-2) s super(-1) for photon energies above 140 GeV, assuming a pointlike source. A comparison with predictions from supersymmetric models is also given. While our results do not constrain the mSUGRA phase parameter space, a very high flux enhancement can be ruled out.
Aims. We searched for very high energy (VHE) \gamma-ray emission from the supernova remnant Cassiopeia A Methods. The shell-type supernova remnant Cassiopeia A was observed with the 17 m MAGIC ...telescope between July 2006 and January 2007 for a total time of 47 h. Results. The source was detected above an energy of 250 GeV with a significance of 5.2\sigma and a photon flux above 1 TeV of (7.3 \pm 0.7_{\rm stat} \pm 2.2_{\rm sys}) \times 10 super(-13) cm super(-2) s super(-1). The photon spectrum is compatible with a power law d N /d E \propto E-\Gamma} with a photon index \Gamma = 2.3 \pm 0.2_{\rm stat} \pm 0.2_{\rm sys}. The source is point-like within the angular resolution of the telescope.
One of the main design goals of the MAGIC telescopes is the very fast repositioning in case of Gamma Ray Burst (GRB) alarms, implying a low weight of the telescope dish. This is accomplished by using ...a space frame made of carbon fiber epoxy tubes, resulting in a strong but not very rigid support structure. Therefore it is necessary to readjust the individual mirror tiles to correct for deformations of the dish under varying gravitational load while tracking an object. We present the concept of the Active Mirror Control (AMC) as implemented in the MAGIC telescopes and the actual performance reached. Additionally we show that also telescopes using a stiff structure can benefit from using an AMC.
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