Long-Distance Quantum Communication with Entangled Photons using Satellites

The use of satellites to distribute entangled photon pairs (and single photons) provides a unique solution for long-distance quantum communication networks. This overcomes the principle limitations of Earth-bound technology, i.e. the narrow range of some 100 km provided by optical fiber and terrestrial free-space links.Comment: 12 pages, 7 figures; submitted to IEEE Journal of Selected Topics in Quantum Electronics, special issue on "Quantum Internet Technologies

Proof-of-Concept Experiments for Quantum Physics in Space

Quantum physics experiments in space using entangled photons and satellites are within reach of current technology. We propose a series of fundamental quantum physics experiments that make advantageous use of the space infrastructure with specific emphasis on the satellite-based distribution of entangled photon pairs. The experiments are feasible already today and will eventually lead to a Bell-experiment over thousands of kilometers, thus demonstrating quantum correlations over distances which cannot be achieved by purely earth-bound experiments.Comment: 15 pages, 10 figures, to appear in: SPIE Proceedings on Quantum Communications and Quantum Imaging (2003

How Much of a Historic Town Can Be Mapped by a Terrestrial Laser Scanner within a Working Day? - A Single Touch Workflow

Downtown Vienna with its world-famous cultural sites and architectural features is most definitely worth conservation. One way to archive at least a digital 3D imprint is laser scanning. While urban mapping with airborne or mobile laser scanning is fast and efficient, the resulting point clouds might not have the required resolution or might experience gaps due to shadowing. Terrestrial laser scanning has the potential to overcome these limitations. However, it has long been considered time-consuming and labour-intensive both while capturing and also while processing the data. In order to challenge this, we performed a field test with the new RIEGL VZ-400i terrestrial laser scanner. For eight hours, in the night from 2nd to 3rd of June 2016, one single operator employed the instrument throughout the city center of Vienna. He managed to take 514 high-resolution laser scans with approximately 9m between the scan positions. The data acquired in the course of this test impressively demonstrates the potential of state-of-the-art terrestrial laser scanning to preserve detailed 3D-information of urban environments within limited amount of time. This paper describes the complete workflow from the one touch operation in the field up to the automatic registration process of the collected laser scans.     

Design of optical space-to-ground links for the international space station

Zsfassung in dt. Sprache10

Finding model parameters for the system waveform of a full-wave lidar: A pragmatic solution

The system waveform (SWFM) of a pulsed LiDAR is obtained from the pulse shape received when pointing the sensor towards a flat, extended target with the surface normal equal to the laser beam direction. The SWFM is determined by the shape of the outgoing laser pulse and the transfer characteristics of the receiver. Knowing the SWFM is essential for performing highly accurate range measurements, for interpreting the LiDAR waveforms correctly, and to derive additional attributes for detected target returns. Often the actual SWFM is not known explicitly, and a Gaussian pulse shape is used in lieu thereof. However, the Gaussian pulse, despite its advantageous properties, does not properly address asymmetries and ringing effects typically present in real-life SWFMs. We present a model of the SWFM composed of harmonic and exponential terms which is able to account for these effects while at the same time being mathematically easy to handle. Unfortunately, the approximation of data by a sum of harmonics and exponentials belongs to the class of ill-posed problems. Nevertheless, we present a pragmatic solution to the problem and demonstrate the versatility of the resulting model.18

Chapter 2: History

The early years of laser hydrography have been traced by Guenther (1985). His review tracks the development of laser hydrography, now more commonly known as Airborne Laser Bathymetry (ALB), from the earliest theoretical and experimental efforts in the mid-1960's dealing with in-water lasers and the first demonstration systems capable of detecting bottom returns through the development of the first operational systems. The history was later extended to 1990 in a paper by Sizgoric, Banic and Guenther (1992). Guenther further detailed this history and provided descriptions of operational systems in the Airborne Lidar Bathymetry chapter of The DEM User's Manual (Guenther 2001), which he later updated in the 2nd Edition of the User's Manual (Guenther 2007). This chapter summarizes and updates these reference documents