TAOS II: THE ROBOTIC OPERATIONS

In this work, we present the general procedure for the robotic observations of the Transneptunian Automated Occultation Survey (TAOS II). The project aims to detect small TNOs (Transneptunian Objects) by serendipitous stellar occultations. To do so TAOS II will operate three 1.3 m telescopes equipped with CMOS cameras which are able to read about 10,000 stars in multiple subapertures at a 20 Hz cadence. At such rates, it will be possible to identify diffraction features in the lightcurves, helping us to estimate a distance and object size to each occultation event. TAOS II is installed in the Observatorio Astronómico Nacional in San Pedro Mártir, Ensenada, México (OAN-SPM). The site has good observing conditions, typically with around 260 useful nights per year. Here, we describe the different process to be performed in a typical observing night: system start up and shut down, monitoring observing conditions, acquisition of calibration images, field selection, pointing, camera synchronization, determination of aperture sizes and positions, and high speed image acquisition.

Programming conventional electron microscopes for solving ultrahigh-resolution structures of small and macro-molecules

Microcrystal electron diffraction (MicroED) is becoming a powerful tool in determining the crystal structures of biological macromolecules and small organic compounds. However, wide applications of this technique are still limited by the special requirement for radiation-tolerated movie-mode camera and the lacking of automated data collection method. Herein, we develop a stage-camera synchronization scheme to minimize the hardware requirements and enable the use of the conventional electron cryo-microscope with single-frame CCD camera, which ensures not only the acquisition of ultrahigh-resolution diffraction data but also low cost in practice. This method renders the structure determination of both peptide and small organic compounds at ultrahigh resolution up to ~0.60 Å with unambiguous assignment of nearly all hydrogen atoms. The present work provides a widely applicable solution for routine structure determination of MicroED, and demonstrates the capability of the low-end 120kV microscope with a CCD camera in solving ultra-high resolution structures of both organic compound and biological macromolecules.

DEVELOPMENT AND EVALUATION OF A UAV BASED MAPPING SYSTEM FOR REMOTE SENSING AND SURVEYING APPLICATIONS

In recent years, unmanned aerial vehicles (UAVs) have increasingly been used in various application areas, such as in the remote sensing or surveying. For these applications the UAV has to be equipped with a mapping sensor, which is mostly a camera. Furthermore, a georeferencing of the UAV platform and/or the acquired mapping data is required. The most efficient way to realize this georeferencing is the direct georeferencing, which is based on an onboard multi-sensor system. In recent decades, direct georeferencing systems have been researched and used extensively in airborne, ship and land vehicle applications. However, these systems cannot easily be adapted to UAV platforms, which is mainly due to weight and size limitations. <br><br> In this paper a direct georeferencing system for micro- and mini-sized UAVs is presented, which consists of a dual-frequency geodetic grade OEM GPS board, a low-cost single-frequency GPS chip, a tactical grade IMU and a magnetometer. To allow for cm-level position and sub-degree attitude accuracies, RTK GPS (real-time kinematic) and GPS attitude (GPS compass) determination algorithms are running on this system, as well as a GPS/IMU integration. <br><br> Beside the direct georeferencing, also the precise time synchronization of the camera, which acts as the main sensor for mobile mapping applications, and the calibration of the lever arm between the camera reference point and the direct georeferencing reference point are explained in this paper. Especially the high accurate time synchronization of the camera is very important, to still allow for high surveying accuracies, when the images are taken during the motion of the UAV. <br><br> Results of flight tests demonstrate that the developed system, the camera synchronization and the lever arm calibration make directly georeferenced UAV based single point measurements possible, which have cm-level accuracies on the ground.

SHADOWGRAPHY OF SHOCK WAVE INDUCED BY DOUBLE PULSE TECHNIQUE

High-speed videography based on double pulse of Nd:YAG laser to capture dynamic expansion of shock wave is reported. A Q-switched Nd:YAG laser was employed as an input signal and disturbance source. Nitrodye laser was utilized as a flash. The shock wave generation was recorded via CCD video camera. Synchronization is organized associated with a digital delay generator. Nd:YAG laser was focused to generate an optical breakdown in distilled water. Double pulses were generated within the interval of one second. The first pulse of Nd:YAG laser was used to trigger the dye laser and the second pulse to generate shock wave. Manipulation of delay times allow to freeze the dynamic expansion of shock wave. The double pulse technique is appropriated for laser system with the absence of external trigger unit. Lack of electronic failure is the advantage offer by the double pulse technique.