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Volume 28, Issue 12
Displaying 1-11 of 11 articles from this issue
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Junji FUJITA2000 Volume 28 Issue 12 Pages 789
Published: December 15, 2000
Released on J-STAGE: March 17, 2010
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Tadashi ARUGA2000 Volume 28 Issue 12 Pages 790-791
Published: December 15, 2000
Released on J-STAGE: March 17, 2010
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2000 Volume 28 Issue 12 Pages 791
Published: December 15, 2000
Released on J-STAGE: March 17, 2010
JOURNAL FREE ACCESSDownload PDF (109K) -
Chester S. GARDNER2000 Volume 28 Issue 12 Pages 792-795
Published: December 15, 2000
Released on J-STAGE: March 17, 2010
JOURNAL FREE ACCESSAtmospheric turbulence severely limits the resolution of groundbased astronomical telescopes. In good seeing conditions at the best observatory sites, resolution at visible wavelengths is typically limited to-1 s of arc. During the past 20 years adaptive optical systems using electrically deformable mirrors have been developed to compensate for turbulence effects. Unfortunately, these systems require bright reference sources adjacent to the object of interest and can be used only to observe the brightest stars. Artificial guide stars suitable for controlling an adaptive imaging system can be created in the upper atmosphere by using a laser to excite resonance backscattering in the mesospheric sodium layer. The design requirements of a laser-guided adaptive telescope, as well as the expected imaging performance, are reviewed in this paper.View full abstractDownload PDF (793K) -
On-Orbit Calibration Techniques for Precise GeolocationDavid D. ROWLANDS, Claudia C. CARABAJAL, Scott B. LUTHCKE, David J. HA ...2000 Volume 28 Issue 12 Pages 796-803
Published: December 15, 2000
Released on J-STAGE: March 17, 2010
JOURNAL FREE ACCESSIn the thirty years since the launch of the Skylab radar altimeter, satellite-based altimetry has proven to be a powerful tool to map the Earth and other planets. In order to fully exploit an orbiting altimeter, it is necessary to calibrate certain parameters not only before launch, but also after the altimeter is in orbit. Over the years, techniques have been worked out for on-orbit calibration of radar altimeters. Our use of Earth-orbiting satellite laser altimetry began in 1996 with the Shuttle Laser Altimeter. Although laser altimetry presents unique opportunities, it also requires new on-orbit calibration techniques. These techniques are still evolving and include the integration of multiple tracking data types with planned pointing maneuvers over oceans and waveform analysis. This paper describes on-orbit calibration techniques for the several missions that have flown laser altimeters to date and for laser altimeter missions which will launch in the near future.View full abstractDownload PDF (1725K) -
Systems, Technologies, and ApplicationsWalter R. LEEB2000 Volume 28 Issue 12 Pages 804-808
Published: December 15, 2000
Released on J-STAGE: March 17, 2010
JOURNAL FREE ACCESSLaser communication links in space are attractive alternatives to present-day microwave links. This tutorial describes the basic concept and the functions of an optical terminal on board a spacecraft. It points out the differences between free-space optical links on one hand and glass fiber systems and microwave directional links on the other hand. The requirements on data transmitters and receivers as well as on optical antennas and pointing, acquisition and tracking mechanisms are discussed. Typical application scenarios are outlined, experimental systems and their technologies are cited.View full abstractDownload PDF (1062K) -
Masakatsu FUJIMOTO2000 Volume 28 Issue 12 Pages 809-813
Published: December 15, 2000
Released on J-STAGE: March 17, 2010
JOURNAL FREE ACCESSLarge-scale laser interferometers are now under construction by several groups in the world, aiming at detecting gravitational waves and at creating a new astronomy, “Gravitational-wave Astronomy”. Japanese interferometer, TAMA300, recently started operation in advance of the other projects. Current status of the TAMA300 and prospective future development in this research field are overviewed.View full abstractDownload PDF (1767K) -
Junzo UCHIDA, Yoshinori ARIMOTO2000 Volume 28 Issue 12 Pages 814-818
Published: December 15, 2000
Released on J-STAGE: March 17, 2010
JOURNAL FREE ACCESSWe are designing the Laser Communications Demonstration Equipment (LCDE) attached to the Japanese Experiment Module “Kibo” on the International Space Station (ISS), for laser communications experiments between the ISS and ground stations. The experiment will demonstrate large-capacity, high-data-rate (2.5 Gbps) two-way communications. A preliminary experiment to detect space debris will also be performed. In the first stage of the experiment, it is necessary to track geodetic satellites and to compensate the optical misalignment of the LCDE in order to achieve precise tracking and pointing. Sunlight reflected from geodetic satellites will be used for tracking. This provides the tracking angle information. As the received power is very low (about - 95 dBm), a sensitive tracking sensor is needed. This paper summarizes the LCDE, studies on the visibility of the geodetic satellites from the ISS, and the tracking performance includingthe sensitivity of the sensor.View full abstractDownload PDF (1000K) -
Shin YOSHIKADO, Shin OYA, Shu Wing LI, Tadashi ARUGA2000 Volume 28 Issue 12 Pages 819-823
Published: December 15, 2000
Released on J-STAGE: March 17, 2010
JOURNAL FREE ACCESSTopical experimental results of artificial star generation are presented. The generation system utilizes a 1.5 m diameter telescope of CRL for transmitting a laser beam to illuminate the atmosphere and for receiving backscattered light. The light source of transmission used is the second harmonics of a pulse-oscillating Nd: YAG laser. A mirror with a small hole at its center is used as a beam splitter for transmission and reception, and it spares us from a power loss of about 6 dB compared to the use of a conventional beam splitter. We executed the first domestic experiment of artificial star generation by atmospheric Rayleigh-scattering, and succeeded in acquiring image data of artificial stars generated at ranges up to ten plus several kilometers. At the same time, data of Polaris in a neighboring direction were obtained as a reference and image comparison.View full abstractDownload PDF (1128K) -
Yukimasa MINAMI, Koichi TOYODA2000 Volume 28 Issue 12 Pages 824-828
Published: December 15, 2000
Released on J-STAGE: March 17, 2010
JOURNAL FREE ACCESSSurface ripples generated by laser-induced surface electromagnetic waves (SEW) are causing interest because the dimensions of the microstructures that are formed are less than the wavelength of the laser light. The generation process is controlled by the laser wavelength used and the dispersion relationship of the SEW. A characteristic difference in the dependence of the ripple period on the incident angle between metals and semiconductors was observed using a femto-second laser. This difference is explained by the different coupling conditions of metals and semiconductors. In the case of metals, the wavenumber of the ripple is given by kSEW - k0sinθ. On the other hand, in the case of semiconductors, the wavenumber of the ripple is given by kSEW + k0sinθ.View full abstractDownload PDF (746K) -
Takeyoshi NAKAYAMA2000 Volume 28 Issue 12 Pages 829-831
Published: December 15, 2000
Released on J-STAGE: March 17, 2010
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