Anthony W. Yu

Compact, passively Q-switched Nd:YAG laser for the MESSENGER mission to Mercury

A compact, passively Q-switched Nd:YAG laser has been developed for the Mercury Laser Altimeter, an instrument on the Mercury Surface, Space Environment, Geochemistry, and Ranging mission to the planet Mercury. The laser achieves 5.4% efficiency with a near-diffraction-limited beam. It passed all space-flight environmental tests at subsystem, instrument, and satellite integration testing and successfully completes a postlaunch aliveness check en route to Mercury. The laser design draws on a heritage of previous laser altimetry missions, specifically the Ice Cloud and Elevation Satellite and the Mars Global Surveyor, but incorporates thermal management features unique to the requirements of an orbit of the planet Mercury.

Single-mode high-peak-power passively Q-switched diode-pumped Nd:YAG laser

We have demonstrated an efficient, compact, passively Q-switched single-mode diode-pumped Nd:YAG laser that uses Cr(4+):YAG as a saturable absorber. Linear- and ring-cavity configurations were demonstrated. Pulse energies and widths were, respectively, 1.5mJ and 3.9ns for the linear cavity and 2.1mJ and 12ns for the ring cavity.

The Geoscience Laser Altimeter System (GLAS) Laser Transmitter

The Geoscience Laser Altimeter System (GLAS), launched in January 2003, is a laser altimeter and lidar for the Earth Observing Systems (EOS) ICESat mission. GLAS accommodates three, sequentially operated, diode-pumped, solid-state, Nd:YAG laser transmitters. The laser transmitter requirements, design, and qualification test results for this space-based remote-sensing instrument is summarized and presented.

Space laser transmitter development for ICESat-2 mission

The first NASA Ice, Cloud and land Elevation Satellite (ICESat) was launched in January 2003 and placed into a nearpolar orbit whose primary mission was the global monitoring of the Earths ice sheet mass balance. ICESat has accumulated over 1.8 B shots in space and provided a valuable dataset in the study of ice sheet dynamics over the past few years. NASA is planning a follow-on mission ICESat-2 to be launched tentatively in 2015. In this paper we will discuss the development effort of the laser transmitters for the ICESat-2 mission.

A dual format communication modem development for the Laser Communications Relay Demonstration (LCRD) program

The LCRD will demonstrate optical communications relay services between a geosynchronous satellite and Earth over an extended period, and thereby gain the knowledge and experience base that will enable NASA to design, procure, and operate cost-effective future optical communications systems and relay networks. LCRD is the next step in NASA eventually providing an optical communications service on the Next Generation Tracking and Data Relay Satellites (TDRS). LCRD will demonstrate some optical communications technologies, concepts of operations, and advanced networking technologies applicable to Deep Space missions. In this paper we describe the integrated dual format (PPM/DPSK) modem testbed development and performance.

The Slope Imaging Multi-polarization Photon-counting Lidar: Development and performance results

The Slope Imaging Multi-polarization Photon-counting Lidar is an airborne instrument developed to demonstrate laser altimetry measurement methods that will enable more efficient observations of topography and surface properties from space. The instrument was developed through the NASA Earth Science Technology Office Instrument Incubator Program with a focus on cryosphere remote sensing. The SIMPL transmitter is an 11 KHz, 1064 nm, plane-polarized micropulse laser transmitter that is frequency doubled to 532 nm and split into four push-broom beams. The receiver employs single-photon, polarimetric ranging at 532 and 1064 nm using Single Photon Counting Modules in order to achieve simultaneous sampling of surface elevation, slope, roughness and depolarizing scattering properties, the latter used to differentiate surface types. Data acquired over ice-covered Lake Erie in February, 2009 are documenting SIMPLs measurement performance and capabilities, demonstrating differentiation of open water and several ice cover types. ICESat-2 will employ several of the technologies advanced by SIMPL, including micropulse, single photon ranging in a multi-beam, push-broom configuration operating at 532 nm.

Laser transmitter for the Lunar Orbit Laser Altimeter (LOLA) instrument

We present the final configuration of the space flight laser transmitter as delivered to the LOLA instrument. The laser consists of two oscillators on a single bench, each capable of providing one billion plus shots.

Spaceborne laser instruments for high-resolution mapping

We discuss past, present and future spaceborne laser instruments for high-resolution mapping of Earth and planetary surfaces. Previous spaceborne-laser-altimeters projected and imaged a single laser spot for surface-height measurements. In contrast, the recent Lunar Orbiter Laser Altimeter (LOLA) instrument on the Lunar Reconnaissance Orbiter (LRO) uses a non-scanning multi-beam system for surface topography mapping. The multi-beam instrument facilitates surface slope measurement and reduces the time-to-completion for global high-resolution topographic mapping. We discuss our first-year progress on a three-year swath-mapping laser-altimetry Instrument Incubator Program (IIP) funded by the NASA Earth Science Technology Office (ESTO). Our IIP is a technology development program supporting the LIdar Surface Topography (LIST) space-flight mission that is a third-tier mission as recommended by the National Research Council (NRC) for NASAs Earth Science programs.

The GLAS Laser Transmitter Breadboard

We have demonstrated a 150 mj, 4 ns, 40 Hz, M2 ≈ 2, diode-pumped Nd:YAG laser as a breadboard for the GLAS laser transmitter.

Laser transceivers for future NASA missions

NASA is currently developing several Earth science laser missions that were recommended by the US National Research Council (NRC) Earth Science Decadal Report. The Ice Cloud and Land Elevation Satellite-2 (ICESat-2) will carry the Advanced Topographic Laser Altimeter System (ATLAS) is scheduled for launch in 2016. The Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) mission and will measure column atmospheric CO2 concentrations from space globally. The Gravity Recovery And Climate Experiment (GRACE) Follow-On (GRACEFO) and GRACE-2 missions measure the spatially resolved seasonal variability in the Earths gravitational field. The objective of the Lidar Surface Topography (LIST) mission is to globally map the topography of the Earths solid surface with 5 m spatial resolution and 10 cm vertical precision, as well as the height of overlying covers of vegetation, water, snow, and ice. This paper gives an overview of the laser transmitter and receiver approaches and technologies for several future missions that are being investigated by the NASA Goddard Space Flight Center.