Global Ecosystem Dynamics Investigation (GEDI) instrument alignment and test

Bente Eegholm; Shane Wake; Zachary Denny; Pete Dogoda; Demetrios Poulios; Barry Coyle; Pete Mulé; John Hagopian; Patrick Thompson; Luis Ramos-Izquierdo; Bryan Blair

doi:10.1117/12.2532471

30 August 2019 Global Ecosystem Dynamics Investigation (GEDI) instrument alignment and test

Bente Eegholm, Shane Wake, Zachary Denny, Pete Dogoda, Demetrios Poulios, Barry Coyle, Pete Mulé, John Hagopian, Patrick Thompson, Luis Ramos-Izquierdo, Bryan Blair

Author Affiliations +

Proceedings Volume 11103, Optical Modeling and System Alignment; 1110308 (2019) https://doi.org/10.1117/12.2532471
Event: SPIE Optical Engineering + Applications, 2019, San Diego, California, United States

Abstract

NASA’s Global Ecosystem Dynamics Investigation (GEDI) instrument was launched Dec. 5, 2018, and installed on the International Space Station 419 km from Earth. The GEDI is a Light Detection and Ranging (LIDAR) instrument; measuring the time of flight of transmitted laser beams to the Earth and back to determine altitude for geospatial mapping of forest canopy heights. The need for very dense cross track sampling for slope measurements of canopy height is accomplished by using three individual laser transmitter systems, where each beam is split into two beams by a birefringent crystal. Furthermore, one transmitter is equipped with a diffractive optical element splitting the two beams into four, for a total of 8 beams. The beams are reflected off of the features and imaged by an 800 mm diameter Receiver Telescope Assembly, composed of a Ritchey-Chrétien telescope, a refractive aft optics assembly and focal plane array which collects and focuses the light from the 8 probe beams into the 8 science fibers, each with a field of view on the Earth subtending 300 μrad. The dense cross-track sampling mandated a custom designed dual-fiber interface. The science fibers had to be aligned to the nominal, projected laser spots. The alignment was highly dependent on optimization and co-positioning of the fibers pair-wise due to mechanical constraints. This paper presents the end-to-end alignment and metrology of the full optical system from transmitter elements through receiver telescope, aft-optics, focal plane and receiver fibers performed at NASA Goddard Space Flight Center.

Conference Presentation

Citation Download Citation

Bente Eegholm, Shane Wake, Zachary Denny, Pete Dogoda, Demetrios Poulios, Barry Coyle, Pete Mulé, John Hagopian, Patrick Thompson, Luis Ramos-Izquierdo, and Bryan Blair "Global Ecosystem Dynamics Investigation (GEDI) instrument alignment and test", Proc. SPIE 11103, Optical Modeling and System Alignment, 1110308 (30 August 2019); https://doi.org/10.1117/12.2532471

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available