HOLOGRAPHIC SCANNING HOLOGRAPHIC SCANNING LIDAR TELESCOPESLIDAR TELESCOPES

HOLOGRAPHIC SCANNING HOLOGRAPHIC SCANNING LIDAR TELESCOPESLIDAR TELESCOPES

Geary K. SchwemmerGeary K. Schwemmer

Laboratory For AtmospheresLaboratory For Atmospheres

NASA Goddard Space Flight NASA Goddard Space Flight CenterCenter

http://harlie.gsfc.nasa.gov/http://harlie.gsfc.nasa.gov/

OUTLINEOUTLINEOUTLINEOUTLINE

ObjectivesObjectives Applications & ESE Applications & ESE

ScienceScience Current State-of-the-ArtCurrent State-of-the-Art Current and Future Current and Future

DirectionsDirections

OBJECTIVEOBJECTIVEOBJECTIVEOBJECTIVE

Decrease weight, volume, and cost of Decrease weight, volume, and cost of scanning lidar receivers by factor of 3 – scanning lidar receivers by factor of 3 – 10 (and more) using Holographic Optical 10 (and more) using Holographic Optical Elements (HOEs)Elements (HOEs)

Combine with composite materials, Combine with composite materials, membrane optical flats, or aerogels for membrane optical flats, or aerogels for featherweight opticsfeatherweight optics

TARGET APPLICATIONSTARGET APPLICATIONSTARGET APPLICATIONSTARGET APPLICATIONS

DIRECT DIRECT DETECTION WIND DETECTION WIND LIDARLIDAR

TOPOGRAPHIC TOPOGRAPHIC MAPPERS MAPPERS (ALTIMETERS)(ALTIMETERS)

3-D ATMOSPHERIC 3-D ATMOSPHERIC STRUCTURE AND STRUCTURE AND DYNAMICS (CLOUD DYNAMICS (CLOUD AND AEROSOLS, AND AEROSOLS, TRACE SPECIES)TRACE SPECIES)

ESE Science ThemesESE Science Themes Global Change –atmospheric water vapor, topographic mapping:Global Change –atmospheric water vapor, topographic mapping:

– How are global precipitation, evaporation, and the cycling of water How are global precipitation, evaporation, and the cycling of water changing?changing?

– What changes are occurring in the mass of the earth's ice cover?What changes are occurring in the mass of the earth's ice cover? Variability Forcings – atmospheric aerosols & greenhouse gases, Variability Forcings – atmospheric aerosols & greenhouse gases,

topographic mapping : topographic mapping : – What trends in atmospheric constituents and solar radiation are driving What trends in atmospheric constituents and solar radiation are driving

global climate?global climate?– What changes are occurring in global land cover and land use, and what are What changes are occurring in global land cover and land use, and what are

their causes?their causes?– How is the earth's surface being transformed and how can such information How is the earth's surface being transformed and how can such information

be used to predict future changes?be used to predict future changes? Responses – cloud heights and fractions, topographic mapping, Responses – cloud heights and fractions, topographic mapping,

atmospheric pollutionatmospheric pollution– What are the effects of clouds and surface hydrologic processes on earth's What are the effects of clouds and surface hydrologic processes on earth's

climate?climate?– How is global sea level affected by climate change?How is global sea level affected by climate change?– What are the effects of regional pollution on the global atmosphere, and the What are the effects of regional pollution on the global atmosphere, and the

effects of global chemical and climate changes on regional air quality?effects of global chemical and climate changes on regional air quality? Consequences –topographic mapping :Consequences –topographic mapping :

– What are the consequences of climate and sea level changes and increased What are the consequences of climate and sea level changes and increased human activities on coastal regions?human activities on coastal regions?

Prediction – better weather and climate dataPrediction – better weather and climate data– How can weather forecast duration and reliability be improved by new How can weather forecast duration and reliability be improved by new

space-based observations, data assimilation, and modeling?space-based observations, data assimilation, and modeling?

Prototype Holographic Prototype Holographic Atmospheric Scanner for Atmospheric Scanner for

Environmental Remote Sensing Environmental Remote Sensing (PHASERS)(PHASERS)

Prototype Holographic Prototype Holographic Atmospheric Scanner for Atmospheric Scanner for

Environmental Remote Sensing Environmental Remote Sensing (PHASERS)(PHASERS)

http://www.anselm.edu/internet/physics/pic_diagram.htm

Holographic Airborne Rotating Holographic Airborne Rotating Lidar Instrument Experiment Lidar Instrument Experiment

(HARLIE)(HARLIE)

Holographic Airborne Rotating Holographic Airborne Rotating Lidar Instrument Experiment Lidar Instrument Experiment

(HARLIE)(HARLIE)

http://harlie.gsfc.nasa.gov

HOE LIDAR INSTRUMENTS

HOE

Fields of view

Foci SHared Aperture Diffractive Optical Elements (SHADOE)

5-HOE Pushbroom Lidar Imager Footprint

Technology Technology Development MilestonesDevelopment Milestones

Technology Technology Development MilestonesDevelopment Milestones 355 nm laboratory prototype for wind 355 nm laboratory prototype for wind

lidar applications.lidar applications. 1 meter diameter HOE for space1 meter diameter HOE for space SHADOE - several optically addressable, SHADOE - several optically addressable,

fixed look angles in one film. No moving fixed look angles in one film. No moving parts.parts.

Holograms applied to featherweight Holograms applied to featherweight composite or stretched membrane composite or stretched membrane substrates.substrates.

Backup slides followBackup slides follow

HOE LIDAR HOE LIDAR TRANSCEIVERTRANSCEIVER

Transmission HOE Transmission HOE used as a used as a scannable laser scannable laser collimating lens and collimating lens and receiver collecting receiver collecting lenslens

SummarySummarySummarySummary Rotating HOE Cuts size and weight of Rotating HOE Cuts size and weight of

scanning lidar receivers in 1/2 - 1/3.scanning lidar receivers in 1/2 - 1/3. Targeted Lidar MissionsTargeted Lidar Missions Demonstrated HOE performance for 355 Demonstrated HOE performance for 355

- 1064 nm wavelength systems- 1064 nm wavelength systems Two operating HOE lidars green and Two operating HOE lidars green and

near-IR (TRL 6)near-IR (TRL 6) Further reductions in weight, size, and Further reductions in weight, size, and

complexity using SHADOE (TRL 2)complexity using SHADOE (TRL 2)

HOE HOE PERFORMANCEPERFORMANCE

80-85% diffraction efficiency in 1st order

150-300 rad focal spots (87% of total energy in diffracted order)

1064, 1047, 905, 770, 532, 523, 355 nm wavelengths

up to 40 cm diameter, f/2.5

HOLOGRAPHIC OPTICAL HOLOGRAPHIC OPTICAL ELEMENT (HOE)ELEMENT (HOE)

Reflection HOEConstruction / reconstruction

Reference beam

Object beam