Photonics technologies are helping improve agriculture in several ways: 1) Infrared sensing helps determine soil health and hydrology while 3D laser scanning allows non-destructive measurement of soil density. 2) Remote sensing from planes and satellites estimates crop yields and monitors plant health through measurements of chlorophyll, nitrogen levels, and evapotranspiration. 3) Fiber optic sensors and spectroscopy determine sugar levels in grapes to optimize harvest times and ensure food safety.

1. July 2009
Agri-Photonics
Agriculture improves with
photonics technologies
Advancing the Laser
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2. Photonics technologies are helping
farmers, food processors, and famine-
plagued areas of the world.
By Beth Kelley
14 SPIE Professional July 2009

3. F
Farming strategies and technologies have networks and surface characterization.
changed and adapted over the millennia to new The USDA-ARS lab also conducts studies
environments, new crops, and new needs. Now, on how water moves through soil and what farm More Info
optical and photonic technologies are helping contaminants might get carried with it. Remote Learn more online about
to make soil stronger, grapes sweeter, and food sensing using narrow spectral bands has produced how your food is scanned,
safer to eat. the best results, Kustas says. poked, squashed, lased,
Lasers and imaging sensors mounted on planes, “Estimation of large-scale surface soil moisture and radiated all before it
fluorescence spectroscopy, lidar, and energy has the potential to improve growing season gets to your plate. Login to
numerical weather prediction accuracy over spie.org/spieprofessional
efficient LEDs are just some of the latest farming
for the extended online
and food processing tools in the emerging field a broad swath of global agricultural areas,” version of this article where
of optical farming, or agri-photonics. Photonics says Kustas. “Such improvements would be of you’ll find links and other
technologies can help predict protein levels in enormous value for agricultural management information about related
wheat harvests, determine when to harvest grapes, applications for the farmer.” technical articles in the
map water quality to observe the health of fish Because water is a particularly important SPIE Newsroom and the
stocks, and screen for contaminants in spinach, farm commodity in arid areas, whether for SPIE Digital Library.
tomatoes, and other foods. large commercial operations in California
or small farms in Africa, Jan Kleissl of the
From the Ground Up University of California, San Diego, developed
Infrared sensing technologies now play key a method of measuring the sensible heat flux
roles in determining the health of soil, nutrient in agricultural fields using laser scintillation.
content, and the hydrology of a particular Originally developed for military application,
agricultural area. Kleissl’s method infers how much heat is emitted
The U.S. Department of Agriculture is a from the scintillation observed.
major player in research and development of “The sensible heat flux is inversely proportional
techniques to determine soil health and to evapotranspiration,” Kleissl says. “The
hydrology. Bill Kustas of the USDA more available soil moisture, the more
Agricultural Research Service, evapotranspiration.”
Hydrology & Remote Sensing Lab,
says drought information “is being Continued on page 16
requested at increasingly high
spatial resolution to assist in yield
forecasting, drought mitigation
and crop loss compensation
efforts.”
The lab uses microwave
radiometry to measure
surface soil moisture. It
Photo courtesy of David Lamb
also uses thermal infrared
remote sensing for mapping
evapotranspiration because
it does not require ancillary
information about rainfall
or soil moisture holding
capacity. This makes it
well-suited for application
in areas lacking extensive David Lamb’s lab has fiber optic color sensors to measure sugar levels in
precipitation monitoring wine grapes.
July 2009 SPIE Professional 15

4. Continued from page 15 wavebands to estimate crop yield and soil carbon sequestration.
“We have also used NASA’s AVIRIS hyperspectral reflectance
This method could be very cost effective for large-scale data (400 –2600 nm) for mapping canopy chlorophyll content,”
evapotranspiration monitoring. “Currently the system is best Kustas says.
used in conjunction with statewide efforts to calibrate satellite David Lamb and his colleagues at the University of New
remote sensing maps that then can be used by every farmer in England, Australia, use remote sensing methods such as spectrum
the state,” he says. “For this, only about 10 measurement sites and Advanced Spaceborne Thermal Emission and Reflection
in the whole state would be necessary.” Radiometer (ASTER) imaging to test nitrogen content in
Another challenge for agri-photonics is measuring soil health, soil, and indirectly the protein content of crops like wheat.
often indicated by soil bulk density. Soil bulk density is often Nitrogen levels in leaves influence chlorophyll concentration
used as an indication of ease of root growth, water concentration, and therefore reflectance, making it easy to take remote sensing
and overall usability and quality. Ann Rossi at the University measurements of the amounts of nitrogen in plants.
of California, Riverside, has developed a 3D laser technique to Wheat is a major crop in northern China, and higher crude
monitor soil density. Low bulk densities suggest more organic protein content makes the wheat more valuable, both to
matter and therefore more nutrient-rich soil. consumers and farmers. The ability to forecast grain quality by
Previously, soil density was measured by water displacement, NRI (nitrogen reflectance index), and thus estimate market
weight, and other methods that require destruction of the soil potential for winter wheat harvest, allows farmers to make
clod. Rossi’s scanner automatically rotates the dirt clod sample operating decisions and adjustments before the wheat goes
and assembles the individual scans to create a 3D model. to market.
“The main advantage of the 3D laser scanning method over Lamb is also looking at ways to analyze wine grapes, a
the ‘clod method’ is that it is non-destructive,” says Rossi. “The huge cash crop in Australia and other parts of the world.
same clod can be used for multiple analyses. 3D laser scanning He uses fiber optics to measure sugar levels in individual
can provide a more precise method of quantifying the size and grapes. Differences in a grape’s sugar concentration create an
shape of soil aggregates.” The 3D scanner is also more portable absorption spectrum that correlates with ripeness. Using fiber
than the clod method and can be easily transported and used optics for measurements is less destructive than creating a grape
in the field. slurry, he notes, as was done previously. And it can provide
crucial information of when to harvest.
Measuring Crop Health
Crop health and overall production can also be measured Ensuring a Safe Harvest
by photonics technologies. Ensuring that food, drink, and pharmaceuticals are all safe for
Kustas says his teams at the USDA have been using remote consumption is another way that photonics plays an important
sensing data in the visible, near-infrared, and thermal-infrared role in enhancing life on the planet.
Lasers and telescopes are used in optical
farming to detect evapotranspiration and
help farmers decide when to irrigate.
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16 SPIE Professional July 2009 fJ
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5. Farming
With LEDs
The ability to grow vegeta-
bles and fruits indoors using
energy-conserving light
sources makes it possible to
cultivate crops year round
in famine-plagued desert
regions or the Arctic.
Blue and red LEDs have
(Photos courtesy of David Lamb) been found to be extremely
effective sources of light for
Left: An airplane-mounted passive imaging sensor with four filters allows David Lamb to create com- indoor farming and are be-
posite images using any combination of blue, green, red, and near infrared wavebands. Right: Lamb’s coming increasingly popular
team uses an active sensor on a small plane that flies low over the fields. in Asia.
Recent innovations in spectral imaging sensors as an indicator of flavor, and analyzing the oxygen • Hiroyuke Watanabe of
Tamagawa University near
have enabled improved food safety and food content of salad dressings. Its Jaz unit is a modular,
Tokyo has reported that
quality inspections with ruggedized in- or at- handheld spectroscopy platform. red LEDs promote root
line processing monitoring and direct real-time Ocean Optics is also developing a new growth, while blue LEDs
monitoring at a high volume. approach to multispectral imaging that has promote chlorophyll pro-
“There is a compelling need to improve process potential for use in food and drug processing, says duction and leaf growth.
capabilities with proven technology advances in Jason Eichenholz, Ocean Optics’ CTO. • In March, Seoul Semicon-
order to maintain a safe food supply,” says David “In both food and drug processing, miniature ductor supplied 300,000
Bannon, CEO of Headwall Photonics. spectroscopy is especially useful because flexibility blue and red LEDs for the
Headwall Photonics is working with the USDA, in detectors, light sources, and sampling optics LED Farming Demonstra-
including the USDA-ARS lab, to investigate allows for rapid implementation of instrumentation tion Project sponsored by
into the process, and it makes it much simpler to the Ministry of Economy,
the spectral characteristics of crops through the
Trade & Industry of Japan.
utilization of near infrared (900–1700 nm) and optimize setups,” Eichenholz says.
There are currently six
short-wave infrared (1000–2500 nm) sensors. A operating plant factories in
new imaging system, the Hyperspec™ Starter Kit, a Future Farming With Optics Japan.
device for which Headwall Photonics was a finalist Much of the agri-photonics technology is • The Rural Development
in the 2008 Prism Awards for Photonics Innovation, already on the production line or in farmers’ Association of Korea says
is customized for agricultural researchers to combine hands, and provides information that farmers can cultivating crops with sup-
the critical analytical technologies of reflectance apply directly to their crops. plementary lighting (LEDs)
and fluorescence spectroscopy. The National Center for Computational over approximately 3,000
The kit can be used to identify levels of bruising Hydroscience and Engineering (NCCHE) at the hectares will save 70% of
in fruits and vegetables, pharmaceutical quality, and energy use compared to
University of Mississippi and the USDA-ARS incandescent lamps.
bacterial contamination, all critically important in are developing a decision support system for land
the $50 billion market for specialty foods like fresh managers and farmers to help them optimize
and dried fruits, vegetables and nuts. their conservation practices. Water quality
(Photo courtesy of Seoul Semiconductor)
BaySpec debuted its food inspection device, surrounding farms can be degraded by pesticides
SAFEINSPECT at SPIE Defense, Security, and and livestock waste, and the new system will
Sensing in April. This hand-held device is a integrate watershed models with a sophisticated
Volume Phase Grating-based dispersive Raman channel erosion model (CCHE1D-3.0).
system with no moving parts that can be easily Many of these optical technologies can also be
transported to the field or border inspection point employed on other applications. Kleissl believes
to check authentication, traceability, and quality his laser scintillation system would also be useful
control. No sample preparation is required. to monitor urban heat islands, the heat emitted
Eric Bergles, vice president of sales and marketing at from urban areas into the atmosphere. It could be
BaySpec, says the new device is a non-destructive and used to quantify the effect of urban heat island
affordable way to make spectroscopic measurements mitigation measures such as tree planting.
compared to mass spectrometer and conventional “The number and market size of spectroscopy Energy-conserving blue and
FTIR approaches. instruments is expected to grow exponentially,” red LEDs have been used to
Ocean Optics has used miniature spectroscopy for says Bergles. grow plants indoors all year
applications such as monitoring the sugar content of round.
fruits and vegetables, measuring the color of wines –Beth Kelley is an SPIE editor.
July 2009 SPIE Professional 17