Tech Briefs Magazine - October 2023 - 45

and experiments. During this time, OGS1
and OGS-2 will act as simulated users,
sending data from one station to LCRD
then down to the next. These tests will allow
the aerospace community to learn
from LCRD and further refine the technology
for future implementation of laser
communications systems. After the experimental
phase, LCRD will support inspace
missions. Missions, like a terminal
on the International Space Station, will
send data to LCRD, which will then beam
it to OGS-1 or OGS-2.
LCRD is a hosted payload on the Department
of Defense's Space Test Program Satellite-6
(STPSat-6). While LCRD is a laser
communications payload, the spacecraft
will still have a radio frequency connection
to the ground. The Payload to Ground
Link Terminal (PGLT) located at the
White Sands Complex near Las Cruces,
New Mexico, will communicate tracking,
telemetry, and command data to the spacecraft
over radio waves. NASA manages
LCRD's ground elements - OGS-1, OGS2,
and PGLT - out of LCRD's mission operations
center at White Sands.
" The mission operations center is the
central brains of the LCRD system, " said
Miriam Wennersten, LCRD's ground segment
manager of NASA Goddard. " It coordinates
the configuration of the payload
and all three ground stations at the same
time, scheduling the various optical services
and links. "
Without ground infrastructure, extraorresearchers
on Earth.
to
dinary science and exploration data would
not make it
LCRD's ground segment will be critical to
the success of the mission, providing engineers
with the opportunity to test and refine
laser communications. In turn, LCRD
will usher in a new era of laser communications,
where missions will have unprecedented
access to insights gleaned from satellites
and probes in space.
For more information, contact Ian J.
O'Neill at ian.j.oneill@jpl.nasa.gov.
Multi-Spectral Imaging Pyrometer
A solid-state broadband infrared imaging system with high dynamic range.
Langley Research Center, Hampton, VA
I
nnovators at NASA Langley Research
Center have developed a multi-spectral
imaging pyrometer utilizing tunable optics.
The system uses a conventional infrared
imaging camera as the basis and then
incorporates an ultrafast, all solid-state,
tunable optical filter combined with
unique data processing algorithms to
function as a multi-color ratio pyrometer
but with true imaging capabilities.
Currently, there is no way to provide
automatic, independent, emissivity-based
temperature corrections at
the pixel level for infrared cameras that
operate with broadband detectors. Multiwavelength
pyrometric systems can
make emissivity-corrected temperature
measurements but are not imaging devices
and lack the ability to view surface
gradients and other subtle variations.
Optical systems that measure at several
discrete wavelengths require the use
of multiple optical filters and are slow,
bulky, and require high power.
This NASA technology transforms a
conventional infrared (IR) imaging system
into a multi-wavelength imaging pyrometer
using a tunable optical filter. The
actively tunable optical filter is based on
an exotic phase-change material (PCM),
which exhibits a large reversible refractive
index shift through an applied energetic
stimulus. This change is non-volatile, and
no additional energy is required to maintain
its state once set.
The filter is placed between the scene
and the imaging sensor and switched between
user-selected center-wavelengths
Tech Briefs, October 2023
IMAGE iλ2
10
iλ2
SCENE
λ2
5
i Qmax
λ1
10
High-T range image
TUNABLE
OPTICAL FILTER
λ1-λ2
λ1
iλ2
iλ2
i
=TEMPERATURE
λ1
1
i Qmin
λ1
6
HDRi (high dynamic range)
IMAGE iλ1
1
Low-T range image
Representation of the algorithm used to create a high dynamic range infrared (HDRi) image.
(Image: NASA)
to create a series of single-wavelength,
monochromatic, two-dimensional images.
At the pixel level, the intensity values
of these monochromatic images represent
the wavelength-dependent, blackbody
energy emitted by the object due to
its temperature. Ratioing the measured
spectral irradiance for each wavelength
yields emissivity-independent temperature
data at each pixel.
The filters Center Wavelength (CWL)
and Full Width Half Maximum (FWHM),
which are related to the quality factor (Q)
of the filter, are actively tunable on the order
of nanoseconds-microseconds (GHzMHz).
This behavior is electronically
controlled and can be operated time-sequentially
(on a nanosecond time scale)
in the control electronics, a capability not
www.techbriefs.com
possible with conventional optical filtering
technologies.
The technology has applications in
aerospace: imaging and analysis of rocket
plumes, combusting flows, and heat
shields; metals manufacturing: process
monitoring the melting of metallic ores
in mixed states or the formation of surface
slag; welding: accurate imaging of
weld pool temperatures; and kiln processing:
process monitoring in cement kilns.
NASA is actively seeking licensees
to commercialize this technology.
Please contact Licensing Concierge at
Agency-Patent-Licensing@mail.nasa.gov
or call at 202-358-7432 to initiate licensing
discussions. For more information,
visit https://technology.nasa.gov/patent/
LAR-TOPS-362.
45

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Tech Briefs Magazine - October 2023

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