Avo Photonics built the laser for the observatory. “Here you have the challenges of spaceborne ruggedness needs, on top of submicron-level optical alignment tolerance requirements. These really push your optical, thermal, and mechanical design chops,” Avo Photonics President Joseph L. Dallas said. “In addition, the narrow linewidth, low noise, and overall stability needed for this mission is unprecedented.” Photonics pioneer Tom Kane invented the monolithic laser oscillator technology that Goddard used to stabilize the frequency of the laser light. “Your average laser can be very messy,” Kane said. “They can wander all around their target frequency. You need a ‘quiet’ laser that’s exactly one wavelength and a perfect beam out to 15 decimal places of accuracy.” His oscillator technology uses feedback loops to keep the laser burning at such precision. “The wavelength ends up becoming the ruler for these incredible distances,” Kane said.
The high-power, low-noise amplifier came from Fibertek. Fibertek also contributed to NASA’s Ice Cloud and Land Elevation Satellite (ICESat) 2 and the CloudAerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), which has been operating a laser pointed at Earth for 15 years. Including time for testing on the ground and potential mission extensions, LISA’s lasers must operate without skipping a hertz for up to 16 years, Goddard’s Yu said. “Once launched, they will need to be in 24/7 operation for five years for the initial mission, with a possible six to seven years of extended mission after that,” Yu explained. “We need them to be stable and quiet.” v CONTACT Anthony.W.Yu@NASA.gov or 301-614-6248
Goddard Lab an Ideal Nursery for Lasers to Probe the Mysteries of the Cosmos Photo credits: NASA/Matt Mullin
At Goddard’s Space Laser Assembly Cleanroom (SLAC), the Laser and Electro-Optics Branch is building lasers for NASA’s Dragonfly mission to Saturn’s moon Titan and the European Space Agency’s (ESA) Laser Interferometer Space Antenna (LISA), which will measure waves in space-time caused by massive collisions. Goddard’s SLAC is a center of expertise for the art and science of building lasers for advanced instruments to explore exotic and extreme environments, including those that will be investigated by Dragonfly and LISA, both of which were developed with the help of Goddard Internal Research and Development, or IRAD funding. Lasers are difficult — they don’t “want” to work, Goddard Physicist Barry Coyle said. “Everything has to perfect. It’s like you’re balancing an egg on its end; it always wants to not work. You’re harnessing photons (particles of light) to do what you want — that’s very hard.” That’s why assembling them in one place is so critical to efficiency in production and cost. This is the
www.nasa.gov/gsfctechnology
This is the SLAC thermal vacuum chamber used to conduct environmental testing on space-flight class laser systems. The ICESAT-2 and GEDI lidar mission made use of this chamber for qualification and risk reduction testing. The flight and engineering model Dragonfly Mass Spectrometer (DraMS) Lasers as well as the engineering model LISA laser will be tested in the SLAC.
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cuttingedge • goddard’s emerging technologies
Volume 18 • Issue 1 • Fall 2021
