Frequency-Agile Single Frequency Lasers.

A key innovation on SPARCLE [the Space Readiness Coherent LIDAR Experiment] was the development of environmentally “ruggedized” (temperature- and vibration-insensitive) single-frequency lasers, as needed for injection-seeding lasers in a space-borne environment. These lasers were also frequency-offset locked to each other over a 10GHz range, which is suitable for correcting for space platform motion in coherent detection systems.

INNOVATION

Coherent Technologies Inc.Lafayette, Colorado

SmallBusinessInnovation Research

GOVERNMENT/SCIENCE APPLICATIONS SPARCLE provided the government with a detailed design for a

coherent Doppler wind LIDAR suitable for global wind measurement from the Space Shuttle using the Hitchhiker Accommodation System.

The “ruggedized” and frequency-agile laser designs established on SPARCLE are being applied to other government contracts/activities by way of CTI’s METEOR® product line, where a single-frequency laser is being used as part of a larger system. Examples include systems being developed at CTI for coherent carbon dioxide DIAL measurements for NASA and vibration imaging of hard targets for military applications.

Marshall Space Flight CenterSubtopic: 8.03, LIDAR Remote Sensing Technology August 2002

LIDAR Technologies Benefiting from SPARCLE

ACCOMPLISHMENTS Existing single-frequency laser designs at Coherent Technologies were ”ruggedized” for

operation from a space-based platform to survive expected Shuttle launch loads. Two such single-frequency lasers were frequency offset-locked with a 5 kHz step-size

resolution over a range of +/- 4.5GHz. The short-term frequency jitter of the locked laser matched that of the reference laser at <100kHz over a 5 meter/second (ms) timescale. No additional noise was introduced by the locking servo.

The frequency offset-locked laser was used to seed a 125mJ, 6Hz Q-switch pulsed Tm,Ho:YLF laser at 2051nm, generating bandwidth-limited pulses over the full +/-4.5GHz tuning range of the seed laser.

A detailed design was established for a coherent Doppler wind LIDAR transceiver, implementing the frequency-agile single-frequency lasers and the Q-switch pulsed Tm,Ho:YLF slave laser. The design was in accordance with the requirements set out in the Hitchhiker Customer Accommodations and Requirements Specifications (CARS) document for transporting and operating hardware on the Space Shuttle.

COMMERCIALIZATION The ”ruggedized” design of the single-frequency lasers developed on SPARCLE has been

adopted into CTI’s standard single-frequency laser METEOR® product line. While SPARCLE developed only lasers at 2051nm (suitable for seeding Tm,Ho:YLF), the METEOR ® product line has since been expanded under CTI and government funding to include a variety of materials, including Nd:YA, Yb:YAG, Yb,Er:glass.

Frequency-agile single-frequency lasers have not shown commercial benefit to date but are currently being applied to the area of carbon dioxide differential absorption LIDAR (DIAL), where significant commercial opportunity exists.

Contacts: MSFC, Tom Knight: 256-544-5353CTI, Mark Phillips: 303-604-2000, ext. 139

NAS8-40640 (1994 Phase II), NAS8-97320 ( Phase III), and

NAS8-98087 (Phase III)