The adaptive control of optical beam jitter

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Author
Watkins, R. Joseph
Date
2004-12Advisor
Agrawal, Brij N.
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Show full item recordAbstract
Acquisition, Tracking and Pointing (ATP) of space and airborne optical beams is becoming an important research topic as the requirements for the control of the beam is increasing. Arc-second accuracy and nano-radian jitter coupled with stringent pointing requirements test the limits of control systems. A unique Laser Jitter Control
Testbed was built in order to study means to correct disturbances in a laser relay system. A new technique, the Adaptive Bias Filter (ABF), applies a compensating bias to the reference
signal for the adaptive filter, allowing rapid convergence in correcting narrowband disturbances. A second technique, the Adaptive Delay Filter (ADF), was applied in a new way
to the adaptive control systems to better correlate the error signal with the reference signal. Experiments using these techniques effectively demonstrated the usefulness of the new control methods, including the use of a combination Linear Quadratic Regulator (LQR) and LMS/ABF
filter to remove disturbances caused by colored noise injected into an optical beam. The combination controller results in a 38 dB decrease in jitter caused by a 50 Hz vibration and a 10
dB decrease in an 87 Hz vibration of the supporting platform, and an overall 75% improvement in the broadband jitter experienced by the optical beam.
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This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.Collections
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