Project Title:

Digital, Optical Phase-Lock-Loop for Non- Destructive Evaluation

04.06-0318
NAS1-19032
Digital, Optical Phase-Lock-Loop for Non-	Destructive Evaluation
Systems & Processes Engineering Corp.
	1406 Smith Road, Suite A
	Austin, TX 78721
		Gary B. McMillian
(512-385-0318)

Abstract:

	The company has developed an innovative design for a digital, optical phase-lock-loop
(DOPLL) for measurement of strain, displacement, or vibration in non-destructive
evaluation applications. The technique offers a number of advantages over previous
analog phase-lock-loop designs. The digital system is capable of seeking multiple
lock-points under software control and successively refining the measurement precision
by seeking lock points at higher modulation frequencies. The digital system has a
broad operating bandwidth through use of a digital frequency synthesizer in place
of a bandwidth-limited voltage-controlled oscillator. The digital system is capable
of significantly faster operation, since the precise modulation frequency is known
at phase lock and no precision measurement is required to determine frequency. The
design is relatively insensitive to the path of the intensity-modulated light, and
a common DOPLL path length measurement system can be utilized with a number of sensor
types, each connected via fiber optics.

Potential Commercial Application:

Potential Commercial Applications: The DOPLL design can be utilized for non-destructive
evaluation and monitoring of aging aircraft structural integrity. The basic DOPLL
design also has applications in direction finding, beam steering, and communications.