Angle of Arrival Detection Through Artificial Neural Network Analysis of Optical Fiber Intensity Patterns
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING
Pagination or Media Count:
The optical sensors of United States Air Force reconnaissance vehicles, such as satellites, are subject to temporary or permanent blinding from hostile or threat laser radiation. By detecting and determining the angle of arrival AOA of the hostile radiation, the reconnaissance vehicle may be able to protect its optical sensors by taking evasive maneuvers or by shutting down the optical sensor such as closing a shutter until the threat has passed. In addition, the vehicle can relay information to its ground terminal allowing the intelligence community to determine the source of the hostile laser radiation. This thesis demonstrated that an intensity pattern out of a short piece of optical fiber could be used to determine the angle of arrival AOA, to within 0.1 deg, of the incident laser energy on the front of the optical fiber. The optical fiber was a one-inch-long, 3mm-diameter, multimode, step-index, plastic fiber. The optical fiber was mounted to the front end of a charge injection device CID camera. The CID cameras angle with respect to the incident laser energy, a uniform amplitude plan wave, would be varied by a computer controlled rotational stage. The output of the CID camera was captured by Spiricon software. Captured outputs representing various AOAs were processed to provide template or test feature vectors. The processing method used a fast Fourier transform routine to create a 24 component low frequency feature vector. Two classification methodologies were used a Euclidean distance method and a radial basis function neural network.
- Optical Countermeasures
- Fiber Optics and Integrated Optics