Optical Phase Estimation from Integrated Samples of the Heterodyned Wavefront.
Abstract
A method for using integrating detectors to estimate the phase of an optical wavefront is investigated. The phase and amplitude are assumed to vary slowly compared to the integration time and the integrated samples are shown to be corrupted by white gaussian noise. A maximum a-posteriori nonlinear Kalman filter is derived and simulated for both constant and random walk phase processes. The performance of the filter is compared to its Cramer-Rao lower bound and a first order linearized phase-locked loop (PLL). The filter never performs a great deal better than the PLL, but it can be implemented in a low bandwidth system whereas the PLL assumes a wideband system. The local oscillator is initially assumed to be stabilized in frequency and amplitude, and later a frequency shift is introduced. The filter manages to acquire and track the phase in a high carrier-to-noise ratio (CNR) environment although it does not estimate the frequency shift well. At 30 db CNR, the phase is estimated within about 0.02 radians, whereas the frequency shift estimation error is on the order of 500 kHz for frequecy shift of 2MHz. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1980
- Accession Number
- ADA100821
Entities
People
- Martin B. Mark
Organizations
- Air Force Institute of Technology