Engineering Commons^™

Frequency-Mixing Detection Of Polarization-Modulated Light Using Different Periodic Analyzers, R.M.A. Azzam

Department of Electrical and Computer Engineering: Faculty Publications

We derive the equations that permit the use of six different periodic analyzers for the frequency- mixing detection (FMD) of polarization -modulated light. The six periodic analyzers are (1) the rotating linear analyzer, (2) rotating half -wave plate and fixed linear analyzer, (3) rotating quarter -wave plate and fixed linear analyzer, (4) rotating linear analyzer and fixed linear analyzer, (5) oscillating -phase retarder and fixed linear analyzer, and (6) oscillating optical rotator and fixed linear analyzer. In all cases, the average polarization and the polarization and intensity modulation parameters of the light beam can be determined easily and explicitly from …

High-Bandwidth Attitude Jitter Determination For Pointing And Tracking Systems, Marcelo C. Algrain

Department of Electrical and Computer Engineering: Faculty Publications

For many reasons smaller spacecraft are becoming more appealing. Because of their lower inertias, these spacecraft are more sensitive to disturbances and likely to have more attitude jitter than the larger units. These jitter levels are unacceptable for some scientific instruments and need to be compensated. In the case of line-of-sight type instruments, the attitude jitter can be mitigated by incorporating a fast steering mirror into the system. To take full advantage of these devices, the spacecraft attitude must be measured at sufficiently high bandwidth, well beyond what is commonly provided by inertial reference units. Various ways to obtain higher …

An Intercomparison Of Two Tunable Diode Laser Spectrometers Used For Eddy Correlation Measurements Of Methane Flux In A Prairie Wetland, David P. Billesbach, Joon Kim, R.J. Clement, S.B Verman, F.G. Ullman

Department of Electrical and Computer Engineering: Faculty Publications

An intercomparison was made between two tunable diode laser spectrometers used to measure methane fluxes by the eddy correlation technique at a prairie wetland site. The spectrometers were built by Unisearch Associates Inc. of Concord, Ontario, Canada, and Campbell Scientific Inc. of Logan, Utah, and were models EMS-50 and TGA-100, respectively. The fluxes were found to agree very well with each other in the range of 0 to 42 mg 􏰑 m-2 h-1.

The TGA-100 was observed to exhibit offset drifts. Most of the time, when the offset was only slowly changing (as compared to the eddy correlation averaging time), …