Efficient framework for the examination of the field of view sensitivity of a field-widened birefringent interferometer.

An efficient approach is presented that allows the field of view sensitivities of a field-widened birefringent interferometer constructed from several stacked birefringent slabs to be examined. The approach utilizes a Jones matrix framework that is valid for birefringent slabs that have their optic axis parallel to the surface of the slab. It neglects Fresnel effects and multiple reflections, but accounts for birefringent splitting and does not neglect higher-order angular effects. The simplified approach allows the angular sensitivity of the optical path difference near the field-widened configuration to be examined in the presence of misalignment and mismatches between the components. Understanding these effects is critical to developing wide-field interferometers that can be utilized for imaging purposes. Here, we present the developed framework and apply it to examine the field of view effects of a three-element field-widened static birefringent interferometer that is being developed for the measurement of upper atmospheric winds. We examine the sensitivity of the device to rotational misalignment, mismatches, and wavelength shifts. Comparisons among the modeled interference fringes, output from Zemax optical design software, and lab observations are used to validate the approach. It is also shown that the approach accurately simulates parasitic fringes associated with unwanted coupling between extraordinary and ordinary waves at the interfaces.

Measurement of water vapor using an imaging field-widened spatial heterodyne spectrometer.

Spatial heterodyne spectroscopy (SHS) has been successfully applied to measure variations in water vapor pressure in the lab. An imaging system is combined with a monolithic field-widened SHS to observe a white-light source through a 1 m length water vapor cell that is designed to produce predictable variations in the water vapor pressure. The performance of the spectrometer design is examined by comparing spectra simulated using a radiative transfer model to observed spectra at several cell pressures. The intended application of the instrument to vertically resolve the water vapor profile in the upper troposphere and lower stratosphere using limb-scattered radiation in a vibrational band of water (1363-1366 nm) is also introduced.

First mesospheric wind images using the Michelson interferometer for airglow dynamics imaging.

The Michelson interferometer for airglow dynamics imaging (MIADI) is a ground-based instrument that combines an imaging capability with the Doppler Michelson interferometry in order to remotely detect motions in the mesopause region using spectrally isolated airglow emissions: the O(S1) emission at 557.73 nm and the OH (6, 2) P1 (2) at 839.918 nm. A measurement and analysis approach has been developed that allows simultaneous images of the line-of-sight Doppler wind field and irradiance field to be obtained. A working field instrument was installed and tested at a field site outside Fredericton, NB (45.96 N, 66.65 W) during the summer of 2014. Successful measurements over a 6 h period were obtained on 31 July 2014. This paper describes the MIADI measurement and analysis approach and presents the work that has been done to extract images of the line-of-sight Doppler wind field and irradiances from these observations. The imaging capability is validated by identifying the presence of large-scale and small-scale geophysical perturbations in the images.