Stacked-grid Collimators Described with Dimensionless Parameters.

The properties of a one-dimensional stacked-grid collimator can be specified by two dimensionless parameters. This is useful because a two-dimensional collimator can usually be described as two one-dimensional collimators. Plots are given that show normal-incidence transmission and FWHM angular response in terms of these parameters. Transmission is calculated with Fourier optics instead of the Fresnel-Kirchhoff integral.

Model for generating global images of emission from the thermosphere.

A general model is presented for the production of images of thermospheric dayglow emissions. Ultraviolet images are generated that are relevant to remote sensing of the principal constituents of the thermosphere (O and N(2)) and the ionosphere (O(+)). The emission features considered here are 1356-Å (O), Lyman-Birge-Hopfield bands of N(2) between 1650 and 1715 Å, and 834 Å (O(+)). The MSIS-86 and International Reference Ionosphere models were used as climatological representations of the distributions of neutrals and ions, respectively. We describe the generation of the images beginning with the production of volume-emission-rate profiles. A detailed description of the generalized image-generation technique is given. This technique permits us to change the observer's altitude and viewing geometry without incurring a large computational burden. The images produced by this technique demonstrate the potential of airglow imaging systems for remote sensing of global variability in thermospheric composition.