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We describe a twin-prism stereoseparator for the Zeiss fundus camera which gives high-quality stereophotographs of the optic disc and simultaneously records both images on the same frame of film. The stereobase of photographs taken with this system ranges from 2.0 to 4.5 mm. It varies linearly with the entrance pupil which ranges from 4.0 to 6.5 mm. The instrument provides a reliable method for monitoring changes in optic disc topography.

A general nonlinear technique is described for determining wave slopes from photographs of an area of the ocean surface that is illuminated by diffuse skylight. This technique is evaluated using uniform, overcast, and bright sky radiance distribution models, and results from its use are compared with the approximate results obtained by previous authors. Under certain clearly defined practical experimental conditions, it is theoretically possible to determine the total wave slope magnitude at the ocean surface.

A gaussian beam from a CO(2) laser emitting at 10.6 mu was used to measure damage thresholds on rabbit cornea at exposure times of 55 msec, 10 msec, and 3.5 msec. A theoretical model of the radiation-tissue interaction is presented and compared with experimental data. The comparison suggests that a critical temperature exists above which lesions are caused by protein denaturation. The model is useful for establishing safe exposure levels within a limited exposure range.