Abstract

A laboratory prototype bathyphotometer for the measurement of bioluminescence in the ocean has been developed and tested. The instrument is designed to collect the light emitted by bioluminescent organisms stimulated by turbulent flow in the measurement chamber. The main features of the design include a mirrored measurement chamber and a totally internally reflecting light funnel which are used to efficiently channel the light into an optical fiber. The goal of the design effort is to develop an expendable instrument which eliminates costly and power consuming electronics in situ, concentrating these components on the deployment platform (e.g., PMT detectors). The optical components must collect light from a distributed, noncollimated source and reduce it to an area and distribution compatible with the size and numerical aperture of the collecting fiber. For a nonimaging system, it can be shown that light tapers (i.e., cones) provide the maximum capability for light collection. A comparison of various cone types and shapes is made including mirrored and solid transparent cones. A computer program has been developed to analyze the light collecting properties of the optical components including the reflecting tube, lenses, cones, and fibers. In particular, the full ray path solution for off-axis and/or distributed sources has been treated, i.e., nonparaxial and nonmeridional (skew) ray paths are calculated. The results of this analysis are discussed. The experimental measurement chamber allows water to be pumped through a grid at its entrance to measure the bioluminescence of organisms introduced to the flow.

© 1989 Optical Society of America