Abstract

Optical sensors sensitive over a narrow spectral region are used in oceanographic instruments where the extremes in dynamic range, both downward through the water column and spectrally from the UV to the red regions of the spectrum, require a high degree of assurance about reported data. These sensors are nonscanning and are thus designed to make measurements over a fixed spectral region centered at the nominal sensor wavelength. Because the output from a sensor results from the convolution of the sensor’s spectral response and the spectral distribution of irradiance, which changes radically with depth, a number of factors are optimized in the specification of the components. This is particularly true in the ultraviolet, where spectral leakage from longer wavelengths may significantly influence the output of a sensor at depth. Using a spectral convolution model, this paper presents some of the implications of spectral leakage on the design and operation of new UV oceanographic optical sensors. Three methods for evaluating sensor response are presented, including predictions of how these may be related to measurement of k, the diffuse attenuation coefficient.

© 1991 Optical Society of America