Calibration and accuracy of optical slope measurements for short wind waves

Bernd Jaehne; Howard J. Schultz

doi:10.1117/12.138851

22 December 1992 Calibration and accuracy of optical slope measurements for short wind waves

Bernd Jaehne, Howard J. Schultz

Proceedings Volume 1749, Optics of the Air-Sea Interface: Theory and Measurement; (1992) https://doi.org/10.1117/12.138851
Event: San Diego '92, 1992, San Diego, CA, United States

Abstract

A thorough understanding of the hydrodynamics of short ocean wave is important for interpreting measurements made by active microwave remote sensing instruments. However, conventional methods for studying the structure of a water surface are not capable of resolving the fine scale structure of the surface, especially in the ultra-gravity and capillary wavelengths. Optical instruments have the potential for resolving the fine-scale structure of the ocean surface, however, methods for calibrating these instruments and verifying the accuracy of the measurements have not been developed. In this paper we describe a multi-faceted approach for verifying the accuracy and calibration of an imaging wave slope gauge (ISG). The first step is a thorough theoretical analysis of the geometrical optics and photometry. A detailed discussion on the relationship between surface slope and observed pixel intensity is presented. This discussion includes second order effects which may tend to bias the results. Secondly, calibration objects formed from thin transparent Perspex sheets with known slope and height profiles are retrieved. The results show that the measurements of the water surface shape are accurate enough to compute 2-D wave number spectra.

Citation Download Citation

Bernd Jaehne and Howard J. Schultz "Calibration and accuracy of optical slope measurements for short wind waves", Proc. SPIE 1749, Optics of the Air-Sea Interface: Theory and Measurement, (22 December 1992); https://doi.org/10.1117/12.138851

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