Accession Number : AD0686716

Title :   A MULTIPLE PURPOSE OPTICAL INSTRUMENT FOR STUDIES OF SHORT STEEP WATER WAVES.

Descriptive Note : Technical rept.,

Corporate Author : HYDRONAUTICS INC LAUREL MD

Personal Author(s) : Wu,Jin ; Lawrence,J. ; Tebay,E. S. ; Tulin,M. P.

Report Date : JAN 1969

Pagination or Media Count : 28

Abstract : An optical instrument, consisting essentially of a light source and a photomultiplier tube and utilizing the light reflection principle, has been designed and tested; it is capable of determining not only surface-slope, but also surface-curvature distribution. This instrument, supported by a beam and arm unit transversely over a wave tank, can be set at any desired inclination from the water surface. The photomultiplier tube receives light only when the angle of the sloping water surface from the horizontal is the same as the angle from the vertical of the plane containing the light source and the telescope. The focal spot of the telescope on the water surface is 0.4 mm in diameter. The image of this spot is partially bright when the curved water surface reflects part of the impinging light away from the telescope. The signal intensity, related to the surface from the telescope. The signal intensity, related to the surface curvature, is proportional to the ratio between the bright portion and the total area of the image. The distribution of the surface-slope is determined with the instrument set at different angles of inclination. As for the surface curvature, the relative frequencies of occurrence of light pulses of different intensities are determined with the instrument set at a particular inclination. Sample results are included to illustrate the applicability of the instrument. (Author)

Descriptors :   (*WATER WAVES, *OPTICAL INSTRUMENTS), INTERFACES, REFLECTION, PHOTOMULTIPLIER TUBES, WATER TANKS, INTENSITY, WIND

Subject Categories : Physical and Dynamic Oceanography
      Optics

Distribution Statement : APPROVED FOR PUBLIC RELEASE