Accession Number : ADD000178

Title :   Direct Measurement of Ship Body Distortion Using a Laser Beam.

Descriptive Note : Patent,


Personal Author(s) : Cook,George W ; Milne,David T

Report Date : 05 Feb 1974

Pagination or Media Count : 9

Abstract : The patent relates to an alignment detector whereby a laser light beam is directed to a cruciform target containing a series array of photo detectors on each arm. The light beam is perpendicular to the cruciform and is orbited about the cruciform center. A differential pulse width modulated (DPWM) wave is generated by the signals emitted from the photo detectors each time they are illuminated by the light beam. The output of the photo detectors are connected to bistable flip-flops which are triggered into positive and negative states and whose pulse width depends upon the time for the rotating laser beam to travel between two arms displaced from each other by a 180 degrees of arc. Angular distortions in the X axis and the Y axis are separately measured by two pairs of arms, the arms of each pair being displaced 180 degrees from each other. The width of the pulse is proportional to the angular distortion.

Descriptors :   *Ship hulls, *Distortion, *Laser beams, *Patents, Alignment, Displacement, Photodetectors

Subject Categories : Marine Engineering
      Test Facilities, Equipment and Methods

Distribution Statement : APPROVED FOR PUBLIC RELEASE