Importance

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Abstract

A retroreflectivity measuring system measures performance data relating to a reflective surface, such as a highway stripe or marking containing reflective glass beads. A laser beam illuminates a portion of the reflective surface with radiation of a predetermined wavelength, the laser being incident on the surface at an incidence angle i. The incident laser beam is then reflected back, at least partially, at a particular observation angle o that is separated from the incidence angle by a divergence angle .delta.. A telephotomultiplier aimed at the illuminated area receives the reflected laser beam at the observation angle o. A preferred telephotomultiplier includes a telescope, a narrow pass optical filter for passing basically only the wavelength of the laser beam, and a sensitive photoelectric device, such as a multiplier phototube. The laser and the telephotomultiplier may be mounted on a servo-motor driven frame in order to scan the target area from a moving vehicle.

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First Claim