Importance

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Abstract

A mobile apparatus for detecting reflectivity of markers on a roadway surface is disclosed. The apparatus includes a vehicle and an elongated shroud assembly which has mounted therein a light source for directing light toward a marker and a light receptor for detecting light reflected from the marker, as the apparatus moves along the roadway surface. An aperture housing is mounted to the shroud and light directed to and reflected from the marker must pass through the aperture housing. In one embodiment the shroud is pivotally connected at one end to the vehicle and positioning means are provided for maintaining that portion of the shroud which will normally overlie the marker when light is reflected therefrom at a uniform and preselected height from the roadway surface. In another embodiment, the shroud is rigidly fixed to the vehicle, but the aperture is constructed to 'float' at a uniform and preselected height from the roadway surface. By so uniformly positioning the aperture housing or a point on the shroud, the length of the light path from the source to the marker and back to the receptor is maintained substantially constant, regardless of vertical movement of the light source relative to the roadway surface due to bouncing, irregular road surfaces, etc.

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First Claim