Laser based tracking device for detecting the distance between a vehicle and a roadway marker

Claim 1

A laser tracking device for determining the distance between a vehicle and a roadway marker on the surface of a roadway, comprising: a laser diode for generating and transmitting a laser beam; a rotating polygonal mirror coupled to a controllable motor, said mirror being located within an optical path of said laser beam, for sweeping said laser beam across said roadway surface, said mirror also receiving a reflection of said laser beam back from said roadway surface, and directing said reflected laser beam to a receiver means; master clock means coupled to said controllable motor for generating a first timing signal and issuing a series of timing pulses when said laser beam starts to sweep across said roadway surface; counter means coupled to said master clock means, said counter means beginning to count said timing pulses when said master clock means generates said first timing signal, said counter means continuing to count said timing pulses concurrently as said laser beam sweeps across said roadway surface; wherein said receiver means generates a second timing signal when said reflected laser beam is incident on it, and wherein said counter ceases counting upon said generation of said second timing signal; and microprocessor means coupled to said receiver means and said master clock means for analyzing the number of said timing pulses counted by said counter means between generation of said first and second timing signals so as to calculate a distance between said tracking device and said roadway marker.

Claim 4

A method for determining the distance between a vehicle and a roadway marker, comprising the steps of: (a) generating a laser beam; (b) sweeping said laser beam across a roadway surface; (c) generating a first timing signal and a series of timing pulses when said laser beam starts to sweep across said roadway surface; (d) counting said timing pulses concurrently as said laser beam sweeps across said roadway surface; (e) receiving a reflection of said laser beam from said roadway marker on said roadway surface; (f) generating a second timing signal when said reflection is received; (g) stopping the count of said timing pulses when said second timing signal is generated; (h) analyzing the number of said timing pulses counted between generation of said first and second timing signals so as to determine the distance between said vehicle and said roadway marker.

Claim 5

A method for determining the distance between a vehicle and a roadway marker, comprising the steps of: (a) generating a laser beam; (b) sweeping said laser beam across a roadway surface; (c) generating a first timing signal and a series of timing pulses when said laser beam starts to sweep across said roadway surface; (d) counting said timing pulses concurrently as said laser beam sweeps across said roadway surface; (e) receiving a reflection of said laser beam from said roadway marker on said roadway surface; (f) generating a second timing signal when said reflection is received; (g) stopping the count of said timing pulses when said second timing signal is generated; (h) analyzing the number of said timing pulses counted between generation of said first and second timing signals so as to determine the distance between said vehicle and said roadway marker.