System for detecting ice or snow on surface which specularly reflects light
First Claim
1. Apparatus for detecting, on a surface which specularly reflects light, the presence of a polarization altering substance on said surface comprising:
- means for transmitting a pulse of light over a transmitting path to said surface;
means for receiving transmitted light;
a receiving path for said transmitted light from said surface and from said substance to said means for receiving;
means for splitting said transmitted light into a non-isolated portion and an isolated portion;
means for delaying one of said non-isolated portion and said isolated portion relative to another thereof to produce a first-to-arrive signal and a second-to-arrive signal;
said first-to-arrive signal being completed at an output of said means for delaying before said second-to-arrive signal arrives at said output;
means for measuring a first intensity of said first-to-arrive signal and outputting a first signal;
means for measuring a second intensity of light of said second-to-arrive signal and outputting a second signal;
means for storing reference data, said reference data including first and second measurements, said first and second measurements corresponding to said first and second intensities respectively measured at an initial time;
means for storing current data, said current data including third and fourth measurements, said third and fourth measurements corresponding to said first and second intensities respectively measured at a subsequent time; and
means for comparing said current data to said reference data to detect the presence of said substance on said surface at said subsequent time.
1 Assignment
0 Petitions
Accused Products
Abstract
A presence of a polarization altering substance on a specular surface is detected by transmitting light from a single strobed light source to the surface over a transmitting path and receiving the transmitted light from the surface. An intensity of the light is measured in both an optical non-isolator state and an isolator state by a same detector by delaying the non-isolated return light for a definite period of time before measuring it with the detector. The measured isolated and non-isolated intensities are converted to logarithmic form, range corrected, and compared to reference data established for the specific specular surface being investigated to detect the presence or absence of the polarization altering substance. Attenuation and backscattering effects of scattering and/or absorbing interference in the transmitted light are compensated so that the reference table is entered at the correct point. Using different intensities of transmitted light increases the dynamic range of the system.
-
Citations
14 Claims
-
1. Apparatus for detecting, on a surface which specularly reflects light, the presence of a polarization altering substance on said surface comprising:
-
means for transmitting a pulse of light over a transmitting path to said surface; means for receiving transmitted light; a receiving path for said transmitted light from said surface and from said substance to said means for receiving; means for splitting said transmitted light into a non-isolated portion and an isolated portion; means for delaying one of said non-isolated portion and said isolated portion relative to another thereof to produce a first-to-arrive signal and a second-to-arrive signal; said first-to-arrive signal being completed at an output of said means for delaying before said second-to-arrive signal arrives at said output; means for measuring a first intensity of said first-to-arrive signal and outputting a first signal; means for measuring a second intensity of light of said second-to-arrive signal and outputting a second signal; means for storing reference data, said reference data including first and second measurements, said first and second measurements corresponding to said first and second intensities respectively measured at an initial time; means for storing current data, said current data including third and fourth measurements, said third and fourth measurements corresponding to said first and second intensities respectively measured at a subsequent time; and means for comparing said current data to said reference data to detect the presence of said substance on said surface at said subsequent time. - View Dependent Claims (2, 3, 4, 5, 6)
-
-
7. Apparatus for detecting, on a surface which specularly reflects light, the presence of a polarization altering substance on said surface comprising:
-
means for transmitting a pulse of light over a transmitting path to said surface; means for receiving transmitted light; a receiving path for said transmitted light from said surface and from said substance to said means for receiving; means for splitting said transmitted light into a non-isolated portion and an isolated portion; means for delaying one of said non-isolated portion and said isolated portion relative to another thereof to produce a first-to-arrive signal and a second-to-arrive signal; said first-to-arrive signal being completed at an output of said means for delaying before said second-to-arrive signal arrives at said output; means for measuring a first intensity of said first-to-arrive signal and outputting a first signal; means for measuring a second intensity of light of said second-to-arrive signal and outputting a second signal; means for storing a plurality of reference data, each of said plurality of reference data includes first and second measurements, said first and second measurements correspond to said first and second intensities respectively measured when said surface is in a known condition, such that at least one reflection characteristic of said surface is characterized by said plurality of reference data; means for storing a plurality of current data, each of said plurality of current data includes third and fourth measurements, said third and fourth measurements corresponding to said first and second intensities respectively measured at a later time; and means for comparing said current data to said reference data to detect the presence of said substance on said surface at said subsequent time. - View Dependent Claims (8, 9, 10, 11, 12, 13)
-
-
14. Apparatus for detecting the presence of a polarization altering substance on a surface comprising:
-
means for transmitting a pulse of polarized light onto said surface; means for receiving a reflected pulse of light; means for directing said reflected pulse on a non-blocking optical path to a detector to isolate a non-blocking component of said reflected pulse; means for directing said reflected pulse on a blocking optical path to said detector to isolate a blocking component of said reflected pulse; means for measuring an amplitude of said non-blocking component and said blocking component; a reference pulse being transmitted by said means for transmitting at an initial time; means for storing reference data, said reference data being first and second measured amplitudes from said means for measuring at said initial time, said first and second amplitudes corresponding to said blocking and said non-blocking component respectively; and means for comparing third and fourth measured amplitudes from said means for measuring with said first and second amplitudes at a subsequent time, said third and fourth measured amplitudes corresponding to said blocking and said non-blocking component respectively measured at said subsequent time whereby a presence of said polarization altering substance on said surface can be detected by comparing said third and fourth measured amplitudes to said reference data which is stored by said means for storing when no polarization altering substance is on said surface.
-
Specification