System for detecting ice or snow on surface which specularly reflects light

Claim 3

A method as in claim 1, wherein the step of transmitting light includes transmitting light sequentially with at least two different intensities.

Claim 4

A method as in claim 1, wherein the step of transmitting light includes scanning the light across said surface.

Claim 5

A method as in claim 1, further comprising compensating for an effect of ambient light.

Claim 6

A method as in claim 1, further comprising compensating for an effect of ground return.

Claim 7

A method as in claim 1, further comprising displaying, to a human eye, said difference and said sameness.

Claim 8

A method as in claim 1, further comprising compensating for an angle of said receiving path with respect to said surface as said receiving path deviates from a normal to said surface.

Claim 11

A method as in claim 8 further comprising compensating for an effect of ambient light.

Claim 12

Apparatus for detecting on a surface which specularly reflects light, the presence of a polarization altering substance comprising: means for transmitting 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; optical means in at least one of said transmitting path and said receiving path; means for alternating said optical means between an optical non-isolator state and an optical isolator state; said means for receiving including means for measuring a first intensity of light received at said means for receiving when said optical means is in said optical non-isolator state, and means for measuring a second intensity of light received at said means for receiving when said optical means is in said optical isolator state; means for detecting a difference between said first and second intensities of light wherein an absence of said substance is indicated; and means for detecting a substantial sameness of said first and second intensities of light wherein the presence of said substance on said surface is indicated.

Claim 13

Apparatus for detecting on a surface which specularly reflects light, the presence of a polarization altering substance comprising: means for transmitting 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; optical means in at least one of said transmitting path and said receiving path; means for alternating said optical means between an optical non-isolator state and an optical isolator state; said means for receiving including means for measuring a first intensity of light received at said means for receiving when said optical means is in said optical non-isolator state, and means for measuring a second intensity of light received at said means for receiving when said optical means is in said optical isolator state; means for detecting a difference between said first and second intensities of light wherein an absence of said substance is indicated; and means for detecting a substantial sameness of said first and second intensities of light wherein the presence of said substance on said surface is indicated.

Claim 14

Apparatus as in claim 10, wherein said optical means produces light with two different alternating polarization characteristics.

Claim 15

Apparatus as in claim 10, wherein said means for transmitting comprises: first and second lamps; means for alternately energizing said first and second lamps; a first circular polarizer optically associated with said first lamp; and a second circular polarizer, of opposite hand to said first circular polarizer, optically associated with said second lamp.

Claim 16

Apparatus as in claim 12, wherein said means for receiving comprises: a video camera; and at least one of said first, said second, and a third circular polarizer being associated with said video camera.

Claim 17

Apparatus as in claim 10, wherein said means for transmitting light transmits light sequentially with at least two different intensities.

Claim 18

Apparatus as in claim 10, wherein said means for transmitting light includes means for scanning the light across the surface.

Claim 19

Apparatus as in claim 10, wherein said means for receiving includes means for compensating for an effect of ambient light received by said means for receiving.

Claim 20

Apparatus as in claim 10, wherein said means for receiving includes means for compensating for a deviation of an angle of said receiving path from a normal to said surface.

Claim 21

Apparatus as in claim 10 wherein: said means for transmitting light includes only one transmitter; and said means for receiving transmitted light includes at least one receiver.

Claim 22

Apparatus as in claim 10 wherein: said means for transmitting light includes at least one transmitter; and said means for receiving transmitted light includes only one receiver.

Claim 23

Apparatus as in claim 10 wherein: said means for transmitting light includes at least one transmitter; and said means for receiving transmitted light includes at least one receiver.

Claim 24

Apparatus for detecting on a surface which specularly reflects light, the presence of a polarization altering substance comprising: means for transmitting light over a transmitting path to said surface; said means for transmitting light including means for strobing such that first and second strobed signals are alternately produced by said means for transmitting light; means for receiving transmitted light; a receiving path for said transmitted light from said surface and from said substance to said means for receiving; optical means in at least one of said transmitting path and said receiving path; said optical means being in an optical isolator state during said first strobed signal and in an optical non-isolator state during said second strobed signal; said means for receiving including means for measuring a first intensity of said first strobed signal and a second intensity of said second strobed signal; and means for comparing said first and second intensities to each other.

Claim 25

Apparatus for detecting on a surface which specularly reflects light, the presence of a polarization altering substance comprising: means for transmitting light over a transmitting path to said surface; said means for transmitting light including means for strobing such that first and second strobed signals are alternately produced by said means for transmitting light; means for receiving transmitted light; a receiving path for said transmitted light from said surface and from said substance to said means for receiving; optical means in at least one of said transmitting path and said receiving path; said optical means being in an optical isolator state during said first strobed signal and in an optical non-isolator state during said second strobed signal; said means for receiving including means for measuring a first intensity of said first strobed signal and a second intensity of said second strobed signal; and means for comparing said first and second intensities to each other.

Claim 26

Apparatus as in claim 21 wherein said means for comparing includes means for compensating for an effect of ambient light.

Claim 27

Apparatus as in claim 21 further including means for displaying an output of said means for comparing.

Claim 28

Apparatus as in claim 21, wherein said means for receiving includes means for compensating for a deviation of an angle of said receiving path from a normal to said surface.