Method and apparatus for measuring distance to an object

Claim 2

Apparatus for determining the distance D of an object with respect to a reference location comprising: illumination means for projecting a preselected feature upon the object along a first direction from the reference point to the object, said feature having at least two distinct points separated laterally by a distance h measured transversely to said first direction, means positioned at said reference location for generating an image of the feature reflected from the object, said image generating means including a thin lens with a focal length F, said image at the focal plane of said lens having a spacing between the image of said at least two distinct points of h i , and processing means for comparing the reflected image h i of the feature with the preselected feature h to determine the distance D where D=hF/h i .

Claim 3

The apparatus of claim 1 wherein the preselected feature is a pair of spaced apart points of light.

Claim 4

The apparatus of claim 2 wherein said illumination means comprises two parallel laser beams.

Claim 5

The apparatus of claim 1 wherein the preselected feature is a circle.

Claim 6

The apparatus of claim 1 wherein the preselected feature is a rectangle.

Claim 7

The apparatus of claim 1 wherein said illumination means projects the feature in a narrow spectral region and wherein the imaging means includes a filter responsive to the narrow spectral region.

Claim 8

The apparatus of claim 4 wherein the processing means is responsive to the major and minor axes of an ellipse resulting from the circular illumination.

Claim 9

Method for determining the distance D of an object with respect to a reference location comprising: projecting a preselected feature upon the object along a first direction from the reference point to the object, said feature having at least two distinct points separated laterally by a distance h measured transversely to said first direction, optically generating an image of the feature reflected from the object at said reference location where the lateral spacing between the image of said at least two distinct points is h i and where said image generating is done in a manner that creates a linear relationship between h and h i that corresponds to the distance D to be measured, and comparing the reflected image h i of the feature with the preselected feature h to determine the distance D where D=hF/h i , F being a constant that is characteristic of said image generating means.

Claim 10

Method for determining the distance D of an object with respect to a reference location comprising: projecting a preselected feature upon the object along a first direction from the reference point to the object, said feature having at least two distinct points separated laterally by a distance h measured transversely to said first direction, optically generating an image of the feature reflected from the object at said reference location where the lateral spacing between the image of said at least two distinct points is h i and where said image generating is done in a manner that creates a linear relationship between h and h i that corresponds to the distance D to be measured, and comparing the reflected image h i of the feature with the preselected feature h to determine the distance D where D=hF/h i , F being a constant that is characteristic of said image generating means.

Claim 11

The method of claim 8 wherein the preselected feature is a pair of spaced apart points of light.

Claim 12

The method of claim 8 wherein the preselected feature is a circle.

Claim 13

The method of claim 8 wherein the preselected feature is a rectangle.