Range finder

A method for measuring a height of objects on a moving surface comprising:

• a. providing
• (i) a linear image sensor positioned transverse to a direction of travel of the moving surface, and
• (ii) a first and second light source that project a unique sequence of lighted bars having differing widths and non-lighted spaces having differing widths across the width of the moving surface, wherein said first and second light sources are spaced apart from each other on opposite sides of the moving surface;
• b. detecting a shift in a portion of said unique sequence of lighted bars and non-lighted spaces as an object passes through said unique light sequence;
• c. determining an amount of shift of said portion of said unique light sequence;
• and
• d. determining a height of the object based on said amount of shift of said portion of said unique light sequence.

A range finder for measuring the height of objects on a moving surface comprising:

• a. a linear image sensor positioned transverse to a direction of travel of the moving surface;
• b. at least one light source positioned collinear to said linear image sensor and proximate to an edge of the moving surface, wherein said light source projects a unique sequence of light bars and respective adjacent non-lighted spaces across a width of the moving surface transverse to the direction of travel;
• and
• c. a processor operatively connected to said linear image sensor and said at least one light source for calculating a height of the object as it passes through said unique sequence of lights bars and respective adjacent non-lighted spaces.