Method and apparatus for positioning a tapered body

An apparatus for positioning a body having a tapered profile when viewed along a first axis, comprising:

• a first light source positioned to expose said body to a first beam of light oriented along said first axis,
• a first linear array of photodetectors disposed along a direction substantially orthogonal to both said first axis and the direction of said taper in a position such that a linear section across said tapered profile is projected by said first light beam, as a first silhouette-like image, onto said first photodetector array,
• a second light source positioned to expose said body to a second beam of light oriented along a second axis substantially orthogonal to said first axis,
• a second linear array of photodetectors disposed along a direction substantially parallel to said first axis in a position such that a second linear section across said body is projected by said second light beam, as a second silhouette-like image, onto said second photodetector array,
• means for moving said body along said first and said second axes to allow said first and said second images to strike predetermined locations along said first and said second photodetector arrays, and
• means for changing the location of said body along a third axis, orthogonal to said first and said second axes, in order to allow the width of said first image to equal a predetermined width measured by the linear magnitude of the first image along said first photodetector array.