Tomographic reconstruction of electronic components from shadow image sensor data

A sensor system for use in reconstructing a tomographically reconstructed outline of an opaque object rotatable through a plurality of angles, the sensor system comprising:

• a housing;
• a source of light providing rays of light;
• a detector for detecting a shadow image formed by the rays of light thereon, each shadow image associated with a one of the plurality of angles;
• and
• electronics receiving the shadow images for computing a set of vertices representative of the outline.

A pick and place machine for placing a component, the pick and place machine comprising:

• a head for releasably holding and rotating the component to a plurality of angles;
• a source of light providing rays of light;
• a detector for detecting a shadow image of the component thereon;
• and
• a processor receiving a plurality of the shadow images, each shadow image associated with one of the plurality of angles, the processor locating an edge of the shadow image and computing a set of vertices representative of an outline of the component from the plurality of shadow images and the plurality of angles.

A method of providing a set of vertices representative of an outline of a portion of an object, the method comprising:

• a) casting a shadow of the object onto a detector at an angle to provide a shadow image on the detector;
• b) detecting at least one edge of the shadow image, the at least one edge of the shadow image and the angle forming a data pair;
• c) changing the angle and repeating the steps of casting and detecting until a plurality of data pairs is stored;
• d) computing the set of vertices as a function of the data pairs;
• and
• e) wherein the two data pairs are used to complete one vertex, where the angles in the data pairs are proximate to each other.

A method of providing a set of vertices representative of an outline of a portion of an object, the method comprising:

• a) casting a shadow of the object onto a detector at an angle to provide a shadow image on the detector;
• b) detecting at least one edge of the shadow image, the at least one edge of the shadow image and the angle forming a data pair;
• c) changing the angle and repeating the steps of casting and detecting until a plurality of data pairs is stored;
• d) computing the set of vertices as a function of the data pairs;
• and
• e) wherein the step of computing the set of vertices is computed by the Equation:
• [ cos ⁢ ⁢ θ I sin ⁢ ⁢ θ I cos ⁢ ⁢ θ I - 1 sin ⁢ ⁢ θ I + 1 ] ⁡ [ x y ] + [ r I r I + 1 ] ⁢ .1
• where ΘI is an angle corresponding to the half shadow width rI, rI is a half shadow width, x is an x-coordinate of a vertex and y is a y-coordinate of a vertex;
• repeating the aforementioned computing step N times, where N represents a plurality of angles;
• and
• using the set of vertices to provide the outline.