Crossed fiber optic tactile sensor

A fiber optic sensor array, comprising:

• a plurality of transmitting optical fibers, the axis of each transmitting fiber being parallel to the axes of the other transmitting fibers;
• a plurality of detcting optical fibers overlapping the transmitting fibers, the axis of each detecting fiber being parallel to the axes of the other detecting fibers and perpendicular to the axes of the transmitting fibers;
• a planar compliant spacer separating the transmitting fibers from the detecting fibers;
• an array of light emitting elements, each element in the emitting array being adapted to transmit light into one of the transmitting fibers;
• and
• an array of light detecting elements, each elment in the detecting array being adapted to detect light emanating from one of the detecting fibers,
• such that a sensor is defined at each location where a detecting fiber overlaps a transmitting fiber, the surfaces of each transmitting fiber and each detecting fiber being modified at the location of each sensor element and an opening being provided in the spacer between the transmitting fiber and the detecting fiber at the location of each sensor element to increase the optical coupling between the transmitting fiber and the detecting fiber at that element, whereby light diverted out of the transmitting fiber at each element by inhomogeneities in the transmitting fiber is coupled into the detecting fiber at the element by inhomogeneities in the detecting fiber, the amount of light coupled into the detecting fiber being proportional to the distance between the transmitting fiber and the detecting fiber at the element.

A method of sensing a force distribution over a two dimensional area, comprising the step of:

• providing a plurality of transmitting optical fibers;
• providing a plurality of detecting optical fibers overlapping the transmitting fibers;
• attaching a planar compliant spacer to the transmitting and detecting fibers to separate the transmitting fibers from the detecting fibers;
• arranging the transmitting and detecting fibers such that a sensor element is defined at each location where a detecting fiber overlaps a transmitting fiber;
• affixing the detecting fibers to a support surface;
• applying the force distribution to the fiber and spacer arrangement;
• sequentially injecting light into each of the transmitting fibers;
• sequentially detecting the light transmitted by each of the detecting fibers after light is injected into each transmitting fiber, thereby measuring the quantity of light diverted from a transmitting fiber by inhomogeneities in the transmitting fiber and coupled to a detecting fiber by inhomogeneities in the detecting fiber at each sensor element;
• and
• relating the relative amount of light detected at each sensor element to the force distribution.