Plasmon tomography

A method comprising:

• producing plasmon energy by exciting a plasmon resonance at at least one excitation position on a first surface of a first material facing a second surface of a second material;
• detecting an amount of plasmon energy at a measurement position on the first surface after the plasmon energy has propagated from the excitation position to the measurement position;
• and
• adjusting a relative position between the first and second surfaces based on the amount of plasmon energy detected at the measurement position.

An apparatus comprising:

• positioning structures configured to align a first surface of a first material with a second surface of a second material;
• an optical energy source, wherein the source is alignable to provide electromagnetic radiation at a frequency operative to excite a plasmon resonance at at least one excitation position on the first surface of the first material;
• and
• a detector configured to produce a signal corresponding to excited plasmon energy at at least one measurement position on the first surface spatially separated from the at least one excitation position;
• wherein the positioning structures are configured to adjust a relative position between the first and second surfaces in response to the signal.

An article comprising a machine-accessible medium that stores executable instructions, the instructions causing electrical circuitry to:

• acquire data indicating an amount of plasmon energy at a measurement position, the acquired data corresponding to a separation distance;
• compare the amount of plasmon energy to a predetermined amount;
• and
• generate a control signal corresponding to a change in the separation distance.