Method and apparatus for spatially limited excitation of an optical transition

An apparatus for exciting an optical transition in a narrowly limited area of a material, the apparatus comprising:

• an excitation light source providing an excitation light beam;
• a first lens system focusing the excitation light beam onto a focal point from one direction;
• a de-excitation light source providing a de-excitation light beam;
• a beam splitter splitting up the de-excitation light beam into at least two partial beams, one of the at least two partial beams being focused onto the focal point by the first lens system;
• at least a second lens system focusing one other of the at least two partial beams from another direction onto the focal point to form an interference pattern spatially extending around the focal point;
• a phase adjusting element designed and arranged for adjusting the relative phase of the at least two partial beams;
• and
• an optical element which is designed and arranged for aberrating wave fronts of both of the at least two partial beams prior to them being focused onto the focus point.

An apparatus for exciting an optical transition in a narrowly limited area of a material, the apparatus comprising:

• an excitation light source providing an excitation light beam whose wavelength is tuned to the optical transition to be excited;
• a first lens system focusing the excitation light beam into a focus area extending beyond a focal point from a first direction;
• a de-excitation light source providing a de-excitation light beam which is at least somehow influencing the optical transition;
• a beam splitter splitting up the de-excitation light beam into at least two partial beams, one of the at least two partial beams being focused onto the focal point by the first lens system;
• at least a second lens system focusing one other of the at least two partial beams from another direction onto the focal point to form an interference pattern spatially extending around the focal point;
• a phase adjusting element designed and arranged for adjusting the relative phase of the at least two partial beams of the de-excitation light beam so that the interference pattern has an intensity minimum at the focal point and a plurality of intensity maxima on different sides of the focal point;
• and
• an optical element which is designed and arranged for aberrating wave fronts of both of the at least two partial beams prior to them being focused onto the focal point so that the intensity maxima of the interference pattern on either sides of the focal point are spatially expanded without eliminating the intensity minimum at the focal point.