MICRO SPOT FORMING METHOD AND MICRO SPOT FORMING DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a micro spot forming method capable of forming a micro spot exceeding the diffraction limit.

SOLUTION: Ultra-short pulse laser beam is converted into laser beam having its far-field pattern of the Bessel mode by passing the ultra-short pulse laser beam through a liquid crystal space modulator displaying the computer hologram for giving the phase differenceπto an inner side of a circle having the radius b around the optical axis at least with respect to an orbicular zone outside the circle having the radius b around the optical axis and inside a circle having the radius a (>b) around the optical axis, and the laser beam is condensed to a material having the bi-photon absorption characteristic or multi-photon absorption characteristic by an objective lens.

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