Laser direct writing device based on combined vortex double focusing light spot

Abstract

The invention discloses a laser direct writing device based on a combined vortex double focusing light spot. The laser direct writing device mainly comprises a 405 nm blue light etching light path, a 650 nm red light self-focusing servo light path, a control computer and a relevant control feedback system, wherein the 405 nm blue light etching light path mainly comprises a circular polarization lens group, a 1/2 wave plate, an electric control rotating platform, a spatial light modulator, a confocal lens group, a dichroism beam splitter, a focusing objective, a self-focusing servo driver, an electric control two-dimensional movement platform and the like; the 650 nm red light self-focusing servo light path mainly comprises a red light collecting lens, a cylindrical mirror and a four-quadrant detector. The laser direct writing device is characterized in that a combined vortex phase modulation is added in an entrance pupil of a conventional laser direct writing light loath focusing objective, thereby achieving double focusing light spot intensity distribution at an objective focusing rear field. The double focusing light spot is capable of achieving hundred-nanometer-order transverse resolution under the medium-numerical aperture focusing, and has a micrometer-order axial focal depth under the medium-numerical aperture focusing.

Description

technical field [0001] The invention relates to a laser direct writing device, in particular to a laser direct writing device based on a composite vortex double-lobe focusing spot. Background technique [0002] The three-dimensional spatial distribution of the focused light field of the objective lens can be said to be the core of the laser direct writing technology. We know that for a conventional optical system, its resolution R and depth of focus DOF ​​are closely related to the numerical aperture NA of the system imaging lens, that is, R∝λ / NA, and the depth of focus DOF∝λ / NA of the imaging system 2 . In the case of a certain wavelength, on the one hand, to improve the resolving power of laser direct writing, it is necessary to increase the numerical aperture NA of the system. However, an increase in numerical aperture means a sharp reduction in the depth of focus of the system. The sharp reduction of the depth of focus poses a severe test to the self-focusing servo sy...

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Problems solved by technology

However, as the working wavelength decreases, especially in the deep ultraviolet band, due to the lack of suitable optical materials, refle

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