Method for extending focal depth based on amplitude modulation, polarization and phase modulation and device thereof

Abstract

The invention discloses a method for extending focal depth, including that: Bessel-Gauss radial polarized light passes through an annular diaphragm, so as to modulate amplitude and split the light into two light beams; one light beam is subject to 0-Phi phase coding and then are incident into the same optical beam combining device with the other light beam after optical reflex, so as to form a combined coaxial light beam, and then lens focusing is carried out, thus obtaining the extended focal depth spot. The invention also discloses a device for extending focal depth, comprising a light source generating Bessel-Gauss radial polarized light, an annular diaphragm, a beam splitter, a 0 / Phi phase plate, an optical reflex device, an optical beam combining device and an apochromatism focusing lens. In the method and device, Bessel-Gauss laser is taken as a work light beam, the focal depth of extended focal spot is more than 8lambda, the focal spot can be less than diffraction limit of system, and light distribution after extending is more uniform, thus being more beneficial to practical application.

Description

technical field [0001] The invention relates to the fields of photolithography, optical storage and tomographic imaging, in particular to a focusing method and device for extending the focal depth. Background technique [0002] Research on extended focal depth in optical disk storage, microscope imaging, optical calibration, and tomographic imaging has been carried out one after another. Among them, Wavefront Coding (WFC) is a new method for extending the focal depth of optical systems that was developed in the 1990s. technology, proposed by Dowski and Cathey in 1995. In recent years, research on obtaining extended depth of focus through polarization effects has also attracted attention. Recently, researches on the use of radial vector beams, quasi-bifocal birefringent lenses, and cemented double lenses to achieve extended depth of focus have been reported. The above methods have carried out extensive and in-depth research on the optical axial extension of the focal depth, ...

AI Technical Summary

Problems solved by technology

The above methods have conducted extensive and in-depth research on the optical axial expansion of the focal depth, but most of the above methods extend the focal depth at the expense of lateral resolution

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