Focal-depth expanding method and device based on phase and polarization

Abstract

The patent refers to the field of 'optical elements, systems, or apparatus'. The invention discloses a focal-depth expanding method comprising the following steps of: converting work beam polarization into cylindrical polarized light and splitting the cylindrical polarized light into two beams, wherein after being coded by 0-Pi phases, one beam and the other beam which is optically replicated irradiate the same optical beam combiner inwards to form a combined coaxial beam, and after the combined coaxial beam is focused by a lens, an expanded focal-depth spot is obtained. The invention also discloses a focal-depth expanding device comprising a light source, a polarized light converter, an optical splitter, a 0 / Pi phase plate, an optical replicating device, an optical beam combiner and an apochromat focusing lens. For the focal depths of specific types of focusing spots, the method and the device use coherent light as work beams, save system cost and increase practicability, meanwhile, the focal depths of the expanded focusing spots are increased by above two times, the beam quality is increased, the focusing spots can reach below the self diffraction limitation of a system, and the expanded light intensity has more even distribution and is more beneficial for practical application.

Description

Technical field [0001] The invention relates to the field of lithography and super-resolution imaging, in particular to a focusing method and device for expanding the focal depth. Background technique [0002] Research on extended focal depth in optical disk storage, microscopy imaging, optical calibration and tomography and other application fields have been successively carried out. Among them, wavefront coding technology (Wavefront Coding, WFC) is a new extension of focal depth of optical system developed in the 1990s. The technology was proposed by Dowski and Cathey in 1995. In recent years, the study of obtaining extended focal depth through polarization effects has also attracted attention. Recently, there have been reports on the use of radial and tangential vector beams, quasi-bifocal birefringent lenses and cemented double lenses to achieve extended focal depth. These methods have carried out extensive and in-depth research on the aspect of optical axial extension of fo...

AI Technical Summary

Problems solved by technology

This kind of superposition is just a simple addition of light intensity, the effect is very poor, and it is greatly limited in practical applications, which increases the cost of the system

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