Azimuthal Polarization Optics for Sub-Diffraction Focusing
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Solution Overview
Problem
Existing light irradiation devices face limitations in reducing the focusing diameter beyond the diffraction limit, particularly when using ring masks, especially with high-numerical-aperture objective lenses, leading to insufficient reduction in focusing diameter and increased optical loss.
Innovation Solution
Incorporating a polarization converter to convert the beam into azimuthally polarized light and a phase converter to apply a spiral phase pattern, in conjunction with a ring mask, to enhance the focusing diameter reduction, utilizing phase modulation type spatial light modulators for adjustable phase patterns and widths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a ring mask is used to reduce the focusing diameter beyond the diffraction limit, then the focusing diameter can be reduced, but the degree of reduction becomes small or insufficient when the numerical aperture of the objective lens is increased
Solution Approach 1:
The patent changes the polarization state parameter of the light beam from conventional linear or circular polarization to azimuthal polarization. This parameter change enables the beam to maintain effective focusing diameter reduction even when using objective lenses with high numerical apertures, where conventional ring masks fail to achieve sufficient reduction.
2Length of moving object
If the widths of the light-shielding portion and the transmitting portion are adjusted to minimize the focusing diameter, then the focusing diameter can be reduced, but optical loss increases and unnecessary focused portions are generated
Solution Approach 1:
The patent changes the polarization parameter to azimuthal polarization, which allows for more efficient light distribution through the ring mask. This parameter change reduces optical loss by directing more light energy to the desired focal region while minimizing unnecessary focused portions and side lobes that result from conventional polarization states.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Significantly improves the degree of focusing diameter reduction and optical efficiency, reducing unnecessary focused portions and optical loss, enabling higher resolution in microscopy and minimizing device size.
Implementation Method 1
The polarization converter is configured to convert the beam input to the polarization converter into azimuthally polarized beam, and to output the azimuthally polarized beam
Implementation Method 2
The phase converter is configured to apply a phase modulation using a spiral phase pattern to the beam input to the phase converter
Implementation Method 3
an objective lens that focuses the beam output from the light output unit on the object
Implementation Method 4
By causing the two beams to interfere with each other at the focusing position, the beams can be focused in a region smaller than the diffraction limit
Implementation Method 5
When the beam is focused in such a manner, a beam waist diameter that is a measure of the size of a focusing diameter thereof can be reduced to only approximately half the wavelength of the beam. This is called a diffraction limit
Data Source
AI summary
A light irradiation device includes a light output unit that outputs coherent beam; and an optical system that irradiates an object with the beam output from the light output unit. The optical system includes an objective lens that focuses the beam output from the light output unit on the object, and a polarization converter, a phase converter, and a ring mask provided on an optical path between the light output unit and the object. The polarization converter is configured to convert the beam input to the polarization converter into azimuthally polarized beam, and to output the azimuthally polarized beam. The phase converter is configured to apply a phase modulation using a spiral phase pattern to the beam input to the phase converter.