Super-oscillatory lens needle focus relaxes z-control
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Solution Overview
Problem
Current optical instruments are limited by the Abbe-Rayleigh diffraction limit, which restricts imaging resolution to features larger than half the wavelength of light, and existing methods to overcome this, such as near-field microscopy, face challenges in sample positioning and imaging complexity.
Innovation Solution
A super-oscillatory lens device that spatially modulates a light beam in amplitude and/or phase, combined with a blocking element, creates a needle-shaped focus extending several wavelengths, allowing sub-diffraction limit imaging and processing with a pencil-like beam, suitable for scanning and materials processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical instruments are used, then the imaging system is simple and easy to operate, but the imaging resolution is limited by the Abbe-Rayleigh diffraction limit to features larger than half the wavelength of light
Solution Approach 1:
The optical system is segmented into three functional components: a spatial light modulator for phase modulation, a super-oscillatory lens for sub-diffraction focusing, and a blocking element for shadow region creation. This segmentation allows each component to perform a specific function, achieving high resolution while maintaining operational simplicity through modular design
Solution Approach 2:
The patent transitions from conventional 2D image plane focusing to 3D needle-shaped focal volume by introducing axial extension through super-oscillation. The focal region extends along the optical axis beyond the diffraction limit, creating a three-dimensional focal structure that enables sub-diffraction resolution in multiple dimensions
2Measurement precision
If near-field microscopy is used to achieve sub-diffraction limit imaging, then imaging resolution beyond the Abbe-Rayleigh limit is achieved, but sample positioning becomes difficult and imaging complexity increases
Solution Approach 1:
The super-oscillatory lens acts as an intermediary optical element that transforms the conventional diffraction-limited focus into a sub-diffraction needle-shaped focus in the far field. This intermediary component enables near-field resolution without requiring near-field geometry, eliminating the need for complex sample positioning while maintaining ease of operation
Solution Approach 2:
The patent replaces the mechanical near-field positioning system with an optical field manipulation system. Instead of physically positioning samples near scanning tips, the system uses spatially coherent light modulation and super-oscillation to achieve sub-diffraction focusing in the far field, eliminating mechanical positioning complexity
3Measurement precision
If a conventional focus is used, then the focal spot is small and intense, but the depth of focus is limited and requires precise z-position control during scanning
Solution Approach 1:
The super-oscillatory lens pre-extends the focal region along the optical axis before scanning begins, creating a needle-shaped focus that spans a large axial distance. This preliminary action of extending the focal volume eliminates the need for continuous z-position adjustment during scanning, as the extended focus naturally accommodates positional variations
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
The device achieves sub-diffraction limit resolution and flexibility in focusing, reducing the need for precise z-position control during scanning and enabling efficient imaging and processing of small features with a stable, elongate focus, suitable for various applications including microscopy and materials processing.
Implementation Method 1
The optical mask is defined so as to create constructive interference of waves known as super-oscillation. Super-oscillation leads to a sub-wavelength focus in a field of view beyond the evanescent fields.
Implementation Method 2
a blocking element formed integrally with the lens, or as a separate component adjacent to the lens, which is opaque to the light beam to cause diffraction of the light beam around the blocking element
Data Source
AI summary
A super-oscillatory lens (10) having a pre-defined pattern to spatially modulate the light beam in amplitude and/or phase which has a blocking element (6) formed integrally with the lens, or as a separate component adjacent to the lens, which is opaque to the light beam to cause diffraction of the light beam around the blocking element and formation of a shadow region (20). The lens and blocking element focus the light beam to form an elongate needle-shaped focus (15) in the shadow region (20). In any application in which it is necessary to scan a small spot over a surface, compared with a conventional objective lens focus the elongate shape of the focus relaxes the requirement on a feedback loop to maintain a constant separation between a scan head and a surface being scanned. The elongate shape is also ideal shape for materials processing applications.