Dark-field Confocal Microscopy Using Multi-fractional Angular Momentum Demodulation
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Solution Overview
Problem
Conventional dark-field confocal microscopy measurement technology has a low response rate to micro-scale defects and inadequate detection sensitivity for nano-scale defects below 50 nm, due to factors such as light source quality, ambient noise, and detector noise, which affect measurement precision and sensitivity.
Innovation Solution
A dark-field confocal microscopy measurement apparatus and method based on multi-fractional angular momentum demodulation, which uses a modulated illumination module to generate vortex light with different fractional orders, a XYZ translation stage to move the sample, and a signal collection and demodulation module to collect reflected light and perform cross-correlation processing to enhance signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional dark-field confocal microscopy is used, then the system provides good optical sectioning capability and imaging resolution, but the response rate to micro-scale defects is low and detection sensitivity for nano-scale defects is inadequate
Solution Approach 1:
The patent applies periodic action by using vortex light with different fractional orders to illuminate the sample sequentially. The modulated illumination module generates vortex light with fractional orders (e.g., 0.1, 0.2, 0.3) that are applied in a periodic sequence, allowing the system to accumulate signal information across multiple illumination cycles. This periodic illumination approach enhances the response rate to micro-scale defects by averaging out random noise while preserving defect signals across multiple measurement cycles.
Solution Approach 2:
The patent implements parameter changes by varying the fractional order parameter of vortex light during measurement. The modulated illumination module changes the fractional order parameter (e.g., from 0.1 to 0.2 to 0.3) to illuminate the same sample region from different optical perspectives. This parameter variation enables the system to detect nano-scale defects with different scattering characteristics, thereby improving detection sensitivity without requiring changes to the physical hardware configuration.
2Measurement precision
If conventional illumination is used, then the measurement process is simple, but ambient noise and detector noise significantly affect measurement precision
Solution Approach 1:
The patent introduces an intermediary element - the vortex phase pattern modulator - between the light source and the sample. This intermediary device modifies the illumination light by imposing vortex phase patterns with different fractional orders, effectively encoding information about the illumination state. The modulator acts as a mediator that transforms ordinary light into structured vortex light, enabling noise suppression through cross-correlation processing while adding minimal complexity to the overall system architecture.
Solution Approach 2:
The patent applies preliminary action by pre-modulating the illumination light with vortex phase patterns before the light reaches the sample. The modulated illumination module prepares the light field in advance with specific fractional order patterns, so that when the light interacts with defects, the scattered signals already contain encoded information that can be decoded through cross-correlation. This preliminary modulation prevents noise from overwhelming the defect signals during the actual measurement process.
3Measurement precision
If multi-fractional angular momentum demodulation is implemented, then detection sensitivity is enhanced and noise is reduced, but the device complexity increases
Solution Approach 1:
The patent replaces complex mechanical scanning and multiple physical detectors with an optical-field-based solution using vortex light demodulation. Instead of mechanically moving multiple detectors or using complex mechanical modulation systems, the invention uses spatial light modulators or phase plates to generate vortex phase patterns, and uses computational cross-correlation algorithms to extract defect signals. This substitution of mechanical systems with optical and computational methods enhances detection sensitivity while managing device complexity through software-based signal processing.
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
This approach enhances response rates, reduces imaging noise, and improves detection sensitivity, enabling a more comprehensive characterization of interlayer defects in 3D integrated circuits by simultaneously acquiring defect responses to multi-order vortex components and suppressing common-mode noise.
Implementation Method 1
Laser light is modulated by using a vortex phase pattern with a first fractional order, to obtain vortex light corresponding to the first fractional order
Implementation Method 2
The vortex light with different fractional orders irradiates the to-be-measured sample and is reflected out
Implementation Method 3
perform cross-correlation processing on the dark-field images generated under the vortex light with different fractional orders, to obtain high-signal-to-noise ratio (SNR) data
Data Source
AI summary
This application relates to the technical field of confocal microscopy measurement, and provides a dark-field confocal microscopy measurement apparatus and method based on multi-fractional angular momentum demodulation. The apparatus includes a modulated illumination module and a signal collection and demodulation module. The modulated illumination module obtains vortex light with different fractional orders through modulation using vortex phase patterns with different fractional orders, so as to scan a to-be-measured sample. The vortex light with different fractional orders irradiates the to-be-measured sample and is reflected out. The signal collection and demodulation module collects the reflected light and generates dark-field images, and finally performs cross-correlation processing on the dark-field images generated under the vortex light with different fractional orders, to obtain high SNR data.