Concentric Annular Body for Optical Path Length Binning
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Solution Overview
Problem
Conventional optical inspection systems struggle to effectively separate and analyze light as a function of optical path length in samples, particularly for absorptive materials, leading to inefficiencies in determining properties like refractive index and analyte concentration.
Innovation Solution
A confocal inspection system employs a body with a surface featuring concentric annular portions that impart unique angular redirections to collected light, allowing for binning based on optical path length, using either angled surfaces or zero-power blazed diffraction gratings to direct light to specific detector locations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical inspection systems are used to image samples, then a specified depth is sharply in focus, but depths away from the specified depth are blurred due to defocus, making it difficult to separate light by optical path length
Solution Approach 1:
The annular surface is divided into multiple concentric annular portions, each corresponding to a specific range of incident angles from the sample. This segmentation allows light from different optical path lengths to be spatially separated and directed to different regions of the detector, enabling precise measurement of light intensity as a function of optical path length while maintaining depth resolution.
2Productivity
If light from different depths is collected simultaneously, then the inspection process is efficient, but the collected light cannot be effectively binned by optical path length for absorptive samples
Solution Approach 1:
The system transitions from temporal or sequential depth analysis to spatial angular analysis by mapping incident angles to radial positions on the detector. The annular surface creates a one-to-one correspondence between incident angle (related to optical path length) and detector radius, allowing simultaneous collection and separation of light from different depths in a single measurement plane.
3Measurement precision
If a complex optical system with multiple lenses and mirrors is used to separate light by angle, then light can be directed to specific detector locations, but the device complexity increases
Solution Approach 1:
The patent extracts the angular separation function from a complex multi-element optical system and implements it using a single annular surface with concentric portions. Each annular portion is designed with specific geometric properties that directly redirect incident light at corresponding angles to specific detector regions, eliminating the need for multiple lenses and mirrors while maintaining precise angular separation.
4Device complexity
If the annular portions are designed with curvature to focus light, then additional focusing lenses are eliminated, but manufacturing precision requirements increase
Solution Approach 1:
The annular portions are designed with specific curvatures that enable them to focus or redirect light without requiring additional lenses. The curved surfaces are optimized to redirect incident parallel rays to specific focal points or regions on the detector, integrating the focusing function into the annular surface geometry itself. This reduces the number of optical elements while maintaining optical performance.
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 enables precise separation and analysis of light by optical path length, enhancing the determination of sample properties such as refractive index and analyte concentration, while rejecting out-of-focus light, thereby improving the accuracy and efficiency of optical inspections.
Implementation Method 1
a body having a surface that includes concentric annular portions that impart unique, and optionally non-focusing, angular redirections to respective portions of the collected light
Implementation Method 2
include respective zero-power, blazed diffraction gratings having unique combinations of blaze angle and blaze orientation with respect to one another
Implementation Method 3
one or more of the annular portions can include curvature, so that the annular portions can focus light passing through the annular portions to the detector plane
Data Source
AI summary
A confocal inspection system can analyze light collected from a sample. For absorptive samples, it can be desirable to bin the collected light as a function of optical path length traversed in the sample. To perform this binning, the optical system can direct the collected light to a body having a surface that includes concentric annular portions that impart unique non-focusing angular redirections to respective portions of the collected light. In some examples, the annular portions are planar and have respective surface normals that are uniquely angled with respect to one another. In other examples, the annular portions are planar and parallel, and include respective zero-power, blazed diffraction gratings having unique combinations of blaze angle and blaze orientation with respect to one another. Light from each annular portion can be focused onto a respective lateral location at a detector plane.