Chromatic Confocal Sensor Multi-Stage Dispersion
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Solution Overview
Problem
Existing chromatic confocal point sensors face a trade-off between measuring range and compact size, as a large numerical aperture is needed for high resolution, but this often results in a larger pen diameter, which is not practical for many applications.
Innovation Solution
A multi-stage optical configuration with axially dispersive focusing elements, including a first and last axially dispersive focusing element, and potentially intermediate elements, that provide increased axial chromatic dispersion, allowing for a compact output lens diameter while extending the measuring range and maintaining high resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a large numerical aperture is used to achieve high resolution measurements, then measurement precision is improved, but the pen diameter increases making the device less compact
Solution Approach 1:
The optical system is divided into multiple stages with separate axially dispersive focusing elements. Each element contributes a portion of the total axial chromatic dispersion, allowing the system to achieve extended measuring range through cumulative effect while maintaining compact individual component sizes and overall pen diameter.
Solution Approach 2:
The patent transitions from a single-stage optical configuration to a multi-stage configuration, adding temporal/dimensional separation of the optical path. This allows the system to achieve extended measuring range through multiple sequential focusing stages rather than requiring a single large aperture element.
2Adaptability or versatility
If the pen diameter is increased to extend the measuring range for a given numerical aperture, then measuring range is improved, but device compactness deteriorates
Solution Approach 1:
The optical system is divided into multiple stages with separate axially dispersive focusing elements. Each element contributes a portion of the total axial chromatic dispersion, allowing the system to achieve extended measuring range through cumulative effect while maintaining compact individual component sizes and overall pen diameter.
Solution Approach 2:
The patent transitions from a single-stage optical configuration to a multi-stage configuration, adding temporal/dimensional separation of the optical path. This allows the system to achieve extended measuring range through multiple sequential focusing stages rather than requiring a single large aperture element.
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 multi-stage optical configuration achieves an unprecedented range-to-resolution ratio in a compact size, enabling measurements over 500 microns with a numerical aperture greater than 0.15, and a compact output aperture diameter of up to 5 mm, surpassing the capabilities of single-stage configurations.
Implementation Method 1
controlled longitudinal chromatic aberration (also referred to herein as axial chromatic dispersion) may be introduced in an optical imaging system, causing the imaging system focal length to vary with wavelength
Implementation Method 2
a lens can be designed whose back focal length (BFL) is a monotonic function of wavelength. In white light operation such a lens exhibits a rainbow of axially dispersed foci
Implementation Method 3
Upon reflection from the surface, the light is refocused onto a small detector aperture, such as a pinhole and/or the end of an optical fiber
Data Source
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AI summary
A chromatic confocal point sensor optical pen 220; 320; 420 comprises a multi-stage optical configuration 250; 350; 450 providing an enhanced range-to-resolution ratio. The optical configuration comprises at least first and last axially dispersive focusing elements 250A, 250B that combine to contribute to the overall axial chromatic dispersion of the optical pen 220; 320; 420. The first focusing element 250A; 350A; 450A receives source radiation and focuses that radiation at a first focal region internal to the multi-stage optical configuration 250; 350; 450 and the last focusing element 250B; 350B; 450D receives radiation from a last focal region internal to the multi-stage optical configuration 250; 350; 450 and outputs the measurement beam. Intermediate focusing elements 450B, 450C may provide additional focal regions internal to the multi-stage optical configuration. This configuration provides an unprecedented combination of extended sensing range, compact lens diameter, and high numerical aperture. The focusing elements may comprise refractive lenses or diffractive optical elements.