Evanescent Wave Optical Profiler Array for Surface Topology
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Solution Overview
Problem
Conventional profilometry techniques face challenges in accurately measuring surface topological features, particularly in determining height variations and textures, which are crucial for assessing manufacturing quality and degradation over time.
Innovation Solution
An array of conically-shaped optical fibers is etched to create spikes, where light is emitted and reflected, generating an evanescent electromagnetic wave that couples with a sample surface, allowing for distance measurement based on the intensity of reflected light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional profilometry techniques are used to measure surface topological features, then measurement can be performed, but measurement precision and accuracy are insufficient for determining height variations and textures
Solution Approach 1:
The patent replaces conventional mechanical profilometry techniques with an optical-based evanescent wave tunneling system. The mechanical contact measurement approach is substituted with a non-contact optical method where light tunnels from evanescent waves generated at the cut-off portion of optical fibers to the sample surface, enabling precise measurement of height variations and textures without mechanical contact.
Solution Approach 2:
The patent utilizes changes in light intensity parameters as the sample surface approaches the cut-off portion of the optical fibers. By measuring the intensity of reflected light and comparing it to emitted light intensity, the system determines precise distance measurements. The parameter change in light intensity correlates with the distance between the optical fiber array and the sample surface, enabling accurate topographical mapping.
2Measurement precision
If the optical fiber array is used to generate evanescent waves for distance measurement, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent divides the measurement function into multiple independent optical fiber elements arranged in an array. Each optical fiber acts as an independent probe generating evanescent waves at its cut-off portion, allowing parallel measurement across the sample surface. This segmentation enables comprehensive surface mapping while maintaining relatively simple individual fiber structures.
Solution Approach 2:
The optical fiber array serves multiple functions: it acts as both the light transmission medium and the evanescent wave generation source. The same optical fibers that guide light also generate the evanescent waves at their cut-off portions, eliminating the need for separate measurement probes and reducing overall device complexity despite the advanced measurement capability.
3Measurement precision
If light is emitted through optical fibers to generate evanescent waves, then surface distance measurement is enabled, but light intensity is reduced due to tunneling loss
Solution Approach 1:
The patent employs feedback by comparing the intensity of reflected light with the intensity of emitted light. The light detector measures the reflected light intensity, and this measurement is fed back to determine the distance between the optical fiber array and the sample surface. The feedback mechanism compensates for the light intensity reduction due to tunneling, converting the energy loss into useful measurement information.
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 method enables precise measurement of surface distances by exploiting the tunneling of light from the spikes to the sample, providing a reliable means to determine height profiles and textures with high accuracy.
Implementation Method 1
the respective spike may include, along its tapered section, a cut-off portion at which the light is reflected. Reflection of the light at the cut-off portion may generate an evanescent electromagnetic wave emanating from the cut-off portion
Implementation Method 2
the light is reflected at the cut-off portion and generates an evanescent electromagnetic wave at the cut-off portion
Implementation Method 3
When a sample is brought sufficiently close to the cut-off portion, the evanescent electromagnetic wave may couple to the sample, resulting in tunneling of some of the light from the respective spike to the sample
Implementation Method 4
the evanescent electromagnetic wave may couple to the sample, resulting in tunneling of some of the light from the respective spike to the sample
Data Source
AI summary
An apparatus includes a support structure defining therein substantially parallel cavities extending from a first side of the support structure to a second side of the support structure. The apparatus also includes optical fiber cores each extending from the second side through a corresponding cavity and protruding axially at the first side. The axial protrusion tapers from a first diameter down to a second diameter. The apparatus additionally includes a light emitter optically connected to the optical fiber cores and configured to emit light thereinto. A cut-off size associated with the light is greater than or equal to the second diameter such that an evanescent electromagnetic wave is generated at the cut-off portion. The apparatus further includes light detectors each being optically connected at the second side to a corresponding optical fiber core and configured to measure an intensity of the light reflected from the cut-off portion.