Dynamic Etalon Filter for Slab Thickness Measurement
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Solution Overview
Problem
Existing methods for determining the thickness of a slab of material greater than 50 μm are hindered by measurement noise and limited spectral resolution due to Schott noise, thermal noise, and stray light.
Innovation Solution
A system comprising a single mode optical fiber, a broadband light source, a beam assembly, a computer-controlled etalon filter, and a computer-controlled spectrometer is used to emit and analyze light reflected or transmitted through the slab, allowing for precise determination of thickness and topography.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If known methods of observation and analysis of Fabry Perot interference fringes are used, then thickness determination is possible for thin slabs, but measurement precision deteriorates for slabs thicker than 50 μm due to noise and limited spectral resolution
Solution Approach 1:
The patent applies dynamics by making the etalon spacing adjustable and variable rather than fixed. The etalon spacing is changed dynamically during measurement to optimize the interference pattern for different slab thicknesses, enabling precise measurement of both thin and thick slabs. This dynamic adjustment allows the system to adapt to different measurement requirements and overcome the limitations of fixed-spacing interferometers.
Solution Approach 2:
The patent changes the physical parameter of etalon spacing to improve measurement capability. By varying the spacing between etalon surfaces, the system can tune the spectral resolution and measurement range. This parameter change enables the system to achieve high precision for thick slabs by optimizing the etalon spacing according to the specific measurement requirements.
2Adaptability or versatility
If etalon spacing is fixed, then device complexity is reduced, but adaptability deteriorates for measuring slabs of varying thickness
Solution Approach 1:
The patent implements dynamic adjustability of the etalon spacing mechanism, allowing the system to adapt to different slab thicknesses. The spacing can be varied to optimize measurements for different thickness ranges, providing versatility without requiring multiple fixed-spacing instruments. This dynamic capability is achieved through mechanical adjustment mechanisms that modify the etalon geometry in real-time.
Solution Approach 2:
The patent creates a universal measurement system that can handle a wide range of slab thicknesses using a single instrument. By making the etalon spacing adjustable, the system becomes multi-functional, capable of measuring both thin and thick slabs with high precision. This eliminates the need for multiple specialized instruments and provides broad adaptability across different measurement scenarios.
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 system achieves greater spectral resolution and accurate thickness measurement of thick slabs by filtering and spectrally analyzing light, overcoming noise and resolution limitations of previous methods.
Implementation Method 1
a single mode optical fiber, a broadband light source configured to emit light over the optical fiber
Implementation Method 2
a computer-controlled etalon filter configured to receive the light over the optical fiber, filter the light, and direct the light over the optical fiber
Implementation Method 3
a computer-controlled spectrometer configured to receive the light over the optical fiber after the light has been filtered by the etalon filter and after the light has been reflected from or transmitted through the slab of material and spectrally analyze the light
Implementation Method 4
these known methods of inspection are based on the observation of interference fringes in an etalon formed by the parallel interfaces of the sample
Implementation Method 5
after the light has been reflected from or transmitted through the slab of material
Implementation Method 6
after the light has been reflected from or transmitted through the slab of material
Data Source
AI summary
According to an aspect of one or more embodiments, a system for inspecting a slab of material may include a single mode optical fiber, a broadband light source configured to emit light over the optical fiber, a beam assembly configured to receive the light over the optical fiber and direct the light toward a slab of material, a computer-controlled etalon filter configured to receive the light over the optical fiber either before the light is directed toward the slab of material or after the light has been reflected from or transmitted through the slab of material, filter the light, and direct the light over the optical fiber, and a computer-controlled spectrometer configured to receive the light over the optical fiber after the light has been filtered by the etalon filter and after the light has been reflected from or transmitted through the slab of material and spectrally analyze the light.