Focused-Beam Ellipsometer Static Optical Design
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Solution Overview
Problem
Conventional ellipsometers require constant speed rotation driving parts, limiting measurement accuracy and speed due to mechanical vibrations and noise, and are not capable of measuring polarization components for multiple incidence surfaces in a static state.
Innovation Solution
A focused-beam ellipsometer design that includes a light source, a linear polarizer, a beam splitter, an objective lens, a light receiving module with an analyzer, and an optical detector with unit devices, allowing for static measurement of ellipsometric angles across 360° incidence surfaces, eliminating the need for motor-driven rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a rotating polarizer or rotating analyzer is used to measure ellipsometric angles, then the measurement can cover multiple incidence surfaces, but mechanical vibrations and noise from the motor reduce measurement accuracy
Solution Approach 1:
The patent replaces the mechanical rotation system (motor-driven polarizer or analyzer rotation) with a static optical system. Instead of physically rotating components, the invention uses a series of fixed polarizers or analyzers positioned at different angles, combined with an optical switching mechanism to sequentially direct light through different static elements. This substitution of mechanical rotation with static optical elements eliminates motor-induced vibrations and noise, thereby improving measurement accuracy while still enabling coverage of multiple incidence surfaces.
2Adaptability or versatility
If a motor-driven rotating polarizer or analyzer is used, then the system can dynamically adjust to different measurement angles, but the mechanical rotation limits measurement speed
Solution Approach 1:
The patent employs periodic switching between multiple static polarizers or analyzers positioned at different fixed angles. Instead of continuous mechanical rotation, the system rapidly alternates between pre-positioned optical elements in a periodic sequence, synchronized with the detection system. This periodic switching action enables dynamic measurement capability across multiple incidence surfaces while operating at speeds limited only by the electronic switching rate rather than mechanical rotation speed, thereby improving measurement speed.
3Adaptability or versatility
If mechanical rotation components are used in the ellipsometer, then the system structure becomes complex with moving parts, but this increases device complexity and potential failure points
Solution Approach 1:
The patent divides the single rotating component function into multiple separate static polarizers or analyzers, each fixed at a specific angle. Instead of one complex rotating assembly, the system uses multiple simpler static elements arranged in sequence. Each element performs a portion of the measurement function, and the optical switching mechanism selectively activates the appropriate element for each measurement angle. This segmentation reduces the complexity of individual components, eliminates mechanical connections and drive mechanisms, and distributes the functional requirements across multiple simple elements.
4Measurement precision
If constant speed rotation is maintained for accurate measurement, then measurement precision can be preserved, but any mechanical vibration or noise from the motor affects reliability
Solution Approach 1:
The patent extracts and removes the motor-driven rotation mechanism entirely from the optical measurement path. The function of angular adjustment is extracted from mechanical rotation and implemented through static optical elements positioned at predetermined angles. By taking out the rotating motor assembly, the source of vibrations and noise is eliminated, leaving only stable, stationary optical components. This extraction improves both measurement precision (by removing vibration-induced errors) and reliability (by eliminating moving parts that can fail).
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 design enhances measurement accuracy and speed by eliminating motor-induced noise and vibration, enabling precise and high-speed measurement of ellipsometric angles for multiple incidence surfaces without mechanical rotation, similar to rotating-analyzer or rotating-polarizer ellipsometers.
Implementation Method 1
a light source part module (120) provided with a linear polarizer for linear polarizing light emitted from the light source (110)
Implementation Method 2
a beam splitter (130) for dividing the light polarized by the light source part module (120)
Implementation Method 3
an objective lens (140) for convergently irradiating a part of the light divided by the beam splitter (130) onto a sample (150)
Implementation Method 4
a light receiving part module (160) provided with an analyzer which is a polarizer for filtering specific polarization of the light reflected on the sample (150)
Implementation Method 5
an optical detector (170) for detecting an intensity of the light passed through the light receiving part module (160) and incident thereto
Implementation Method 6
a processing device (180) for processing an intensity signal of the detected light in combination with information of an azimuth angle of polarization axis of the polarizer in the light source part module (120) and information of an azimuth angle of polarization axis of the polarizer in light receiving part module (160)
Data Source
AI summary
The present invention relates to an ellipsometer, and more particularly, to an ellipsometer to find out the optical properties of the sample by analyzing the variation of the polarization of a light which has specific polarisation then reflected on a surface of the sample.