UV-IR Ellipsometer Collimator with Dual Off-Axis Mirrors
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Solution Overview
Problem
There is a need for a reflectometer, spectrophotometer, ellipsometer, polarimeter, or scatterometer system capable of operating effectively in the infrared range of wavelengths, as existing systems do not adequately address the requirements for such applications.
Innovation Solution
A system comprising an arc lamp source, monochromator, fiber optic capable of transmitting wavelengths from below 2.2 microns to at least 3.5 microns, and a beam collimator with two off-axis concave spherical mirrors that cancel total off-axis astigmatism over a range of 190 nm to 5.5 microns, along with a sample supporting stage and detector system, allowing for precise measurement and analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single off-axis concave spherical mirror is used for beam collimation, then the device complexity is reduced, but off-axis astigmatism is not substantially canceled over a wide wavelength range
Solution Approach 1:
The patent combines two off-axis concave spherical mirrors into a single collimator assembly, where the first mirror receives light from the fiber optic and the second mirror receives light from the first mirror. This merging of multiple optical elements resolves the contradiction by achieving astigmatism cancellation (improving manufacturing precision) while maintaining a integrated collimator structure (managing device complexity).
Solution Approach 2:
The patent employs asymmetric positioning and configuration of the two off-axis concave spherical mirrors, where each mirror has specific off-axis angles and positions that are not symmetric to each other. This asymmetric arrangement enables the cancellation of off-axis astigmatism across a wide wavelength range (190 nm-5.5 microns) while keeping the overall collimator design practical and manufacturable.
2Adaptability or versatility
If conventional optical components are used, then the device complexity is low, but the wavelength transmission range is limited and cannot cover UV to infrared
Solution Approach 1:
The patent uses a fiber optic with a refractive index profile specifically designed to transmit wavelengths from below 2.2 microns up to at least 3.5 microns, and the two off-axis concave spherical mirrors are configured to handle this broad spectrum. This multi-functional optical path resolves the contradiction by achieving wide wavelength coverage (improving adaptability) while using a unified optical design that manages complexity rather than multiplying separate component systems.
Solution Approach 2:
The patent changes the refractive index profile parameter of the fiber optic to enable transmission across the UV-IR range (below 2.2 microns to at least 3.5 microns). This parameter modification allows a single fiber optic to replace multiple wavelength-specific optical components, thereby improving adaptability while actually reducing overall device complexity.
3Measurement precision
If astigmatism is not canceled, then the optical path is simpler, but measurement precision is degraded in the infrared range
Solution Approach 1:
The patent applies preliminary anti-action by configuring the two off-axis concave spherical mirrors to pre-compensate and cancel astigmatism before the light reaches the sample and detector. The first mirror introduces certain optical transformations, and the second mirror is specifically positioned to counteract the astigmatism, thereby improving measurement precision in the infrared range while maintaining a relatively straightforward optical path without requiring complex post-correction systems.
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 system enables accurate and comprehensive analysis in the infrared range by minimizing astigmatism and providing a wide range of wavelength detection, enhancing the precision and effectiveness of measurements in spectroscopic reflectometry, spectrophotometry, ellipsometry, and polarimetry.
Implementation Method 1
a fiber optic capable of transmitting wavelengths from below 2.2 microns up to at least 3.5 microns
Implementation Method 2
a beam collimator which comprises a combination of two off-axis concave spherical mirrors arranged such that total off-axis astigmatism caused within the beam collimator is substantially canceled
Data Source
AI summary
An ellipsometer, polarimeter, reflectometer, spectrophotometer or scatterometer system for use in the UV and infrared range of wavelengths, characterized by the combination of a fiber optic capable of transmitting wavelengths from below 2.2 micron up to at least 3.5 microns, and a beam collimator formed from a combination of two off-axis concave astigmatism reducing spherical mirrors capable of operating between about 190 nm up to 5.5 microns.