Ellipsometer Spatial Filter Relay Using Spherical Mirrors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing optical systems for focusing broadband electromagnetic radiation suffer from optical aberrations and high costs due to non-ideal mirror surfaces and the expense of non-spherical optics, particularly in ellipsometers and related instruments.
Innovation Solution
A combined spatial filter and relay system comprising three or five elements, including concave and convex spherical mirrors and flat mirrors, arranged to minimize aberrations and polarization effects, with the option of additional components like polarizers and compensators, to achieve low aberration and cost-effective focusing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If reflective or refractive optics are used to focus broadband beam onto small spot, then focusing capability is improved, but optical aberrations increase
Solution Approach 1:
The patent employs spherical mirrors (both concave and convex) instead of traditional parabolic or aspheric optics. The concave spherical mirror focuses the beam while the convex spherical mirror corrects aberrations. This curvature-based approach achieves effective focusing with reduced optical aberrations compared to conventional optics.
Solution Approach 2:
The convex spherical mirror acts as an intermediary element between the concave spherical mirror and the final focus point. It receives the beam from the concave mirror and modifies its path to correct aberrations while maintaining the focusing effect, thereby mediating between the focusing requirement and aberration correction.
2Manufacturing precision
If non-spherical optics are used to reduce aberrations, then optical performance is improved, but manufacturing cost increases
Solution Approach 1:
The patent uses standard spherical mirrors that can be manufactured using conventional techniques rather than expensive non-spherical optics requiring specialized manufacturing processes. Spherical surfaces are easier and cheaper to produce, making the system cost-effective while maintaining adequate optical performance.
Solution Approach 2:
The invention changes the optical parameters by using a combination of concave and convex spherical mirrors with specific focal length relationships (f_concave = 2*f_convex). This parameter configuration allows spherical optics to achieve aberration correction that would otherwise require more complex and expensive non-spherical surfaces.
3Manufacturing precision
If spherical optics are used for 1:1 magnification relay, then aberration is reduced, but device complexity increases
Solution Approach 1:
The patent combines the spatial filter function and relay function into a single integrated system using the concave and convex spherical mirrors. The concave mirror performs both focusing and spatial filtering through its aperture, while the convex mirror handles the relay function. This merging reduces the number of separate components needed compared to traditional systems with dedicated spatial filters and relays.
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 effectively minimizes optical aberrations and polarization effects, providing a low-cost, high-performance solution for focusing electromagnetic radiation in instruments like ellipsometers and spectrophotometers, maintaining the polarization state and achieving a 1:1 imaging relationship.
Implementation Method 1
electromagnetic radiation caused to approach the concave spherical mirror passes through said aperture hole and reflects from said flat mirror onto a first location of a concave surface of said concave spherical mirror
Implementation Method 2
It then reflects from said first location onto a convex spherical surface of said convex spherical mirror and reflects therefrom onto a second location of said concave surface of said concave spherical mirror
Implementation Method 3
a concave spherical mirror having at least one concave spherical surface and an aperture hole therethrough
Implementation Method 4
electromagnetic radiation caused to approach the concave spherical mirror passes through said aperture hole and reflects from said flat mirror
Data Source
Figure 1~3
Figure 2b~2c
Figure 2d~2e
AI summary
Low aberration relay systems modified to perform as spatial filters in reflectometer, spectrophotometer, ellipsometer, polarimeter and the like systems.