Ellipsometer Prism for Wobble Compensation
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Solution Overview
Problem
Existing systems fail to effectively reduce distortions in electromagnetic radiation spectra caused by sample surface precession 'wobble' during investigation of rotating samples, particularly when the sample surface is not oriented normal to the rotation axis, leading to signal wobble and polarization state issues.
Innovation Solution
A dual reflection surface 'prism' system that redirects a polarized electromagnetic beam by 90 degrees, compensating for polarization state effects by canceling the effects of the first reflection on the p or s component with a similar effect on the s or p component, thereby reducing the impact of sample wobble on the beam's polarization state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a spherical mirror is used to intercept and redirect the beam back onto the rotating sample surface, then signal wobble is reduced, but beam polarization state is distorted
Solution Approach 1:
A dual reflective surface prism is introduced as an intermediary component between the spherical mirror and the sample. This prism compensates for the polarization state distortion caused by the mirror's total internal reflection by applying an equal and opposite polarization correction through its own reflective surfaces, thereby preserving the beam's polarization information while maintaining the wobble reduction benefit
Solution Approach 2:
The beam directing system combines two different optical components (spherical mirror and dual reflective surface prism) with complementary functions. The mirror provides beam redirection and wobble reduction, while the prism provides polarization compensation, creating a composite system that achieves both objectives simultaneously
2Measurement precision
If beam directing means relying on specular reflection are used to correct polarization state effects, then uncorrelated PSI and DELTA are achieved, but device complexity increases
Solution Approach 1:
The dual reflective surface prism combines multiple polarization correction functions into a single integrated optical component. By merging the correction of both p and s component polarization effects into one prism element, the system achieves comprehensive polarization state correction while minimizing the number of separate components and reducing overall system complexity
3Measurement precision
If a dual reflection surface prism is used to redirect the beam by 90 degrees, then polarization state effects are compensated, but the system complexity increases
Solution Approach 1:
The dual reflective surface prism is designed to perform multiple functions simultaneously: it redirects the beam by 90 degrees, compensates for polarization state distortion, and maintains beam coherence. By making the prism multi-functional, the system achieves polarization preservation without requiring additional separate components, thereby limiting the increase in system complexity
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 approach significantly reduces beam precession and signal intensity variation, achieving near elimination of wobble effects, with testing showing a reduction from 25 mm to <1 mm precession and signal intensity variation from 100% to <2%, providing consistent data between rotating and stationary samples.
Implementation Method 1
beam directing means that operate based on Total Internal Reflection or on Specular reflection
Implementation Method 2
beam directing means that operate based on Total Internal Reflection or on Specular reflection
Implementation Method 3
placing a spherical mirror in a Spectroscopic Ellipsometer so that it intercepts a beam of electromagnetic radiation that has reflected from a rotating sample surface, and directs it back onto said rotating sample surface
Data Source
AI summary
An improved system and method for investigation of a wobbling surface of a sample with an electromagnetic beam, involving application of a beam directing dual reflection surface “prism” system, which, while effecting beam locus direction rotation of 90 degrees also preserves beam polarization state. The system allows causing an electromagnetic beam to access an otherwise difficult to access sample in, for instance, a vacuum deposition chamber, and enables achieving very closely spaced incident and spherical mirror reflected points of beam reflection from a sample surface in use.