Terahertz Ellipsometer Using Odd-Bounce Polarization Rotation

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

There is a lack of commercially available ellipsometer or polarimeter systems that can operate effectively in the Terahertz (THz) frequency range, and existing systems struggle to provide Infrared (IR) frequency capability, making it difficult to practice ellipsometry at these frequencies without access to synchrotrons.

Innovation Solution

A practical ellipsometer or polarimeter system is developed, combining a source of electromagnetic radiation, such as a backward wave oscillator, Smith-Purcell cell, or free electron laser, with a polarization state generator and an odd-bounce polarization state rotation system, allowing for the generation and detection of polarized beams in the THz range, and extending to IR frequencies, using detectors like Golay cells or bolometers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional ellipsometer systems are used, then they can operate in visible or infrared ranges, but they cannot effectively operate in the Terahertz frequency range without access to synchrotrons

Engineering Contradiction:

Improvefrequency range capabilityVSAvoidoperational effectiveness in THz range

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The system changes the operating frequency parameter from conventional visible/infrared ranges to Terahertz frequencies by incorporating THz-compatible components including THz sources (such as free electron lasers or cyclotron radiation sources), THz detectors (such as bolometers or Golay cells), and THz-appropriate polarizers and analyzers. This parameter change enables the system to operate effectively in the THz range without requiring synchrotron access.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If existing THz systems are used, then they can detect in the Terahertz range, but they struggle to provide Infrared frequency capability

Engineering Contradiction:

Improvedual frequency range capabilityVSAvoidellipsometry accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The system achieves multi-functionality by incorporating both THz and IR frequency capabilities within a single ellipsometer platform. This is accomplished through the use of frequency-selective components and a modular design that allows the system to operate at different frequency ranges using appropriate sources and detectors for each range, thereby providing universal coverage from THz to IR frequencies while maintaining measurement precision through range-specific optimization.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Ease of operation

If polarization state rotation is implemented using conventional methods, then polarization can be rotated, but significant beam deviation or displacement occurs

Engineering Contradiction:

Improvepolarization state controlVSAvoidbeam alignment accuracy

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The system replaces conventional mechanical polarization rotation methods (which cause beam deviation) with a THz-appropriate polarization state generator that uses electromagnetic field manipulation rather than mechanical rotation. This substitution allows for precise polarization state control without significant beam deviation or displacement, maintaining both ease of operation and beam alignment accuracy.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 enables accurate characterization of samples by providing a novel, practical solution for general application in the THz and IR frequency ranges, overcoming the limitations of existing systems by allowing for the rotation of polarization states without significant deviation or displacement, and enabling the use of fixed polarizers and analyzers, thus improving data acquisition and system alignment.

Implementation Method 1

a source such as a backward wave oscillator

Methodology Applied

Scientific EffectBackward wave oscillation:

Implementation Method 2

a Smith-Purcell cell

Methodology Applied

Scientific EffectSmith-Purcell radiation:

Implementation Method 3

a free electron laser

Methodology Applied

Scientific EffectFree electron laser radiation:

Implementation Method 4

a detector such as a Golay cell

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 5

a bolometer

Methodology Applied

Scientific EffectBolometer effect: Bolometer

Data Source

PatentUS8934096B2Terahertz-infrared ellipsometer system, and method of use

Publication Date: 2015.01.13 J A WOOLLAM CO

AI summary

The present invention relates to ellipsometer and polarimeter systems, and more particularly is an ellipsometer or polarimeter or the like system which operates in a frequency range between 300 GHz or lower and extending to higher than at least 1 Tera-hertz (THz), and preferably through the Infra-red (IR) range up to, and higher than 100 THz, including:a source such as a backward wave oscillator; a Smith-Purcell cell; a free electron laser, or an FTIR source and a solid state device; anda detector such as a Golay cell; a bolometer or a solid state detector;and preferably including at least one odd-bounce polarization state image rotating system, and optionally including a polarizer, at least one compensator and/or modulator, in addition to an analyzer.