THz Layer Thickness Measurement with Optical Triangulation

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Solution Overview

Problem

Existing methods for determining layer thickness using Terahertz radiation face challenges in precision due to distance variations, particularly in harsh industrial environments, where accurate and efficient distance measurement is crucial for reliable layer thickness analysis.

Innovation Solution

The apparatus employs a Terahertz transmitter and receiver with an optical triangulation sensor system, utilizing laser radiation and a beam splitter with an optical delay stage to determine layer thickness by compensating for distance variations through a delay parameter, enabling precise measurements even in environments with vibrations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If distance measurement is performed using conventional methods in harsh industrial environments, then measurement speed is maintained, but measurement precision deteriorates due to distance variations and vibrations

Engineering Contradiction:

Improvelayer thickness measurement precisionVSAvoidmeasurement reliability in harsh environments

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent replaces conventional mechanical distance measurement systems with an optical triangulation sensor system that uses laser radiation and optical detection. This substitution enables precise distance measurement by detecting the position of a laser spot on the measurement object, thereby achieving high measurement precision and reliability even in harsh industrial environments with vibrations and distance variations

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The apparatus integrates multiple functions into a single system: the optical triangulation sensor simultaneously performs distance measurement and provides reference for layer thickness determination, while the THz measurement system determines layer thickness. This multi-functional integration maintains measurement precision across different operational conditions

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Measurement precision

If optical triangulation sensor is added to the apparatus, then measurement precision is improved, but device complexity increases

Engineering Contradiction:

Improvedistance measurement precisionVSAvoidapparatus structure complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent merges the optical triangulation sensor system with the existing THz measurement apparatus by integrating the distance measurement functionality into the same measurement head or positioning system. This combining approach reduces overall system complexity compared to using separate independent measurement systems, while maintaining high measurement precision through the optical triangulation method

Inventive Principle:

Principle #5Merging (Combining)

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 solution provides precise and efficient layer thickness measurements, compensating for undesired distance variations and vibrations, thereby enhancing the accuracy and reliability of Terahertz-based layer thickness determination in industrial settings.

Implementation Method 1

said distance measuring device comprises at least one optical triangulation sensor. The optical triangulation sensor enables efficient and yet precise distance measurements

Methodology Applied

Scientific EffectOptical triangulation: Parallax

Implementation Method 2

a Terahertz, THz, transmitter configured to emit a THz signal to said plurality of layers and a THz receiver configured to receive a reflected portion of said THz signal that has been reflected by at least one layer of said plurality of layers

Methodology Applied

Scientific EffectTerahertz radiation reflection: Reflection

Implementation Method 3

said apparatus comprises a laser source, a beam splitter, and an optical delay stage, wherein said beam splitter is configured to a) split said laser signal into a first signal and a second signal

Methodology Applied

Scientific EffectBeam splitting:

Implementation Method 4

provide said second signal to said optical delay stage, wherein said optical delay stage is configured to apply a predetermined time-variable, preferably periodical, delay to said second signal

Methodology Applied

Scientific EffectOptical delay:

Data Source

PatentUS12061077B2Apparatus for determining a layer thickness and method of operating such apparatus

Publication Date: 2024.08.13 HELMUT FISCHER GMBH & CO INSTITUT FUER ELEKTRONIK UND MESTECHNIK

AI summary

An apparatus determines a layer thickness of a plurality of layers arranged on a body. The apparatus includes a THz transmitter configured to emit a THz signal to said plurality of layers and a THz receiver configured to receive a reflected portion of said THz signal that has been reflected by at least one layer of said plurality of layers. The apparatus is configured to determine the layer thickness of at least one of said plurality of layers based on said reflected portion of said THz signal. The apparatus further includes a distance measuring device for determining at least one parameter characterizing a distance between said apparatus and said body, wherein said distance measuring device may include at least one optical triangulation sensor.