Index-Matching Fluid Cylinder for Full-Angle Optical Testing

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Solution Overview

Problem

Current techniques for measuring optics, particularly coatings on plate-shaped elements, are limited to small ranges of angles and suffer from inconsistencies and inaccuracies due to refraction, failing to provide full-range angular measurement capabilities.

Innovation Solution

A rotatable assembly with a glass cylinder and index-matching fluid allows for full-range angular testing of coated glass plates by rotating the cylinder through ±90°, enabling accurate measurement of coatings over a wide range of angles, overcoming limitations of conventional methods that typically measure in air and are restricted by Snell's law.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional measurement techniques are used in air, then the setup is simple, but the measurement range is limited to small angles and accuracy deteriorates due to refraction

Engineering Contradiction:
Improvemeasurement accuracyVSAvoidsetup complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent introduces an index-matching fluid as an intermediary medium between the optical element and the surrounding environment. This fluid has a refractive index matched to the optical element, eliminating refraction at the interfaces and enabling accurate measurements over a full range of angles without the complications that would arise from direct air-contact measurements.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If measurements are performed in air, then the apparatus is simpler, but the angular measurement range is restricted by Snell's law

Engineering Contradiction:
Improveangular measurement rangeVSAvoidapparatus complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent changes the refractive index parameter of the surrounding medium by introducing an index-matching fluid. This parameter change allows the system to overcome the angular limitations imposed by Snell's law in air, enabling measurements across the full angular range from -90 to +90 degrees without the refraction constraints that would otherwise apply.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If a rotatable assembly with index-matching fluid is used, then full-range angular measurement is achieved, but the device complexity increases

Engineering Contradiction:
Improvemeasurement consistencyVSAvoidapparatus structure
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The rotatable assembly serves multiple functions simultaneously: it holds the optical element, contains the index-matching fluid, provides angular positioning capability, and enables full-range measurement. This multi-functionality reduces the need for separate components and justifies the increased structural complexity by delivering consistent, high-precision measurements across the complete angular range.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 solution enables precise, accurate characterization and measurement of coatings over a full range of angles, improving consistency and accuracy in optical testing, particularly for glass plates, by using a refractive index matching fluid and rotating the cylinder to simulate various angles, thus addressing the limitations of existing methods.

Implementation Method 1

Current techniques for measuring optics, in particular coatings, are limited to a small range of angles, or a small set of discrete angles, and/or have significant problems due to refraction.

Methodology Applied
Scientific EffectRefraction: Refraction

Implementation Method 2

The receptacle is configured to contain 0.5 cubic centimeters (cc) to 50 cc of fluid... indexes of refraction of the general-cylinder, the sample, and the fluid are substantially equal.

Methodology Applied
Scientific EffectRefractive index matching: Refraction

Data Source

PatentEP3775827B1Apparatus for optical testing of plate-shaped optical elements
Publication Date: 2023.07.05 LUMUS LTD
  • EP3775827B1 patent drawingFigure 1A~1B
  • EP3775827B1 patent drawingFigure 2~3
  • EP3775827B1 patent drawingFigure 4

AI summary

Optical sample characterization facilitates measurement and testing such as transmittance or reflectance at any discrete angle in a full range of angles of light propagation through a coated glass plate having a higher than air index of refraction. A rotatable assembly includes a cylinder having a hollow, and a receptacle including the hollow. The receptacle also contains a fluid having a refractive index matching the refractive index of the cylinder and coated plate. An optical light beam is input normal to the surface of the cylinder, travels through the cylinder, then via the index matching fluid through the coating, the coated glass plate, the fluid, the other side of the cylinder, and is collected for analysis. Due at least in part to the index matching fluid surrounding the coated plate, the plate can be rotated through a full range of angles (±90°, etc.) for full range testing of the coating.