Off-axis reflective afocal optical relay aberration correction

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Solution Overview

Problem

Traditional optical relay systems using on-axis optical elements suffer from artifacts such as ghost images, chromatic aberration, and aberrations like astigmatism, which degrade the relayed image, and require expensive aspherical elements for correction.

Innovation Solution

The use of four or more reflective optical elements oriented in a tilted configuration, with each element tilted about a specific axis to correct for aberrations induced by the tilted configuration, forming an optical relay system that relays an optical plane without obscurations or significant aberrations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If on-axis refractive optical elements are used, then the optical relay system can be simplified in structure, but ghost images are generated due to reflections from optical surfaces

Engineering Contradiction:

Improveoptical relay system structureVSAvoidghost images

Core Design Contradiction:

Device complexityVSObject-generated harmful factors

Solution Approach 1:

The patent replaces refractive optical elements with reflective optical elements. This substitution eliminates the generation of ghost images caused by reflections from refractive surfaces, while maintaining the optical relay function through reflective surfaces that do not produce the same artifact problems.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Device complexity

If on-axis refractive optical elements are used, then the system structure is simplified, but chromatic aberration is induced

Engineering Contradiction:

Improveoptical relay system structureVSAvoidchromatic aberration

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent substitutes refractive optics with reflective optics to eliminate chromatic aberration. Reflective surfaces do not disperse light by wavelength like refractive materials do, thereby removing the chromatic aberration problem while keeping the system structurally simple.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Manufacturing precision

If on-axis reflective optical elements are used, then ghost images and chromatic aberration are eliminated, but holes or obscurations are required to allow light propagation which induce artifacts

Engineering Contradiction:

Improveimage qualityVSAvoidartifacts from obscurations

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The patent employs off-axis reflective optical elements arranged in an asymmetric configuration. This asymmetry allows light to propagate between the reflective elements without requiring holes or obscurations, thereby eliminating the artifacts that would be generated by such openings while maintaining the benefits of reflective optics.

Inventive Principle:

Principle #4Asymmetry

4Object-generated harmful factors

If off-axis reflective optical elements are used, then obscurations are eliminated, but aberrations such as astigmatism and coma are introduced

Engineering Contradiction:

Improveartifacts from obscurationsVSAvoidoptical aberrations

Core Design Contradiction:

Object-generated harmful factorsVSManufacturing precision

Solution Approach 1:

The patent uses multiple off-axis reflective optical elements where the aberrations introduced by each element are compensated for by the subsequent elements in the sequence. The harmful aberrations are converted into a manageable condition through the combined optical path, achieving both elimination of obscurations and correction of aberrations.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

5Manufacturing precision

If aspherical optical elements are used to correct aberrations, then image quality is improved, but the system becomes more expensive

Engineering Contradiction:

Improveimage qualityVSAvoidsystem cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent divides the aberration correction function across multiple spherical reflective optical elements rather than using a single expensive aspherical element. Each spherical element introduces specific aberrations that are compensated for by the combination of all elements, achieving high image quality while using only relatively inexpensive spherical components.

Inventive Principle:

Principle #1Segmentation

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 provides an aberration-corrected optical relay system that minimizes artifacts and eliminates the need for expensive aspherical elements, improving image quality and spectral bandwidth across a broad range of wavelengths.

Implementation Method 1

four or more reflective optical elements oriented in a tilted configuration

Methodology Applied

Scientific EffectReflection: Reflection

Data Source

PatentUS10527830B2Off-axis reflective afocal optical relay

Publication Date: 2020.01.07 KLA CORP

AI summary

An optical relay system includes four or more reflective optical elements oriented in a tilted configuration. Each of the four or more reflective optical elements is tilted about one of four or more tilt axes. Further, the four or more tilt axes are oriented to correct for aberrations induced by the tilted configuration.