Optical Surface Figuring via Line-Removal Process

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Solution Overview

Problem

Conventional sub-aperture finishing techniques for optical elements are limited by physical constraints, leading to long processing times, surface quality degradation, and edge exclusion issues, especially when dealing with large optical elements.

Innovation Solution

A method combining global and local figuring approaches using a line-removal process that scales to accommodate the full-width of the substrate, allowing for efficient removal of material across the entire aperture and varying orientations to achieve precise surface profiling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If sub-aperture figuring techniques are used to correct high spatial period surface errors, then manufacturing precision is improved, but processing time increases significantly

Engineering Contradiction:
Improvesurface figure correctionVSAvoidprocessing time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent segments the surface correction process into two distinct modes: bulk removal mode for long spatial length errors and sub-aperture mode for high spatial period errors. This segmentation allows each mode to be optimized independently, achieving both high precision and reduced processing time by applying the appropriate mode to the appropriate error type.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements dynamic switching between bulk removal and sub-aperture modes based on the spatial frequency of the surface errors being corrected. The system adapts its processing approach in real-time, transitioning from aggressive bulk removal for low-frequency errors to precise sub-aperture processing for high-frequency errors, thereby optimizing both speed and precision.

Inventive Principle:
Principle #15Dynamics

2Manufacturing precision

If sub-aperture processing is used to achieve determinism in surface shaping, then manufacturing precision is improved, but surface quality and micro-roughness deteriorate

Engineering Contradiction:
Improvesurface profile accuracyVSAvoidsurface roughness degradation
Core Design Contradiction:
Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by using sub-aperture processing only where high precision is needed (for high spatial period errors) while using bulk removal for areas requiring less precision. This localized application of processing intensity maintains surface quality in regions where aggressive processing is unnecessary while achieving determinism only where required.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent uses partial action by applying sub-aperture processing selectively to correct only the high spatial period errors rather than processing the entire surface with high-precision methods. This partial application of deterministic processing achieves the necessary precision without the excessive roughness degradation that would result from applying sub-aperture processing uniformly across the entire surface.

Inventive Principle:
Principle #16Partial or excessive action

3Manufacturing precision

If multiple processing techniques are combined to figure a single optical element, then manufacturing precision is improved, but device complexity increases

Engineering Contradiction:
Improvesurface figure accuracyVSAvoidprocessing system complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent merges bulk removal and sub-aperture processing into a single integrated system that can switch between modes. Rather than requiring separate processing steps with multiple setups, the system combines both approaches in one apparatus, reducing the operational complexity despite maintaining both processing capabilities.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent creates a universal processing system that performs both bulk removal and sub-aperture figuring functions. The single system adapts its operation mode based on the processing requirements, eliminating the need for multiple specialized devices and reducing overall system complexity while maintaining high manufacturing precision.

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

4Manufacturing precision

If sub-aperture finishing is used for large optical elements, then manufacturing precision is improved, but productivity decreases due to long processing times

Engineering Contradiction:
Improvesurface figure correctionVSAvoidthroughput
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent employs periodic action by alternating between bulk removal phases and sub-aperture correction phases. The system periodically switches between aggressive material removal and precise surface shaping, maintaining high productivity during bulk removal while achieving high precision during sub-aperture phases, thereby increasing overall throughput for large optical elements.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent ensures continuity of useful action by seamlessly transitioning between bulk removal and sub-aperture modes without interrupting the processing workflow. The system maintains continuous material removal and surface correction, eliminating idle time and maximizing productivity while preserving manufacturing precision throughout the entire processing sequence.

Inventive Principle:
Principle #20Continuity of useful action

Data Source

PatentEP3931160B1Method for figure control of optical surfaces
Publication Date: 2025.04.09 ZYGO CORP
  • EP3931160B1 patent drawingFigure 1A
  • EP3931160B1 patent drawingFigure 1B
  • EP3931160B1 patent drawingFigure 2

AI summary

A method for figuring an optical surface of an optical element to achieve a target profile for the optical surface includes: applying a removal process to an extended region of the optical surface extending along a first direction to remove material from the extended region of the optical surface; adjusting a position of the optical surface relative to the removal process along a second direction perpendicular to the first direction to remove material from additional extended regions of the optical surface extending along the first direction at each of different positions of the optical surface along the second direction; and repeating the applying of the removal process and the adjusting of the optical surface relative to the removal process for each of multiple rotational orientations of the optical surface about a third direction perpendicular to the first and second directions to achieve the target profile of the optical surface.