Magnetron Sputtering Coating for Shaped Optics Thickness Control

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Solution Overview

Problem

Existing methods for coating optical components with curved or freeform surfaces, such as lenses and aspheres, fail to provide a settable film thickness profile, leading to non-uniform coatings that result in light reflection, ghost images, and spectral shifts due to varying angles of incidence, which are not effectively addressed by current PVD and ALD processes.

Innovation Solution

A device and method utilizing a magnetron sputtering system with a controllable motor and gradient mask to achieve a settable film thickness profile, allowing for homogeneous and inhomogeneous coatings on substrates with shaped surfaces, using a controllable motor and gradient mask to adjust film thickness gradients based on the substrate's shape.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional PVD or ALD coating methods are used on curved or freeform optical surfaces, then the coating process can be performed, but the film thickness becomes non-uniform due to varying angles of incidence, resulting in spectral shifts and ghost images

Engineering Contradiction:

Improvefilm thickness uniformityVSAvoidspectral shifts and ghost images

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by varying the film thickness according to the local geometry of the optical component. The coating thickness is adjusted at different locations on the surface to compensate for varying angles of incidence, ensuring uniform optical performance across the entire component rather than applying a uniform thickness everywhere.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the film thickness parameter as a function of position on the optical component. By modifying the thickness parameter according to the local surface geometry and angle of incidence, the system achieves consistent optical properties across curved and freeform surfaces despite the varying illumination conditions.

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If the film thickness is increased to reduce residual reflection over a larger spectral range, then the anti-reflection performance improves, but the total film thickness and number of layers increase, complicating the coating process

Engineering Contradiction:

Improveresidual reflectionVSAvoidnumber of layers and total film thickness

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses partial action by applying coating material selectively to different regions of the optical component with different thicknesses. Instead of uniformly over-coating the entire surface, the system applies the appropriate amount of material only where needed, achieving the required anti-reflection performance without unnecessary additional layers.

Inventive Principle:

Principle #16Partial or excessive action

3Manufacturing precision

If a gradient mask is introduced to achieve settable film thickness profiles on shaped surfaces, then the coating uniformity improves, but the device complexity increases due to additional components and control mechanisms

Engineering Contradiction:

Improvefilm thickness profile controlVSAvoidcoating device structure

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent introduces a gradient mask as an intermediary element between the coating source and the optical component. This mask mediates the coating process by spatially modulating the deposition flux, creating the desired thickness gradient without requiring complex real-time control of the coating source or substrate positioning.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces complex mechanical positioning and real-time control systems with a static gradient mask that pre-determines the thickness profile. Instead of using sophisticated mechanical systems to dynamically adjust coating parameters, the solution uses a fixed mask structure that passively creates the desired thickness distribution through its geometry.

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

Enables uniform coating on optical components with shaped surfaces, reducing light reflection and spectral shifts, thereby improving imaging quality and system compactness by compensating for varying angles of incidence.

Implementation Method 1

a) at least one film is deposited on the at least one substrate using at least one coating source consisting of at least one magnetron source, with the layers of source material of the magnetron electrodes being formed by sputter gas

Methodology Applied

Scientific EffectSputtering: Sputtering

Data Source

PatentUS12421592B2Device and method for coating substrates having planar or shaped surfaces by means of magnetron sputtering

Publication Date: 2025.09.23 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV

AI summary

According to the invention, a device is provided for coating substrates having planar or shaped surfaces by means of magnetron sputtering, by means of which device surfaces having any shape, for examples lenses, aspheres or freeform surfaces which have an adjustable layer-thickness profile, can be coated such that a layer function is maintained on the substantially complete surface. A method for coating substrates having planar or shaped surfaces by means of magnetron sputtering is also provided.