Refractive Surface Design for High-Contrast Caustic Images

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing methods for designing refractive surfaces struggle to produce high-contrast caustic images with smooth transitions, singularities of infinite light density, and completely black areas, due to limitations in computational cost, local minima, and restrictive bijective mappings.

Innovation Solution

A method that determines the shape of a refractive surface to match a desired irradiance distribution using optimal transport and adaptive Voronoi discretization, allowing for piecewise smooth surfaces and non-bijective mappings, enabling the creation of rich caustic images with high-contrast regions and singularities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If traditional means of shaping or sculpting a refractive material are used, then the manufacturing process is simple, but it is virtually impossible to create complex caustic images with high-contrast regions and singularities

Engineering Contradiction:
Improverange of achievable caustic imagesVSAvoidfabrication difficulty
Core Design Contradiction:
Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent inverts the traditional design approach by working backwards from the desired caustic image to determine the required refractive surface shape. Instead of shaping the material and observing the result, the method calculates the precise surface geometry needed to produce a target irradiance distribution, enabling creation of complex caustic patterns that would be impossible to achieve through manual shaping.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The patent performs preliminary computational design before fabrication by solving the inverse light transport problem to predetermined the optimal surface shape. This preliminary action involves calculating the refractive surface geometry that will produce the desired caustic image, allowing complex patterns to be manufactured with standard fabrication techniques rather than requiring complex manual shaping processes.

Inventive Principle:
Principle #10Preliminary action

2Manufacturing precision

If discrete patch-based approaches are used to design refractive surfaces, then the computational complexity is reduced, but the method cannot produce smooth distributions and does not scale well to high resolutions

Engineering Contradiction:
Improvecaustic image qualityVSAvoidcomputational optimization complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex NP-hard spatial arrangement optimizations with a direct analytical solution based on light transport physics. By formulating the problem as an inverse light transport calculation rather than a discrete optimization problem, the method achieves high-resolution smooth caustic images without requiring computationally intensive NP-hard solvers or approximation methods.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If continuous optimization methods with bijective mappings are used, then smooth surfaces are produced, but high-contrast regions and completely black areas are very difficult to achieve due to large deformations required

Engineering Contradiction:
Improvecontrast range of caustic imagesVSAvoidsurface deformation accuracy
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent introduces dynamic adaptability in the light mapping process by allowing non-bijective mappings that can concentrate light from multiple source points to single target points. This dynamic approach enables the system to adaptively handle high-contrast regions and black areas by redistributing light flux according to the target irradiance distribution, rather than being constrained by fixed one-to-one correspondences.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the fundamental parameter of the mapping relationship from bijective (one-to-one) to non-bijective (many-to-one or one-to-many). This parameter change allows the refractive surface to concentrate light from multiple source points into single target points, creating high-contrast regions and singularities without requiring unrealistic surface deformations.

Inventive Principle:
Principle #35Parameter changes

4Ease of operation

If stochastic perturbation methods are used to optimize caustic images, then the approach is simple to implement, but the optimization incurs high computational cost and can be prone to local minima leading to undesirable artifacts

Engineering Contradiction:
Improveoptimization implementation simplicityVSAvoidcaustic image accuracy
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The patent inverts the optimization direction by calculating the exact surface shape needed to produce a desired caustic image through inverse light transport, rather than stochastically perturbing a surface and evaluating the result. This inversion eliminates the need for iterative stochastic optimization, avoiding both high computational costs and susceptibility to local minima while maintaining implementation simplicity through direct analytical calculation.

Inventive Principle:
Principle #13The other way round (Inversion)

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 significantly expands the range of achievable caustic images, facilitating easier fabrication and enabling creative applications in design, lighting, and art by producing smooth transitions, singularities, and completely black areas with reduced computational artifacts.

Implementation Method 1

determining a refraction of incident illumination through the refractive surface with the initial geometry to create a source irradiance ES distribution on a receiver

Methodology Applied
Scientific EffectRefraction: Refraction

Data Source

PatentUS10732405B2Refractive surface
Publication Date: 2020.08.04 ECOLE POLYTECHNIQUE FEDERALE DE LAUSANNE (EPFL)
  • US10732405B2 patent drawing
  • US10732405B2 patent drawing
  • US10732405B2 patent drawing

AI summary

Method of designing a refractive surface, comprising providing a refractive object having a refractive surface with an initial geometry, determining a refraction of incident illumination through the refractive surface with the initial geometry to create a source irradiance ES distribution on a receiver; and determining a shape of the refractive surface of the refractive object such that a resulting irradiance distribution on the receiver matches a desired target irradiance ET provided by a user.