Monocentric Lens TIR Virtual Aperture Stop
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Solution Overview
Problem
Conventional lenses suffer from non-uniform field illumination, particularly at larger input scene field angles, due to the tilt of the lens entrance aperture and the physical aperture stop, leading to reduced brightness and image quality issues.
Innovation Solution
A monocentric lens with a total internal reflection (TIR) layer forming a virtual aperture stop, which provides a convex interface between media of different refractive indices, enabling uniform light transmission and minimizing aberrations across a wide range of angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a physical aperture stop is used in conventional lenses, then the aperture can be controlled, but non-uniform field illumination and vignetting occur at larger field angles
Solution Approach 1:
The patent replaces the mechanical aperture stop with an optical phenomenon-based solution. By using total internal reflection at a curved interface between media of different refractive indices, the system creates an effective aperture without requiring a physical iris or stop mechanism. This substitution eliminates the mechanical components while achieving aperture control through optical physics.
Solution Approach 2:
The patent changes the refractive index parameter by introducing a layer of material with a different refractive index than the surrounding lens material. This parameter change enables total internal reflection at specific angles, creating an angle-independent effective aperture that maintains uniform illumination across the field of view.
2Volume of moving object
If the lens entrance aperture is tilted relative to the object, then the lens can be compact, but light collection efficiency decreases by a factor of cos(θ)
Solution Approach 1:
The patent employs a curved (spherical or aspherical) interface instead of a flat aperture stop. This curvature is essential for creating the total internal reflection effect and for maintaining a constant effective aperture radius regardless of the angle of incidence. The curved geometry allows the lens to remain compact while preserving light collection efficiency across wide field angles.
3Illumination intensity
If a virtual aperture stop is formed by total internal reflection, then uniform illumination is achieved, but the interface between media must be precisely controlled
Solution Approach 1:
The patent performs preliminary design and calculation of the interface curvature and refractive index values to ensure that total internal reflection occurs at the desired angles. By pre-calculating the optimal parameters before manufacturing, the system achieves the required precision without needing excessive manufacturing tolerances. The curvature and material selection are optimized in advance to achieve the desired optical performance.
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 TIR layer ensures a relatively angle-independent aperture, maintaining uniform illumination and improving image quality by reducing cosine-related apodization factors, resulting in a wider field of view with minimized vignetting and enhanced resolution.
Implementation Method 1
total internal reflection from the first medium to the second medium forms an aperture on light transmission with edges dependent on the angle of light incidence
Data Source
AI summary
In some example embodiments, there is provided an apparatus comprising a lens comprising a first medium having a first index of refraction and a second medium having a second index of refraction, wherein the first index of refraction is greater than the second index of refraction; wherein an interface between the first medium and the second medium is convex, and wherein total internal reflection from the first medium to the second medium forms an aperture on light transmission with edges dependent on the angle of light incidence. Related system, methods, and the like are also disclosed.