Achromatic Doublet Prism Array for Compact Wide-Angle Camera
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Solution Overview
Problem
Wide-angle camera systems using prism-based optical components suffer from severe chromatic aberration, which significantly reduces the modulation transfer function (MTF) and image quality due to the limitations of conventional prism designs.
Innovation Solution
A novel achromatic doublet prism array is developed using wafer-level fabrication, comprising two asymmetric prisms made of different materials with specific refractive indices and Abbe numbers, aligned to reduce chromatic aberration and enhance optical resolution, allowing for a compact wide-angle camera with improved image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional single prism is used to achieve wide-angle viewing, then the field of view is increased, but chromatic aberration increases significantly reducing MTF and image quality
Solution Approach 1:
The single prism is divided into two separate prisms with different materials and optical properties. The first prism has a first material with refractive index n1 and Abbe number V1, while the second prism has a second material with refractive index n2 and Abbe number V2. This segmentation allows each prism to contribute differently to light refraction, achieving wide-angle viewing while compensating for chromatic aberration through the combined optical path.
Solution Approach 2:
Different regions of the optical path are assigned different material properties. The first prism uses a material optimized for certain wavelength ranges while the second prism uses a material optimized for complementary wavelength ranges. This local differentiation of optical properties enables chromatic aberration compensation while maintaining wide-angle capability.
2Manufacturing precision
If an achromatic doublet prism array is implemented to reduce chromatic aberration, then image quality and MTF are improved, but device complexity increases
Solution Approach 1:
The two prisms are combined into a single integrated optical element where the first prism and second prism are bonded or coupled together. This merging creates a compact achromatic doublet structure that functions as one unit, reducing the overall device complexity compared to separate prism assemblies while maintaining the chromatic aberration reduction benefits.
Solution Approach 2:
The achromatic doublet prism uses composite material construction with two different optical materials having distinct refractive indices and Abbe numbers. This composite approach enables the prism array to achieve achromatic performance without requiring complex individual prism designs, as the material properties themselves provide the chromatic correction.
3Manufacturing precision
If wafer-level fabrication is used to manufacture the prism array, then manufacturing precision and consistency are improved, but fabrication process complexity increases
Solution Approach 1:
The prism array is fabricated using wafer-level processing techniques where the first prisms are formed on a substrate, then the second prisms are formed on top of the first prisms in a sequential manner. This preliminary structuring allows for precise alignment and bonding interfaces to be established before final assembly, improving manufacturing precision while managing fabrication complexity through staged processing.
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 achromatic doublet prism array significantly reduces chromatic aberration, enhancing the optical resolution and image quality of wide-angle cameras to levels comparable to those without prisms, while maintaining a compact format.
Implementation Method 1
the use of the prism causes severe chromatic aberration that lowers the modulation transfer function (MTF) of the optical system significantly
Implementation Method 2
each of the achromatic doublet prisms is aligned to provide a viewing angle with a different one of the optical elements
Data Source
AI summary
A wide-angle camera and fabrication method thereof includes a sensor with a plurality of pixel sub-arrays and an array of optical elements on a first side of a substrate. Each of the optical elements is capable of forming an image from a field of view onto a different one of the pixel sub-arrays. The wide-angle camera also includes an array of achromatic doublet prisms on a second side of the substrate, where each of the achromatic doublet prisms is aligned to provide a viewing angle with a different one of the optical elements. The sensor captures a wide-angle field of view while having a compact format.