Light-collecting device with distributed index lens for solid-state imaging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional solid-state imaging apparatuses face challenges in achieving high resolution and sensitivity due to reduced light-collection efficiency, especially with high-angle incident light, and difficulties in manufacturing smaller pixel sizes without compromising light-collection efficiency.
Innovation Solution
A light-collecting device with a distributed index lens formed by a plurality of light-transmitting films, each zone's width being equal to or shorter than the wavelength of incident light, creating an effective refractive index distribution, which enhances light-collection efficiency and is more resistant to high-angle incident light, and can be manufactured using semiconductor lithography and conventional semiconductor processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If microlens structure is used to collect light, then light-collection efficiency is improved for vertical light, but light-collection efficiency deteriorates for high-angle incident light
Solution Approach 1:
The microlens is segmented into multiple concentric zones with different refractive indices. Each zone has a specific refractive index value that varies from the center to the periphery, allowing different zones to handle light at different incident angles effectively. This segmentation enables the lens to maintain high light-collection efficiency across a wide range of incident angles.
Solution Approach 2:
Different regions of the microlens are assigned different optical properties (refractive indices) according to their local requirements. The center region has a higher refractive index for capturing vertical light, while peripheral regions have progressively lower refractive indices to capture oblique light effectively. This local optimization of optical properties resolves the contradiction between vertical and oblique light collection.
2Measurement precision
If pixel size is reduced to achieve higher resolution, then manufacturing control of microlens formation becomes more difficult, but higher resolution is achieved
Solution Approach 1:
The microlens structure is divided into multiple concentric zones that can be formed using standard semiconductor lithography processes. Each zone corresponds to a specific pattern layer, allowing the complex multi-refractive-index structure to be manufactured using conventional fabrication techniques even at reduced pixel sizes.
Solution Approach 2:
The invention transitions from controlling microlens formation in three dimensions (requiring precise reflow control) to controlling lens properties through two-dimensional concentric zone patterns. This dimensional simplification enables better manufacturing control at smaller scales while maintaining the desired optical functionality.
3Ease of manufacture
If conventional microlens is used, then manufacturing process is simple, but light-collection efficiency is lost at peripheral pixels with high incident angles
Solution Approach 1:
The microlens is segmented into multiple concentric zones with different refractive indices, where each zone can be formed using standard semiconductor lithography processes. This segmentation allows the complex optical structure to be manufactured using conventional fabrication techniques while achieving superior light-collection efficiency across the entire sensor array.
Solution Approach 2:
The refractive index parameter is varied spatially across different zones of the microlens rather than being uniform. This parameter change enables the lens to adapt to different incident angles across the sensor, maintaining high light-collection efficiency at peripheral pixels while remaining compatible with standard manufacturing processes.
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 solution increases light-collection efficiency, enables high-resolution and high-sensitive solid-state imaging, optimizes lens structure for different wavelengths and positions, and maintains efficiency even with increased incident angles, facilitating the use in miniaturized camera systems.
Implementation Method 1
a plurality of light-transmitting films form an effective refractive index distribution
Data Source
AI summary
A solid-state imaging apparatus includes unit pixels arranged in a two-dimensional array. Each unit pixel includes a light-collector and light-receiver. The light-collector includes light-transmitting films that form a refractive index distribution and multiple zones, each of which has a width equal to or shorter than a wavelength of incident light. For each central unit pixel, a center axis of the light-receiver matches a central axis of the light-collector. For each peripheral unit pixel, a central axis of the light-collector is displaced from the central axis of the light-receiver toward the center of the imaging area. The line width of each light-transmitting film of a central unit pixel is different than the line width of each light-transmitting film of a peripheral unit pixel in a same relative position, and the sum of line widths of the central unit pixel differs from the sum of line widths of the peripheral unit pixel.