Shifted Microlens Array for 3D Distance Measurement
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Solution Overview
Problem
Current 3D image capturing methods, such as active methods requiring additional light sources and optical systems, and passive stereo camera methods, face challenges in obtaining precise distance information without complex configurations.
Innovation Solution
A light field image capturing apparatus with a microlens array where microlenses are shifted relative to pixels, allowing for the capture of overlapping images with different viewing points without a complicated optical configuration, using an existing image sensor like CCD or CMOS without modification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If active methods (TOF or triangulation) are used to obtain distance information, then measurement precision is improved, but device complexity increases due to additional light sources and optical systems
Solution Approach 1:
The patent extracts only the necessary functional elements for depth measurement by removing the need for additional light sources and complex optical systems. It uses solely the microlens array and existing image sensor, taking out the unnecessary components from active methods while preserving the depth measurement capability through passive light field capture.
Solution Approach 2:
The microlens array serves multiple functions: it acts as both the optical element for capturing light field information and the structure for generating multiple virtual viewing points. This multi-functional design eliminates the need for separate light sources and additional optical components, reducing device complexity while maintaining measurement precision.
2Device complexity
If passive stereo camera method is used to avoid additional light sources, then device complexity is reduced, but measurement precision deteriorates due to difficulty in obtaining precise distance information
Solution Approach 1:
The patent segments the image capture function into multiple virtual viewing points through the microlens array, where each microlens captures light from a slightly different angle. This segmentation of the optical function allows for precise depth measurement through parallax analysis while maintaining a simple device structure without additional cameras or light sources.
Solution Approach 2:
The patent transitions from traditional two-dimensional image capture to four-dimensional light field capture by adding two angular dimensions through the microlens array. This dimensional expansion enables precise depth information extraction from passive light field data, overcoming the limitations of conventional stereo camera methods while keeping the device simple.
3Ease of manufacture
If microlenses are aligned with pixels without shift, then ease of manufacture is improved, but measurement precision deteriorates due to inability to capture overlapping images with different viewing points
Solution Approach 1:
The patent introduces a deliberate asymmetric offset between the microlens array and pixel array, where microlenses are shifted by a specific distance (e.g., half the pixel pitch) relative to the pixels. This asymmetric configuration enables each microlens to capture light from slightly different viewing angles, creating overlapping images necessary for precise depth measurement, while still maintaining manufacturability through standardized offset distances.
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 simplifies the optical system and image capturing unit, enabling precise distance information extraction without additional light sources or optical systems, using existing image sensors and allowing for the generation of 3D images with increased precision.
Implementation Method 1
a microlens array disposed between the objective lens and the image sensor and including a plurality of microlenses arranged in a two-dimensional manner, the plurality of microlenses corresponding to the plurality of pixels
Data Source
Figure 1~3a
Figure 3b~5
AI summary
A light field image capturing apparatus including a shifted microlens array, the light field image capturing apparatus including: an objective lens focusing light incident from an external object; an image sensor including a plurality of pixels, the image sensor outputting an image signal by detecting incident light; and a microlens array disposed between the objective lens and the image sensor and including a plurality of microlenses arranged in a two-dimensional manner, the plurality of microlenses corresponding to the plurality of pixels, wherein at least a part of the plurality of microlenses is shifted in a direction with respect to the pixels corresponding to the at least a part of the plurality of microlenses.