Dynamic Infrared Cut-Off Filter for 3D Reconstruction and Color Imaging
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Solution Overview
Problem
Conventional digital cameras with 2D image sensors struggle to simultaneously capture high-quality visible light images and perform 3D reconstruction using time-of-flight measurements, as they require an infrared cut-off filter to prevent infrared interference, which complicates the design and affects color accuracy.
Innovation Solution
A digital camera equipped with a 2D image sensor that can dynamically activate, deactivate, or partially activate an infrared cut-off filter, allowing individual areas to be used for 3D reconstruction or infrared imaging, while the remaining areas capture high-quality visible light images, utilizing dielectric interference filters, micro-mirror arrays, piezo-electrically controllable filters, or electrically tunable liquid crystal filters to manage infrared light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an infrared cut-off filter is permanently installed in front of the 2D image sensor, then color accuracy in the visible light spectrum is improved, but the ability to perform 3D reconstruction using infrared light is lost
Solution Approach 1:
The patent applies the dynamics principle by making the infrared cut-off filter dynamically controllable rather than permanently fixed. The filter can be switched between blocked and transparent states, allowing the system to adapt its optical properties based on the current imaging task. This enables the same sensor to achieve both color-accurate visible light imaging (when filter is blocked) and infrared-based 3D reconstruction (when filter is transparent), resolving the contradiction between color accuracy and 3D capability.
2Adaptability or versatility
If an infrared cut-off filter is completely removed to enable 3D reconstruction, then adaptability for infrared imaging is improved, but color accuracy in the visible range deteriorates
Solution Approach 1:
The dynamically controllable infrared cut-off filter allows the system to switch between two operational modes: when the filter is in the transparent position, the sensor can capture infrared light for 3D reconstruction and infrared imaging; when the filter is in the blocked position, the sensor captures only visible light for high-quality color images. This dynamic switching mechanism enables the system to achieve both infrared adaptability and visible light color quality without permanent compromise.
3Device complexity
If a conventional 2D image sensor with fixed infrared cut-off filter is used, then device structure is simplified, but the ability to simultaneously perform multiple imaging tasks is reduced
Solution Approach 1:
By implementing a dynamically controllable infrared cut-off filter mechanism, the patent adds controlled complexity to the device structure in exchange for significantly enhanced multi-task imaging capability. The filter can be programmatically controlled to switch between blocked and transparent states, enabling the same hardware to perform diverse functions including color photography, 3D reconstruction, and infrared imaging, thereby achieving versatility without requiring multiple separate sensors or permanently fixed filter configurations.
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
Enables simultaneous evaluation of images in the infrared and visible light spectra, maintaining high image quality and allowing for flexible mode switching between different imaging tasks, including 3D reconstruction, without the need for a permanent infrared cut-off filter, enhancing robustness and accuracy in various lighting conditions.
Implementation Method 1
measure distances using TOF (time of flight) cameras based on runtime measurements in synchronization with a pulsed infrared source
Implementation Method 2
the detected infrared light can originate exclusively from reflections of the object to be observed
Implementation Method 3
individual wavelengths are refracted differently. This causes the incident light to split and fall onto individual pixels in dependence on the wavelength
Implementation Method 4
dielectric interference filters can be used as infrared cut-off filters wherein, in dependence on the filter structure, in particular the coating thickness and the structuring of the filter, individual wavelengths are refracted differently
Implementation Method 5
piezo-electrically controllable interference filters can be used as the infrared cut-off filters and, by using the piezoelectric effect, can dampen or amplify targeted wavelength ranges
Implementation Method 6
electrically tunable liquid crystal filters can be used as infrared cut-off filters
Data Source
AI summary
A digital camera has a 2D image sensor designed as a CCD or CMOS sensor that can be used to measure distances based on a runtime measurement in synchronization with a pulsed infrared source. The measured distances are used to carry out a 3D reconstruction of a detected object. The digital camera does not have to have an infrared cut-off filter; however, it can have an infrared cut-off filter that can be dynamically activated in full or in part or deactivated in relation to pixels of the image sensor. In the latter event, individual areas of the image sensor, for which the infrared cut-off filter is deactivated, are used for the 3D reconstruction or for images in the infrared range. The remaining areas of the sensor are used for images of high color quality in the visible light spectrum. In the event that no infrared cut-off filter is present, individual areas of the image sensor are used for the 3D reconstruction or for images in the infrared range. The remaining areas of the sensor are used for images in the visible light spectrum.