Passive 3D Sensing via Chromatic Focal Differentiation
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Solution Overview
Problem
Conventional active techniques for three-dimensional image sensing, such as time-of-flight and structured illumination, face limitations in portable digital electronics due to power consumption, spatial constraints, and difficulty in dynamic calibration, especially in smartphones where they are not reliable or accurate enough to support advanced features.
Innovation Solution
A passive three-dimensional image sensing system based on chromatic focal differentiation, which uses a lens assembly and image sensor with photodetector elements to detect light components of different wavelengths focused to different focal lengths, calculating object distance by computing the ratio of chromatic responses from smaller-wavelength and larger-wavelength components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If active techniques (time-of-flight, structured illumination) are used for three-dimensional image sensing, then depth measurement capability is improved, but device complexity and power consumption increase
Solution Approach 1:
The system uses the object's own reflected light to enable depth measurement without requiring active illumination. The chromatic focal differentiation is inherent in the lens-optics themselves, eliminating the need for additional active components. This resolves the contradiction by achieving depth measurement capability while reducing device complexity and power consumption.
Solution Approach 2:
The patent replaces active mechanical/optical systems (laser transmitters, structured light projectors) with a passive optical system that exploits inherent chromatic focal differentiation. By substituting active illumination mechanisms with passive light detection and inherent optical dispersion, the system achieves depth measurement without the complexity of active components.
2Adaptability or versatility
If active illumination sources are integrated into portable devices, then three-dimensional sensing capability is improved, but spatial constraints are violated
Solution Approach 1:
The system leverages the existing camera's light sensor and lens to achieve three-dimensional sensing without adding separate active illumination sources. The chromatic focal differentiation is an inherent property of the lens system itself, eliminating the need for additional volumetric components and maintaining compact device form factor.
3Reliability
If conventional active techniques are used, then depth information can be captured, but reliability and accuracy are insufficient for advanced features
Solution Approach 1:
The system uses the object's reflected light and inherent chromatic focal differentiation to achieve reliable depth measurement without active illumination. This passive approach eliminates the power consumption issues associated with active techniques while maintaining or improving measurement reliability through the use of well-established optical physics.
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 accurate and efficient depth mapping in portable devices without the need for active illumination, overcoming power and spatial constraints, and providing reliable distance measurements by leveraging chromatic focal differences.
Implementation Method 1
Light components of different wavelengths tends to be focused through the lens to different focal lengths
Implementation Method 2
an object can be imaged by using a photodetector array to detect light that has reflected off of the object
Implementation Method 3
a photodetector array to detect light that has reflected off of the object
Data Source
AI summary
Techniques are described for passive three-dimensional (3D) image sensing based on chromatic differentiation. For example, an object can be imaged by using a photodetector array to detect light reflected off of the object and focused through a lens onto the array. Light components of different wavelengths tends to be focused through the lens to different focal lengths, which can tend to impact the brightness of each wavelength as detected. For example, if the detector array is closer to a shorter-wavelength focal plane, a white spot will tend to be detected with a higher magnitude of blue light components than of red light components. Ratios of brightness magnitudes for different wavelengths vary in a manner that strongly correlates to object distance from the lens. Embodiments exploit this correlation to passively detect object distance. Some embodiments further provide various types of distance and/or chromatic calibration to further facilitate such detection.