Rotating Point Spread Function Mask for Depth Resolution
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Solution Overview
Problem
Existing methods for optical imaging and ranging are limited by the depth of field, which restricts the resolution beyond the numerical aperture of the system, failing to achieve super-resolution.
Innovation Solution
The system employs a mask with a rotating point spread function that evolves with the object's position, allowing for deconvolution of images to estimate object distance using computational logic, and includes a sensor array to detect light through the imaging system, optimizing Fisher information for enhanced depth estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If classical apertures are used for imaging, then the system structure is simple, but the depth resolution is limited by diffraction and depth of field
Solution Approach 1:
A rotating diffuser is introduced as an intermediary element between the object and the imaging system. This diffuser rotates during the exposure time to scramble spatial information and encode depth information into the image formation process, enabling depth resolution beyond the classical depth of field limit without requiring complex multi-camera or multi-lens systems
Solution Approach 2:
The diffuser is made dynamic by rotating it during the image capture process. This dynamic element modulates the light paths in a time-varying manner, allowing the system to encode multiple depth information into a single image and achieve super-resolution depth measurement without increasing the static structural complexity
2Measurement precision
If depth of field cues are used for ranging, then fewer images are needed compared to stereo imaging, but the depth resolution is still limited by the numerical aperture
Solution Approach 1:
The rotating diffuser acts as an information-preserving intermediary that encodes depth information that would otherwise be lost beyond the depth of field. By scrambling and re-encoding the light paths, it preserves depth information that can be recovered through computational processing, preventing information loss beyond the classical DOF limit
Solution Approach 2:
The system changes the optical parameters dynamically by rotating the diffuser, which modifies the point spread function over time. This parameter change allows the system to capture depth information across different focal planes within a single exposure, recovering depth information that would be lost in static imaging systems
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 provides extreme accuracy in estimating object distance and brightness, overcoming the depth-of-field limitations by achieving resolution beyond the numerical aperture constraints.
Implementation Method 1
The mask is designed to maximize and/or optimize Fisher information... encoding one or more three-dimensional responses of the imaging system for calculating a point spread function that evolves as a function of a position of the object
Data Source
AI summary
The distance of objects to an optical system is estimated. An optical mask such as a diffractive optical element, continuous phase mask, hologram, amplitude mask, or combination thereof is placed within the optics in front of a sensor array such as a CCD, CID or COMAS device. The optical mask encodes the three-dimensional response of the system. The mask is designed to optimize depth estimation, for example, by maximizing Fisher information. A particular implementation creates a point spread function (“PSF”) that rotates as a function of the object position. The image or images obtained with different PSFs may be digitally processed to recover both a depth map of the scene and other parameters such as image brightness. The digital processing used to recover the depth map of the object may include deconvolution of a PSF from detected images.