Random Phase Aperture Mask for Extended Depth of Focus Imaging
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Solution Overview
Problem
Conventional imaging systems face limitations in extended depth of focus and geometrical resolution, particularly due to diffraction and the need for mechanical focusing techniques, which restrict their application in medical and industrial imaging.
Innovation Solution
An imaging system utilizing a random phase aperture mask in the aperture plane of the imaging lens, which generates an axially-dependent randomized phase distribution in the Optical Transfer Function (OTF), enabling extended depth of focus and digital estimation of object distances without triangulation-based processing, and enhancing geometrical resolution through orthogonal coding of spectral bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional focusing techniques using mechanical movement of lenses are used, then focusing capability is improved, but device complexity and loss of time increase
Solution Approach 1:
The patent replaces mechanical focusing systems with an optical coding approach. A random phase mask is placed in the aperture plane to encode depth information optically, eliminating the need for mechanical lens movement. The focused image is obtained through digital processing of the encoded image, substituting mechanical operations with optical and computational methods.
Solution Approach 2:
The patent changes the optical parameters by introducing a random phase mask that modifies the phase distribution across the aperture. This parameter change enables extended depth of focus by creating an axially-dependent randomized phase distribution in the Optical Transfer Function, allowing multiple depth planes to be encoded simultaneously without mechanical adjustment.
2Measurement precision
If conventional imaging systems are used, then geometrical resolution is limited by diffraction, but improving resolution requires complex optical systems
Solution Approach 1:
The patent substitutes complex optical correction systems with a digital processing approach. The random phase mask encodes depth and resolution information optically, and the focused image is recovered through digital deconvolution algorithms, replacing complex mechanical optical systems with simpler optical elements and computational methods.
Solution Approach 2:
The patent introduces an additional optical dimension by placing the random phase mask in the aperture plane, creating an axially-dependent phase distribution. This dimensional addition enables simultaneous encoding of depth information and improved resolution, allowing the system to overcome diffraction limits through the encoded spectral bands rather than requiring complex optical correction.
3Adaptability or versatility
If extended depth of focus is achieved through aperture coding, then depth of focus is improved, but signal to noise ratio and contrast decrease
Solution Approach 1:
The patent employs feedback through iterative deconvolution algorithms that process the encoded image to recover the focused image. The random phase mask encoding is reversed computationally, using feedback loops to enhance the signal-to-noise ratio and restore contrast while maintaining extended depth of focus. This feedback mechanism allows the system to compensate for the degradation introduced by the phase mask.
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 system achieves almost infinite extended depth of focus and improved geometrical resolution, allowing for precise 3D information extraction and super-resolved imaging without the need for mechanical focusing or phase correction, while reducing noise and signal processing complexity.
Implementation Method 1
an optical element located in the vicinity of the lens aperture, said optical element introducing aperture coding by an array of regions differently affecting a phase of light incident thereon which are randomly distributed within the lens aperture, thereby generating an axially-dependent randomized phase distribution in the Optical Transfer Function (OTF)
Implementation Method 2
an imaging lens arrangement, a light detector unit at a certain distance from the imaging lens arrangement
Data Source
AI summary
An imaging system is presented for imaging objects within a field of view of the system. The imaging system comprises an imaging lens arrangement, a light detector unit at a certain distance from the imaging lens arrangement, and a control unit connectable to the output of the detection unit. The imaging lens arrangement comprises an imaging lens and an optical element located in the vicinity of the lens aperture, said optical element introducing aperture coding by an array of regions differently affecting a phase of light incident thereon which are randomly distributed within the lens aperture, thereby generating an axially-dependent randomized phase distribution in the Optical Transfer Function (OTF) of the imaging system resulting in an extended depth of focus of the imaging system. The control unit is configured to decode the sampled output of the detection unit by using the random aperture coding to thereby extract 3D information of the objects in the field of view of the light detector unit.