Axicon Scatter Filter Assembly for LIDAR Image Clarity
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Solution Overview
Problem
Scattering of light due to particles in the environment, such as fog and dust, causes image distortions and blurs, particularly in applications like time of flight cameras and LIDAR, which require accurate two and three-dimensional image generation.
Innovation Solution
An axicon scatter filter assembly is used, comprising a series of axicons positioned at specific distances and angles to generate and manipulate Bessel beams, effectively filtering out incoherent light and reducing distortions in the image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If light transmission occurs through scattering environments (fog, dust, water particles), then light carries information from distant objects, but scattering causes image distortion and blurring
Solution Approach 1:
The patent segments the light field into coherent and incoherent components using multiple axicons arranged in sequence. Each axicon processes specific angular components of the light, separating the useful coherent light carrying object information from the harmful incoherent scattered light through spatial and angular segmentation
Solution Approach 2:
The patent introduces axicons as intermediary optical elements that mediate between the scattered light field and the imaging sensor. These axicons transform the light distribution pattern, converting scattered light into a separable format that allows selective filtering while preserving useful image information
2Measurement precision
If conventional imaging methods are used in scattering environments, then the system structure remains simple, but image quality deteriorates due to scattering distortions
Solution Approach 1:
The imaging system is segmented into multiple functional stages with three axicons performing distinct operations. This segmentation allows each component to be optimized for its specific function while collectively solving the scattering problem, balancing complexity with performance improvement
Solution Approach 2:
The patent changes key optical parameters including axicon apex angles, separation distances, and beam propagation characteristics to optimize performance. By carefully selecting and adjusting these parameters, the system achieves effective scatter filtering without requiring excessively complex optical arrangements
3Measurement precision
If axicon scatter filter assembly is used to remove scattering distortions, then image quality improves, but the device complexity increases
Solution Approach 1:
The patent merges multiple axicon elements into a unified optical assembly where the components work synergistically. The first, second, and third axicons are combined in a specific configuration that achieves enhanced scatter rejection through their collective action, rather than requiring separate independent systems
Solution Approach 2:
The axicon assembly performs multiple functions simultaneously: it filters scattered light, reconstructs coherent light patterns, and maintains image formation capability. This multi-functionality reduces the need for additional separate components, managing overall system complexity while achieving multiple objectives
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 axicon scatter filter assembly enhances image quality by removing distortions caused by scattering, resulting in sharper, more accurate two and three-dimensional images in scattering environments.
Implementation Method 1
a first axicon adapted to be positioned proximate the object and having a planar surface positioned proximal to the object, a first alpha angle and a first apex angle, wherein the first axicon is adapted to generate and output a first Bessel beam
Implementation Method 2
An axicon scatter filter assembly is used, comprising a series of axicons positioned at specific distances and angles to generate and manipulate Bessel beams, effectively filtering out incoherent light and reducing distortions in the image
Implementation Method 3
the first axicon is adapted to generate and output a first Bessel beam; a second axicon adapted to be positioned downstream from the first axicon by a first predetermined distance and with its conical surface proximal to the incoming first Bessel beam output by the first axicon, the second axicon having a second alpha angle and a second apex angle, wherein the second axicon is adapted to generate and output a second Bessel beam
Data Source
AI summary
An axicon scatter filter assembly operates on light that is approximately temporally and spatially coherent (requiring either active illumination or a very narrow field of view). The filter exploits the difference in behavior between spatially coherent and spatially incoherent light. Spatially coherent light is shaped and moved by the axicons. This allows the spatially coherent light to diverge and then be reconstructed into a rectified image. The spatially incoherent light is neither shaped nor moved by the axicons. Where the coherent light diverges, the incoherent (scattered) light does not. Thus, masks can be used to block a portion of the incoherent light while passing all of the incoherent light. The filter assembly thus removes undesired scattered light that degrades image quality. The axicons then reconstruct the original image with less scattering, which can be imaged by a lens and camera.