Plenoptic imaging device with a virtual intermediate image
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Solution Overview
Problem
Conventional plenoptic imaging devices, particularly in the X-ray domain, suffer from limited lateral, longitudinal, and angular resolution due to the small numerical aperture of X-ray optics, complicating 3D reconstruction of partially X-ray transparent samples.
Innovation Solution
A plenoptic imaging device configuration where the object is placed between the object focal plane and the primary lens, forming a virtual image on the object side, with a main optical assembly and a light field sampling assembly to enhance spatio-directional information capture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the object is placed at a distance greater than the object focal length to form a real intermediate image, then the image can be captured by the microlens array, but the lateral and longitudinal resolution are limited by the small numerical aperture of X-ray optics
Solution Approach 1:
The patent inverts the conventional image formation approach by placing the object within the focal length to create a virtual intermediate image instead of a real image. This inversion allows the main optical assembly to operate at high numerical aperture while the microlens array captures the divergent rays, thereby improving lateral and longitudinal resolution without being constrained by the small numerical aperture limitation.
Solution Approach 2:
The patent changes the object distance parameter from being greater than the focal length (conventional) to less than the focal length (invention). This parameter change transforms the image type from real to virtual, enabling the rays to diverge appropriately for the microlens array to capture angular information while maintaining high spatial resolution through the main optical assembly's high numerical aperture.
2Loss of information
If the microlens array is placed in the plane of the real intermediate image, then the spatial and angular components can be separated, but the depth of field is limited and 3D reconstruction of transparent samples is complicated
Solution Approach 1:
By inverting the image formation to create a virtual intermediate image, the patent allows the microlens array to capture divergent rays that contain rich angular information. This inversion enables the separation of spatial and angular components while extending the depth of field, making 3D reconstruction of transparent samples more effective by preserving longitudinal resolution information.
3Measurement precision
If the object distance is less than the object focal length to form a virtual intermediate image, then the numerical aperture is increased and resolution is improved, but the image formation mechanism differs from conventional plenoptic devices
Solution Approach 1:
The patent applies the inversion principle by placing the object within the focal length to form a virtual intermediate image, causing the main optical assembly to operate at high numerical aperture. This increases angular resolution as the divergent rays carry more angular information to the microlens array, while the optical configuration difference from conventional devices becomes the enabling feature rather than a complication.
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
Improves lateral, longitudinal, and angular resolution, and depth of field, overcoming the limitations imposed by low numerical aperture X-ray optics, enabling more effective 3D reconstruction of X-ray transparent samples.
Implementation Method 1
a main optical assembly, arranged to focus rays from the light field of said object
Implementation Method 2
an array of microlenses arranged at a distance a of the intermediate image plane, the photodetector being arranged at a distance b of the microlens array, each microlens being of diameter d2 and having a focal length f2 and being adapted to form a micro-image of a respective part of the virtual image of the object on a respective portion of the photodetector
Data Source
Figure 1A~1B
Figure 1C~1D
Figure 2
AI summary
A plenoptic imaging device (1) for forming an image of the light field of an object (O), comprising: - a sample holder (SH) suitable for holding said object; - a main optical assembly (LP), arranged to focus rays of the light field of said object, at a distance z0, referred to as the object distance, from the sample holder, which distance is smaller than an object focal distance f1 from said main optical assembly so as to form an intermediate optical image (Iv) of said object in an intermediate image plane at a distance z1 from said optical assembly; - an assembly for sampling the light field (LFS), which assembly is suitable for acquiring spatio-directional information on the rays forming the virtual image and for forming said image of the light field.