Directional Imaging Array Apertures for Compact Aberration Control
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Solution Overview
Problem
Image-space telecentric lens designs with a front aperture stop are unsuitable for compact cameras due to increased total track length, which is a critical constraint for devices like mobile telephones, leading to image degradation from optical aberrations.
Innovation Solution
A detector assembly with limited active areas and aligned optical apertures in the rear focal plane of objective optics emulates a front aperture stop, using a singlet lens or metasurface elements to create an effective aperture stop, reducing aberrations without a physical stop, suitable for compact cameras.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a front aperture stop is used in image-space telecentric lens design, then optical aberrations are reduced and image quality is improved, but total track length increases making it unsuitable for compact cameras
Solution Approach 1:
The patent inverts the conventional telecentric lens design by moving the aperture stop from the front focal plane to the rear focal plane, and by swapping the positions of the objective lens and detector assembly. This inversion maintains the aberration-reduction benefits while enabling a compact total track length suitable for mobile devices.
Solution Approach 2:
The patent changes the key parameter of aperture stop position from front focal plane to rear focal plane, and adjusts the spacing between optical elements to achieve both compact size and aberration control. The specific spacing relationships (e.g., distance between aperture stop and detector assembly) are optimized to maintain image quality in a compact form.
2Manufacturing precision
If active area width is reduced to less than 90% of pitch, then directional response is enhanced and aberrations are suppressed, but light gathering area is reduced
Solution Approach 1:
The patent applies local quality by creating non-uniform spacing between optical apertures and sensing elements. The aperture-to-sensor distance is specifically optimized at each location to achieve directional selectivity, while the active area width is locally constrained to less than 90% of pitch to enhance angular response without uniformly reducing light gathering across the entire sensor.
Solution Approach 2:
The patent introduces asymmetry in the optical path by positioning aperture stops at specific distances from sensing elements (no less than twice the active area width). This asymmetric configuration creates directional response characteristics that suppress aberrations while maintaining adequate light gathering through optimized geometric relationships.
3Manufacturing precision
If optical apertures are positioned at distance no less than twice the active area width, then directional selectivity is improved and aberrations are reduced, but optical path length increases
Solution Approach 1:
The patent resolves the dimensional conflict by repositioning the aperture stop to the rear focal plane (another spatial dimension relative to the conventional front focal plane location). This dimensional repositioning allows the aperture-to-sensor distance to be optimized for directional selectivity while the overall optical path remains compact due to the inverted lens assembly configuration.
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 configuration achieves improved image quality by suppressing aberrations, maintaining a short total track length, and enhancing optical efficiency with directional response, suitable for compact imaging devices.
Implementation Method 1
Objective optics are configured to focus light from a scene onto the detector assembly
Implementation Method 2
the matrix of optical sensing elements includes a material between the active areas that absorbs at least 80% of optical radiation that is incident on the material
Implementation Method 3
An array of optical apertures are respectively aligned with the optical sensing elements such that each optical aperture is positioned at a distance from a respective optical sensing element that is no less than twice the width of the active area
Implementation Method 4
the array of optical apertures includes microlenses disposed respectively in the optical apertures
Implementation Method 5
the detector assembly includes baffles disposed between the optical sensing elements and configured to prevent light passing through each optical aperture from impinging on any of the optical sensing elements other than the respective optical sensing element with which the optical aperture is aligned
Data Source
AI summary
An image sensing device includes a detector assembly, which includes a matrix of optical sensing elements having a predefined pitch. Each optical sensing element includes an active area having a width that is less than 90% of the pitch. An array of optical apertures are respectively aligned with the optical sensing elements such that each optical aperture is positioned at a distance from a respective optical sensing element that is no less than twice the width of the active area. Objective optics are configured to focus light from a scene onto the detector assembly.