Rectangular Frusto Pyramidal Reflector for 3D Time-of-Flight Camera Illumination
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Solution Overview
Problem
Current 3D time of flight cameras face challenges in matching the field of illumination (FOI) with the field of view (FOV) due to limited commercially available emission angles, leading to inefficient light distribution and potential multi-path artifacts from objects outside the FOV, which increases costs and reduces detection accuracy.
Innovation Solution
A frusto pyramidal reflector with a rectangular or square cross-section is used in conjunction with a light emitter to direct light efficiently onto the scene, ensuring better coverage of the camera's FOV without the need for custom-made micro-optics, allowing for flexible adaptation of the field of illumination to match the camera's specifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a micro-lens is used to narrow the emission angle, then the light distribution becomes more concentrated, but the field of illumination no longer matches the rectangular field of view and illumination uniformity is lost
Solution Approach 1:
A reflector is introduced as an intermediary component between the LED and the scene. The reflector redirects light that would otherwise be emitted at wide angles, shaping it to match the rectangular field of view while maintaining illumination uniformity across the entire area.
Solution Approach 2:
The emission parameters of the light source are modified by adding a reflector with specific geometric parameters (rectangular shape, tailored dimensions). This changes the angular distribution and spatial pattern of emitted light to achieve better matching with the camera's field of view.
2Illumination intensity
If a wide field of illumination is used, then illumination uniformity over the field of view improves, but light power is wasted outside the field of view
Solution Approach 1:
The reflector acts as a mediator that captures light emitted at wide angles and redirects it into the field of view. This allows the system to use a wide-emission LED while preventing energy waste, as the reflector ensures all light contributes usefully to illuminating the scene within the FOV.
Solution Approach 2:
The wide emission angle, which initially appears to be a waste of light power, is converted into a benefit by the reflector. The reflector captures the otherwise wasted wide-angle light and redirects it to illuminate the scene, turning potential energy loss into useful illumination.
3Manufacturing precision
If custom-made micro-optics are developed to match field of illumination with field of view, then the matching precision improves, but manufacturing costs increase
Solution Approach 1:
Instead of investing in expensive custom-made micro-optics, the patent uses a simple, inexpensive reflector that can be easily manufactured and integrated. The reflector achieves sufficient matching precision without requiring costly custom optical design and fabrication processes.
Solution Approach 2:
The reflector serves as a simple intermediary component that provides the necessary optical function (shaping the light distribution) without the complexity and cost of custom micro-optics. This intermediate solution achieves practical matching precision at low manufacturing cost.
4Loss of energy
If the field of illumination is narrower than the field of view, then light power efficiency improves, but objects outside the field of view can still create multi-path artifacts
Solution Approach 1:
The reflector acts as a precise intermediary that controls the field of illumination to exactly match the field of view. This prevents light from reaching objects outside the FOV, thereby eliminating the source of multi-path artifacts while maintaining efficient light power usage within the intended illumination area.
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 solution enhances the matching of FOI and FOV, reduces complexity and costs associated with custom optics, and minimizes undetectable multi-path artifacts, resulting in improved illumination uniformity and detection accuracy across the camera's field of view.
Implementation Method 1
a frusto pyramidal reflector for directing light from the light emitter onto the scene
Data Source
AI summary
Improved field-of-illumination (FOI) and field-of-view (FOV) matching for 3D time-of-flight cameras is provided using light emitters with rectangular reflectors. A better adjustment of the FOI with the camera's FOV has the following advantages: optimal use of emitted light and reduced multi-path problems. Furthermore, embodiments bring the benefit for rather low-cost customization of the illumination to match the FOI to the specified FOV.