Optoelectronic Triangulation Scanner with Microlens Array
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Solution Overview
Problem
Conventional triangulation light scanners face issues with accurate object detection due to asymmetrical illumination and non-uniform backscattering or reflection from objects, leading to incorrect distance measurements and detection artifacts.
Innovation Solution
The use of a microlens array and pixel array, including subpixels and metapixels, allows for the determination of object distance from signal distribution patterns, enabling correction of detection errors and improved accuracy by considering the angle of incidence and asymmetries in illumination, with options for linear or two-dimensional arrays and various interconnection configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pinhole diaphragm is used as receiver optics to ensure detection independence from interference, then measurement reliability is improved, but device complexity and signal intensity are worsened
Solution Approach 1:
The receiver optics are segmented into multiple zones (first receiver zone, second receiver zone, third receiver zone) with different aperture characteristics. Each zone handles specific angular ranges of backscattered light, allowing the system to achieve pinhole-like measurement reliability for distant objects while maintaining higher signal intensity for closer objects through larger apertures in other zones.
2Illumination intensity
If an aperture is used in receiver optics to improve sensitivity, then signal detection capability is improved, but measurement accuracy deteriorates due to asymmetrical illumination
Solution Approach 1:
Different zones of the receiver optics are assigned different aperture sizes and characteristics tailored to their specific functions. The first receiver zone has a smaller aperture for precise distance measurements of distant objects, while the second and third zones have larger apertures optimized for detecting closer objects. This local optimization allows each zone to achieve both high sensitivity and high measurement accuracy for its designated range.
Solution Approach 2:
The system dynamically selects which receiver zone to use based on the detected object's distance and the characteristics of the backscattered light. The evaluation unit determines the appropriate zone based on signal distribution patterns, allowing the effective aperture to adapt dynamically to measurement conditions, thereby maintaining both sensitivity and accuracy across varying ranges.
3Illumination intensity
If reflected light beams are detected along with backscattered beams, then signal intensity is improved, but detection accuracy deteriorates due to position shifts in the receiver plane
Solution Approach 1:
The receiver optics are segmented into multiple zones that spatially separate the detection of backscattered light from reflected light. The first receiver zone is positioned to detect backscattered light from distant objects, while the second and third zones detect light from closer objects. This spatial segmentation allows the system to selectively process different light types and apply appropriate evaluation methods to each zone, preventing reflected light from contaminating distance measurements of backscattering objects.
Solution Approach 2:
The evaluation unit analyzes the signal distribution pattern across the receiver zones to determine whether the detected light is backscattered or reflected. Based on this analysis, the system applies appropriate evaluation methods or corrects the distance measurement accordingly. This feedback mechanism allows the system to maintain high detection accuracy even when both backscattered and reflected light are present in the detection field.
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 approach enhances the reliability of object detection by accounting for asymmetrical signal distributions and non-uniform illumination, providing more accurate distance measurements and reducing errors caused by non-ideal scattering surfaces.
Implementation Method 1
Each macropixel comprises a plurality of individual subpixels. The focal lengths and/or the apertures of the receiver optics and the microlenses are selected in such a way that at least the light beams backscattered from an object arranged within a detection area and which completely illuminate the receiver optics can be deflected by a number of adjacent microlenses
Implementation Method 2
Depending on the distance of the object from the receiver optics, the beams scattered back from the object pass through the receiver optics at different angles and thus hit different lateral positions in the receiver plane
Implementation Method 3
The light source, which can also be provided with an optical transmission system, emits an ideally parallel bundle of rays which, when it hits the surface of an object, generates a light spot that is scattered back by the object
Data Source
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Figure 3a~3b
AI summary
In a device for detecting an object using an optoelectronic device, in which light rays generated by a light source and backscattered and/or reflected by an object are detected by a receiving arrangement according to the triangulation principle, and an object detection signal is output by an evaluation unit, the light rays in the receiving arrangement impinge on a pixel array consisting of photodetectors via a receiver optic and a microlens array, wherein each microlens is assigned a macropixel comprising several subpixels. The evaluation unit includes a unit for determining the distribution of the received signal across the subpixels within a macropixel.In one method for operating the device, the object detection signal is generated depending on the received signal distribution across the macropixels and/or depending on the received signal distribution across the subpixels of at least one macropixel and/or depending on the received signal distribution across the metapixels. In another method for operating the device, the received signal distribution across the subpixels within a macropixel is determined in each case. The received signals supplied by a macropixel are used for object detection if the subpixels of the respective macropixel exhibit a substantially symmetrical signal distribution. If the subpixels of the respective macropixel exhibit a substantially asymmetrical signal distribution, the received signals supplied by a macropixel are not used for object detection, or only after a correction step has been performed.