Optoelectronic Sensor Micro-Optic Deflection for Spot Size Reduction
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Solution Overview
Problem
Optoelectronic sensors with multiple light sources face challenges in achieving small light spots due to the large angular distribution of light, leading to increased light losses and reduced resolution, as existing methods like additional lenses or microlenses either fail to improve the situation or introduce aberrations.
Innovation Solution
The use of non-imaging micro-optics to deflect individual light beams inward, creating a virtual image that appears to originate from a more compact area, reducing the light spot size without increasing the angular distribution, thereby improving resolution and reducing light losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple individual light sources are used to increase optical output power, then the emission angle can be better controlled, but the overall light spot size becomes larger due to the larger area encompassing all light-emitting surfaces
Solution Approach 1:
The light source is segmented into multiple individual light-emitting surfaces (mesas) arranged in close proximity, allowing each surface to be controlled independently while collectively providing high optical output power
Solution Approach 2:
Multiple light-emitting surfaces are nested in close proximity within a compact VCSEL structure, enabling them to function as a unified high-power source while maintaining a small overall footprint
2Device complexity
If a single transmitting lens is used to image the VCSEL, then the structure is simple, but the larger area of multiple light-emitting surfaces results in larger light spots in the monitored area
Solution Approach 1:
Instead of attempting to reduce the light spot size by modifying the lens imaging geometry, the solution addresses the problem in a different dimension by controlling the emission characteristics at the source level through multiple small light-emitting surfaces
3Area of moving object
If an additional single lens is placed between the light source and transmitting optic to reduce the light spot size, then the intermediate image becomes smaller, but the beam angle increases causing light losses
Solution Approach 1:
The patent converts the potential harm of increased beam angle into a benefit by using the multiple small light-emitting surfaces to inherently provide better emission angle control, transforming what would be a disadvantage into an advantage
4Manufacturing precision
If microlenses are assigned to each light-emitting surface to create real intermediate images, then the divergence angle of individual light sources remains constant, but the overall beam divergence angle increases due to tilting of principal rays
Solution Approach 1:
Each light-emitting surface is given the same uniform properties and arrangement, creating local consistency that results in overall improved beam quality without the need for complex individual microlens assemblies
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 effectively reduces the size of the transmitted and received light spots, enhancing the resolution and minimizing light losses, while avoiding the need for high refractive power lenses that cause aberrations.
Implementation Method 1
an optical deflection element (18) with non-imaging micro-optic areas (34a-b) assigned to the individual light sources (14a-b), which deflect the individual light beams (36a-b) inwards towards each other
Data Source
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AI summary
An optoelectronic sensor (10) for detecting objects (24) in a monitoring area (22) is specified, comprising a light transmitter (12) with a plurality of individual light sources (14) and an upstream transmitting optic (20) for emitting a transmitting light beam (16) composed of individual light beams (36) of the individual light sources (14), a light receiver (30) for generating a received signal from the transmitted light beam (26) remitted in the monitoring area (22) and falling on the light receiver (30), and an evaluation unit (32) for detecting the objects (24) from the received signal.An optical deflection element (18) is arranged between the light transmitter (12) and the transmitting optics (20), which has micro-optical areas (34) assigned to the individual light sources (14), which deflect the individual light beams (36) towards each other in such a way that the cross-sections of the individual light beams (36) in a virtual image plane (42) in front of the transmitting optics (20) together occupy a smaller area than the individual light sources (14) themselves.