Optical Distance Sensor With Coaxial Visible Pilot Beam
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Solution Overview
Problem
Optical distance sensors operating with non-visible wavelength light beams lack the ability for visual beam guidance and are susceptible to reduced reliability due to poor resistance to ambient light when using visible wavelength emitters.
Innovation Solution
Incorporating a pilot transmitter unit that emits visible pilot light beams coaxially with non-visible light beams, allowing for visual guidance and enhanced resistance to ambient light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If visible wavelength light beams are used for beam guidance, then visual control and adjustment are enabled, but resistance to ambient light deteriorates significantly
Solution Approach 1:
The light source is segmented into two distinct functional components: a non-visible wavelength source (infrared VCSEL) for distance measurement and a visible wavelength source (visible LED) for beam guidance. This segmentation allows each component to perform its specialized function without compromising the other, enabling visual control while maintaining immunity to ambient light interference.
Solution Approach 2:
The visible wavelength light acts as an intermediary that provides visual feedback about the non-visible measurement beam's path. The visible beam does not participate in distance measurement but serves as a guide, allowing operators to see and adjust the invisible infrared beam's alignment and coverage area without affecting the measurement reliability.
2Reliability
If non-visible wavelength light beams are used, then resistance to ambient light is improved, but visual control of beam guidance is lost
Solution Approach 1:
The system separates the measurement function (infrared) from the guidance function (visible), allowing the infrared beam to maintain its ambient light resistance while the visible beam provides the necessary visual feedback for operation and alignment.
Solution Approach 2:
The system uses different wavelengths (colors) of light for different purposes: infrared for measurement and visible light for guidance. The visible wavelength component emits light in the visible spectrum to provide visual feedback, while the infrared component operates in the non-visible range to ensure resistance to ambient light interference.
3Ease of operation
If visible wavelength VCSEL units are used, then beam guidance becomes visible, but detection sensitivity is reduced due to poor ambient light resistance
Solution Approach 1:
The system uses two different types of light sources with distinct characteristics: an infrared VCSEL for sensitive distance measurement and a visible LED for beam alignment. This segmentation allows the measurement component to operate in the low-noise infrared band while the guidance component provides visible feedback, achieving both high detection sensitivity and visual beam alignment.
Solution Approach 2:
The system changes the wavelength parameter of the light source based on the functional requirement. For measurement, it uses infrared wavelengths that are resistant to ambient light and provide high detection sensitivity. For guidance, it uses visible wavelengths that provide visual feedback. The variable aperture further adjusts the spatial parameters to match the measurement beam's coverage 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
The solution provides high detection sensitivity and reliability by enabling visual beam alignment and monitoring, while maintaining high performance in various lighting conditions.
Implementation Method 1
These modules employ a VCSEL (vertical-cavity surface-emitting laser) diode or a VCSEL array as the transmitter, emitting laser light in the infrared range
Implementation Method 2
The time-of-flight modules typically use an array of SPADs (single-photon avalanche diodes) as the receiver
Implementation Method 3
an optical element for coaxially superimposing the measuring light beam and the pilot light beam
Implementation Method 4
an optical element for coaxially superimposing the measuring light beam and the pilot light beam
Data Source
Figure 1~1a
Figure 2~3
Figure 4~5
AI summary
The invention relates to an optical distance sensor (1) comprising a transmitter (3) emitting light beams (2) in a non-visible wavelength range, a receiver (4) configured to receive light beams (2) reflected from an object, and an evaluation unit configured to determine the distance of the object based on received signals from the receiver (4). A pilot transmitter (9, 9') is provided, emitting visible pilot light beams (10, 10'), the pilot light beams (10, 10') being coupled into the beam path of the light beams (2) by means of coupling means such that the pilot light beams (10, 10') and the light beams (2) are coaxial with at least partially overlapping beam cross-sections.