Optoelectronic Sensor Temperature-Compensating Deflection Element
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Laser scanners face challenges in accurately detecting objects due to temperature-related changes in focal length, leading to increased extraneous light interference and reduced sensitivity, especially when using avalanche photodiodes in Geiger mode, which are prone to false triggering by extraneous light and become inactive for measurement.
Innovation Solution
A temperature-compensating deflection element with a curvature that changes over a known temperature range, opposing the focal length changes of the receiving optics, ensures a stable focus position and reduces extraneous light entry, allowing for improved sensitivity and robustness in object detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the acceptance angle is increased to compensate for focal length changes, then the robustness against temperature variations is improved, but the amount of extraneous light detected increases
Solution Approach 1:
The patent changes the curvature parameter of the deflection element with temperature to compensate for focal length variations. The deflection element's curvature is adjusted as a function of temperature to maintain a constant focus position on the light receiver, thereby avoiding the need to increase the acceptance angle while remaining robust against temperature variations.
Solution Approach 2:
The patent implements a feedback mechanism where the temperature-dependent curvature change of the deflection element responds to temperature variations to actively compensate for focal length drift. This closed-loop approach maintains stable focusing conditions without requiring a larger acceptance angle, thus preventing extraneous light interference.
2Measurement precision
If avalanche photodiodes in Geiger mode are used to increase detection sensitivity, then the sensitivity to weak light signals is improved, but the susceptibility to false triggering by extraneous light increases
Solution Approach 1:
The patent converts the temperature-dependent focal length variation, which was previously a harmful factor causing focus drift and increased extraneous light, into a beneficial compensation mechanism. By deliberately adjusting the deflection element's curvature with temperature, the system uses this variation to maintain stable focusing, thereby protecting the sensitive avalanche photodiodes from false triggering while preserving their high detection sensitivity.
3Adaptability or versatility
If the field stop diameter is increased to accommodate focal length variations, then the adaptability to temperature changes is improved, but the acceptance angle increases leading to more ambient light detection
Solution Approach 1:
The patent changes the curvature parameter of the deflection element with temperature to compensate for focal length variations. This dynamic parameter adjustment maintains a constant focus position on the light receiver across the temperature range, eliminating the need to increase the field stop diameter or acceptance angle, thereby preventing ambient light interference.
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 maintains a small acceptance angle and high spatial resolution, effectively reducing extraneous light interference and enhancing the performance of sensitive avalanche photodiodes, even under temperature variations, without the need for enlarging the acceptance space angle, thus improving the detection accuracy and reliability.
Implementation Method 1
A deflection element with a beam shape that is temperature-dependent in particular a curved deflection element with a focal length, whose curvature and thus focal length changes through targeted deformation over a known temperature range
Implementation Method 2
A receiving optic, in particular with at least one refractive element or a receiving lens, for focusing the received light onto the light receiver
Implementation Method 3
In an avalanche photodiode (APD), the incident light triggers a controlled avalanche breakdown (avalanche effect). This multiplies the charge carriers generated by the incident photons, creating a photocurrent that is proportional to the light-receiving intensity
Implementation Method 4
A light source generates transmitted light and emits it into the monitoring area... a light beam generated by a laser is periodically scanned across a monitoring area
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
An optoelectronic sensor (10) for detecting objects in a monitoring area (20) is described, comprising a light transmitter (12) for emitting transmitted light (16), a light receiver (26) for generating a received signal from received light (22) from the monitoring area (20), a movable deflection unit (18) for periodically deflecting the transmitted light (16) and the received light (22), a control and evaluation unit (32) for acquiring information about objects in the monitoring area (20) based on the received signal, and an optical deflection element (18, 40) in the beam path of the received light (22). The deflection element (18, 40) exhibits temperature-dependent beam shaping properties.