Optical Moisture Sensor Parabolic Mirror Beam Shaping
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Solution Overview
Problem
Existing optical moisture sensors for transparent panes, such as windshields, face challenges in achieving high sensitivity and large sensitive areas while maintaining a compact and robust design, with limited utilization of radiation power and space efficiency.
Innovation Solution
The use of a parabolic mirror combined with a collimating lens to separate the radiation into two beams, creating overlapping or separate sensitive areas on the outer surface of the pane, enhancing sensitivity and utilizing radiation power effectively, along with a miniaturized geometry using surface mount devices and a printed circuit board, and focusing lenses for improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional collimating lenses are used to couple radiation into the pane, then the sensor structure is simple, but the radiation power utilization is low and the sensitive area is limited
Solution Approach 1:
The beam shaping unit segments the emitted radiation into multiple beams using a parabolic mirror that divides the radiation into a first beam and a second beam, each directed at different angles to create multiple sensitive areas on the pane surface
Solution Approach 2:
The parabolic mirror introduces angular dimensionality by reflecting radiation at different angles (first angle and second angle), transforming a single-direction beam into multi-directional beams that expand the sensitive area coverage on the pane
2Measurement precision
If the sensitive area is enlarged to improve moisture detection coverage, then the measurement accuracy improves, but the sensor size and space requirements increase
Solution Approach 1:
The sensor achieves enlarged sensitive area by utilizing angular dimension through the parabolic mirror, which directs beams at different angles to create multiple sensitive areas without increasing the physical footprint of the sensor components
Solution Approach 2:
The parabolic mirror uses its curved surface to reflect and shape radiation beams, creating focused sensitive areas on the pane surface while maintaining a compact sensor geometry
3Productivity
If multiple collimating lenses are used to create multiple sensitive areas, then the radiation power utilization improves, but the device complexity and manufacturing cost increase
Solution Approach 1:
The parabolic mirror merges the functions of multiple collimating lenses into a single optical component, achieving multi-beam radiation shaping through its curved reflective surface while simplifying the overall device structure and manufacturing process
Solution Approach 2:
The parabolic mirror serves multiple functions simultaneously: it acts as a beam splitter, a collimating element for multiple beams, and a focusing component, replacing what would traditionally require multiple separate optical elements
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 configuration results in a highly sensitive and accurate moisture detection system with reduced space requirements, capable of effectively assessing moisture coverage and integrated into various automotive components, such as the foot of a rear view mirror.
Implementation Method 1
the beam shaping unit comprises at least one parabolic mirror for forming a first radiation beam from a first portion of the emitted radiation
Implementation Method 2
the beam shaping unit comprises at least one collimating lens for forming at least one second radiation beam from a second part of the emitted radiation
Implementation Method 3
The radiation emitter 202 emits radiation, for instance infrared radiation, towards the transparent pane 204
Implementation Method 4
a radiation detector 214, for instance a photodiode (PD)
Implementation Method 5
a moisture droplet 216 with a refractive index of approximately n=1.3 is present on the pane 204 in the sensitive area 212, a part of the radiation 212 is coupled out of the pane 204
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
The present invention relates to an optical moisture sensor of the internal reflection type which may be attached to a first surface of a transparent pane for detecting moisture on a second, opposing surface of the pane. The moisture (100) comprises at least one radiation emitter (102) for generating radiation be directed towards said second surface (106) of the pane (104), at least one radiation detector (114) for detecting radiation reflected by the second surface (106) of the pane (104), and a beam shaping unit (116) for shaping the radiation emitted by said emitter (102), wherein the beam shaping unit (116) comprises at least one collimating lens (118) for forming a first radiation beam (120) from a first portion of the emitted radiation, and at least one parabolic mirror (122) for forming at least one second radiation beam (124) from a second part of the emitted radiation.