Flat Light Guide Plate Diffractive Sensor for Compact Distance Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional optoelectronic sensors face challenges in achieving a compact design with large receiving apertures due to the contradiction between aperture size and focal length, limiting their use in applications with minimal overall depth, such as miniature light barriers.
Innovation Solution
The use of a diffractive flat collector with a flat light guide plate that deflects received light to its lateral edge, allowing for a spatially resolving light receiver to determine distance information, enabling a compact design with a small overall depth and large aperture, and incorporating a diffractive structure that acts as an optical bandpass filter to improve signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a large receiving aperture is used to achieve long detection ranges, then the detection range is improved, but the installation depth increases
Solution Approach 1:
The patent transitions from a conventional three-dimensional optical path to a two-dimensional planar light guide structure. Light is guided laterally across the flat surface of the light guide plate rather than through a deep focal path, enabling large aperture with minimal installation depth. The light receiver is positioned at the lateral edge of the flat plate, exploiting the planar geometry to achieve long detection ranges without increasing depth.
Solution Approach 2:
The light guide plate serves as an intermediary component between the large receiving aperture and the light receiver. It captures light across a large aperture area and transports it laterally to the edge where the light receiver is positioned, decoupling the aperture size from the installation depth requirement.
2Area of stationary object
If a conventional receiving optic with large aperture is used, then the receiving aperture is improved, but the focal length and installation depth increase
Solution Approach 1:
The patent replaces the conventional lens-based optical system with a planar light guide plate system. Instead of using a lens to focus light through a long focal path, the light guide plate uses total internal reflection and lateral guidance to transport light, eliminating the need for a long focal length while maintaining large aperture capability.
Solution Approach 2:
The optical system is transformed from a three-dimensional lens configuration to a two-dimensional planar structure. The light guide plate spreads the optical path laterally across its surface, converting the depth-direction focal length requirement into a lateral dimension, thereby achieving large aperture without long focal length.
3Measurement precision
If optical triangulation is used for distance measurement, then distance measurement capability is improved, but the installation depth increases
Solution Approach 1:
The triangulation geometry is reconfigured from a deep three-dimensional arrangement to a shallow planar configuration. The light source and light receiver are positioned at the lateral edge of the flat light guide plate, creating triangulation angles in the lateral dimension rather than requiring deep separation in the depth dimension, thus enabling distance measurement with minimal installation depth.
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 allows for distance measurement and background suppression in optoelectronic sensors, enabling a previously unattainable flat design for both background-suppressing light scanners and triangulation probes, while maintaining high sensitivity and efficiency with minimal depth.
Implementation Method 1
Light incident on the holographic layer is deflected laterally at an angle and then deflected sideways by the substrate under total internal reflection
Implementation Method 2
Light incident on the holographic layer is deflected laterally at an angle and then deflected sideways by the substrate under total internal reflection
Implementation Method 3
the received light incident on the flat surface is directed to a light receiver by light-refracting sub-apertures, wedge surfaces, or layers with different refractive indices
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
An optoelectronic sensor (10), in particular a light barrier or light sensor, for detecting objects (30) in a monitoring area (14) is specified, which has a light receiver (18) with an upstream receiving optic (16) for generating a received signal from received light (12) that strikes the sensor (10) in a direction of incidence from the monitoring area (14), wherein the receiving optic (16) comprises at least one flat light guide plate (34) with a first main surface (36) and a lateral edge (40) bounding the first main surface (36) on one side, the light guide plate (34) being arranged with its first main surface (36) transversely to the direction of incidence of the light and having a diffractive structure (38) to deflect the incident received light (12) to the lateral edge (40), and a control and evaluation unit (20) for evaluating the received signal is provided. is.The light receiver (18) is spatially resolving, and the control and evaluation unit (20) is designed to obtain distance information of a detected object (30) from the point of impact of the received light (12) on the light receiver (18).