Optoelectronic Sensor Optics for Angle-Matched Light Filtering
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Solution Overview
Problem
Existing optoelectronic sensors face challenges in improving measurement accuracy due to the dependence of bandpass filters on the angle of incidence, which is exacerbated by extraneous light sources like sunlight, and the need for additional optical components to achieve parallelization, leading to increased construction space and costs.
Innovation Solution
The sensor employs a reception optics optimized for an annular image field with a filter positioned to ensure parallel received light, eliminating the dependence on the angle of incidence by using a two-lens objective that integrates the filter directly into the optical path, allowing for a narrow bandpass filter without additional components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a bandpass filter is used for extraneous light suppression, then the signal-to-noise ratio is improved, but the filter performance deteriorates due to large angle of incidence range from non-parallel received light
Solution Approach 1:
Instead of attempting to parallelize non-parallel light bundles through additional optical components, the invention inverts the approach by designing a reception optics that intentionally generates non-parallel light bundles. This is achieved through an annular image field configuration where the receiver optics are optimized for a specific image field angle, naturally producing divergent light paths that eliminate the need for parallelization while maintaining effective filter performance.
Solution Approach 2:
The invention changes the optical parameters by optimizing the reception optics for an annular image field with a specific image field angle. This parameter optimization allows the system to work effectively with non-parallel light bundles, transforming the filter performance issue from a problem into an acceptable operating condition through precise parameter matching between the optics and filter characteristics.
2Measurement precision
If additional optical components are added to parallelize received light, then the filter effectiveness is improved, but the device complexity and construction space increase
Solution Approach 1:
The invention extracts and eliminates the unnecessary parallelization function from the optical system. By recognizing that parallel light bundles are not required for effective filter operation, the design removes additional optical components (such as field lenses or beam shaping elements) that would otherwise be needed to achieve parallelization, thereby simplifying the overall device structure.
Solution Approach 2:
The reception optics serves multiple functions simultaneously: it collects reflected light from the measurement zone, defines the measurement angle through its annular image field configuration, and directly provides the non-parallel light bundles suitable for filter operation. This multi-functionality eliminates the need for separate parallelization components, reducing device complexity while maintaining extraneous light suppression effectiveness.
3Measurement precision
If the pass band of the filter is narrowed to improve extraneous light rejection, then the signal-to-noise ratio is improved, but useful light is blocked due to angle of incidence variations
Solution Approach 1:
The invention applies local quality by optimizing the reception optics for a specific image field angle, creating a localized optical path configuration. This localized optimization ensures that the light bundles incident on the filter have consistent angular characteristics matched to the filter's pass band, allowing narrow bandpass filters to transmit useful light effectively while rejecting extraneous light, without requiring broad pass bands that would compromise rejection performance.
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 enhances signal-to-noise ratio by effectively blocking extraneous light while using a compact design, enabling precise measurement with a large aperture and wide measurement range without additional optical elements.
Implementation Method 1
Such extraneous light can be filtered by use of an optical bandpass filter that is adapted to the wavelength of the transmitted light
Implementation Method 2
a light beam is transmitted into the monitored zone and the light beam reflected by objects is received again
Data Source
AI summary
An optoelectronic sensor for the detection of objects in a monitored zone is provided that has a light transmitter for transmitting transmitted light of a wavelength range, a light receiver for generating a received signal from the transmitted light remitted at the objects, a reception optics arranged upstream of the light receiver and having an optical filter adapted to the wavelength range for the suppression of extraneous light that is arranged in the reception beam path where the remitted transmitted light forms parallel bundles of beams, and a control and evaluation unit that is configured to detect information on the objects from the received signal. The reception optics here is optimized for an annular image field having an image field angle α and the filter is optimized to a non-perpendicular angle of incidence of the remitted transmitted light corresponding to the image field angle α.