Laser Scanner Converging Lens for Full Mirror-Facet Reception
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Solution Overview
Problem
Existing laser scanners suffer from periodic sensitivity dips due to the reception aperture being smaller than the active mirror facet, leading to reduced reception sensitivity and a narrower scanning range.
Innovation Solution
The laser scanner design includes a converging lens positioned downstream of the mirror pyramid, with a reception aperture larger than the mirror facets, ensuring the entire active facet is utilized for reception, and a diaphragm to mask non-active facets, optimizing reception sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the reception aperture is made smaller than the active mirror facet, then the laser scanner can be designed more compactly, but periodic sensitivity dips occur due to the aperture cutting effect during mirror rotation
Solution Approach 1:
Instead of making the reception aperture smaller than the mirror facet (conventional approach), the patent inverts the relationship by making the reception aperture larger than the mirror facet. This inversion eliminates the cutting effect during rotation while maintaining compact design through the use of a converging lens to focus the larger aperture area effectively.
Solution Approach 2:
The patent changes the key parameter of reception aperture size from being smaller to larger than the mirror facet area. This parameter change, combined with the introduction of a converging lens, resolves the contradiction by eliminating periodic sensitivity dips while preserving compactness through optical focusing.
2Reliability
If the reception aperture is made larger than the mirror facet, then reception sensitivity is improved and sensitivity dips are eliminated, but the device complexity increases due to additional optical elements
Solution Approach 1:
The converging lens serves multiple functions: it focuses the reception beam onto the photodetector, enables the use of a larger reception aperture than the mirror facet area, and maintains a compact overall design. This multi-functionality reduces the need for additional optical elements, thereby limiting the increase in device complexity.
Solution Approach 2:
The converging lens acts as an intermediary optical element that mediates between the larger reception aperture and the photodetector. It focuses the divergent reception beam from the large aperture onto the smaller photodetector surface, enabling the system to benefit from the larger aperture without proportionally increasing complexity.
3Reliability
If the converging lens is made larger than twice the mirror facet area, then the entire active mirror facet is utilized for reception, but parasitic reflections from non-active facets increase
Solution Approach 1:
The patent applies local quality by making the converging lens larger than twice the mirror facet area specifically in the region where the active mirror facet is located during rotation. This localized enlargement ensures complete utilization of the active facet for reception while limiting the increase in lens size to only where needed, thereby reducing parasitic reflections from non-active facets.
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 design enhances reception sensitivity by utilizing the entire active mirror facet for reception, reducing sensitivity dips and enabling a broader scanning range, particularly in compact designs with minimized parasitic reflections.
Implementation Method 1
a converging lens arranged downstream of the mirror pyramid in the reception beam path
Implementation Method 2
the converging lens, viewed in the direction of the axis of rotation, in its region of overlap with the mirror facets, is at least as large, in area comparison, as twice the largest of all mirror facets
Data Source
AI summary
The present invention relates to a laser scanner, comprising a housing, a laser transmitter including a transmission aperture for a transmission beam, a laser receiver for a reception beam, and a beam deflection device in the form of a mirror pyramid, the pyramid axis of which forms its axis of rotation, and the pyramid sides of which each form a mirror facet The laser transmitter and the laser receiver are each directed at the mirror pyramid parallel to the axis of rotation of the mirror pyramid. The laser receiver comprises at least one converging lens arranged downstream of the mirror pyramid in the reception beam path. The converging lens, viewed in the direction of the axis of rotation, in its region of overlap with the mirror facets, is at least as large, in area comparison, as twice the largest of all mirror facets viewed in the direction of the axis of rotation.