Triple-Prism Retroreflector Target with Reduced Interference
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Solution Overview
Problem
Existing surveying technologies face challenges with limited angular incidence range and interfering reflections, particularly when the pole is not vertically aligned, leading to reduced measurement accuracy and susceptibility to damage, especially at oblique angles.
Innovation Solution
A target object design featuring an arrangement of four or eight triple prisms with a shading element and support frame, configured to provide 360° retroreflection with reduced interfering reflections, enhanced stability, and protection against external forces and moisture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional retroreflector arrangement is used, then retroreflection is provided within a limited vertical measuring range (±30°), but measurement accuracy is reduced at oblique angles
Solution Approach 1:
The retroreflector is divided into multiple triple prisms (first, second, third, and fourth prisms) arranged in a specific geometric configuration. Each prism segment handles specific angular ranges, with the first and second prisms optimized for oblique angles and the third and fourth prisms for perpendicular incidence, enabling full 360° horizontal and ±90° vertical coverage while maintaining measurement precision across all angles
Solution Approach 2:
The patent employs asymmetric positioning and orientation of the triple prisms relative to each other and to the shading element. The prisms are not uniformly distributed but positioned at specific angles and distances to optimize retroreflection for both oblique and perpendicular light incidence, resolving the contradiction between angular versatility and measurement accuracy
2Loss of time
If the pole is not perfectly vertical, then measurement time is reduced, but measurement accuracy deteriorates due to oblique light incidence
Solution Approach 1:
The retroreflector design dynamically adapts to any pole orientation by providing effective retroreflection regardless of the angle of incidence. The multi-prism configuration ensures that whether the pole is vertical or tilted at any angle, the surveying instrument can accurately measure the target position without requiring time-consuming levelling operations, thus eliminating the trade-off between speed and precision
3Adaptability or versatility
If multiple triple prisms are arranged to provide 360° retroreflection, then angular coverage is improved, but interfering reflections increase
Solution Approach 1:
A shading element is strategically positioned to block and extract harmful interfering reflections that would otherwise reach the surveying instrument. The shading element selectively removes parasitic reflections from certain angular ranges while preserving the useful retroreflected beams from all four triple prisms, thus enabling 360° coverage without the penalty of increased interference
Solution Approach 2:
The shading element acts as an intermediary component between the multiple triple prisms and the surveying instrument. It mediates the light paths by blocking specific interfering reflections while allowing the desired retroreflected beams to pass through, resolving the contradiction between comprehensive angular coverage and minimization of harmful reflections
4Ease of operation
If the retroreflector is positioned at oblique angles, then ease of operation is improved, but reliability decreases due to susceptibility to damage
Solution Approach 1:
The robust mounting structure and protective design elements are pre-configured to protect the triple prisms and shading element from damage regardless of pole orientation. This preliminary structural preparation ensures that when the pole is positioned at oblique angles for ease of operation, the retroreflector components remain securely protected, maintaining reliability while enabling operational flexibility
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
Enables accurate and robust spatial detection of target points from various angles, maintaining measurement precision and reducing the risk of damage, even at oblique setups, while minimizing interfering reflections and enhancing durability.
Implementation Method 1
each of the triple prisms having a light entry surface and three reflective surfaces
Implementation Method 2
each of its other two reflective surfaces is aligned parallel to a reflective surface of a respective adjacent triple prism of the four triple prisms
Implementation Method 3
a shading element, which is arranged axially on side of the pyramid base, wherein, in a direction perpendicular to the arrangement axis, an opaque part of the shading element extends beyond a maximum extension of the four reflective surfaces aligned parallel to the pyramid base
Data Source
AI summary
A target object providing a large angular incidence range for retroreflection and a reduced amount of interfering reflections. The target object is configured to provide a 360° all-around retroreflection about a vertical axis and ±45° angular incidence range from the horizontal. According to one aspect, the target object comprises eight triple prisms arranged around the arrangement axis in such a way that their contour embeds in an octahedral shape, wherein four of the eight triple prisms are arranged to embed in a first pyramidal body and other four of the eight triple prisms are arranged to embed in a second pyramidal body. Each of the first and the second pyramidal bodies comprises a pyramid base and four lateral surfaces, wherein the pyramid bases of the first and the second pyramidal bodies are arranged parallel to each other.