Tunable Interference Filter for Geodetic Distance Measurement
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Solution Overview
Problem
Existing geodetic surveying and coordinate measuring devices face challenges in precise distance and direction measurements due to interference from ambient or extraneous light, which is not optimally suppressed by current filter technologies, leading to inaccuracies and complex device designs.
Innovation Solution
A tunable interference filter system with multi-layered mirror elements and adjustable optical thickness, allowing for continuous adjustment of the filter's wavelength range to match the emission wavelength of the radiation source, effectively blocking ambient light and maintaining measurement accuracy across varying conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed wavelength filter is used to block ambient light, then measurement precision is improved, but adaptability to varying radiation source wavelengths deteriorates
Solution Approach 1:
The patent applies the dynamics principle by making the optical filter tunable rather than fixed. The filter's wavelength selection capability is dynamically adjusted to match the radiation source wavelength, allowing the system to adapt to varying conditions while maintaining high measurement precision through optimal filtering at each wavelength.
Solution Approach 2:
The patent implements parameter changes by varying the optical properties of the filter (specifically its transmission wavelength) based on the radiation source characteristics. This allows the filter to optimize its performance for different wavelengths, resolving the contradiction between maintaining precision and adapting to changes.
2Measurement precision
If multiple separate transmission and reception channels are provided for coaxial electronic distance measurement, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent applies the merging principle by integrating the distance measurement function into the existing optical viewing channel. Instead of providing separate transmission and reception channels, the invention uses the same optical path for both viewing and distance measurement, thereby reducing device complexity while maintaining measurement precision through wavelength-specific detection.
3Measurement precision
If high-precision specialized optics are used in the sighting device, then measurement precision is improved, but ease of manufacture deteriorates
Solution Approach 1:
The patent applies partial action by using standard optics for the viewing function and adding wavelength-specific filtering only where needed for distance measurement. This approach maintains measurement precision through selective wavelength detection while avoiding the need for completely specialized high-precision optics throughout the entire system, thereby improving ease of manufacture.
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
The system enables precise and reliable distance and direction measurements by adaptively filtering out unwanted light, reducing measurement errors and simplifying device construction, while maintaining optimal detection of the desired wavelength range.
Implementation Method 1
a filter unit for extracting electromagnetic radiation of a defined wavelength range according to the interference principle
Data Source
Figure 1a~1b
Figure 2~3b
Figure 4a~5
AI summary
The invention relates to an optical measuring system for determining coordinates of points, more particularly for distance measurement, more particularly a geodetic surveying apparatus, coordinate measuring machine or scanning device. The measuring system comprises a radiation source (52, 53) for emitting electromagnetic radiation having an emission wavelength and a receiving unit having a filter unit (51) for extracting electromagnetic radiation in a defined wavelength range according to the interference principle and a detector (56), arranged in such a way that the radiation that can be extracted by means of the filter unit (51) is detectable by the detector (56) Moreover, the filter unit (51) comprises at least two mirror elements which are at least partly reflective and which are constructed in a multilayered fashion, wherein the mirror elements are oriented substantially parallel to one another and two adjacent mirror elements in each case enclose a cavity and are arranged at a specific distance with respect to one another. An optical thickness is defined by a refractive index of the cavity and by the distance between the mirror elements. Optical thickness varying means are provided for varying the optical thickness, such that an extractable wavelength range of the filter unit (51) is varied, more particularly wherein the optical thickness varying means have actuating means for changing the position of the mirror elements and/or refractive index adjusting means for changing the refractive index of the cavity, more particularly wherein the optical thickness can be varied continuously during operation.