Interferometric Distance Measuring Assembly Parallel Channels
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Solution Overview
Problem
Existing interferometric distance measuring methods face challenges in efficiently scanning large surfaces without moving the probe head, due to limitations in coherence length, complexity, and thermal loading, which restricts speed and accuracy in industrial metrology applications.
Innovation Solution
The implementation of a wavelength-modulated laser source with frequency multiplexing and chromatic multiplexing, allowing multiple channels to measure simultaneously by shifting zero positions and dividing the coherence length, enabling parallelization without increasing probe head complexity or thermal loading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple measurement channels are implemented in parallel to scan large surfaces simultaneously, then measurement speed and productivity are improved, but device complexity increases due to polarization-dependent separation and limited channel implementation
Solution Approach 1:
The measurement range is divided into multiple sub-measuring ranges, each assigned to a separate measurement channel. The coherence length of the laser source is divided among the channels through different delay lines, allowing parallel measurement of different depth ranges without requiring complex polarization separation. This segmentation enables multiple channels to operate independently within the available coherence length.
Solution Approach 2:
Instead of using polarization direction (one dimension) to separate measurement channels, the invention introduces a new dimension: time delay. By assigning different delay lines to different channels, the patent creates a temporal dimension for channel separation, allowing multiple channels to be implemented without relying on polarization-dependent beam splitters and significantly reducing structural complexity.
2Measurement precision
If the probe head is moved over the path of measurement points to scan the surface, then measurement accuracy is maintained, but measurement time increases and productivity decreases
Solution Approach 1:
The surface measurement task is segmented into multiple independent measurement channels, each measuring a different sub-range of depths simultaneously. This allows parallel acquisition of measurement data from different points on the surface without moving the probe head, maintaining accuracy while dramatically increasing measurement speed through parallelization.
Solution Approach 2:
Multiple measurement channels operate continuously and simultaneously to measure different portions of the surface. Instead of sequentially moving the probe head from one measurement point to another, the system maintains continuous measurement action across multiple channels, eliminating idle movement time and maximizing productivity while preserving measurement precision.
3Productivity
If scanning mirrors are used to move the measuring beam over the surface without moving the probe head, then measurement speed is improved, but thermal loading and complexity increase
Solution Approach 1:
The scanning mirrors and their associated thermal loading are extracted from the measurement system. Instead of using mirrors to deflect the beam across the surface, the invention takes out the mechanical scanning component and replaces it with a multi-channel parallel measurement approach, eliminating the source of thermal loading while maintaining high measurement speed.
4Length of stationary object
If the coherence length is increased to extend measurement range, then measurement range is improved, but manufacturing precision requirements increase and complexity rises
Solution Approach 1:
Instead of requiring a single long coherence length, the measurement range is segmented into multiple sub-ranges, each within the coherence length of the laser source. Different delay lines are assigned to different channels, each operating within the available coherence length. This segmentation allows extended overall measurement range while keeping the precision requirements for individual delay lines manageable and achievable with standard manufacturing tolerances.
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 approach allows for high-speed, accurate measurement of multiple points on a surface with reduced thermal stress and complexity, maintaining high spatial resolution while achieving frame rates comparable to single-point measurements.
Implementation Method 1
The measurement radiation is emitted with a modulated wavelength by means of a laser source
Implementation Method 2
The measurement radiation scattered back from the surface is received again and is used for interferometric distance measurement
Data Source
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AI summary
The invention relates to an interferometric distance measuring arrangement for measuring surfaces, with at least one laser source, which can be tuned, with a coherence length for generating measurement radiation modulated by a wave length ramp, an optical beam path with an optical transmitting system for emitting the measurement radiation to the surface and an optical capturing system for capturing the measurement radiation back-scattered by the surface, comprising a measuring arm and a reference arm and a radiation detector and an evaluation unit for determining the distance from a reference point of the distance measuring device to the surface. Channels are defined by at least one beamsplitter n ≥ 2 for the parallel emission of measurement radiation, respectively one different sub area of the measurement range defined by the coherence length is allocated to the channels.