Interferometric Distance Sensor Using Asymmetric Beam Deflection
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Solution Overview
Problem
Existing interferential distance measurement devices are prone to errors due to wavelength fluctuations and tilting of the measurement reflector, as they rely on wavelength-dependent phase shifts, leading to inaccurate distance measurements.
Innovation Solution
A device with a splitting grating and deflection elements arranged perpendicular to the measurement reflector, ensuring identical optical path lengths for measurement and reference beams, independent of wavelength changes and tilting, using symmetrical beam guidance and diffractive structures to maintain accurate distance measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional beam guidance is used with wavelength-dependent phase shifts, then interferential distance measurement can be performed, but measurement accuracy deteriorates due to wavelength fluctuations and tilting
Solution Approach 1:
The patent applies asymmetry by arranging deflection elements at different positions in the measurement beam path compared to the reference beam path. Specifically, the measurement beam is deflected by deflection elements located at different optical path positions than those in the reference beam, creating an asymmetric configuration that eliminates wavelength-dependent phase shifts while maintaining tilting sensitivity for accurate distance measurement.
Solution Approach 2:
The patent introduces a new dimensional approach by using deflection elements that operate in a spatial dimension perpendicular to the traditional beam path arrangement. The deflection elements are positioned and oriented such that they deflect beams in a direction that creates path length differences independent of wavelength, thereby resolving the contradiction between measurement precision and reliability under wavelength fluctuations.
2Adaptability or versatility
If the measurement reflector is tilted, then the device can accommodate orientation changes, but measurement accuracy deteriorates due to wavelength-dependent phase shifts
Solution Approach 1:
The asymmetric arrangement of deflection elements creates a measurement system where the phase shift becomes dependent on the physical path length difference rather than wavelength. This allows the system to accommodate reflector tilting through the asymmetric geometry while maintaining measurement accuracy, as the phase relationship is determined by the fixed asymmetric configuration rather than wavelength variations.
3Reliability
If symmetrical beam guidance with identical optical path lengths is used, then wavelength independence is achieved, but device complexity increases due to additional deflection elements
Solution Approach 1:
The deflection elements serve multiple functions simultaneously: they deflect both the measurement and reference beams, create the necessary path length differences for interferential measurement, and establish the asymmetric configuration that eliminates wavelength dependence. This multi-functionality reduces the need for additional separate components, thereby managing device complexity while achieving wavelength independence.
4Ease of operation
If conventional splitting elements are used, then beam splitting is achieved, but measurement accuracy deteriorates due to incorrect distance signals under tilting conditions
Solution Approach 1:
The deflection elements act as intermediary components between the beam splitting element and the measurement reflector. They modify the beam paths after splitting by introducing controlled asymmetric deflections that compensate for tilting effects. This intermediary function allows the simple beam splitter to maintain ease of operation while the deflection elements ensure measurement accuracy under tilting conditions.
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 solution provides completely wavelength-independent and tilt-insensitive distance measurements, ensuring precise interferential distance measurement regardless of environmental conditions or reflector orientation.
Implementation Method 1
a splitting element in the form of a beam splitter cube... A beam emitted by the light source is split by the splitting element into at least one measuring beam and at least one reference beam
Implementation Method 2
the measuring beam impinges on the measuring reflector four times before it arrives at the combining element for interfering superimposition with the reference beam
Implementation Method 3
the reference beam and the measuring beam reach the interfering superimposition at the combining element
Data Source
Figure 1
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Figure 3~4
AI summary
The device has a splitting portion which splits the light emitted from a light source beams into a measuring beam and reference radiation beam. A reference beam bundle interferes the superposition of measuring beam and reference radiation beam. A splitting grating is formed in a light source. The beam is emitted parallel to the surface of a measurement reflector in the direction of the splitting grating. The splitting grating is arranged perpendicular to the surface of the measurement reflector.