Adaptive Delay Line for Interferometry Distance Measurement
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Solution Overview
Problem
The application of Frequency Scanning Interferometry to long-range (˜10 m), high-speed (upwards of 105 coordinates per second) absolute distance measurement is impractical at reasonable cost due to extremely high modulation frequencies (typically 100 GHz or more).
Innovation Solution
An interferometry apparatus incorporating an adaptive delay line that adjusts the optical path difference between the object and reference beams, reducing the frequency of the interference signal by matching the optical path lengths, thereby reducing the required signal sampling rate and data processing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If Frequency Scanning Interferometry is used for long-range, high-speed absolute distance measurement, then measurement speed and range are improved, but modulation frequency becomes extremely high (100 GHz or more) making the system impractical at reasonable cost
Solution Approach 1:
The patent introduces an adaptive delay line that dynamically adjusts the optical path difference between reference and object beams. This dynamic adjustment allows the system to adapt to varying measurement conditions and reduce the modulation frequency to manageable levels while maintaining high measurement speed and long-range capability
Solution Approach 2:
The patent changes the optical path difference parameter by introducing an adaptive delay line that can adjust the reference beam path length. This parameter change reduces the optical path difference and consequently the modulation frequency, making the system practical for high-speed, long-range measurements without requiring extremely high frequency components
2Length of stationary object
If the optical path difference between object beam and reference beam is large, then long-range measurement capability is achieved, but the modulation frequency becomes extremely high making data acquisition impractical
Solution Approach 1:
The adaptive delay line acts as an intermediary component that mediates between the long optical path difference required for long-range measurement and the need for manageable modulation frequency. It introduces a compensating delay that reduces the net optical path difference, making data acquisition feasible while preserving long-range capability
Solution Approach 2:
The patent changes the optical path difference parameter using an adaptive delay line that can adjust the reference beam path. This allows the system to maintain long measurement range while reducing the modulation frequency to levels that can be handled by standard data acquisition systems
3Ease of manufacture
If standard data acquisition systems are used, then cost is reduced, but they cannot handle extremely high modulation frequencies required for long-range, high-speed measurements
Solution Approach 1:
The patent changes the modulation frequency parameter by introducing an adaptive delay line that reduces the optical path difference. This parameter change enables standard, lower-cost data acquisition systems to handle the signal frequencies, making high-speed, long-range measurements affordable while maintaining measurement capability
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 adaptive delay line reduces the modulation frequency to levels manageable by standard data acquisition systems, enabling high-speed and long-range absolute distance measurements at a lower cost.
Implementation Method 1
an adaptive delay line located a distance along the reference beam arm, the adaptive delay line being configured to provide, in use, one or more length-adjusted reference beams
Implementation Method 2
Interference between the object beam and the reference beam may be detected
Implementation Method 3
a photodetector operable to detect interference between the object beam and the length-adjusted reference beam(s)
Implementation Method 4
a beam splitter arranged to split the first light beam into an object beam and a reference beam
Data Source
AI summary
An interferometry apparatus comprising: a laser source operable to emit a first light beam; a beam splitter arranged to split the first light beam into an object beam and a reference beam, the object beam passing along an object beam arm and the reference beam passing along a reference beam arm; an adaptive delay line located a distance along the reference beam arm, the adaptive delay line being configured to provide, in use, one or more length-adjusted reference beams; a beam splitter arranged to recombine the object beam from the object beam arm and the length-adjusted reference beam(s) from the reference beam arm; and a photodetector operable to detect interference between the object beam and the length-adjusted reference beam(s).