Interferometer Range Mapping Using Coherence Length Variation
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Solution Overview
Problem
Conventional range detection techniques require fast and sensitive hardware, which increases costs and reduces detection range and sensitivity, necessitating a novel method that uses low-cost hardware while maintaining accurate distance measurement.
Innovation Solution
The technique utilizes the coherence properties of electromagnetic signals to determine range by varying coherence length through noise generators, using interferometer loops with different coherence lengths to measure interference contrast, enabling accurate distance determination without time-related measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional range detection techniques (TOF, FMCW) are used, then accurate distance measurement can be achieved, but fast and sensitive hardware is required which increases costs and reduces detection range
Solution Approach 1:
The patent replaces conventional time-based measurement methods (TOF, FMCW) with an interferometric method that measures coherence properties of electromagnetic waves. Instead of using fast hardware to measure time delays in the gigahertz regime, the system uses interference patterns and coherence length to determine range, substituting a different physical principle that allows slower, less expensive hardware to achieve accurate measurements.
Solution Approach 2:
The patent changes the measurement parameter from time delay to coherence length. By measuring how the coherence length of electromagnetic waves changes with distance, the system can determine range without requiring fast hardware. The coherence length is a different physical parameter that can be measured using standard interferometric techniques, avoiding the need for high-speed detectors and processors.
2Measurement precision
If conventional range detection techniques are used, then distance measurement can be performed, but detection range is reduced when hardware costs are reduced
Solution Approach 1:
The patent substitutes time-based detection with coherence-based detection. This replacement allows the system to achieve long detection ranges without requiring expensive fast hardware, as the interferometric method can measure distances by analyzing coherence patterns that persist over long path differences, unlike conventional methods that are limited by detector speed and processing capability.
3Measurement precision
If time-related measurements are used for range detection, then distance can be determined, but the measurements are dependent on time which introduces complexity and cost
Solution Approach 1:
The patent replaces time measurement with coherence measurement. Instead of measuring how long it takes for light to travel to and from a target (which requires fast detectors and precise timing), the system measures the coherence properties of the returned light waves. This substitution eliminates time measurement dependency and allows for simpler, less expensive hardware that can still accurately determine distance.
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 accurate distance measurement using low-cost hardware, independent of time measurements, and enables simultaneous detection of multiple objects at varying ranges with adjustable sensitivity and accuracy.
Implementation Method 1
The technique utilizes the coherence properties of electromagnetic signals and a relation between the range to a target and the coherence length of the EM signal directed thereto. This relation is measurable using variation in contrast of interference (between maximal intensity and minimal intensity)
Data Source
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AI summary
An optical system and respective method are described. The system comprising one or more coherent light, an optical arrangement, and a detection unit. The optical arrangement comprises optical elements forming at least first and second interferometer loops, each comprising a reference arm and an interrogating arm and are associated with at least first and second detectors of the detection unit. Light propagating in said interrogating arm is directed at a target object via an output optical element and a reflection of light from said target object is collected by an input optical element. The detection unit is configured to determine data indicative of a relation between signals detected by the at least first and second detectors. One of said first and second interferometer loops comprises a first noise generator positioned to affect light propagating in both of the corresponding reference and interrogating arms, thereby affecting coherence of light in said interferometer loops.