Optical Measurement Device Background Light Elimination
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Solution Overview
Problem
Conventional optical measurement techniques struggle to effectively eliminate strong background light, especially when there is little deviation in delay time or optical axis between the desired light and background light, leading to interference with weak signal detection.
Innovation Solution
An optical measurement device utilizing an optical frequency comb with adjustable carrier envelope offset frequency and repetition frequency to control the pulse interval and inter-pulse phase difference, allowing for interference between measurement result light and delayed light to cancel out background light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If time division or spatial separation is used to eliminate background light, then background light can be removed when there is sufficient deviation, but the method becomes ineffective when delay time difference or optical axis deviation is minimal
Solution Approach 1:
The patent changes the temporal parameters of the measurement light by adjusting the delay time of the measurement result light. By dynamically adjusting the delay time to match the pulse interval of the optical frequency comb, the measurement light can be selectively separated from background light even when their spatial paths are similar, resolving the limitation of fixed time/space separation methods
Solution Approach 2:
The patent utilizes the periodic pulse structure of the optical frequency comb with a predetermined repetition frequency. By synchronizing the delay time of measurement result light with this periodic pulse interval, the system creates periodic temporal windows where measurement light can be separated from continuous background light, enabling effective elimination even with minimal spatial deviation
2Measurement precision
If conventional time/space separation methods are used, then the device structure remains simple, but the measurement precision deteriorates when background light cannot be effectively eliminated
Solution Approach 1:
The patent employs feedback control by detecting the temporal characteristics of received light and dynamically adjusting the delay time of measurement result light. This feedback mechanism automatically optimizes the separation between measurement light and background light, improving measurement precision while keeping the control system relatively simple through automated adjustment rather than complex manual configuration
3Illumination intensity
If strong background light is present, then the overall light intensity increases, but the weak desired signal becomes buried and undetectable
Solution Approach 1:
The patent segments the total light signal in the time domain by separating measurement result light and background light into different temporal windows using delay time adjustment. This temporal segmentation allows the weak measurement signal to be extracted from the strong total light intensity by analyzing only the specific time window where measurement light arrives, effectively isolating the weak signal from the overwhelming background
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 enables selective elimination of background light, enhancing the visibility of weak signals by controlling the phase difference between optical pulse trains, thereby improving measurement accuracy.
Implementation Method 1
an interference unit causing measurement result light guided by the second optical path and delay light guided by the third optical path to interfere with each other
Data Source
AI summary
An optical measurement device includes: a light source generating an optical frequency comb; a first optical path guiding an optical pulse train having a pulse interval based on the repetition frequency of the optical frequency comb and an inter-pulse phase difference based on a carrier envelope offset frequency and a repetition frequency to a measurement target; a second optical path guiding measurement result light acquired from the measurement target; a third optical path guiding delay light acquired by delaying the optical pulse train; an interference unit causing the measurement result light guided by the second optical path and the delay light guided by the third optical path to interfere with each other; and a control unit performing variable control of at least one of the carrier envelope offset frequency and the repetition frequency of the light source on the basis of the state of light.