Interferometer Noise Compensation via Orthogonal Polarization
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Solution Overview
Problem
Interferometric measuring devices face challenges in effectively compensating for excess intensity noise from broad-spectrum spontaneous emission light sources, which affects the accuracy of measurements, particularly in applications like gyrometers and inertial navigation units, due to the complexity of additional electronic processing required.
Innovation Solution
An interferometric measurement device is designed with a compensation channel that includes polarization rotation means and optical looping, allowing for optical compensation of excess intensity noise using a single optical radiation detector, where the compensation light signal is polarized orthogonally and time-delayed to subtract noise optically, reducing or eliminating excess intensity noise at specific frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a broad-spectrum spontaneous emission light source is used in the interferometric measurement device, then the device can operate with such a light source, but excessive intensity noise affects measurement accuracy
Solution Approach 1:
The patent converts the harmful excessive intensity noise into a useful signal by detecting it with a first photodetector and then subtracting it from the measurement signal. The noise, which would normally degrade measurement accuracy, is now measured and eliminated through electronic processing, transforming a harmful factor into a beneficial noise cancellation mechanism
Solution Approach 2:
The patent introduces an intermediary noise compensation channel that includes a second photodetector and electronic processing means. This intermediary system measures the excessive intensity noise separately and uses it to compensate for the noise in the main measurement channel, acting as a mediator between the light source and the measurement process
2Measurement precision
If a noise compensation channel with separate detection means is used to compensate for excessive intensity noise, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent merges the noise compensation function with the main measurement channel by using optical coupling means to combine the output signals from both the measurement interferometer and the noise compensation channel. This allows both measurement and noise compensation functions to be integrated into a single detection system, reducing device complexity while maintaining measurement precision
Solution Approach 2:
The detection means in the patent serve multiple functions: the first photodetector detects excessive intensity noise, the second photodetector detects the measurement signal, and the optical coupling means combines both signals. This multi-functionality reduces the need for separate dedicated components, thereby reducing device complexity while maintaining measurement accuracy
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 configuration simplifies the measurement process by using a single detector and processing chain, effectively reducing or eliminating excess intensity noise, thereby enhancing the accuracy of parameter measurements in devices like gyrometers and inertial navigation units.
Implementation Method 1
a measurement interferometer which includes a phase modulator and a Sagnac ring, of natural frequency fp, sensitive to said parameter to be measured, said interferometer receiving, at input, an input light signal of input light power P IN and producing, at output, an output light signal of output light power P OUT depending on said physical parameter to be measured and proportional to said input light power P IN
Implementation Method 2
polarization rotation means adapted to produce said compensation light signal in a second polarization direction crossed with said first polarization direction
Implementation Method 3
optical looping means of said compensation channel to said measurement channel, said looping means receiving said compensation light signal circulating on said compensation channel and redirecting at least a portion of said compensation light signal to said measurement channel
Implementation Method 4
a measurement interferometer which includes a phase modulator and a Sagnac ring, of natural frequency fp, sensitive to said parameter to be measured
Data Source
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AI summary
The present invention relates to an interferometric measurement device (100) comprising a light source (110) emitting a source signal and optical coupling means (121) receiving the source signal, directing a part of the latter towards a measurement pathway (102) comprising a Sagnac ring interferometer (141), of natural frequency fp, producing, as output, an output power output signal Ρoυτ polarized according to a first direction of polarization, tapping off another part of the source signal towards a compensation pathway (103) producing a return power compensation signal PRET, and directing the output signal and the compensation signal towards detection means. According to the invention, the compensation pathway comprises polarization rotation means (131) producing the compensation signal according to a second cross-direction of polarization, and optical looping means (132) redirecting a part of the compensation signal towards the measurement pathway; the detection means comprise a single detector (150) connected to the coupling means so as to receive the output signal and the compensation signal; the device furthermore comprises power equilibration means (132) equalizing the output power and/or the return power that are routed towards the detector, and the compensation pathway exhibits a length adjusted so that the output signal exhibits, with respect to the compensation signal, a time delay x equal to 1 /(2*fp) at the level of the detector.