25-03-2021 дата публикации
Номер: US20210088558A1
Принадлежит:
In order to carry out the polarimetric detection of a measurand, light of two polarization states is passed through a sensing element, where the two states suffer a differential phase shift depending on the value of the measurand. In order to compensate for only imperfections of the device, a method is proposed that is based on calibration values obtained in a low-value regime of the measurand only. Yet the method can still be used for accurately determining higher values of the measurand. 1. A method for measuring a value Z of an alternating measurand by means of a sensing device , said method comprising:sending two different polarization states of a light beam through a sensing element, where the two different polarization states experience a measurand-dependent differential phase shift Δφ,{'sub': 1,raw', '2,raw, 'claim-text': [{'br': None, 'i': S', 'S', 'K, 'sub': 1,raw', 'o1', '1', '1, '=(/2)·[1+sin(Δφ+θ)],'}, {'br': None, 'i': S', 'S', 'K, 'sub': 2,raw', 'o2', '2', '2, '=(/2)·[1+sin(Δφ+θ)],'}], 'splitting light having passed at least once through said sensing element into at least two channels and carrying out different polarimetric measurements in the two channels, thereby generating two raw signals S, Sdepending on the phase shift Δφ as follows'} [{'sub': o1', 'o2, 'S, Sare parameters depending at least on a light source power and optical losses in the sensing device,'}, {'sub': 1', '2, 'K, Kare parameters of the sensing device,'}, {'sub': 1', '2, 'claim-text': {'sub': 1,raw', '2,raw', '1', '2', 'o, 'claim-text': [{'br': None, 'i': S', 'Y', 'K, 'sub': 1', 'o', '1', '1, '=(/2)·[1+sin(Δφ+θ)],'}, {'br': None, 'i': S', 'Y', 'K, 'sub': 2', 'o', '2', '2, '=(/2)·[1+sin(Δφ+θ)],'}], 'normalizing the two raw signals S, S, to two sensor signals S, Sof equal amplitudes Y/2'}, 'θ, θare parameters depending at least on the sensing device and having absolute values much smaller than π/2,'}], 'wherein'} {'br': None, 'i': S', 'S', '−S', 'C, 'sub': 1', '2, '=()/'}, ' ...
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