High-sensitivity large-range interference measurement method based on virtual reference cavity and vernier effect

Abstract

The invention discloses a high-sensitivity large-range interference measurement method based on a virtual reference cavity and a vernier effect, and relates to the field of optical signal processing. Comprising the following steps: 1) determining the free spectrum width and the cavity length of a sensing interferometer; 2) determining the cavity length of the reference interferometer; 3) determining a sensitivity amplification factor in the measurement process; (4) during large-range measurement, the difference between the cavity length of the sensing interferometer and the cavity length of the virtual reference interferometer is increased, and when the sensitivity amplification factor is reduced to a preset minimum value, the cavity length of the virtual reference interferometer is adjusted to restore to an initial value; and 5) repeating the step 4) until the measurement is finished. The virtual reference interferometer is constructed based on numerical simulation and is not changed due to the influence of environmental factors and measured physical quantities, the system structure is greatly simplified, the cost is reduced, and the stability is improved; and when the sensing interferometer is used for large-range measurement, the sensing system always keeps high sensitivity, and the implementation mode is flexible and reliable.

Description

technical field [0001] The invention relates to the field of optical signal processing, in particular to a high-sensitivity and large-range interferometric measurement method based on a virtual reference cavity and a vernier effect. Background technique [0002] The vernier effect was originally applied to vernier calipers to improve the resolution of length measurements. In recent years, with the increasing demand for improving the sensitivity of interferometric optical sensors, the application of the vernier effect to achieve high-sensitivity interferometric optical sensing and measurement of different physical quantities has received extensive attention. The measurement principle based on the vernier effect is to construct two optical interferometers with a small difference in free spectral range (FSR) in the measurement system, one of which is a measurement interferometer and the other is a reference interferometer. By detecting the shift of the wavelength corresponding...

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Problems solved by technology

However, it is very difficult to accurately manufacture two interferometers with a small difference in FSR in practice; at the same time, it is also very difficult to avoid changes in the reference interferometer due to the influence of the environment and the measured physical quantity during the measurement process; in addition, practical applications The biggest problem encountered in the reference interferometer with fixed FSR is that when the FSR of the sensing interferometer and the FSR of the reference interferometer are quite different in large-scale measurement, the sensitivity brought by the vernier effect based on the spectral superposition of the double interferometer The lifting effect will drop sharply or even disappear, making the vernier effect unable to play a role in large-scale measurement

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