OEO (optoelectronic oscillator) based wide-range and high-precision absolute distance measurement system with self-calibration function

Abstract

The invention discloses an OEO (optoelectronic oscillator) based wide-range and high-precision absolute distance measurement system with a self-calibration function. The system comprises four lasers, two wavelength division multiplexers, an electro-optic modulator, an erbium-doped optical fiber amplifier, an optical add-drop multiplexer, two optical fibers with different lengths, two optical fiber tensioners, three optical couplers, two photoelectric detectors, two microwave filters with different center frequencies, two microwave amplifiers, two microwave power beam splitters and a microwave synthesizer. An oscillation loop comprises an optical path part and a circuit / microwave part. By means of OEOs, the accumulative amplification principle is applied to the wide-range absolute distance length measurement scheme for large-scale absolute distance measurement (km magnitude), and very high measurement precision (mu m magnitude) can be realized; the system can be widely applied to fields of industrial measurement and control, precision instrument manufacture and the like, is high in interference resisting capacity and good in stealthiness and has very good application prospect in the military field.

Description

Technical field [0001] The invention relates to a light-borne microwave ranging system, in particular to a large-range, high-precision absolute distance measurement system with self-calibration function based on two photoelectric oscillators. Background technique [0002] The development of measurement technology is the prerequisite and basis for all scientific and technological development. Length is one of the seven basic physical quantities. It and angle measurement form the basis of all geometric measurement. Its development determines the ability of mankind to understand and transform the world, and it is also a symbol of measuring a country's measurement technology level. [0003] Although the current method of using laser interferometer can reach the measurement accuracy of nm in the range of tens of meters. However, it can only measure the relative change of distance (also called relative distance measurement). This requires a precision rail larger than the object to be me...

AI Technical Summary

Problems solved by technology

Since the OEO system uses long-length optical fibers (usually on the order of km) for energy storage, the cavity length is easily changed by the influence of ambient temperature and stress, and the resulting change in the fundamental frequency will cause the high-frequency output of OEO to occur Severe drift or even mode hopping, and it is impossible to distinguish between the change of the cavity length of the test system itself and the change of the distance to be measured

It is impossible to obtain f without any stabilization measures N and f b The exact value of the distance to be measured cannot be obtained

[0017] f N There is another limiting factor in the measurement accuracy: that is, it must be ensured that the OEO works in a single-frequency oscillation state, excluding f N The interference of the side mode on the test results

In fact, if no additional measures are taken, due to the limitation of microwave filter bandwidth (usually on the order of 10MHz), there are often multiple modes in its passband (OEO fundamental frequency is on the order of more than ten kHz), and at frequency There will be mutual interference in the measurement

In previous studies, the optical domain double loop constructed by using polarization beam splitter / combiner can improve the side mode suppression ratio of OEO, but due to the limited extinction ratio of polarization beam splitter / combiner (about 20dB), the two There is still random noise caused by interference between two orthogonally polarized lights of the same wavelength, which will deteriorate the output signal quality of the OEO, which will also adversely affect the accuracy of distance measurement.

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