Laser self-mixing multi-dimensional measuring device and method based on triangular wave current modulation

Abstract

The invention provides a laser self-mixing multi-dimensional measuring device and method based on triangular wave current modulation. The laser self-mixing multi-dimensional measuring device comprises a laser device, optical fibers, an optical fiber beam splitter, an optical fiber focuser, a photoelectric detector and a signal processing circuit. A laser self-mixing sensing system comprises a plurality of paths of different optical path structures with the triangular wave current modulation, and a band-pass filtering signal processing circuit; and the multi-dimensional speed size and direction can be accurately measured on line by virtue of the single laser device and the single detector. The laser self-mixing multi-dimensional measuring device provided by the invention has the advantages of simple structure, easiness in adjustment, low cost and high space resolution, effectively expands a speed sensing method based on a laser self-mixing effect, and particularly provides a reliable solution scheme for non-contact online monitoring on the three-dimensional motion speed of a long-distance object.

Description

technical field [0001] The invention relates to a laser self-mixing multi-dimensional velocity measurement device and method based on triangular wave current modulation, which is especially suitable for rapid non-contact measurement of water flow velocity and solid particle movement velocity. Background technique [0002] For complex multi-dimensional motion velocity measurement, laser Doppler velocimetry technology has been proved to be more effective at present. Laser Doppler velocimetry technology has the advantages of non-contact, fast response, and high spatial resolution. It is widely used in flow velocity measurement in many fields such as fluid mechanics, chemical industry, water conservancy, biomedicine, and environment, especially the measurement of three-dimensional flow velocity. [0003] In the laser Doppler multi-dimensional velocity measurement technology, the system structure scheme of the reference beam type is mainly used. The Doppler frequency shifts in d...

AI Technical Summary

Problems solved by technology

However, due to the use of multiple optical splitters and detectors, and the need to keep the optical path difference within the laser coherence length, there are problems such as complex systems and difficult adjustment of the optical path, so it is difficult to fully develop and apply

Subsequently, schemes such as multispectral lasers and acousto-optic modulators were gradually developed, which improved the system structure and signal separation, but also created new problems: multispectral lasers are expensive and have short lifespans, which are not conducive to Popularization and application; the frequency shift range of the acousto-optic frequency shift device has a certain limit, and the introduced optical splitting device increases the complexity of the system

However, in addition to the increased complexity and cost of the system, the main problems are: ① The signal drift and light source modulation characteristics of multiple sets of single-channel laser self-mixing systems cannot be consistent

The measurement of laser self-mixing effect is based on the detection of laser output light intensity, and the light intensity is sensitive to the external environment and pumping level. Different signal drift will greatly affect the measurement results of multiple sets of systems, which cannot be avoided. The measurement error will hinder the accurate acquisition of the real-time change process and high-order correlation of multi-dimensional velocity or multi-point displacement; ② It is difficult to realize the synchronous detection of signals when multiple systems are measured at the same time, that is, the accurate measurement of physical quantities such as three-dimensional velocity at the same point is very difficult. Difficult to achieve

Images