Research Of Displacement Sensor Based On Optical Feedback Self-mixing Interference

With the theory of laser self-mixing interferometry more and more maturity and deepening, measurement depend on optical feedback self-mixing interferemence is attracting a lot of researcher. For its high resolution, high integration, non-contact,it is unparalleled for other measurement devices. Now, measurement depend on optical feedback self-mixing interferometry including velocity measurement, displacement measurement, vibration measurement, distance measurement, profile measurement and so on.This thesis studies a method of displacement measurement. Nowadays, for displacement measurement always adopt optical interferometer fringe counting method, phase measurement and so on. In our issue, we offer another method, called bright-speckle tracking method, which is based on the theory of speckle statistics, in the past it is usually employed in the measurement of vibration.We improve this theory by adding a Automatic Gain Control loop. And the measurement is more accurate, effective and convenient.In addition, we built displacement sensor based on this model. By signal preconditioning, AD converter, digital signal processing and displacement recovery. We achieved the Counting statistics of the pulse signal, we achieve the hardware realization of displacement measurement. For AD conversion, we select the ADC chip AD7262, the processing of the digital and the recovery of the displacement we select the S3C2440 chip kernel-based on RM920T. we got the displacement result, and it is validated by a software called labviewIn this subject our research mainly consists of two aspects:first we build the OFSMI system with bright-speckle tracking loop and automatic gain control loop, and the other is the processing of self-mixing signal and the recovery of the displacement...