| With the rapid development of the industry, the requirement of the measurement technology is gradually increased. The laser interference is widely applied as a kind of non-contact interferometry because of its advantages. In recent years, laser diode feedback interference has attracted much interest for its different interference theory from traditional interference and it can lead to new technology which is very important for the extension of interferometry to industrial applications. A fringe locking phenomenon in a laser diode feedback interferometer with optical feedback in a certain extent can be observed, which is studied in this paper. Based on the laser diode feedback interference theory, the fringe locking phenomenon was researched theoretically, and the application was expected. A theoretical model has been proposed which is based on a four-mirror equivalent cavity. Through theoretical deduction and numerical analysis using the model, the resonant condition of the laser diode was concluded and the dependence of wavelength on the change of the optical path difference of the interferometer calculated, then the fringe locking phenomenon can be well explained. A experiment system was setup to observe the phenomenon and measure the data, the experimental results agree well with the theoretical calculations. |
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