New absolute distance measurement technique with a self-mixing interferometer
نویسندگان
چکیده
A new compact self-aligned noncontact range finder is described. It uses the selfmixing effect inside a laser diode. Double modulation technique is proposed to improve the measurement accuracy. Wavelength modulation (WM) of the laser beam is obtained by modulating the injection current of the laser diode. Phase modulation (PM) of the laser beam is obtained by an electro-optic crystal (EOC) in the external cavity. Absolute distance of the external target is determined by Fourier analysis method. Experimental results show that an accuracy of ±0.3mm can be achieved for absolute distance ranging from 277mm to 477mm.
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