Patent ID: 8179522

Claim:
A distance measuring device comprising: a laser unit for generating an optical frequency comb as a laser light flux; a dividing device for dividing the laser light flux into reference light and distance measuring light; a reference light receiving unit for receiving the reference light and outputting multiple beat signals; a measuring light receiving unit for receiving the distance measuring light and outputting multiple beat signals having frequency components to be extracted; an oscillator for oscillating a periodic signal having a frequency that is different from the frequency components extracted from the beat signals of the measuring light receiving unit; a first mixer for generating sum and difference frequency components of the beat signal from the measuring light receiving unit and the periodic signal oscillated by the oscillator; a second mixer for generating sum and difference frequency components of the beat signal from the reference light receiving unit and the periodic signal oscillated by the oscillator; a fourth filter for extracting a beat signal having the difference frequency component from the frequency components generated by the first mixer; a fifth filter for extracting a beat signal having a frequency component, which is different from the frequency component extracted by the fourth filter, from the frequency components generated by the second mixer; a third mixer for generating sum and difference frequency components of the beat signal extracted by the fourth filter and the beat signal extracted by the fifth filter; a sixth filter for extracting a beat signal having the difference frequency component from the frequency components generated by the third mixer; a second filter for extracting a beat signal having the same frequency component as the frequency component extracted by the sixth filter, from the beat signals of the reference light receiving unit; a phase difference measuring unit for measuring a phase difference of the two beat signals extracted by the sixth filter and the second filter; and a distance measuring unit for measuring a distance based on the phase difference measured by the phase difference measuring unit.