| 摘要 |
PURPOSE:To improve the signal to noise ratio, by applying a intensity modulation or phase modulation to at least a signal light and a reference light to detect information on the intensity of light causing an interference depending on the narrow and frequency containing modulation frequency. CONSTITUTION:An interferable luminous flux outputted from a light source 1 is modulated 2 in the intensity and separated two with a half-transmitting mirror 3. The light flux transmitted 3 propagates through an optical fiber 4 to be measured as signal light. ON the other hand, the luminous flux reflected 3 propagates through the space as reference light, reflected 5 and 6, being transmitted through a half-transmitting mirror 7 and reflected with a mobile mirror 8. The signal light outputted from the optical fiber 4 is transmitted through the half-transmitting mirror 7 while the reference light reflected with the mobile mirror 8 is reflected with the half-transmitting mirror 7 and converge and passes through a linear photo detector 9 to be incident into a photo detector 10. The light signal incident into the detector 10 is modulated 2 in the intensity and hence, a head filter 12 uses a reference signal of a frequency from a transmission circuit 11 to extract frequency components from the output signal of the detector 10. Then, the output of the filter 12 is recorded 13. |
