| 摘要 |
PURPOSE:To omit temperature control of an LD for monitoring, by performing monitoring based on the difference between the maximum value and the minimum value of light, which has passed an etalon that is rotated at a specified angular velocity. CONSTITUTION:The output light of an LD2 is converged by a lens 3 and the parallel light is obtained. Part of the light is taken out of a beam splitter 4. The split light is made to pass an etalon plate 8, which is attached to a tuning fork 7 having electrostriction elements 9a and 9b. The etalon plate 8 is vibrated at a period of a signal from a driving circuit 10. The vibration width (rotary angle) is controlled by the vibration period and a voltage. For example, at least one of the peaks of the light passing the etalon is inputted. The transmitted light is received by a light receiver 11, amplified by an amplifier 12 and converted into a digital signal by an AD converter 13. The time slot is about several times the finesse of the etalon. Then, the maximum value Pmax and the minimum value Pmin are detected by a maximum value detecting circuit 14 and a minimum value detecting circuit 15. The computation of (Pmax-Pmin)/(Pmax+Pmin) is performed by an operating circuit 16. |
