Optisches Gerät zum Ziehen einer Zwischenfrequenz in einen bestimmten Frequenzbereich.

摘要

In an optical apparatus for pulling an intermediate frequency in a predetermined frequency range, a local oscillation light source (15) is swept in an oscillation frequency thereof in accordance with a signal applied to a frequency adjusting terminal thereof. The signal is of a counted value of a counter (9) which counts pulse signals of an oscillator (18). When an intermediate frequency is pulled in a predetermined frequency range including a predetermined intermediate frequency, the counter (9) is stopped to count the pulse signals, and is controlled to hold a then counted value which will be a fixed driving signal for the local oscillation light source (15).