A cw dye laser was automatically tuned as wide as 100 cm-1 with a very simple control system while retaining a narrow spectral width of 15 MHz. This wide scanning was accomplished by repetitive 5-cm-1 sweeps of both the laser cavity and an internal étalon along with a continuous tuning of a birefringent filter. Mode jumps were prevented by locking the cavity to the internal étalon by a novel type of integrating servoamplifier which has an auto-reset function. This scan system proved very useful for a wide-ranged spectral measurement of the Doppler-limited resolution. The jumpless scanning with a constant rotational speed of the birefringent filter is extendable up to 230 cm-1 at around 1.7 × 104 cm-1.
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