Laser diode operated in amplitude modulation and pulse amplitude modes

摘要

A laser imaging apparatus includes a laser diode which is controlled to produce a laser beam the power of which varies linearly as a function of a digital image input signal. The laser beam is deflected by scanning optics to expose photosensitive media such as film. When the digital image input signal is in a first range of values to operate the laser diode in its linear region, the laser diode is controlled to operate in an amplitude modulation mode. When the digital image input signal is in a second, lower, range of values which would operate the laser diode in its non-linear operating region, the laser diode is controlled to operate in the linear region but in a pulse amplitude modulation mode.