Direct modulation method for laser diode in a laser film printer

摘要

A laser imaging apparatus comprising: a laser diode which is always operable in a linear lasing region; an amplitude modulator for amplitude modulating said laser diode for a digital image signal applied to said laser diode, when said digital image signal has a code value in a first range of code values in the mid to high range of signal code values; and a high speed pulse width modulator for pulse width modulating said laser diode when said digital signal, which is applied to said laser diode, has a code value in a second range of code values below said first range of code values, said laser diode being operated at a constant predetermined power level which is above the threshold power level of said laser diode.