Abstract: 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; anda 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.

Abstract: Laser imaging apparatus includes a laser which produces a laser beam. An image media is scanned with a laser beam in a raster pattern to produce a scanned image. A photodetector converts the scanned image into an image signal. An amplifier amplifies the image signal and has varying gain. A control circuit controls the laser beam scanning device to scan image media of different sizes with laser beam raster patterns of different sizes. The control circuit includes detectors for detecting the size of the image media. The control circuit varies the gain of the amplifier as a function of the detected size of the scanned image media.

Abstract: A technique for automatically setting a threshold current for a laser diode which has a linear laser operating region and a lower non-linear operating region. The laser diode is controlled (1) during a warm-up period during which no operating current is supplied to the laser diode, to allow the electronics and laser diode to stabilize; (2) during an initialization period, during which the current through the laser diode is brought up to a threshold operating point above said non-linear operating region and during which no image data is applied to the laser diode; and (3) during an operating period in which digital image data is applied to the laser diode to operate it in the linear laser operating region.

Abstract: A laser imaging system, such as a storage phosphor laser imaging system, includes a correction circuit for correcting laser noise in a scanned image signal.

Abstract: A radiographic printer has a laser diode light source which is directly modulated by an input image signal. The laser diode has two operating regions, a linear laser region and a non-linear low-level light emitting region. The laser diode is amplitude modulated in the lasing region and is pulse width modulated in the light emitting region. A programmable digital delay produces the pulse width modulating signal and a digital comparator determines whether the laser diode operates in the amplitude modulation mode or the pulse width modulation mode. A current steering circuit is used in the pulse width modulation mode to rapidly switch the diode on and off. In addition, programmable digital to analog converters are used to compensate for changes in different diode slope efficiencies and threshold currents.