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AssigneeHarris Corporation
InventorsAndrew M. Bardos, Jon E. Holmes, Edward Tegge
Estimating the term…
A laser driver mechanism for image reproduction maintains linear operation over a wide frequency an dynamic range of amplitude-modulated input signals by means of a first feedback loop and a second feedback loop. The second feedback loop contains a first amplifier coupled to receive the input signals and an output coupled to a second amplifier that drives an injection laser diode. A photodetector is coupled downstream of and external to a sealed unit in which the injection laser diode emitter, an associated photodetector of the first feedback loop and beam extraction optics are housed. The photodetector of the second loop has an output coupled to the second amplifier, so that the second feedback loop serves to compensate for non-linearities in the laser driver including those of the first feedback loop. Because the second photodetector is supported externally of the sealed unit, the feedback path from the second photodetector effectively forms an outer loop feedback path relative to the first feedback path, so that the ambient operating conditions of the second photodetector are not affected by the operation of the laser. The sealed unit is mounted in a module that effectively equalizes the cross-sectional spatial distribution of optical energy within the light beam emitted by the injection laser diode and ensures that the spatial cross-section of the image spot seen by the photodetector is effectively constant regardless of laser output beam intensity. For precision scanning of the recording medium, the laser output beam is scanned by a linearly swept galvanometer.
A device for controlling the generation of a light beam comprising:
A device for controllably producing a light beam comprising:
For use with an apparatus for controllably producing a light beam, the amplitude of which is modulated in accordance with an amplitude modulation control signal applied to an input terminal, said apparatus having an electro-optic light-emitting output device which is operative to produce an amplitude-modulated light beam in response to said input control signal, and wherein said electro-optic light-emitting output device has a light output characteristic that is non-linear with respect to an input signal applied thereto, a drive circuit for causing said electro-optic light-emitting output device to emit said amplitude-modulated light beam in response to said input control signal, said drive circuit including a first amplifier circuit having an input to which a signal representative of said input control for controlling the operation of said electro-optic light-emitting output device is coupled and an output, and a first opto-electronic detector device which is coupled to receive light produced by said electro optic light-emitting output device and having an output coupled in a first feedback loop to said first amplifier circuit, so as to control the operation of said first amplifier circuit to reduce the non-linear light output characteristic of said electro-optic light-emitting output device, an arrangement for enhancing the gain-bandwidth product of said drive circuit comprising a second feedback loop for further reducing the non-linear light output characteristic of said electro-optic light-emitting output device, said second feedback loop containing a second amplifier circuit having an input coupled to said input terminal and an output coupled to said first amplifier circuit, and a second opto-electronic detector device which is coupled to receive light produced said electro-optic light-emitting output device and having an output coupled to said second amplifier circuit.
A method for generating a light beam comprising the steps of:
Dependencies are inferred from the claim text.