Ecrm Trust

James A Carl

John L Connolly, Iii

W Thomas Boston

A method and apparatus for maintaining a controlled precise energy output level for a laser diode, particularly useful in a precision scanning environment, provide for a thermal stabilization current to be added to the normal bias exposure current of the diode The thermal stabilization current is modeled to account for the temperature variation of the laser diode junction which affects the light energy output as a function of current. The addition of the thermal stabilization current provides a substantially flat and constant, precise output energy from the laser diode during its 'on' time as a function of an input exposure value.

Method and apparatus for stabilizing laser diode energy output

A method and apparatus for accurately controlling a hysteresis synchronous motor velocity eliminate low frequency hunting, which is characteristic of the motor. A nominal input phase current is modified by providing feedback information, thereby enabling a microprocessor control system to modify the phase of quadrature input current signal to the motor and thereby eliminating hunting of the motor. Accordingly, in a high resolution scanning application, speed variations which could cause disturbing artifacts to appear in an output image are eliminated. Velocity control, better than 15 parts per million, can be achieved

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Littleton, MA, United States of America

James A Carl