LASER BEAM SCANNING DEVICE EMPLOYING A SCANNING ELEMENT HAVING A FLEXIBLE PHOTO-ETCHED GAP REGION DISPOSED BETWEEN AN ANCHORED BASE PORTION AND A LIGHT BEAM DEFLECTING PORTION HAVING A NATURAL FREQUENCY OF OSCILLATION TUNED BY THE PHYSICAL DIMENSIONS OF SAID FLEXIBLE PHOTO-ETCHED GAP REGION AND FORCIBLY OSCILLATED ABOUT A FIXED PIVOT POINT AT AN ELECTRONICALLY-CONTROLLED FREQUENCY OF OSCILLATION SUBSTANTIALLY DIFFERENT FROM SAID NATURAL RESONANT FREQUENCY OF OSCILLATION

摘要

Disclosed is laser beam scanning apparatus in the form of an electronically-controlled mechanically-damped off-resonant laser beam scanning mechanism. The scanning mechanism comprises an etched scanning element having a small flexible gap region of closely-controlled dimensions disposed between an anchored base portion and a laser beam deflection portion The light beam deflection portion supports a permanent magnet and a light beam deflecting element (e.g., mirror or hologram). A reversible magnetic force field producing device (e.g., an electromagnet) is placed in close proximity with the permanent magnet so that it may be forcibly driven into oscillation in response to electrical current flowing through the electromagnet. The resonant frequency of oscillation of the laser beam deflecting portion relative to the anchored base portion is determined by the closely controlled dimensions of the flexible gap region set during manufacture. The steady-state frequency of oscillation of the laser beam deflecting portion is determined by the frequency of polarity reversal of the electromagnet, which is electronically controlled by the polarity of electrical current supplied thereto. In the illustrative embodiments, the forcing frequency of the electromagnet is selected to be at least ten percent off (i.e. greater or less than) the natural resonant frequency of the laser beam deflecting portion of manufacture to be any one of a very large range of values (e.g., 25-127 Hz) for use in both low-speed and high-speed laser scanning systems.