Coherent light generators – Particular resonant cavity – Folded cavity
Reexamination Certificate
1999-01-13
2001-08-28
Font, Frank G. (Department: 2877)
Coherent light generators
Particular resonant cavity
Folded cavity
C372S094000, C372S010000, C372S050121, C372S092000
Reexamination Certificate
active
06282224
ABSTRACT:
FIELD OF INVENTION
This invention relates to a non-planar, Q-switched ring laser system, and more particularly to a high power, optically self aligning, non-planar Q-switched ring laser system.
BACKGROUND OF INVENTION
Pulsed lasers such as used in laser radar and industrial applications are limited in output pulse energy by the risk of damage to the internal optics. The output energy can be increased by increasing the mode volume by increasing the radius of curvature of the resonator mirrors. However, as the mirror radius is made longer the resonator becomes more susceptible to misalignment: the larger the mirror radius the greater is the shift of the optical axis for a given tilt misalignment of the mirrors or other optical elements of the resonator. Non-planar ring lasers promote enhanced optic axis stability but the light circulates within a closed path in two distinct directions, e.g., clockwise and counterclockwise, so that the output of such lasers is emitted in two beams which cannot be efficiently combined into a single beam to maximize the output energy for a given input energy. Power output can be enhanced using Q-switching but this adds significant complexity and expense to the laser.
SUMMARY OF INVENTION
It is therefore an object of this invention to provide an improved non-planar passively Q-switched ring laser system.
It is a further object of this invention to provide such a non-planar passively Q-switched ring laser system which is high power and optically self-aligning.
It is a further object of this invention to provide such a non-planar passively Q-switched ring laser system with greatly reduced alignment sensitivity.
It is a further object of this invention to provide such a non-planar passively Q-switched ring laser system with simple monolithic resonator structure.
It is a further object of this invention to provide such a non-planar passively Q-switched ring laser system which is reliable, robust, low maintenance and high performance.
It is a further object of this invention to provide such a non-planar passively Q-switched ring laser system which tolerates relaxed manufacturing and alignment accuracy.
The invention results from the realization that a reliable, robust, high power laser system with reduced alignment sensitivity can be effected using a Q-switch to increase the power and utilizing the inherent self-aligning properties of a non-planar ring laser configuration to reduce susceptibility to misalignment while avoiding the complexity of an active Q-switch by using a passive Q-switch.
This invention features a non-planar Q-switched ring laser system including a ring laser including a gain medium and a closed optical path lying in at least two distinct planes, and a Q-switch in the closed optical path for automatically varying the loss in the closed optical path.
In a preferred embodiment the closed optical path may include a non-planar arrangement of an even number of reflectors, at least four in number. The Q-switch may be a passive Q-switch and may be integrally formed with the gain medium. The gain medium may include Nd:YAG, the Q-switch may include Cr:YAG and the Nd:YAG and Cr:YAG may be fused together. There may be an optical diode for limiting the direction of oscillation to one or two possible senses. There may be at least one pair of optically adjacent reflectors including means for totally internally reflecting the beam from the laser. The plane of incidence of one of the pair of means for totally internally reflecting may be substantially perpendicular to the plane of incidence of the other of the pair. The angle of incidence of the laser output beam on each of the means for totally internally reflecting may be substantially equal.
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Sharp Richard C.
Smith Irl W.
Flores Ruiz Delma R.
Font Frank G.
Iandiorio & Teska
Raytheon Company
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