Coherent light generators – Particular beam control device – Q-switch
Reexamination Certificate
2000-04-24
2002-10-15
Ip, Paul (Department: 2828)
Coherent light generators
Particular beam control device
Q-switch
C372S011000, C372S018000, C372S100000, C372S101000, C372S107000
Reexamination Certificate
active
06466593
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to solid state lasers. More specifically, the present invention relates to solid state lasers operative in the 8-12 micron range.
2. Description of the Related Art
Lasers are currently widely used for communication, research and development, manufacturing, directed energy and numerous other applications. For certain applications, the nominal characteristic power output level of the laser is acceptable. However, for certain applications, it is desirable to optimize the output power of the laser. For this purpose, Q-switches have been used to Q-switch lasers and optimize the output energy thereof. Q-switches cause the energy of the laser to be contained within the lasing medium until a high density of excited states is achieved.
Many techniques have been developed to hold off lasing action. One approach involves use of an electro-optic (EO) Q-switch. The electro-optic Q-switch typically involves use of a thin film polarizer in the cavity which does not allow any other polarization to exit the laser except that which is p-polarized with respect to the thin film polarizer. The electro-optic Q-switch forces the beam in the cavity to the orthogonal polarization of the energy passed by the fixed polarizer until the target excited state is achieved. When the target state is achieved, a voltage is applied to the EO Q-switch. As a result, the switch is activated and changes the polarization of the beam to the state at which it is passed by the fixed polarizer.
Passive Q-switches absorb energy in the laser cavity at the lasing frequency. Hence, no lasing action occurs until (depending on the concentration and the path length of the switch) a state is reached at which the atoms of the switch can no longer absorb radiation. At this point, the switch becomes transparent and lasing action is allowed to occur.
Unfortunately, for certain applications, the weight, size, cost and power requirements associated with electro-optic Q-switches is such that these devices provide a suboptimal solution.
Passive Q-switches are generally of fixed thickness. Consequently, conventional passive Q-switches may provide only a fixed hold off of lasing action. Unfortunately, over time, the pump sources or the optical elements wear and the operating characteristics of the laser change. As is well known in the art, the hold off of the laser must be matched to its operating characteristics to achieve optimal performance.
Hence, a need exists in the art for a passive Q switch capable of providing variable hold off of lasing action for solid state and other lasers.
SUMMARY OF THE INVENTION
The need in the art is addressed by the passive Q-switch of the present invention. The inventive Q-switch includes a first wedge of material adapted to absorb electromagnetic energy. The first wedge has a first thickness on a first end thereof and a second thickness on a second end thereof diametrically opposite the first end. The first wedge has a first surface connecting the first and second ends and a second surface connected the first and second ends. The second surface is slanted relative to the first surface.
A second wedge of material is included in the inventive passive Q-switch. As per the first wedge, the second wedge has a first thickness on a first end thereof and a second thickness on a second end thereof diametrically opposite the first end. The second wedge has a first surface connecting the first and second ends and a second surface connecting the first and second ends. The second surface is slanted relative to the first surface. The second surface of the first wedge is mounted in optical alignment with the second surface of the second wedge and in a plane parallel thereto.
In the illustrative embodiment, the wedges are made of chromium:yttrium aluminum garnet (Cr
30 2
:YAG) and mounted to allow the first and second wedges to translate relative to each other while maintaining a constant distant ‘d’ between the second surfaces thereof.
The inventive Q-switch allows for a variable thickness and lasing hold off in a passive arrangement.
REFERENCES:
patent: 5303256 (1994-04-01), Sumida
Alkov Leonard A.
Ip Paul
Lenzen, Jr. Glenn H.
Raufer Colin M.
Raytheon Company
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