Coherent light generators – Particular beam control device – Control of pulse characteristics
Reexamination Certificate
1999-11-23
2002-09-10
Ip, Paul (Department: 2828)
Coherent light generators
Particular beam control device
Control of pulse characteristics
C372S034000, C372S036000, C257S601000, C257S625000, C257S706000
Reexamination Certificate
active
06449295
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention relates generally to the field of light emission devices and more specifically to a method and system for generating laser light.
BACKGROUND OF THE INVENTION
Applications that require fixed, stable laser wavelengths, for example laser range finding, consume a significant amount of electrical power in order to keep the laser module at a constant temperature. Solid state laser diodes typically have an output wavelength that is temperature dependent, and thus they need go be maintained at a constant temperature and below a specified maximum temperature. The maximum temperature depends on the module material and construction, but is generally in the range of 95° C. to 125° C. Stabilizing the temperature of laser modules, however, is difficult. When the laser emits a laser pulse, the temperature of the laser emitter rapidly increases and then rapidly decreases. Moreover, laser Todules generally have significant thermal inertia, because they have a mass of generally 50-100 grams and are in thermal contact with the rest of the system. Consequently, efficiently stabilizing the temperature of laser modules has proven to be difficult.
A known method and system for generating laser light uses a thermo-electric cooler and an electrical heater to stabilize the temperature of a laser emitter. The cooling unit is used to cool the laser emitter, and the heater stabilizes the temperature of the laser assembly. Heating the laser assembly, however, consumes power. Moreover, cooling the laser emitter with a cooling unit consumes even more power. Additionally, providing a cooling unit to the laser assembly is costly.
While these methods and systems have provided a significant improvement over prior approaches, the challenges in the field of light emission devices have continued to increase with demands for more and better techniques having greater efficiency. Therefore, a need has arisen for a new method and system for generating laser light.
SUMMARY OF THE INVENTION
In accordance with the present invention, a method and system for generating laser light are provided that substantially eliminate or reduce disadvantages and problems associated with previously developed systems and methods.
According to one embodiment of the invention, a laser system is disclosed. The system comprises laser emitters forming a laser stack. A heater resistor is coupled to the laser stack and is operable to stabilize the temperature of the laser stack. A heat reservoir is also coupled to the laser stack and is operable to store the heat flow from and release the heat flow to the laser stack. A temperature monitor is coupled to the laser stack and operable to monitor the temperature of the laser stack.
According to one embodiment of the invention, a six-step method for generating laser light is disclosed. Step one calls for monitoring the heat flow of a laser stack. Step two provides initiating the stabilization of the temperature of the laser stack using a heater resistor. Step three requires emitting a laser pulse during an on-time. In step four, the method provides for conducting the heat flow from the laser stack to a heat reservoir. The next step calls for stopping the laser pulse during an off-time. The last steps calls for directing the heat flow to a laser case.
A technical advantage of the present invention is that it does not require a cooling unit, resulting in a lowered power consumption and cost. Another technical advantage of the present invention is that only the temperature of the emitters, and rot the entire laser assembly, is stabilized, lowering power consumption. Another technical advantage of the present invention is that the emitter heat flow is passively stabilized, again lowering power consumption.
REFERENCES:
patent: 5414370 (1995-05-01), Hashinaga et al.
patent: 5526373 (1996-06-01), Karpinski
patent: 5898211 (1999-04-01), Marshall et al.
International Search Report in PCT International Application No. PCT/US00/41716, dated May 4, 2001.
Baker & Botts L.L.P.
Ip Paul
Jackson Cornelius H
Litton Systems Inc.
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