Coherent light generators – Particular temperature control – Heat sink
Reexamination Certificate
2002-05-31
2004-02-03
Ip, Paul (Department: 2828)
Coherent light generators
Particular temperature control
Heat sink
Reexamination Certificate
active
06687271
ABSTRACT:
This application claims the benefit of the Korean Application No. P2001-0032522 filed on Jun. 11, 2001, which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a laser, and more particularly, to a high powered laser, in which an array of micro-chip lasers is provided and a cooling system of the array is improved for enhancing an output.
2. Background of the Related Art
A laser beam is obtained by exciting a material containing atoms of a high energy level placed between two reflectors, to repeat reflection of light emitted by the excitation between the two reflectors enough to stimulate emission. The laser beam is a coherent monochromic light with characteristics like an electronic wave. Utilizing those characteristics, the laser beam is used in various fields, such as space communication, precision machining, medical treatment, and physical property study.
Depending on the materials that cause the stimulated emission, lasers are classified into gas lasers, solid state lasers, semiconductor lasers, dye lasers, and the like.
FIG. 1
illustrates a related art DPSS (Diode Pumped Solid State) laser, schematically.
Referring to
FIG. 1
, the related art DPSS laser is provided with a laser diode array (LD array)
11
used as a pumping light source, a focusing optical system
12
, a first reflector
13
, a laser medium
14
, a second reflector
15
, and a nonlinear optical material
16
.
The DPSS laser shoots the laser beam by directing a light from the laser diode array
11
to the laser medium
14
for pumping the light, and amplifying the pumped light. The DPSS laser provides high power considering its small size in comparison to an existing solid state, or liquid laser, of which application is increasing significantly.
Particularly, the laser with the laser medium
14
and the nonlinear material
16
joined together is called as a microchip laser, which is shown in
FIGS. 2-3B
.
Referring to
FIG. 2
, LD array
11
and focusing optical system
22
are shown. The microchip laser
20
has the laser medium
24
and the nonlinear material
26
joined together. A reflector
23
or
25
is coated on a surface of the laser medium
24
or the nonlinear material, to form a resonator
27
.
The resonator
27
has a first reflector
23
and a second reflector
25
coated on opposite surfaces of the laser medium
24
as one form, and the first reflector
23
coated on a surface of the laser medium
24
and the second reflector
25
coated on a surface of the nonlinear material as the other form, which are best shown in
FIGS. 3A-3B
.
Operation of the related art microchip laser will be explained, briefly.
A light &lgr;
0
from the laser diode array
21
is incident to, and pumped at, the laser medium
24
, and emitted therefrom in a light of a particular wavelength &lgr;
1
. Then, the light &lgr;
1
is amplified, and shoots as the light &lgr;
1
goes back and forth repeatedly within the resonator
27
. In this process, the light &lgr;
1
is turned into a light with a wavelength &lgr;
2
one half of a natural frequency by second harmonic generation of the nonlinear material
26
.
The microchip laser has advantages in that a length thereof can be reduced since the laser medium
24
and the nonlinear material
26
are joined, and a size thereof can be made smaller since the resonator
27
is formed by coating the reflectors
23
and
25
on surfaces of the laser medium
24
and the nonlinear material
26
.
In the meantime, a plurality of microchip lasers
20
may be arranged on more than one line to fabricate one laser for providing a high powered laser beam, of which temperature gradient is best shown in FIG.
4
.
Referring to
FIGS. 4A and 4B
, ‘A’, ‘B’, ‘C’, and ‘D’ regions represents regions of the same temperatures, wherein it can be noted that the temperature becomes lower as it goes the farther away from the pumping light focus part, and there is heat transfer between adjacent microchip lasers
20
.
In this instance, a desired power may not be obtainable due to the heat transfer between the adjacent microchip lasers
20
, or, when excessive, the shooting of the laser beam is not possible. That is, when the power of the laser diode array
21
is made higher for shooting a high powered laser beam, the laser medium
24
and the nonlinear material
26
cause a thermal lens effect in which a light is refracted by heat. Moreover, the heat transfer between adjacent microchip lasers
20
makes the thermal lens effect greater.
In summary, the microchip laser array has a disadvantage in that a power higher than a certain limit can not be provided due to the thermal lens effect even if a high powered pumping light is incident thereto.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a high powered laser that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a high powered laser, in which an array of micro-chip lasers is provided and a cooling system of the array is improved for enhancing an output.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the high powered laser includes a microchip laser array having an array of microchip laser beam shooting parts, and a heat transfer member of a material with a high thermal conductivity fitted between, and in contact with, the microchip laser beam shooting parts, for transferring heat from the microchip laser beam shooting parts to outside of the high powered laser.
The high powered laser further includes a cooling member fitted in contact with the heat transfer member for forcible cooling of the heat transferred to the heat transfer member by water or air.
In another aspect of the present invention, there is provided a high powered laser including a microchip laser array having an array of microchip laser beam shooting parts, a heat transfer member of a material with a high thermal conductivity fitted between, and in contact with, the microchip laser beam shooting parts, for transferring heat from the microchip laser beam shooting parts to outside of the high powered laser, a cooling member fitted in contact with the heat transfer member for forcible cooling of the heat transferred to the heat transfer member by water or air, and focusing means fitted to an output end of the microchip laser array for focusing lights from the microchip laser beam shooting parts into a single laser beam.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
REFERENCES:
patent: 5835515 (1998-11-01), Huang
patent: 6428307 (2002-08-01), Early et al.
Lee Han Bae
Um Kee Tae
Um Ki Young
Birch & Stewart Kolasch & Birch, LLP
Ip Paul
LG Electronics Inc.
Menefee James
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