CN101262113B - A loop concave output mirror laser resonance cavity - Google Patents

A loop concave output mirror laser resonance cavity Download PDF

Info

Publication number
CN101262113B
CN101262113B CN2008100474182A CN200810047418A CN101262113B CN 101262113 B CN101262113 B CN 101262113B CN 2008100474182 A CN2008100474182 A CN 2008100474182A CN 200810047418 A CN200810047418 A CN 200810047418A CN 101262113 B CN101262113 B CN 101262113B
Authority
CN
China
Prior art keywords
mirror
output
laser
concave
output mirror
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
CN2008100474182A
Other languages
Chinese (zh)
Other versions
CN101262113A (en
Inventor
秦应雄
唐霞辉
程祖海
肖龙胜
李�根
肖瑜
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Huazhong University of Science and Technology
Original Assignee
Huazhong University of Science and Technology
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Huazhong University of Science and Technology filed Critical Huazhong University of Science and Technology
Priority to CN2008100474182A priority Critical patent/CN101262113B/en
Publication of CN101262113A publication Critical patent/CN101262113A/en
Application granted granted Critical
Publication of CN101262113B publication Critical patent/CN101262113B/en
Expired - Fee Related legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Abstract

The invention discloses a laser resonant cavity with an annular and a concave output mirror, which comprises a reflecting mirror, a laser medium and an output mirror; the output mirror is an annular concave mirror of which the working surface comprises one or a plurality of homocentric, annular and circular arc shaped concave cambers; the central part of the working surface of the output mirror can also be a circular working surface or the central part of the out mirror can be non-working surface or hollowness; an annular and concave reflecting mirror can also be adopted by the laser resonant cavity of the invention. The laser resonant cavity provided by the invention has the advantages of simple processing, convenient adjustment, steady operation, large available mode volume, very small divergence angle and good beam quality, thus being able to be applicable to gas lasesr or solid lasers with medium and high power, in particular to large volume gain medium and cylindrical and toroidal gain medium.

Description

A kind of loop concave output mirror laser resonance cavity
Technical field
The present invention relates to laserresonator, be specially a kind of loop concave output mirror laser resonance cavity.
Background technology
In many occasions of laser applications, in little Precision Machining such as for example laser drilling, welding, cutting and laser medicine, hope that all laser preferably can be operated in the top-quality basic mode state of angle of divergence minimum beam.Tradition mode selection technique (as using aperture diaphragm) can make the beam quality of laser output improve, but use aperture diaphragm to a great extent limit mode volume, increased mode loss.
High power laser light device key for design is how to obtain to realize the running of high power single mode, thereby can from activated material, extract energy expeditiously in the transverse mode distinguishing ability that big as far as possible mode volume becomes reconciled, can keep high beam quality again.
Laserresonator commonly used has three kinds of stable cavity, unsteady cavity and critical resonators.
The loss of stable cavity is very low, and how much deviation losses of paraxial ray are zero, and as long as the Fresnel number in chamber is not too little, and diffraction loss is also little of usually can ignoring, thus in the overwhelming majority, low-power device all adopts stable cavity.But when we require the operation of laser high power basic mode; Because the basic mode mode volume of stable cavity is too little; And it is irrelevant with resonant cavity minute surface size; This just means the lateral dimension that increases active medium or increases the raising that resonant cavity minute surface size is helpless to basic mode laser beam power output, causes many transverse mode runnings of laser on the contrary easily, reduces the quality of output beam.
With generally stablize the sphere chamber and compare, the waveform limitation capability of unsteady cavity significantly improves; In addition, more insensitive because waveform is a spherical wave to influences such as the dynamic refractive index distortion of operation material, therefore be used for the high-gain laser system, can obtain the quite little high brightness output beam of the angle of divergence.The loss of unsteady cavity mainly is the divergence loss of paraxial ray, and the loss of one way is very big, can reach tens percent.For obtaining high power output, the lateral dimension of operation material is often bigger, so diffraction loss can be ignored.Because the loss in chamber is bigger, need to adopt side effusion output coupling usually, so be output as the empty annular beam in center.This intonation is whole to require height, and can not be used for all kinds of Optical Maser Systems low gain or thin bore.
Plane-parallel resonator is a kind of chamber type of extensive use in the critical resonator, and it is made up of a plane mirror and a plane semi-transparent semi-reflecting lens.The major advantage of plane-parallel resonator is: beam directionality's fabulous (angle of divergence is little), mode volume is bigger, than being easier to obtain single-mode oscillation.The major defect of plane-parallel resonator is: the high and easy imbalance of adjustment required precision, to compare with stable cavity, and loss is also bigger, and is not quite suitable to little gain device.
Summary of the invention
The objective of the invention is to overcome the weak point of above-mentioned prior art, a kind of loop concave output mirror laser resonance cavity is provided.This laserresonator can obtain the output of big mode volume and high power under the prerequisite that guarantees laser beam quality.The chamber mirror is easy to process simultaneously, and Heat stability is good is cheap.
For realizing above-mentioned purpose; The technical scheme that the present invention adopts is: a kind of loop concave output mirror laser resonance cavity; Comprise speculum, laser working medium and outgoing mirror; It is characterized in that: outgoing mirror is a loop concave output mirror, and its working face comprises the circular-arc concave surface of one or more concentric annulars.
Compared with prior art, the present invention has following advantage:
(1) to have an output beam quality good in the present invention, and the angle of divergence is little, and mode volume is big, and the characteristics that power output is high can realize the output of high light beam quality and high-power laser simultaneously.
(2) the present invention can export annular beam, and the beam center power density is low, can reduce because the thermal deformation and the heat damage of the too high light path lens that causes of center power density.
(3) the present invention has the low-loss of stable cavity, the characteristic of difficult imbalance.Adjustment requires low, installation, use, easy to maintenance, and dependable performance.Easily existing laserresonator is reequiped, can not only improve the beam quality of existing laser, can also improve the power output of laser.
(4) the present invention is easy to process, low cost of manufacture.
Description of drawings
Fig. 1 is the structural representation of first kind of embodiment of loop concave output mirror laser resonance cavity provided by the invention.
Fig. 2 is the right view of loop concave output mirror among Fig. 1.
Fig. 3 is the output beam sketch map of laserresonator shown in Figure 1.
Fig. 4 is the structural representation of second kind of embodiment of loop concave output mirror laser resonance cavity provided by the invention.
Fig. 5 is the right view of loop concave output mirror among Fig. 4.
Fig. 6 is the structural representation of the third embodiment of loop concave output mirror laser resonance cavity provided by the invention.
Fig. 7 is the right view of loop concave output mirror among Fig. 6.
Fig. 8 is the structural representation of the 4th kind of embodiment of loop concave output mirror laser resonance cavity provided by the invention.
Fig. 9 is the right view of many with one heart ring concave output mirrors among Fig. 8.
Figure 10 is the structural representation of the 5th kind of embodiment of loop concave output mirror laser resonance cavity provided by the invention.
Figure 11 is the right view of many with one heart ring concave output mirrors among Figure 10.
Figure 12 is the structural representation of the 6th kind of embodiment of loop concave output mirror laser resonance cavity provided by the invention.
Figure 13 is the right view of many with one heart ring concave output mirrors among Figure 12.
Figure 14 is the structural representation of the 7th kind of embodiment of loop concave output mirror laser resonance cavity provided by the invention.
Figure 15 is the right view of loop concave output mirror among Figure 14.
Figure 16 is the left view of loop concave reflector among Figure 14.
Figure 17 is the output beam sketch map of the embodiment of the invention 7.
Figure 18 is the structural representation of the 8th kind of embodiment of loop concave output mirror laser resonance cavity provided by the invention.
Figure 19 is the right view of loop concave output mirror among Figure 18.
Figure 20 is the left view of loop concave reflector among Figure 18.
Figure 21 is the structural representation of the 9th kind of embodiment of loop concave output mirror laser resonance cavity provided by the invention.
Figure 22 is the right view of loop concave output mirror among Figure 21.
Figure 23 is the left view of loop concave reflector among Figure 21.
Embodiment
Below in conjunction with accompanying drawing and instance the present invention is done further detailed description.
At loop concave output mirror laser resonance cavity provided by the invention, include speculum 2, laser working medium 3 and outgoing mirror 1.Different are that the structure of outgoing mirror 1 is different with prior art, specify for example below.
Embodiment 1
By Fig. 1~shown in Figure 2, a kind of loop concave output mirror laser resonance cavity comprises speculum 2, laser working medium 3 and outgoing mirror 1, and outgoing mirror 1 is a loop concave output mirror, and its working face is made up of the circular-arc concave surface of an annular.
Laserresonator analysis to embodiment 1 can be known; The loop concave output mirror laser resonance cavity output beam in the form of a ring; The power peak position is or not the center of minute surface, but on a circle that with the minute surface center is the center of circle, can reduce the temperature at outgoing mirror, speculum and outer light path lens center like this; Reduce thermal deformation, improve beam stability.Fig. 3 is the output beam sketch map of the embodiment of the invention 1.Compare with stable cavity, adopt loop concave output mirror laser resonance cavity guaranteeing the output laser beam quality, under the constant situation of the angle of divergence, its mode volume can increase about four times, can improve laser output power greatly.Under the constant situation of mode volume, can greatly reduce the angle of divergence, the better laser beam of output quality.This resonant cavity all can use when working media is gas or solid, particularly when gain region is big, more can give full play to its advantage.
Embodiment 2
By Fig. 4~shown in Figure 5, outgoing mirror 1 is a loop concave output mirror, and its working face is made up of circular-arc concave surface and a central circular working face of an annular.Above-mentioned central circular working face can be plane or sphere.
Laserresonator analysis to embodiment 2 can be known; The loop concave output mirror laser resonance cavity output beam in the form of a ring; The power peak position is or not the center of minute surface, but on a circle that with the minute surface center is the center of circle, can reduce the temperature at outgoing mirror, speculum and outer light path lens center like this; Reduce thermal deformation, improve beam stability.Compare with stable cavity, adopt loop concave output mirror laser resonance cavity guaranteeing the output laser beam quality, under the constant situation of the angle of divergence, its mode volume can increase greatly, can improve laser output power greatly.Under the constant situation of mode volume, can greatly reduce the angle of divergence, the better laser beam of output quality.This resonant cavity all can use when working media is gas or solid, particularly when gain region is big, more can give full play to advantage.
Embodiment 3
By Fig. 6~shown in Figure 7, outgoing mirror 1 is a loop concave output mirror, and its working face comprises the circular-arc concave surface of an annular, and the minute surface center is a non-working surface or for hollow, laser working medium 3 is the circular cylindrical working media.
Laserresonator analysis to embodiment 3 can be known; The loop concave output mirror laser resonance cavity output beam in the form of a ring; The power peak position is or not the center of minute surface, but on a circle that with the minute surface center is the center of circle, can reduce the temperature at outgoing mirror, speculum and outer light path lens center like this; Reduce thermal deformation, improve beam stability.Compare with stable cavity, adopt loop concave output mirror laser resonance cavity guaranteeing the output laser beam quality, under the constant situation of the angle of divergence, can improve laser output power greatly.Under the constant situation of mode volume, can greatly reduce the angle of divergence, the better laser beam of output quality.This resonant cavity all can use when working media is gas or solid, particularly when the working media gain region is the circular cylindrical structure, more can give full play to its advantage.
Embodiment 4
By Fig. 8~shown in Figure 9, outgoing mirror 1 is many with one heart ring concave output mirrors, and its working face is made up of the circular-arc concave surface of a plurality of concentric annular.
Laserresonator analysis to embodiment 4 can be known; Many with one heart ring concave output mirror laser resonance cavity output beams in the form of a ring; The power peak position is or not the center of minute surface, but is being on a plurality of concentric circless in the center of circle with the minute surface center, can reduce the temperature at outgoing mirror, speculum and outer light path lens center like this; Reduce thermal deformation, improve beam stability.Compare with stable cavity, adopt many with one heart ring concave output mirror laser resonance cavities guaranteeing the output laser beam quality, under the constant situation of the angle of divergence, its mode volume can increase many, thereby improves laser output power greatly.And under the constant situation of mode volume, compare with stable cavity or monocycle concave mirror resonant cavity, the angle of divergence of the output beam of many with one heart ring concave output mirror laser resonance cavities is littler, and focal beam spot is littler; The focal beam spot of many with one heart ring concave output mirror laser resonance cavities output simultaneously is the polycyclic hot spot, and energy density distribution gets more even, the laser processing better effects if.This resonant cavity all can use when working media is gas or solid, particularly when gain region is big, more can give full play to its advantage.
Embodiment 5
By Figure 10~shown in Figure 11, outgoing mirror 1 is many with one heart ring concave output mirrors, and its working face is made up of circular-arc concave surface and a central circular working face of a plurality of concentric annular, and this central circular working face can be plane or sphere.
Laserresonator analysis to embodiment 5 can be known; Many with one heart ring concave output mirror laser resonance cavity output beams in the form of a ring; The power peak position is or not the center of minute surface, but is being on a plurality of concentric circless in the center of circle with the minute surface center, can reduce the temperature at outgoing mirror, speculum and outer light path lens center like this; Reduce thermal deformation, improve beam stability.Compare with stable cavity, adopt many with one heart ring concave output mirror laser resonance cavities guaranteeing the output laser beam quality, under the constant situation of the angle of divergence, its mode volume can increase many, thereby improves laser output power greatly.And under the constant situation of mode volume, compare with stable cavity or monocycle concave mirror resonant cavity, the angle of divergence of the output beam of many with one heart ring concave output mirror laser resonance cavities is littler, and focal beam spot is littler; The focal beam spot of many with one heart ring concave output mirror laser resonance cavities output simultaneously is the polycyclic hot spot, and energy density distribution gets more even, the laser processing better effects if.This resonant cavity all can use when working media is gas and solid, particularly when gain region is big, more can give full play to its advantage.
Embodiment 6
By Figure 12~shown in Figure 13, outgoing mirror 1 is many with one heart ring concave output mirrors, and its working face comprises the circular-arc concave surface of a plurality of concentric annular, and the minute surface center is a non-working surface or for hollow, laser working medium 3 is the circular cylindrical working media.
Laserresonator analysis to embodiment 3 can be known; Many with one heart ring concave output mirror laser resonance cavity output beams in the form of a ring; The power peak position is or not the center of minute surface, but is being on a plurality of concentric circless in the center of circle with the minute surface center, can reduce the temperature at outgoing mirror, speculum and outer light path lens center like this; Reduce thermal deformation, improve beam stability.Compare with stable cavity, adopt many with one heart ring concave output mirror laser resonance cavities guaranteeing the output laser beam quality, under the constant situation of the angle of divergence, its mode volume can increase many, thereby improves laser output power greatly.And under the constant situation of mode volume, compare with stable cavity or monocycle concave mirror resonant cavity, the angle of divergence of the output beam of many with one heart ring concave output mirror laser resonance cavities is littler, and focal beam spot is littler; The focal beam spot of many with one heart ring concave output mirror laser resonance cavities output simultaneously is the polycyclic hot spot, and energy density distribution gets more even, the laser processing better effects if.This resonant cavity all can use when working media is gas or solid, particularly when the working media gain region is the circular cylindrical structure, more can give full play to advantage.
Embodiment 7
By Figure 14~shown in Figure 16, a kind of loop concave mirror laserresonator comprises speculum 2, laser working medium 3 and outgoing mirror 1.Outgoing mirror 1 is the loop concave mirror with speculum 2, and its reflecting surface and output face are formed by the circular-arc concave surface of an annular.
Laserresonator analysis to embodiment 7 can be known; Loop concave mirror laserresonator output beam in the form of a ring; The power peak position is or not the center of minute surface, but on a circle that with the minute surface center is the center of circle, can reduce the temperature at speculum, outgoing mirror and outer light path lens center like this; Reduce thermal deformation, improve beam stability.Figure 17 is the output beam sketch map of the embodiment of the invention 7.Compare with stable cavity, adopt loop concave mirror laserresonator guaranteeing the output laser beam quality, under the constant situation of the angle of divergence, its mode volume can increase about four times, can improve laser output power greatly.Under the constant situation of mode volume, adopt loop concave mirror laserresonator can greatly reduce the angle of divergence, the focal beam spot of output is the polycyclic hot spot, the better effects if of laser processing.This resonant cavity all can use when working media is gas and solid, particularly when gain region is big, more can give full play to its advantage.
Embodiment 8
By Figure 18~shown in Figure 20; A kind of loop concave mirror laserresonator; Comprise speculum 2, laser working medium 3 and outgoing mirror 1, outgoing mirror 1 is the loop concave mirror with speculum 2, and its reflecting surface and output face are formed by circular-arc concave surface and a central circular face of an annular.Above-mentioned central circular working face can be plane or sphere.
Laserresonator analysis to embodiment 8 can be known; Loop concave mirror laserresonator output beam in the form of a ring; The power peak position is or not the center of minute surface, but on a circle that with the minute surface center is the center of circle, can reduce the temperature at speculum, outgoing mirror and outer light path lens center like this; Reduce thermal deformation, improve beam stability.Compare with stable cavity, adopt loop concave mirror laserresonator guaranteeing the output laser beam quality, under the constant situation of the angle of divergence, its mode volume can increase greatly, can improve laser output power greatly.Under the constant situation of mode volume, adopt loop concave mirror laserresonator can greatly reduce the angle of divergence, the focal beam spot of output is the polycyclic hot spot, the better effects if of laser processing.This resonant cavity all can use when working media is gas and solid, particularly when gain region is big, more can give full play to its advantage.
Embodiment 9
By Figure 21~shown in Figure 23, a kind of loop concave mirror laserresonator comprises speculum 2, laser working medium 3 and outgoing mirror 1.Speculum 2 is the loop concave mirror with outgoing mirror 1, and its reflecting surface and output face all comprise the circular-arc concave surface of an annular, and the minute surface center is non-reflecting surface or is hollow that laser working medium 3 is the circular cylindrical working media.
Laserresonator analysis to embodiment 9 can be known; Loop concave mirror laserresonator output beam in the form of a ring; The power peak position is or not the center of minute surface, but on a circle that with the minute surface center is the center of circle, can reduce the temperature at speculum, outgoing mirror and outer light path lens center like this; Reduce thermal deformation, improve beam stability.Compare with stable cavity, adopt loop concave mirror laserresonator guaranteeing the output laser beam quality, under the constant situation of the angle of divergence, can improve laser output power greatly.Under the constant situation of mode volume, adopt loop concave mirror laserresonator can greatly reduce the angle of divergence, the focal beam spot of output is the polycyclic hot spot, the better effects if of laser processing.This resonant cavity all can use when working media is gas and solid, particularly when the working media gain region is the circular cylindrical structure, more can give full play to its advantage.
In above-mentioned each instance, outgoing mirror 1 or speculum all can be made up of a plurality of working faces, also can be overall operation faces.
The present invention not only is confined to above-mentioned embodiment; Persons skilled in the art are according to content disclosed by the invention; Can adopt other multiple embodiment embodiment of the present invention, therefore, every employing project organization of the present invention and thinking; Do some simple designs that change or change, all fall into the scope of the present invention's protection.

Claims (1)

1. loop concave output mirror laser resonance cavity; Comprise speculum, laser working medium and outgoing mirror, it is characterized in that: outgoing mirror is a loop concave output mirror, and its working face is the overall operation face of the circular-arc concave surface of an annular; The as a whole working face of speculum; Said laserresonator output beam in the form of a ring, the power peak position is or not the center of minute surface, but on a circle that with the minute surface center is the center of circle.
CN2008100474182A 2008-04-20 2008-04-20 A loop concave output mirror laser resonance cavity Expired - Fee Related CN101262113B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN2008100474182A CN101262113B (en) 2008-04-20 2008-04-20 A loop concave output mirror laser resonance cavity

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN2008100474182A CN101262113B (en) 2008-04-20 2008-04-20 A loop concave output mirror laser resonance cavity

Publications (2)

Publication Number Publication Date
CN101262113A CN101262113A (en) 2008-09-10
CN101262113B true CN101262113B (en) 2012-02-29

Family

ID=39962401

Family Applications (1)

Application Number Title Priority Date Filing Date
CN2008100474182A Expired - Fee Related CN101262113B (en) 2008-04-20 2008-04-20 A loop concave output mirror laser resonance cavity

Country Status (1)

Country Link
CN (1) CN101262113B (en)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102593698B (en) * 2012-03-07 2014-01-08 华中科技大学 Laser resonant cavity with pan-shaped mirror surface
CN103151691B (en) * 2013-01-18 2015-02-18 华北电力大学(保定) Solid laser with annular reflecting mirror
CN103151690B (en) * 2013-01-18 2015-02-18 华北电力大学(保定) Solid laser with annular table-shaped reflecting prism
CN103996964A (en) * 2014-06-10 2014-08-20 鞍山华科大激光科技有限公司 Hollow mirror laser resonant cavity
CN103996963A (en) * 2014-06-10 2014-08-20 鞍山华科大激光科技有限公司 Q-switched laser with shared output mirror and double resonant cavities
CN105490143A (en) * 2016-01-25 2016-04-13 武汉浩宏科技有限公司 Novel holmium laser
CN112749484B (en) * 2020-12-28 2024-03-19 华中科技大学 Design method of large Fresnel number free-form surface mirror laser resonant cavity and resonant cavity

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5479429A (en) * 1990-09-05 1995-12-26 Fraunhofen Gesellschaft Zur Forderung Der Angewandten Forschung E.V. Laser cavity for laser media with annular cross section

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5479429A (en) * 1990-09-05 1995-12-26 Fraunhofen Gesellschaft Zur Forderung Der Angewandten Forschung E.V. Laser cavity for laser media with annular cross section

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
JP特开平1-189972A 1989.07.31
JP特开平9-102641A 1997.04.15

Also Published As

Publication number Publication date
CN101262113A (en) 2008-09-10

Similar Documents

Publication Publication Date Title
CN101262113B (en) A loop concave output mirror laser resonance cavity
CN101262114B (en) A loop concave reflector laser resonance cavity
US4050036A (en) Optical system for lasers
US4598408A (en) High extraction efficiency cylindrical ring resonator
US4164366A (en) Variable output coupled resonator
JP2006512616A (en) Optical fiber lens and manufacturing method
JP3073022B2 (en) Confocal diode pumped laser device
US3824487A (en) Unstable ring laser resonators
CN103594918A (en) Method and device for outputting hollow laser beam
WO2020248929A1 (en) Closed-loop control high-power single-fiber output continuous all-fiber laser system
CN100405678C (en) Combined holophote laser resonant cavity composed of right-angle round platform inboard surface and right-angle taper outboard surface
WO2021143176A1 (en) Rod-like photonic crystal fiber amplifier
CN103326224B (en) A kind of radial polarization beam laser
JPH0362579A (en) Laser system
CN203536721U (en) Device for outputting hollow laser beam
CN108521068B (en) The adjusting device of laser device of adjustable wavelength, pulse width and power
US5327449A (en) Laser resonator
CN101938080B (en) Active optical fiber with characteristics of single-mode output TM01 mode
CN112421360A (en) Integrated optical fiber resonant cavity and manufacturing method and application thereof
CN102593698B (en) Laser resonant cavity with pan-shaped mirror surface
US3825856A (en) Laser generator for single transverse mode operation
CN202602079U (en) Pan-shaped mirror surface laser resonant cavity
CN100367581C (en) High-power laser resonance cavity
US4123150A (en) Stable resonators for radial flow lasers
US7068700B2 (en) Optical bench for diode-pumped solid state lasers in field applications

Legal Events

Date Code Title Description
C06 Publication
PB01 Publication
C10 Entry into substantive examination
SE01 Entry into force of request for substantive examination
C14 Grant of patent or utility model
GR01 Patent grant
CF01 Termination of patent right due to non-payment of annual fee

Granted publication date: 20120229

Termination date: 20150420

EXPY Termination of patent right or utility model