CN2793723Y - Electronic diffraction device for researching ultrafast procedure of substance movement - Google Patents

Electronic diffraction device for researching ultrafast procedure of substance movement Download PDF

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Publication number
CN2793723Y
CN2793723Y CN 200520018037 CN200520018037U CN2793723Y CN 2793723 Y CN2793723 Y CN 2793723Y CN 200520018037 CN200520018037 CN 200520018037 CN 200520018037 U CN200520018037 U CN 200520018037U CN 2793723 Y CN2793723 Y CN 2793723Y
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electron
matter
sample chamber
utility
laser
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张�杰
刘运全
梁文锡
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Institute of Physics of CAS
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Institute of Physics of CAS
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Abstract

The utility model discloses an electron diffracting device for studying the ultrafast motion course of matter. The utility model comprises a laser source, an electron generating and controlling system, a sample chamber, an electron measuring and imaging system, a vacuum system and a sample controlling system, wherein the electron generating and controlling system is the kernel of the utility model, and comprises a photocathode, an anode, a magnetic lens, an X-direction and a Y-direction deflecting plates. The utility model has the advantage that the X-direction or the Y-direction deflection plate is used as a scanning plate for measuring the pulse width of femtosecond electrons. Thus, the distance that the electrons move from the photocathode to samples is shortened. Thus, the problem that the pulse width of electron beams moving over long distances is widened for space charge effects is overcome. Furthermore, the time resolution of the utility model is enhanced. The electron diffracting device for studying the ultrafast motion course of matter of the utility model has the advantage of high time and space resolution. The utility model can be used for measuring the structural dynamic information of the projecting and the reflecting diffraction of samples.

Description

A kind of electron diffraction apparatus that is used to study motion of matter ultrafast process
Technical field
The utility model relates to a kind of electron diffraction apparatus that is used to study motion of matter ultrafast process, particularly relates to a kind of femtosecond electronic diffraction device that is used to study motion of matter ultrafast process.
Background technology
In laser technology research, the ultrafast process that scientist studies the motion of matter that appears as of femtosecond laser provides strong tool.But Wavelength of Laser is oversize, generally greater than 200nm, studies the motion of matter like this, and its spatial discrimination is far from being enough.In order to obtain the information of high-space resolution, generally adopt electronics and X ray as detection means.At present can be very ripe as the technology of femtosecond laser, titanium precious stone laser can obtain the laser pulse of several femtoseconds.TIME RESOLVED TECHNIQUE is to be familiar with a kind of important method of dynamic process.In the last few years, optical pumping-electron beam probing method provides a kind of important laboratory facilities for scientific research.As document 1:Ihee, V.A.Lobastov, U.M.Gomez, et al Science 2001,291:458; Document 2:C.-Y.Ruan, V.A.Lobastov, F.Vigliotti et al Science 2004,304:80; Document 3:B.J.Siwick, J.R.Dwyer, et al, Science, 2003,302:1382; Document 4: Liu Yunquan, Zhang Jie etc., physics, 2005.4.
The method of nanosecond in the past, psec electronic diffraction in time resolution refletcion high-energy electron diffraction and relevant experiments such as gas phase electronic diffraction, has been brought into play important effect.The appearance of femtosecond laser, in order further to improve temporal resolution, the method for femtosecond electronic diffraction will further be brought into play bigger effect.In femtosecond electronic diffraction device,,, microworld provides strong tool for disclosing the dynamic (dynamical) unique property of material transient state in conjunction with the time resolution characteristics of femtosecond laser and the high-space resolution characteristic of electron beam.
No matter be ultrashort electronic impulse diffraction, or optical pumping-beam methods, all need space-time character electron beam preferably.In order to produce the electronic impulse that pulse width is the femtosecond magnitude, the method for electronics is not accomplished.Utilize femtosecond laser and photocathode to interact and can produce ultrashort electron beam, such electron beam has duplicated the time response of light pulse.Electron beam focuses on through quickening like this, interacts with sample, and its diffraction information band high spatial and time-resolved feature.Wherein generation of femtosecond electron beam and control section are the cores of femtosecond electronic diffraction device, and this part combines the high time resolution characteristic of femtosecond laser and the high-space resolution characteristic of electron beam.At present, correlative study equipment has been set up in some laboratories successively, as document 1: " Femtosecond electron diffraction fordirect measurement of ultrafast atomic motions ", APPLIED PHYSICS LETTERS, VOLUME 83 NUMBER 5,4 AUGUST 2003 disclose a kind of femtosecond electron beam and have produced and control device.But the deficiency of this covering device is: as shown in Figure 1, after electron beam produces from photocathode 6, will pass through anode 7, magnetic lens 8, directions X deflecting plate 9, Y direction deflecting plate 10, scanning board 11 arrival samples, electron beam has experienced long move distance in this process; And because electron beam has space charge effect, long like this corresponding broadening of pulse width meeting apart from the ELECTRON OF MOTION bundle, thus time resolution reduced.
In order further to improve the time resolution of femtosecond electronic diffraction device, can accomplish by 2: the laser pulse width that 1) reduces the exposure light negative electrode; 2) field intensity of the accelerating field between increase photocathode and the anode suppresses space charge effect, reduces the move distance of electron beam simultaneously, makes electron beam arrive sample surfaces in the shortest time.
Summary of the invention
The purpose of this utility model is to overcome above-mentioned deficiency of the prior art, and a kind of electron diffraction apparatus that is used to study motion of matter ultrafast process that can reduce electron beam move distance, raising time and spatial property, raising time resolution is provided.
In order to achieve the above object, the technical scheme taked of the utility model is as follows:
In the electronic diffraction experimentation of reality, at first the beam pulse width is measured, carry out the electronic diffraction experiment again, like this, deflecting plate and scanning board can not use simultaneously, the utility model deflecting plate as scanning board, can reduce the electronic motion distance, concrete technical scheme is as follows:
A kind of electron diffraction apparatus that is used to study motion of matter ultrafast process as shown in Figure 2, comprising:
One light source 5;
One electron production and control system 31 are placed on the place ahead light path of output light of described light source 5, are communicated with a sample chamber 20 by the second sealing and fixing parts 25;
One electronic surveying is connected with described sample chamber 20 by the 3rd sealing and fixing parts 26 with imaging system 32;
One vacuum system 13 is communicated with described sample chamber 20 by push-pull valve 12;
First Five-Year Plan axle control system 18 is connected with sample chamber 20 by the first sealing and fixing parts 24, and these five control system 18 have a control lever 22 to put in the sample chamber 20, and there is a sample stage 23 on its top, fixing testing sample 21 on the described sample stage 23;
In technique scheme, described electron production and control system 31 as shown in Figure 2, comprising: in the light path of a photocathode 6 with the output light that is placed on light source 5 perpendicular to the outgoing direction of light; One anode 7 is parallel staggered relatively with described photocathode 6, opens the aperture 3 of an electron beam outgoing on it; One magnetic lens 8 is placed on a side of the described aperture of described anode 7; One directions X deflecting plate 9 is placed on after the described magnetic lens 8, a Y direction deflecting plate 10 and described directions X deflecting plate 9 orthogonal being placed on the same axis.
In technique scheme, described light source 5 is a femtosecond laser frequency tripling generator, as shown in Figure 3, comprising: a femto-second laser 51, the laser that this laser instrument sends are through a frequency-doubling crystal 52, again through 55 beam splitting of first beam splitting dichroic mirror; Wherein frequency doubled light arrives second beam splitting dichroic mirror 62 through first catoptron 56, second catoptron 57, the 3rd catoptron 58 backs; Wherein fundamental frequency light is through half-wave plate 53 and the 4th catoptron 59, the lag line of forming through the 5th catoptron 60 and the 6th catoptron 61 again, through second beam splitting dichroic mirror, 62 backs overlaps with above-mentioned frequency doubled light incide one and frequency crystal 54 places carry out non-colinear and frequency.
In technique scheme, described electronic surveying and imaging system 32, as shown in Figure 2, comprise: a micro-channel plate detector 14, an optical fiber transducer 15, a video screen 16 and an image detector 17 sequentially connect to form, and make as a whole the 3rd sealing and fixing parts 26 that pass through and be connected with described sample chamber 20.
In technique scheme, described vacuum system 13 makes the vacuum tightness of described sample chamber 20 be better than 1.0 * 10 -6τ;
In technique scheme, there are at least two light incidence windows 19 described sample chamber 20;
In technique scheme, described image detector 17 is a figure image intensifying detector;
In technique scheme, the diameter of described aperture 3 is 100 microns;
In technique scheme, described photocathode 6 adopts the silverskin of 40nm thickness;
In technique scheme, described femto-second laser 51 is meant the femtosecond ti sapphire laser.
The course of work of the utility model device is:
Laser that femtosecond ti sapphire laser 51 sends through the photocathode 6 that incides electron production and control system 31 behind the frequency tripling and with its interaction after, produce electron beam, its time characteristic has been duplicated the characteristic of light pulse, also is the femtosecond magnitude; Voltage is zero on the anode 7, applies negative high voltage on photocathode 6; Under effect of electric field, electron beam is accelerated to very high energy, and electron wavelength has very high spatial resolving power; Focus on and directions X deflecting plate 9 through magnetic lens 8,10 pairs of electron beams of Y direction deflecting plate carry out spacescan; As Y direction deflecting plate 10 scanning boards as the Measurement of Electron Beam time response, be used for measuring the pulse width of femtosecond electron beam, concrete grammar is: when electron beam arrives the inlet of Y direction deflecting plate 10, the ramp voltage that on Y direction deflecting plate 10, adds transition in time, so just can be converted to horizontal measurable amount to the longitudinal length of electron beam (can be scaled the electronic impulse width), thereby realize the measurement of beam pulse width; Electron beam through pulse width measuring can be used for carrying out sample is surveyed; Magnetic lens 8 can be regulated the focal position of electron beam, and directions X deflecting plate 9 and Y direction deflecting plate 10 can be regulated the yawing moment of electron beam.Sample control system 18 is by adjusting the orientation of sample 21, the transmission diffraction that can measuring samples 21 or the structure multidate information of reflection diffraction.
Compared with prior art, the beneficial effects of the utility model are:
1) produces femtosecond magnitude electron beam with femtosecond magnitude pulse laser;
2) improve time resolution, make it reach the following time resolution of 100 femtoseconds;
3) have the high-space resolution ability, can be better than 0.01 dust;
4) Y direction deflecting plate 10 has reduced the move distance of electron beam in electron gun, thereby has reduced the temporal dispersion of electron beam in motion process simultaneously as the scanning board of beam pulse width measure.
Description of drawings
Fig. 1 represents that document 1 disclosed femtosecond electron beam produces and the control system synoptic diagram;
Fig. 2 represents the electron diffraction apparatus synoptic diagram that is used to study motion of matter ultrafast process of the present utility model;
Fig. 3 represents that femto second titanium precious stone laser frequency tripling of the present utility model produces index path;
The drawing explanation: ↑ expression plane of polarization is parallel to paper
 represents that plane of polarization is perpendicular to paper
Fig. 4 represents the embodiment synoptic diagram of electron production of the present utility model and control system 31.
Embodiment
Below in conjunction with the drawings and specific embodiments the utility model is described in further detail:
As shown in Figure 2, a kind of electron diffraction apparatus that is used to study motion of matter ultrafast process comprises light source 5, electron production and control system 31, sample chamber 20, electronic surveying and imaging system 32, vacuum system 13 and five control system 18; Wherein:
As shown in Figure 3, light source 5 is femto second titanium precious stone laser frequency tripling generation devices, its implementation is: the pulsewidth of femtosecond ti sapphire laser 51 output laser is 30 femtoseconds, centre wavelength is 800nm, this laser is through frequency-doubling crystal 52, this frequency-doubling crystal cutting angle is θ=29.2 °, φ=0 °, and laser is first beam splitting dichroic mirror, 55 beam splitting through wavelength 800nm full impregnated, 400nm are all-trans again; Wherein frequency doubled light arrives second beam splitting dichroic mirror 62 through first catoptron 56, second catoptron 57, the 3rd catoptron 58 backs; Wherein fundamental frequency light is through half-wave plate 53 and the 4th catoptron 59, the lag line of forming through the 5th catoptron 60 and the 6th catoptron 61 again, overlap with frequency doubled light through second beam splitting dichroic mirror 62 and to incide and crystal 54 places and frequently frequently, the frequency tripled laser wavelength is 266nm; Should and frequently cutting angle of crystal 54 be θ=44.3 °, φ=0 °; Adopting as document 1 " femtosecond ti sapphire laser frequency tripling theory and experimental study ", Liu Yun congruence, Acta Physica Sinica of present embodiment with the frequency process, Vol.54, No.4, April, disclosed non-colinear method in 2005 can reduce the absorption of beam split optical device to the frequency tripling Ultra-Violet Laser.
As shown in Figure 4, electron production and control system 31 are placed on the same horizontal axis and are formed by photocathode 6, anode 7, magnetic lens 8, directions X deflecting plate 9, Y direction deflecting plate 10 orders, wherein:
Photocathode 1 adopts the silverskin of 40nm thickness, and after femtosecond laser that light source 5 sends and photocathode 6 interacted, the produce power dispersity was less than the electron beam of 1eV, and its time characteristic has been duplicated the characteristic of light pulse;
Anode 7 adopts the conventional electrodes material, and with the photocathode parallel placement in 6 parallel surface opposites, distance is d between the two 1=5mm; Open a diameter on the anode 7 and be 100 microns aperture 3; On photocathode 6, add-high pressure of 50kV anode 7 ground connection; Under electric field quickened, electronics obtained the energy of 50keV, and this moment, electron wavelength was 0.054828 dust.
The magnetic gap of magnetic lens 8 is d to the distance of photocathode 6 2=62.5mm can make electron beam focus on the different positions adding different ampere turns or exciting current in the magnetic lens 8.
When magnetic lens 8 adopted ampere turns (NI) to be 1354, electron beam gathered in the porch of Y direction deflecting plate 10, and the focal length of magnetic lens 8 is F 1=58.5mm is used for the measurement of beam pulse width this moment.Present embodiment simultaneously as the scanning board of Measurement of Electron Beam time response, is used for measuring the pulse width of femtosecond electron beam to Y direction deflecting plate 10.Concrete grammar is when electron beam arrives the inlet of Y direction deflecting plate 10, to add the ramp voltage 6kV/ns of transition in time on Y direction deflecting plate 10; When electron beam from Y direction deflecting plate 10 during outgoing, electron beam is discrete coming on the scanning direction of an electric field that ramp voltage forms just, so just can be converted to horizontal measurable amount to the longitudinal length of electron beam (suitable and electronic impulse width), by being placed on magnetic lens 8 back d 3The micro-channel plate detector 14 at=464.5mm place is surveyed, thereby has realized the measurement of beam pulse width.
When magnetic lens 4 adopted ampere turns (NI) to be 636, electron beam focused on sample 21 places, and the focal length of magnetic lens 8 is F 2=264.5mm is used for ultrashort electronic impulse diffraction experiment this moment.Behind the electron beam arrival sample 21 after quickening and focusing on, with its effect, can produce the electronic diffraction signal, because the pulse width of electron beam is 30 femtoseconds, so the diffracted signal that obtains just has the multidate information in 30 femtoseconds, thereby realize high-space resolution and time-resolved measurement.
Electronic surveying and imaging system 32 are sequentially connected to form in a usual manner by micro-channel plate detector 14, optical fiber transducer 15, video screen 16, image detector 17, and do as a wholely to be connected with sample chamber 20.When electronics arrives micro-channel plate detector 14, signal is amplified, carry out image zoom through optical fiber transducer 15 then, arrive video screen 16, further strengthen amplification through 17 pairs of images of image detector again; The image detector 17 of present embodiment adopts figure image intensifying electric charge coupling detector.
Five control system 18 can be carried out X to sample, Y, and Z, the High Accuracy Control of θ and φ five dimensions realizes measuring the transmission diffraction of testing sample 21 or the structure multidate information of reflection diffraction.
Sample chamber 20 is connected by push-pull valve 12 with vacuum system 13, makes the vacuum tightness of sample chamber 20 be better than 1.0 * 10 -6τ.
Sample chamber 20 is provided with two pump light incidence windows 19, makes this device can increase pumping-delay system.
Sealing and fixing parts in the device, the corresponding conventional products that all adopts market to sell as the first sealing and fixing parts 24, the second sealing and fixing parts 25, the 3rd sealing and fixing parts 26.
The electron diffraction apparatus that is used to study motion of matter ultrafast process according to the present embodiment design, 21 move distance is 327mm to electronics from photocathode 6 to sample, compact conformation, reduce electronics produces sample 21 from photocathode 6 move distance, thereby raising time resolution, make it reach the following time resolution of 100 femtoseconds, its spatial resolving power can be better than 0.01 dust.

Claims (9)

1. electron diffraction apparatus that is used to study motion of matter ultrafast process comprises:
One light source (5);
One electron production and control system (31) are placed on the place ahead light path of output light of described light source (5), are communicated with sample chamber (20) by the second sealing and fixing parts (25);
One electronic surveying is connected with described sample chamber (20) by the 3rd sealing and fixing parts (26) with imaging system (32);
One vacuum system (13) is communicated with described sample chamber (20) by push-pull valve (12);
First Five-Year Plan axle control system (18), be connected with sample chamber (20) by the first sealing and fixing parts (24), these five control system (18) have a control lever (22) to put in the sample chamber (20), there is a sample stage (23) on described control lever (22) top, and described sample stage (23) goes up fixedly testing sample (21);
It is characterized in that,
Described electron production and control system (31) comprising: in the light path of a photocathode (6) with the output light that is placed on light source (5) perpendicular to the outgoing direction of light; One anode (7) is parallel staggered relatively with described photocathode (6), opens the aperture (3) of an electron beam outgoing on it; One magnetic lens (8) is placed on a side of the described aperture of described anode (7); A pair of directions X deflecting plate (9) is placed on described magnetic lens (8) afterwards, and a pair of Y direction deflecting plate (10) is placed on the same axis with described directions X deflecting plate (9) is orthogonal;
Described photocathode (6) adopts silverskin, or golden film.
2. the electron diffraction apparatus that is used to study motion of matter ultrafast process according to claim 1, it is characterized in that, described light source (5) is a femtosecond laser frequency tripling generator, comprise: a femto-second laser (51), the laser that this laser instrument sends is through a frequency-doubling crystal (52), again through first beam splitting dichroic mirror (55) beam splitting; Wherein frequency doubled light arrives second beam splitting dichroic mirror (62) through first catoptron (56), second catoptron (57), the 3rd catoptron (58) back; Wherein fundamental frequency light is through half-wave plate (53) and the 4th catoptron (59), the lag line of forming through the 5th catoptron (60) and the 6th catoptron (61) again, through second beam splitting dichroic mirror (62) back overlaps with above-mentioned frequency doubled light incide one and frequency crystal (54) locate to carry out non-colinear and frequency.
3. the electron diffraction apparatus that is used to study motion of matter ultrafast process according to claim 1, it is characterized in that, described electronic surveying and imaging system (32), comprise: a micro-channel plate detector (14), an optical fiber transducer (15), a video screen (16) and an image detector (17) sequentially connect to form, and make as a whole the 3rd sealing and fixing parts (26) that pass through and be connected with described sample chamber (20).
4. the electron diffraction apparatus that is used to study motion of matter ultrafast process according to claim 1 is characterized in that, described vacuum system (13) makes the vacuum tightness of described sample chamber (20) be better than 1.0 * 10 -6τ.
5. the electron diffraction apparatus that is used to study motion of matter ultrafast process according to claim 1 is characterized in that, described sample chamber (20) have at least two pump light incidence windows (19).
6. the electron diffraction apparatus that is used to study motion of matter ultrafast process according to claim 1 is characterized in that, described image detector (17) is a figure image intensifying detector.
7. the electron diffraction apparatus that is used to study motion of matter ultrafast process according to claim 1 is characterized in that, the diameter of described aperture (3) is 100 microns.
8. the electron diffraction apparatus that is used to study motion of matter ultrafast process according to claim 1 is characterized in that, described photocathode (6) adopts the silverskin of 40nm thickness.
9. the electron diffraction apparatus that is used to study motion of matter ultrafast process according to claim 2 is characterized in that, described femto-second laser (51) is meant the femtosecond ti sapphire laser.
CN 200520018037 2005-04-30 2005-04-30 Electronic diffraction device for researching ultrafast procedure of substance movement Expired - Fee Related CN2793723Y (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102903591A (en) * 2012-10-12 2013-01-30 上海交通大学 Ultrafast lens-free coherent electron diffraction imaging method and device

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102903591A (en) * 2012-10-12 2013-01-30 上海交通大学 Ultrafast lens-free coherent electron diffraction imaging method and device

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Granted publication date: 20060705

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