CN2423582Y - Polarization delay Thomson sattering investigating device - Google Patents
Polarization delay Thomson sattering investigating device Download PDFInfo
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- CN2423582Y CN2423582Y CN 00217938 CN00217938U CN2423582Y CN 2423582 Y CN2423582 Y CN 2423582Y CN 00217938 CN00217938 CN 00217938 CN 00217938 U CN00217938 U CN 00217938U CN 2423582 Y CN2423582 Y CN 2423582Y
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Abstract
The utility model relates to a polarization delay Thomson scattering measuring device. The utility model comprises a light source part and a collection detecting part which are divided by using the internal target of a vacuum target chamber as the center, wherein, the inside of the light source part is provided with a laser and a focusing device, wherein, the inside of the laser is provided with birefringence crystals generating double-pulse laser beams; the collection detecting part comprises a primary convex lens, a polarization analyzer, a secondary convex lens, a color filter, and a receiver. The utility model has the characteristics of simplicity, convenient operation, accurate delay, no loss, high sensitivity, and low cost. The utility model is especially suitable for the parameter diagnosis of the mutual effect of super-strength ultra-fast lasers and plasma.
Description
The utility model is the measurement mechanism about a kind of polarization time-delay Thomson scattering.Be specially adapted to the diagnosis of the parameter of ultrashort ultra-intense laser and plasma interaction.
Technology [1] formerly: people such as U.S. A.K.Lal provide a kind of bifrequency CO
2The low-angle Thomson scattering diagnostic device of laser excitation plasma wave (being published in Phys.Plasmas 4 (5), 1443,1997).Its pump light is beat frequency CO
2Laser (wavelength is respectively 10.3 and 10.6 microns, complete half high pulsewidth 300 psecs, 70 joules of energy), 0.53 micron of probe optical wavelength, becomes 87 ° of angle incidents at complete half high 2 nanoseconds of pulsewidth with pump light, it is that scanning obtains by streak camera that its time differentiates, and resolution is 10 psecs.The weak point of this type of device has following 3 points: 1. the probe light source needs to introduce separately, and is more loaded down with trivial details on device and light path; 2. its time is differentiated the resolution that is subject to streak camera, this device is unsuitable for desk-top femtosecond laser device, because the relaxation time of the plasma wave that femtosecond laser excites in plasma is at picosecond magnitude, and resolution is very expensive less than the streak camera of psec; 3. this matching requirements pump light and probe light have certain included angle, thereby can not be used for the laser that is in the research focus is in the world diagnosed in the process of the plasma activated plasma ripple that is subjected to the kapillary constraint.
Technology [2] formerly: people such as United States Naval Research Laboratory A.Ting have had bigger improvement (to be published in Phys.Rev.Lett.77 based on the relevant Thomson scattering technology of femtosecond laser than said apparatus, 5377,1996. and Phys.Plasmas 4 (5), 1889,1997).Its lasing light emitter parameter is: 1.06 microns of wavelength, pulsewidth 400 femtoseconds, energy 1000 millijoules.At first from pump light, tell sub-fraction light as probe light with a beam-splitter, this probe light is coaxial with pump light again after by phosphoric acid deuterium potassium (KDP) crystal double frequency (just separating with pump light on the frequency spectrum like this), and the light path of regulating two-beam respectively can obtain different time delay.Scattered light enters spectrometer after through a color filter.This is apparatus simplified many on the structure, and its probe is the part of pump light only, does not need extra LASER Light Source, and the time-delay of its pump light and probe light is that light path is adjustable, does not need expensive equipment, and can carry out the zero degree diagnosis.But this device still has following defective: 1. beam-splitter and KDP crystal are understood the broadening femtosecond pulse, reduce to focus on and use (target practice) power; 2. the optical path difference with respect to the time-delay of 1 psec is 0.3 millimeter, and the subtle change of two light paths all can change the time interval of pump light and probe light, and the absolute light path difference of two light paths is difficult definite, needs monitoring system; 3. owing to the off-axis parabolic mirror focusing focal spot that needs on the device to use is minimum, radius is less than 10 microns, and probe light is adjusted into coaxial and focuses on the so little zone with pump light again is very difficult; The frequency spectrum of scattered light spectrum move be proportional to the probe optical wavelength square, for this wide range lasing light emitter of femtosecond pulse, must have enough frequency shift amounts just might obtain the scattered signal do not covered, and the KDP crystal can make observation scattered light signal difficulty more undoubtedly to the frequency multiplication of probe light at forward direction by bias light.
The purpose of this utility model is for overcoming the problem in the above technology formerly, mainly is the application at laser plasma interactions, provides a kind of simple and easy to do, need not the Thomson scattering measurement mechanism of expensive components and parts.Overcome formerly and produce probe light and the shortcoming of regulating the light path complexity of delaying time in the technology, further improve sensitivity to small scattered signal, and be suitable for all kinds of laser systems, comprise the ultrashort ultra-intense laser system that adopts chirped pulse to amplify (CPA) and adopt optical parameter chirped pulse amplification (OPCPA) technology.
The structure of measurement mechanism of the present utility model can be divided into two ingredients as shown in Figure 1 on function.To place the targets 3 in the vacuum target chamber 4 is the center, and first is from producing double-pulse laser bundle the Lights section till the target 3 that places in the vacuum target chamber 4, comprising laser instrument 1 and focus device 2.Wherein laser instrument 1 contains laser oscillator 101, and laser amplifier 102 expands bundle compression device 104; Between laser amplifier 102 and expansion bundle compression device 104, be equipped with the birefringece crystal 103 that produces the double-pulse laser bundle.Second portion is to begin collection test section till the receiving device 9 from the targets 3 in the vacuum target chamber 4, contains: first convex lens 5 and the focus that are positioned at by focus on the target 3 of vacuum target chamber 4 are positioned at the compound lens that second convex lens 7 on the receiving device 9 constitute.Placing between first convex lens 5 and second convex lens 7 has analyzer 6, and placing between second convex lens 7 and the receiving device 9 has color filter 8, and receiving device 9.Wherein focus device 2 can change the optical element that it comprises according to different experiment conditions, be catoptron and focus lamp etc., significant feature is that the laser beam with light source focuses on the target 3, so as long as the focus of focus device 2 is positioned on the target 3, just do not influence the work of single unit system.
The concrete course of work is as follows:
In the first, birefringece crystal 103 is put in the laser instrument 1, between laser amplifier 102 and expansion bundle compression device 103, it is by transparent to the laser beam wave band and do not have a uniaxial crystal of obvious nonlinear effect, as calcite crystal, or lithium columbate crystal, or rutile crystal constitutes.The selection of concrete uniaxial crystal can be decided according to the pump light of job requirement and the time interval between the probe light, machining shape with do not influence laser beam pass through be as the criterion.The optical axis of birefringece crystal 103 is parallel to optical surface, and birefringece crystal 103 are optical axises perpendicular to the laser beam direction of propagation place light path in the laser instrument 1.Because laser oscillator 101 is a linearly polarized light with laser amplifier 102 emitted laser pulses, when one angle theta being arranged with birefringece crystal 103 optical axises, birefringence according to uniaxial crystal, this laser pulse can be split into two laser pulses after by birefringece crystal 103, these two laser pulses are still linearly polarized light, but the polarization direction is vertical mutually, an optical axis that is parallel to birefringece crystal 103, optical axis perpendicular to birefringece crystal 103, do not separate on the space, and certain interval is arranged in time.The time interval of two laser pulses is by the refringence and the crystal thickness decision of the ordinary light and the special light of birefringece crystal 103, and the energy of two laser pulses is than being determined by angle theta.Like this, one is pump light in two laser pulses, and one is probe light, then can adjust the energy of pump light and probe light when changing angle θ.This two bundles laser pulse is again through after expanding bundle compression device 104, promptly can be used as pump light in the work and probe light.Enter vacuum target chamber 4 inner focusings on target 3 by focus device 2 again, produce laser and the mutual effect of plasma.
Second portion is for collecting the test section: the focus of first convex lens 5 drops on the target 3, gets first convex lens 5 and second convex lens 7 for compound lens, influences with color difference eliminating.The laser beam of dispersing after laser and the action of plasma comprises pump light, and probe light scattering and scattered portion not become directional light through first convex lens 5.Pass through analyzer 6 again,, the polarization angle of adjustment analyzer 6 because probe light is vertical mutually with the pump light polarization direction, is selected the probe light transmission, the filtering pump light.Usually the probe light that adopts is about 1/10 with the energy ratio of pump light, and the polarization efficiency of analyzer 6 can reach 1/1000, is mainly the probe light signal so can guarantee the signal that sees through.The probe light that sees through is focused on the receiving device 9 by second convex lens 7 again.Be equipped with color filter 8 between second convex lens 7 and the receiving device 9, color filter 8 is the bandpass filter of a special plated film, its spectral response curve is high saturating to the scattered signal wave band, and the light of its commplementary wave length is ended, in embodiment of the present utility model, show as the scattered light of 740-765 nano wave length high thoroughly, high anti-to the not scattered light of 785 nano wave lengths, this has just improved the signal to noise ratio (S/N ratio) of scattered signal.The receiving device 9 that is positioned at second convex lens, 7 focus places is introduced the spectrometer that is connected with computing machine with the flashlight that receives, and can dynamically show the scattered signal spectrum on display.
It is coaxial that the utility model adopts the birefringence effect of birefringece crystal 103 to produce two bundles, and the polarization direction is vertical, energy ratio and adjustable laser beam of the time interval, and this technical characterictic can be made multiple use.In the laser plasma interactions field, also can utilize this kind technology to produce prepulsing-pump light sequence and practice shooting, promptly previous pulse energy is lower, as prepulsing and target effect, produce plasma, a back pulse energy is higher, as pump light and plasma interaction.Utilize the reflection of polarization sheet this two bundles axis light spatially can also be separated, carry out the diagnosis of different angles.Because two pulse polarization directions are vertical, utilize polaroid to diagnose respectively two-beam, comprise spectral analysis and focal spot imaging etc.
The advantage of the utility model device:
The utility model device is compared with the relevant Thomson scattering diagnostic device of technology formerly, and following characteristics are arranged:
1. simple and direct property: produce pump light-probe light dipulse, need not external light source, the optical element that produces the double-pulse laser bundle is a slice birefringece crystal 103, more formerly uses a laser instrument in the technology or produces probe light with beam-splitter, and the utility model has accomplished that maximum simplifies.
2. ease for operation: because pump light never separates on light path with probe light, there is not the adjustment problem on the light path in the two.And formerly to guarantee that two-beam finally focuses in the tiny area of tens microns of diameters in the technology, this requirement is the comparison difficulty.
3. Yan Shi accuracy: determine with shapes (refractive index and thickness) because pump light and time-delay between the probe light are character by birefringece crystal 103 itself, have nothing to do, do not need monitoring device with later light path, not high to outside conditional request.And formerly in the technology 2, the pump light light path does not overlap with probe light light path, the asymmetric shake that the two is small, and for example 30 microns relative light path changes, time-delay will corresponding change 100 femtoseconds, and this kinetics process for the following plasma of research 1 psec is very disadvantageous.In addition, formerly technology 2 can't directly be determined the absolute time-delay of the two, must rely on additional device, for example streak camera.
4. non-destructive: as for the pulsewidth of the light pulse of laser oscillator 101 and laser amplifier 102 outputs below 100 femtoseconds, the burnt ultrashort pulse of energy tens millis all can cause the broadening of pulse by general optical element, reduces focusing on target practice power.And the utility model places laser instrument 1 inside with birefringece crystal 103, and laser beam is to pass through birefringece crystal 103 before being compressed, and just there is not above-mentioned problem in this.
5. high sensitivity: because scattered light intensity is about the not per mille of scattered light in the probe light, and probe light light intensity is one of percentage of pump light light intensity, formerly adopt frequency multiplication probe light to remove the noise of pump light in the technology, but because scattered light with respect to the frequency displacement Δ λ of scattered light not be proportional to wavelength square, and femtosecond pulse is wide spectrum (the full halfwidth of 45 femtosecond pulses is 22 nanometers), and scattered signal will be submerged in again not in the scattering probe light like this.The pump light that adopts birefringece crystal 103 to produce is vertical with the probe light polarization direction, utilizes analyzer 6 can effectively remove pump light, is not cost in order to the frequency displacement of sacrificing scattered signal.Pump light is by behind the analyzer 6 in embodiment of the present utility model, and energy reduces more than 1000 times.
6. low-cost: as to expand before the bundle compression device 104 because birefringece crystal 103 is positioned at, only 20 millimeters of bores, 103 of a birefringece crystal needs hundreds of unit: if birefringece crystal 103 is put in laser instrument 1 outside, because expanding bundle back laser beam diameter is 50 millimeters, large-sized crystal growth like this is very difficult, process technology also requires very high, for example processes the KDP crystal of 50 millimeters of diameters, spends nearly ten thousand yuan.And the utility model has not just needed to spend the expense of big figure so.Simplifying on light path also reduced the spending of all kinds of optical elements.Diagnostic instrments of the present utility model also only needs to have an optical fiber spectrometer behind receiving device 9.And formerly in the technology,, special instrument must be arranged for determining the time-delay below the psec between pump light-probe light.
Description of drawings:
Fig. 1 is the structural representation of measurement mechanism of the present utility model.
Embodiment:
Structure as shown in Figure 1 is used for research and adopts chirped pulse to amplify the ultrashort ultra-intense laser of (CPA) and employing optical parameter chirped pulse amplification (OPCPA) technology at plasma activated plasma wave process.Wherein focus device 2 is to be made of first catoptron, 201, the second catoptrons 202 and off axis paraboloid mirror focus lamp 203.Color filter 8 is bandpass filter of plated film, and is high saturating to the scattered light of 740～765 nano wave lengths, high anti-to the not scattered light of 785 nano wave lengths.The parameter of laser instrument 1 is: centre wavelength 785 nanometers, pulse width 45 femtoseconds, full halfwidth 22 nanometers, peak power 2 terawatt (TW)s.To between 100 femtoseconds, through calculating, selecting birefringece crystal 103 is that calcite crystal and lithium columbate crystal are comparatively desirable in 5 psecs in the pump light that needs-probe light time-delay.For example the calcite crystal time delay interval of 9 millimeters of thickness is 5 psecs, the lithium columbate crystal time delay interval that thickness is 0.3 millimeter is 100 femtoseconds, birefringece crystal 103 is processed into the flat board of 20 millimeters of diameters that thickness do not wait, and birefringece crystal 103 optical axises are parallel to optical surface.With birefringece crystal 103 vertically be positioned over expand bundle compression device 104 in the laser instrument 1 before.When the different time delay interval of needs, the birefringece crystal 103 that only needs to insert different-thickness gets final product.Make θ=15 °, can obtain the energy ratio and be 1: 0.07 pump light and probe optical pulse, rotation analyzer 6 obtains pump light and probe light spectrum.The receiving device 9 of one ccd detector is placed on the focus of second convex lens, and to the focal spot imaging of pump light and probe light, imaging results shows that pump light overlaps with probe light focal beam spot.Placing the target 3 in the vacuum target chamber 4 is to adopt double helix electromagnetic gas valve, and under 2 barometric pressures, the plasma electron density that laser that records and gas interaction produce is about 1 * 10
18Cm
-3, the scattered light frequency displacement corresponding with 800 nanometers of optical maser wavelength 400 nanometers is respectively 4.8 nanometers and 19.2 nanometers, obviously formerly utilizes 400 nano-probe light signals of frequency multiplication structure generation will be positioned at former laser spectrum in the technology, is to detect.
Claims (3)
1. the measurement mechanism of polarization time-delay Thomson scattering comprises:
To place the target (3) in the vacuum target chamber (4) be the center, is divided into the Lights section of containing laser instrument (1) and focus device (2) and begins collection test section till the receiving device (9) from the interior target (3) of vacuum target chamber (4);
It is characterized in that:
Laser instrument in the Lights section (1) contains laser oscillator (101), laser amplifier (102), expands bundle compression device (104) and places laser amplifier (102) and expands bundle and compress birefringece crystal (103) between the device (104);
Collect in the test section and contain: be positioned at the compound lens that first convex lens (5) and focus on the target (3) of vacuum target chamber (4) is positioned at second convex lens (7) formation on the receiving device (9) by focus, between first convex lens (5) and second convex lens (7), be equipped with analyzer (6), between second convex lens (7) and receiving device (9), be equipped with color filter (8).
2. the measurement mechanism of polarization time-delay Thomson scattering according to claim 1, it is characterized in that said to place laser instrument (1) inner laser amplifier (102) and expand birefringece crystal (103) between the bundle compression device (104) be to be calcite crystal by uniaxial crystal transparent to the laser beam wave band and that do not have an obvious nonlinear effect, or lithium columbate crystal, or rutile crystal constitutes.
3. the measurement mechanism of polarization time-delay Thomson scattering according to claim 1 and 2, it is characterized in that said birefringece crystal (103) is that optical axis is parallel to optical surface, and the optical axis of birefringece crystal (103) places the light path in the laser instrument (1) with being perpendicular to the laser beam direction of propagation.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 00217938 CN2423582Y (en) | 2000-06-08 | 2000-06-08 | Polarization delay Thomson sattering investigating device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 00217938 CN2423582Y (en) | 2000-06-08 | 2000-06-08 | Polarization delay Thomson sattering investigating device |
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| Publication Number | Publication Date |
|---|---|
| CN2423582Y true CN2423582Y (en) | 2001-03-14 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN 00217938 Expired - Fee Related CN2423582Y (en) | 2000-06-08 | 2000-06-08 | Polarization delay Thomson sattering investigating device |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102661908A (en) * | 2012-04-27 | 2012-09-12 | 中国科学院上海光学精密机械研究所 | Single-beam femtosecond probe for diagnosing laser plasma parameters |
| CN104185353A (en) * | 2014-09-05 | 2014-12-03 | 中国人民解放军陆军军官学院 | Fusion reactor plasma density and temperature diagnosing method based on Thomson scattering weak coherent technique |
| CN105979689A (en) * | 2016-01-12 | 2016-09-28 | 中国科学院等离子体物理研究所 | Optical positioning system suitable for EAST boundary Thomson scattering diagnosis |
| CN108333147A (en) * | 2017-12-14 | 2018-07-27 | 中国科学院西安光学精密机械研究所 | Nearly backscattering optics measuring system |
| CN113507775A (en) * | 2021-06-07 | 2021-10-15 | 中国工程物理研究院激光聚变研究中心 | Multipurpose optical Thomson scattering spectrum measuring system suitable for large laser device |
-
2000
- 2000-06-08 CN CN 00217938 patent/CN2423582Y/en not_active Expired - Fee Related
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102661908A (en) * | 2012-04-27 | 2012-09-12 | 中国科学院上海光学精密机械研究所 | Single-beam femtosecond probe for diagnosing laser plasma parameters |
| CN102661908B (en) * | 2012-04-27 | 2013-12-25 | 中国科学院上海光学精密机械研究所 | Single-beam femtosecond probe for diagnosing laser plasma parameters |
| CN104185353A (en) * | 2014-09-05 | 2014-12-03 | 中国人民解放军陆军军官学院 | Fusion reactor plasma density and temperature diagnosing method based on Thomson scattering weak coherent technique |
| CN105979689A (en) * | 2016-01-12 | 2016-09-28 | 中国科学院等离子体物理研究所 | Optical positioning system suitable for EAST boundary Thomson scattering diagnosis |
| CN105979689B (en) * | 2016-01-12 | 2021-08-03 | 中国科学院等离子体物理研究所 | Optical positioning system suitable for EAST boundary Thomson scattering diagnosis |
| CN108333147A (en) * | 2017-12-14 | 2018-07-27 | 中国科学院西安光学精密机械研究所 | Nearly backscattering optics measuring system |
| CN108333147B (en) * | 2017-12-14 | 2024-04-12 | 中国科学院西安光学精密机械研究所 | Near back scattering optical measurement system |
| CN113507775A (en) * | 2021-06-07 | 2021-10-15 | 中国工程物理研究院激光聚变研究中心 | Multipurpose optical Thomson scattering spectrum measuring system suitable for large laser device |
| CN113507775B (en) * | 2021-06-07 | 2023-11-21 | 中国工程物理研究院激光聚变研究中心 | Multipurpose optical Thomson scattering spectrum measuring system suitable for large-scale laser device |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C19 | Lapse of patent right due to non-payment of the annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |