CN105181616B - A kind of measuring method of laser ablation process plasma absorptivity - Google Patents
A kind of measuring method of laser ablation process plasma absorptivity Download PDFInfo
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- CN105181616B CN105181616B CN201510608854.2A CN201510608854A CN105181616B CN 105181616 B CN105181616 B CN 105181616B CN 201510608854 A CN201510608854 A CN 201510608854A CN 105181616 B CN105181616 B CN 105181616B
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Abstract
The invention provides a kind of measuring method of laser ablation process plasma absorptivity, and the measurement of plasma absorption rate is converted into the measurement to nick chamber appearance and size obtained by laser ablation.First, in smooth bright and clean target material surface, using certain pulses laser, a series of nick chambers are processed, in process even variation laser energy density；Then, the diameter and depth of nick chamber are measured by three-dimensional appearance instrument, Laser Ablation Threshold F is tried to achieve by diameter laser energy density profileth；Then in conjunction with nick chamber depth, skin-material coefficient of efficiency α is obtained by theoretical calculation, and then obtains laser ablation process plasma absorptivity b；This method is easily operated, and it is reliable and stable to measure result, applied widely.
Description
Technical field
The present invention relates to a kind of measuring method of laser ablation process plasma absorptivity, refer in particular to one kind and pass through measurement
Nick chamber size measures the method for laser plasma absorptivity.
Background technology
Since laser comes out, laser is widely used in all trades and professions.Wherein, laser interacts with various types of materials
Characteristic and rule are always the study hotspot of numerous scholars.When high-power laser beam incides target material surface, target material surface is inhaled
Laser energy is received, temperature rises rapidly, reaches boiling point, and gasification phenomenon is aggravated, continues to rise with temperature, gasification substance suddenly
Continue absorption laser energy to complete to ionize, then form the plasma of high-temperature high-density.High-temperature high-density plasma
There is strong absorption to incident laser.For most of Laser Processings, this sink effect can prevent fraction of laser light
Energy reaches target surface, has shielding action to the energy coupling on laser beam and target surface, reduces its processing efficiency, even result in
Processing failure.Absorptivity of the plasma to laser is accurately and reliably measured, for the studying of light-matter interaction rule, is swashed
The development and application of light process technology are all most important.
However, plasma and laser interaction are an extremely complex processes, different laser parameters (such as wavelength,
Pulsewidth, power etc.), target, environmental gas can all influence the interaction of laser and target, further influence plasma to swashing
The absorptivity of light.Absorption of the plasma to laser simultaneously is a transients.Above-mentioned factor, cause to obtain accurately wait from
Daughter absorptivity, there is extreme difficulty.To solve above-mentioned problem, we have invented in a kind of simple and feasible laser ablation process
Plasma absorption rate experimental measurement method.
The content of the invention
The invention aims to solve deficiency of the prior art, and provide a kind of simple, reliable, accurate laser
The measuring method of plasma absorption rate.
The technical scheme is that：A kind of measuring method of laser ablation process plasma absorptivity, including with
Lower step：
S1, the surface for choosing target and the smooth bright and clean target, the surface roughness Ra for making the target material surface are
0.05-0.1μm；
S2, using pulse laser in a series of nick chambers of the target material surface ablation, in process, laser energy
Metric density F-rule increases or reduced；
S3, the nick chamber diameter D and depth h with ablation acquisition in the three-dimensional appearance analyzer measurement S2；
S4, in the two-dimensional coordinate system that abscissa is laser energy density F and ordinate is cavity diameter D, described in drafting
Energy density F and each data points of the corresponding nick chamber diameter D, and pass through logarithmic relationship fitting function curve；The function
The intersection point of curve and the abscissa is the ablation threshold F described in the pulse laser ablation corresponding to targetth；Calculate simultaneously
Coefficient of efficiency α of the target skin-material during the pulse laser ablation；
S5, pass through the nick chamber depth h, the ablation threshold FthIt is close with the coefficient of efficiency α, and laser energy
Degree, derives laser ablation process plasma absorptivity b.
In such scheme, the step S1 specifically includes following steps：
1), polished the target using abrasive paper for metallograph, the rough surface Ra degree of the target is reached 0.05-0.1 μm；
2), to wipe clean the target block surface with the cotton balls for being soaked with absolute alcohol to be processed.
In such scheme, the step S2 specifically includes following steps：
3) target, is fixed into clamping on the table, by the pulse laser focusing to the target to be processed
Surface, the laser spot diameter ω after focusing0Value be 0.001-1mm, the wavelength of the pulse laser is 193nm-10.6 μ
M, pulsewidth 1fs-1ms, single pulse energy E are 1 μ J-100J；
4), by changing the single pulse energy E of the pulse laser, laser energy density F, the single pulse energy are changed
E and the laser energy density F relation is：Using the laser pulse of laser energy density F changes in institute
A series of nick chambers of target material surface ablation are stated, in process, the value of the laser energy density F meets
It is distributed than ordered series of numbers or arithmetic progression；The laser energy density F values number is equal with a series of number of nick chambers；Institute
A series of number for stating nick chambers is more than or equal to 5；
5), target post-processes：The target material surface slag is removed, is polished；
6), the target block after polishing is put into the measuring cup equipped with absolute ethyl alcohol, is placed in supersonic wave cleaning machine clear
Wash, take out drying after cleaning in case detection.
In such scheme, the step S3 specifically includes following steps：
7), before the nick chamber topography measurement, the cotton balls for being first soaked with absolute alcohol wipes the net target block surface；
8) geometrical morphology, is carried out to the nick chamber Surface Texture using WYKO-NT1100 three-dimensional surface shapes measuring instrument
Measurement, including the nick chamber diameter D and depth h.
In such scheme, in the step S4, the method for obtaining the coefficient of efficiency α is：Pass through the laser tried to achieve
Ablation threshold Fth, it is determined that not producing the energy density F of ablation plasma0, energy density F0Span be (Fth,3Fth]；
Using energy density F0Pulse laser machining described in nick chamber, the depth for measuring the nick chamber is h0, according to formulaTry to achieve the skin-material coefficient of efficiency α of the target.
In such scheme, the formula that the gas ions absorptivity b is derived in the step S5 is：
Wherein, b is laser plasma absorptivity；
FthFor Laser Ablation Threshold；
α is coefficient of efficiency, and the coefficient of efficiency is optical absorption coefficient or heat leak coefficient；
F is laser energy density；
H is nick chamber depth corresponding under the laser energy density.
In such scheme, the energy density distribution at the pulse laser focusing hot spot is in dimensional gaussian distribution.
The present invention is that the measurement of absorptivity is converted into nick chamber pattern obtained by ablation by the present invention compared with prior art
The measurement of size.First, in smooth bright and clean target material surface, using certain pulses laser, a series of nick chambers is processed, are being processed
During even variation laser energy density F；Then, the nick chamber diameter D and depth h are measured by three-dimensional appearance instrument, led to
Cross diameter-laser energy density curve and try to achieve Laser Ablation Threshold Fth；Then in conjunction with nick chamber depth h, obtained by theoretical calculation
Skin-material coefficient of efficiency α, and then obtain laser ablation process plasma absorptivity b；This method is easily operated, measures knot
Fruit is reliable and stable, applied widely, is highly suitable for monitoring and controlling of the commercial Application to laser processing procedure, and science is ground
Study carefully middle photo plasma research.
Brief description of the drawings
Fig. 1 is the schematic flow sheet of the measuring method of one embodiment of the invention.
Fig. 2 is the nick chamber diameter D and laser energy density F matched curve figures of one embodiment of the invention.
Fig. 3 is the laser plasma absorptivity b of one embodiment of the invention with laser energy density F change curve.
Embodiment
Embodiment is described in further detail to the present invention below in conjunction with the accompanying drawings, but protection scope of the present invention is simultaneously
Not limited to this.
The laser micro-processing equipment used in the present embodiment includes pulse Nd:YAG laser, collimator and extender mirror, 45 ° it is complete
Anti- mirror, condenser lens and workbench.From pulse Nd:The laser beam that YAG laser is sent, pass sequentially through collimator and extender mirror, 45 ° it is complete
Anti- mirror, condenser lens, the target material surface finally focused on workbench.Described topography measurement equipment is WYKO-NT1100 tables
Face three-dimensional shape measuring apparatus.
With 45#Exemplified by steel target, the measuring method of laser plasma is as shown in figure 1, comprise the following steps：
S1, choose 45#Steel is the surface of target and the smooth bright and clean target, makes the surface roughness of the target material surface
Ra is 0.05-0.1 μm, is concretely comprised the following steps：
Choose 45#Steel and using 250#, 600#, 800#, 1200#With 1500#The abrasive paper for metallograph polishing target is smooth bright and clean
Its surface, the surface roughness Ra for making the target material surface are 0.05-0.1 μm；Then dried with the cotton balls for being soaked with absolute alcohol
The net target block surface is to be processed.
S2, using certain pulses laser 45#A series of nick chambers of steel surface ablation, in process, laser
Energy density F-rule increases or reduced, and the number of nick chamber is more than or equal to 5, concretely comprises the following steps：
1) by 45#Steel fixes clamping on the table, by certain pulses Laser Focusing to be processed 45#Steel surface, after focusing
Laser spot diameter ω0For 60 μm, the pulse laser wavelength of stating of selection is 532nm, pulsewidth 200ns, and single pulse energy is
0.1mJ-5mJ；
2) by changing the single pulse energy E of pulse laser, laser energy density F is changed, relation between the two is：Specifically, the method for changing the single pulse energy E of pulse laser is, adjusts pulse frequency or change average output work
Rate；Choose one group of single pulse energy E and take 0.2mJ, 0.4mJ, 0.7mJ, 1.1mJ, 1.6mJ, 2.2mJ, 2.9mJ, 3.7mJ respectively,
4.6mJ, according to formulaIt is respectively 14.15J/cm that laser energy density F, which can be calculated,2, 28.31J/cm2,
49.54J/cm2, 77.85J/cm2, 113.23J/cm2, 155.70J/cm2, 205.24J/cm2, 261.85J/cm2, 325.55J/
cm2；Laser micro-processing equipment is then turned on, 45#The cavity pattern of steel surface processing micron magnitude；
3) target post-processes：First with 1500#45 after abrasive paper for metallograph polishing processing#Steel surface removes surface slag, reuses
The diamond polishing agent of 0.5um particle diameters, polishes 10-20min on polishing machine；
4) the target block after polishing is put into the measuring cup equipped with absolute ethyl alcohol, is placed in supersonic wave cleaning machine and cleans
20min, taken out after cleaning and dry up and be placed in after it is numbered in drying basin in case detecting.
S3, the nick chamber obtained with morphology analysis instrument measuring process S2 ablations diameter D and depth h, specific steps
For：
5) before measuring the nick chamber pattern, the cotton balls for being first soaked with absolute alcohol wipes net described 45#Steel target block surface；
6) geometrical morphology is carried out to the nick chamber Surface Texture using WYKO-NT1100 three-dimensional surface shapes measuring instrument
Measurement, including the nick chamber diameter D and depth h.
S4, in the two-dimensional coordinate system that abscissa position laser energy density F and ordinate are cavity diameter D, described in drafting
Energy density F and each data points of the corresponding nick chamber diameter D, and pass through logarithmic relationship fitting function curve；The function
The intersection point of curve and abscissa is the pulse laser ablation 45#The ablation threshold F of steelth；45 are calculated simultaneously#Steel skin-material
Coefficient of efficiency α during the pulse laser ablation, is comprised the following steps that：
7) 45 are calculated#Steel Laser Ablation Threshold Fth：In abscissa be laser energy density F and ordinate is cavity diameter D
Two-dimensional coordinate system in, draw energy density F and the corresponding cavity diameter D in the step S3 and correspond to each point, and pass through
Logarithmic relationship fitting function curve, matched curve is as shown in Fig. 2 the equation corresponding to curve is as follows：
D=25.161ln (F) -48.467 (1)
The intersection point of curve and abscissa is 45#The Laser Ablation Threshold F of steelth=6.86J/cm2；
8) single pulse energy E is taken0=0.2mJ, laser energy density F0=14.15J/cm2, 45#Steel is in energy density F0=
14.15J/cm2 ablation nick chamber depth h0=1.89 μm.Due to energy density F0It is smaller, it is believed that material surface does not have shape
Into plasma, now, it is believed that plasma does not have notable absorption loss to incident laser energy, incides material surface
Actual energy density is energy density F0, so 45#Steel is in energy density F0Lower ablation nick chamber depth h0With inciding material
The actual energy density F on surface0Relation be：
Wherein α is coefficient of efficiency, and the coefficient of efficiency is optical absorption coefficient or heat leak coefficient, when pulsewidth length, thermal effect
Represented with heat leak coefficient when answering obvious, represented using during ultrashort pulse with the absorption coefficient of light.
By energy density F0With nick chamber depth h0Numerical value substitute into formula (2), try to achieve 45#The coefficient of efficiency α of Steel material=
0.493μm-1。
S5, pass through the nick chamber depth h, the ablation threshold FthWith the coefficient of efficiency α, and specific laser energy
Density conditions, derive under specific laser energy density, laser ablation process plasma absorptivity b, concretely comprise the following steps：
When the laser energy density F is more than 3Fth, material surface can form obvious plasma, therefore, laser penetration
Plasma reach material surface energy density be：
Finc=(1-b) F (3)
Wherein, FincThe energy density of material surface is incided for pulse laser, b is absorptivity of the plasma to laser,
The ablation depth h of the target and actual energy density F for inciding material surfaceincRelation be：
Wherein α is coefficient of efficiency, and the coefficient of efficiency is optical absorption coefficient or heat leak coefficient.
With reference to formula (3) and (4), the relation that can be obtained between plasma absorption rate b and nick chamber depth h is：
Wherein, b is laser plasma absorptivity；
FthFor Laser Ablation Threshold；
α is coefficient of efficiency, and the coefficient of efficiency is optical absorption coefficient or heat leak coefficient；
F is laser energy density；
H is nick chamber depth corresponding under the laser energy density.
By nick chamber depth h, Laser Ablation Threshold Fth, coefficient of efficiency α etc. substitutes into formulaIt can obtain
The absorptivity b of laser plasma under to different-energy density F, laser plasma absorptivity b with laser energy density F change
Curve is as shown in Figure 3.
The embodiment is preferred embodiment of the invention, but the present invention is not limited to above-mentioned embodiment, not
Away from the present invention substantive content in the case of, those skilled in the art can make it is any it is conspicuously improved, replace
Or modification belongs to protection scope of the present invention.
Claims (6)
1. a kind of measuring method of laser ablation process plasma absorptivity, it is characterised in that comprise the following steps：
S1, the surface for choosing target and the smooth bright and clean target, the surface roughness Ra for making the target material surface is 0.05-
0.1μm；
S2, using pulse laser in a series of nick chambers of the target material surface ablation, in process, laser energy is close
Spend F-rule increase or reduce；
S3, the nick chamber diameter D and depth h with ablation acquisition in the three-dimensional appearance analyzer measurement S2；
S4, in the two-dimensional coordinate system that abscissa is laser energy density F and ordinate is cavity diameter D, draw the energy
Density F and each data points of the corresponding nick chamber diameter D, and pass through logarithmic relationship fitting function curve；The function curve
Intersection point with the abscissa is the ablation threshold F corresponding to target described in the pulse laser ablationth；Calculate simultaneously described in
Coefficient of efficiency α of the target skin-material during the pulse laser ablation；
S5, pass through the nick chamber depth h, the ablation threshold FthWith the coefficient of efficiency α, and laser energy density, push away
Laser ablation process plasma absorptivity b is exported,
The formula of the gas ions absorptivity b is：
<mrow>
<mi>b</mi>
<mo>=</mo>
<mn>1</mn>
<mo>-</mo>
<mfrac>
<msub>
<mi>F</mi>
<mrow>
<mi>t</mi>
<mi>h</mi>
</mrow>
</msub>
<mi>F</mi>
</mfrac>
<mi>exp</mi>
<mrow>
<mo>(</mo>
<mi>&alpha;</mi>
<mi>h</mi>
<mo>)</mo>
</mrow>
</mrow>
Wherein, b is laser plasma absorptivity；
FthFor Laser Ablation Threshold；
α is coefficient of efficiency；
F is laser energy density；
H is nick chamber depth corresponding under the laser energy density.
2. the measuring method of laser ablation process plasma absorptivity according to claim 1, it is characterised in that institute
State step S1 and specifically include following steps：
1), polished the target using abrasive paper for metallograph, the rough surface Ra degree of the target is reached 0.05-0.1 μm；
2), to wipe clean the target block surface with the cotton balls for being soaked with absolute alcohol to be processed.
3. the measuring method of laser ablation process plasma absorptivity according to claim 1, it is characterised in that institute
State step S2 and specifically include following steps：
3) target, is fixed into clamping on the table, by the pulse laser focusing to the target material surface to be processed,
Laser spot diameter ω after focusing0Value be 0.001-1mm, the wavelength of the pulse laser is 193nm-10.6 μm, arteries and veins
A width of 1fs-1ms, single pulse energy E are 1 μ J-100J；
4), by changing the single pulse energy E of the pulse laser, change laser energy density F, the single pulse energy E with
The relation of the laser energy density F is：Using the laser pulse of laser energy density F changes in the target
Material ablated surface processes a series of nick chambers, and in process, the value of the laser energy density F, which meets, etc. compares number
Row or arithmetic progression distribution；The laser energy density F values number is equal with a series of number of nick chambers；Described one
The number of serial nick chamber is more than or equal to 5；
5), target post-processes：The target material surface slag is removed, is polished；
6), the target block after polishing is put into the measuring cup equipped with absolute ethyl alcohol, is placed in supersonic wave cleaning machine and cleans, clearly
Drying is taken out after washing in case detection.
4. the measuring method of laser ablation process plasma absorptivity according to claim 1, it is characterised in that institute
State step S3 and specifically include following steps：
7), before the nick chamber topography measurement, the cotton balls for being first soaked with absolute alcohol wipes the net target block surface；
8) geometrical morphology survey, is carried out to the nick chamber Surface Texture using WYKO-NT1100 three-dimensional surface shapes measuring instrument
Amount, including the nick chamber diameter D and depth h.
5. the measuring method of laser ablation process plasma absorptivity according to claim 1, it is characterised in that institute
State in step S4, the method for obtaining the coefficient of efficiency α is：Pass through the Laser Ablation Threshold F tried to achieveth, it is determined that not producing
The energy density F of ablation plasma0, energy density F0Span be (Fth,3Fth]；Using energy density F0Pulse
The nick chamber is laser machined, the depth for measuring the nick chamber is h0, according to formulaTry to achieve the target
The skin-material coefficient of efficiency α of material.
6. the measuring method of laser ablation process plasma absorptivity according to claim 1, it is characterised in that institute
It is in dimensional gaussian distribution to state the energy density distribution at pulse laser focusing hot spot.
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| CN107498176B (en) * | 2017-08-02 | 2019-05-14 | 中国科学院光电研究院 | A kind of the excimer laser polishing and detection method of porous ceramics |
| CN112513345A (en) * | 2018-08-01 | 2021-03-16 | 国立大学法人九州大学 | Diamond smoothing method |
| CN109948288B (en) * | 2019-04-01 | 2020-08-25 | 大连理工大学 | Nanosecond laser ablation micro-groove section profile prediction method |
| CN110186949B (en) * | 2019-05-21 | 2021-10-15 | 北京工业大学 | Method for rapidly measuring absorption rate of boiling point temperature of material to incident laser |
| CN115620847B (en) * | 2022-12-06 | 2023-03-28 | 中国空气动力研究与发展中心计算空气动力研究所 | Method for determining ablation morphology of silicon-based composite material and related device |
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