CN116851911A - Femtosecond laser processing system and three-dimensional surface morphology online measurement method - Google Patents
Femtosecond laser processing system and three-dimensional surface morphology online measurement method Download PDFInfo
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
- B23K26/06—Shaping the laser beam, e.g. by masks or multi-focusing
- B23K26/062—Shaping the laser beam, e.g. by masks or multi-focusing by direct control of the laser beam
- B23K26/0622—Shaping the laser beam, e.g. by masks or multi-focusing by direct control of the laser beam by shaping pulses
- B23K26/0624—Shaping the laser beam, e.g. by masks or multi-focusing by direct control of the laser beam by shaping pulses using ultrashort pulses, i.e. pulses of 1ns or less
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- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
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Abstract
The invention relates to the technical field of femtosecond laser, in particular to a three-dimensional surface morphology online measurement method, which comprises the following steps: obtaining photocurrent signal I of processing point in non-processing state 0 The method comprises the steps of carrying out a first treatment on the surface of the In the processing process, receiving the femtosecond laser beam reflected by the element to be processed, dividing the femtosecond laser beam into two laser beams, and respectively transmitting the two laser beams to the first photoelectric detector and the second photoelectric detector; decoding the light current intensity in real time and decoding I according to the light current intensity calibrated in advance AM The corresponding relation between the axial depth Z and the axial depth Z is used for obtaining the axial depth Z of the surface of the processing point; and drawing the three-dimensional shape of the processing area of the processing element.
Description
The patent is ZL202210141374X, and the invention is a division application of a femtosecond laser processing system and a three-dimensional surface appearance and an online measurement method.
Technical Field
The invention relates to the technical field of femtosecond laser, in particular to a femtosecond laser processing system and a three-dimensional surface morphology online measurement method.
Background
Femtosecond laser brings revolutionary changes to material micro-nano processing by the ultra-short pulse width and the extremely high peak intensity characteristic, and is widely applied to the fields of front processing, manufacturing and measuring of relationship nationalities such as aerospace, quantum communication, new energy, biomedical treatment and the like.
The processing quality of the femtosecond laser processing element is generally detected by two-dimensional offline measurement such as an optical microscope or a scanning electron microscope, which puts high requirements on repeated positioning accuracy of clamping the processing element and finally leads to the fact that the processing quality cannot be ensured.
Most of the conventional integrated measuring platforms for processing and measuring are provided with a commercial CCD camera on the basis of the processing platform or are coupled with an AFM and an SEM. The scheme of additionally arranging the commercial CCD camera on the processing platform can effectively observe the processing state of the processing element in the processing process in real time, but is limited to two-dimensional imaging. For the scheme of coupling the SEM to the processing platform, the three-dimensional sense of the imaging is strong, but the three-dimensional imaging is limited to two-dimensional imaging, so that the three-dimensional imaging in the full sense cannot be performed, and the scheme is high in cost, and the problem of high cost is also faced when the AFM is coupled to the processing platform.
Because the three-dimensional surface morphology monitoring function is not achieved, time and effort are consumed in repeatedly searching a processing point during measurement, the processing quality cannot be monitored on line, and finally the reliability of processing and measurement cannot be guaranteed.
Disclosure of Invention
The invention aims to provide a processing and three-dimensional surface morphology online measurement integrated system of a femtosecond laser confocal system, which solves the problems that the time and the labor are consumed for repeatedly searching a processing point in the traditional offline measurement, the positioning accuracy of repeated clamping of a processing element cannot be ensured, the surface morphology of the processing element cannot be monitored online, and the like.
The purpose of the invention is realized in the following way:
the online measurement method of the three-dimensional surface morphology of the femtosecond laser processing comprises the following steps:
(1) Positioning the femtosecond laser beam to a processing point of an element to be processed in a non-processing state;
(2) Entering a processing state, focusing a femtosecond laser beam on a designated position of a processing element to perform ablation processing;
(3) In the processing process, receiving the femtosecond laser beam reflected by the element to be processed, dividing the femtosecond laser beam into two laser beams, and respectively transmitting the two laser beams to the first photoelectric detector and the second photoelectric detector;
the first photodetector converts the detected optical signal into a photocurrent signal I 1 ；
The second photodetector converts the detected optical signal into a photocurrent signal I 2 ；
Decoding I in real time for light current intensity AM ＝(I 1 -I 2 )/(I 1 +I 2 )；
(4) Decoding I according to photocurrent intensity calibrated in advance AM And a corresponding coefficient a and a corresponding coefficient b between the axial depth Z, obtaining an axial depth z=i of the machining point surface AM *a+b；
Photocurrent intensity decoding I AM Linear relation with axial depth Z of the surface of the processing element;
(5) The processing element is displaced in the XY direction to realize point-by-point scanning of the XY plane, and the axial depth Z of each point of the XY plane is obtained;
(6) And summarizing the coordinate information and the axial depth Z of the processing element in real time, and drawing the three-dimensional morphology of the surface of the processing element.
The invention also provides a femtosecond laser processing system, which comprises
The XYZ three-coordinate linear displacement platform is used for fixing the processing element and controlling the displacement of the processing element in the XYZ direction;
a femtosecond laser emitter for emitting a laser beam;
the polarizing beam splitter and the quarter wave plate are used for modulating the laser beam into circularly polarized light and then transmitting the circularly polarized light to the first unpolarized beam splitter;
a first unpolarized beam splitter that reflects an incident laser beam into the spatial light modulator;
the spatial light modulator changes the polarization direction of an incident laser beam and the energy distribution of laser according to the requirement, and the incident laser beam is emitted to the first unpolarized beam splitter and then transmitted to the 4f system;
4f, the system carries out low-pass filtering on the received laser beam and then transmits the laser beam to a second unpolarized beam splitter;
the second unpolarized beam splitter splits the laser beam into N Shu Chushe light again and transmits the N Shu Chushe light to the focusing objective lens in a set mode;
focusing objective lens to focus the laser beam on the appointed position of the processing element to process ablation;
a third unpolarized beam splitter for receiving the laser beam reflected by the element to be processed, dividing the laser beam into at least two laser beams, and transmitting the two laser beams to the first photoelectric detector and the second photoelectric detector respectively;
before processing, the first photodetector and the second photodetector cooperate to record the initially detected optical signal as a photocurrent signal I 0 ；
In the processing process, the first photoelectric detector converts the detected optical signal into a photocurrent signal I 1 ；
In the processing process, the second photoelectric detector converts the detected optical signal into a photocurrent signal I 2 ；
Computer according to photocurrent signal I 0 Photocurrent signal I 1 And photocurrent signal I 2 And calculating and drawing the three-dimensional shape of the surface of the processing element by combining preloaded software.
Preferably, a first middle gray scale mirror and a first focusing lens are arranged between the third unpolarized beam splitter and the first photoelectric detector, and a second middle gray scale mirror and a second focusing lens are arranged between the third unpolarized beam splitter and the second photoelectric detector.
Preferably, the detection end of the first photoelectric detector is clung to a first pinhole plate, and a pinhole of the first pinhole plate corresponds to a focus of the first focusing lens; the detection end of the first photodetector is positioned on the focal plane of the first focusing lens and is offset by an off-axis distance v relative to the focal center of the first focusing lens d ；
The detection end of the second photoelectric detector is tightly attached with a second pinhole plate, the pinhole of the second pinhole plate corresponds to the focus of the second focusing lens, the center of the detection end of the second photoelectric detector is aligned with the focus center of the second focusing lens and has a defocusing distance u from the focus plane d 。
Preferably, the 4f system comprises a third focusing lens, a third pinhole plate and a fourth focusing lens which are sequentially arranged;
the third focusing lens and the fourth focusing lens are matched to focus and diffuse the incident laser beam, and then the incident laser beam is emitted to the second unpolarized beam splitter; a third needle plate hole is arranged on a focal plane between the third focusing lens and the fourth focusing lens, and a needle hole of the third needle plate hole corresponds to a focal point of the third focusing lens.
Compared with the prior art, the invention has the following outstanding and beneficial technical effects:
according to the invention, the depth of a processing point can be monitored in real time by a designed differential mode and the proposed signal processing method, and the three-dimensional shape of the surface of the processing element can be obtained;
the invention realizes real-time online measurement of the depth of the processing point of the processing element, can further obtain the three-dimensional morphology of the surface of the processing element, and realizes the simultaneous ablation processing and morphology measurement by using the same femtosecond laser source.
The spatial light modulator changes the polarization direction of an incident laser beam and the energy distribution of laser, and combines the polarization beam splitter and the quarter wave plate to ensure that the emergent femtosecond laser beam is not retroreflected to the laser resonant cavity any more, so that the cross influence is avoided and the femtosecond laser component can be protected.
The invention discards the design idea of adding an expensive commercial measuring instrument in a processing light path, uses femtosecond laser for processing as a measuring light source instead, adopts a measuring scheme of a confocal system with high axial chromatography characteristic, adopts a photodiode with low cost but high maturity as a measuring element, and ensures the precision of three-dimensional imaging while greatly reducing the cost.
Drawings
Fig. 1 is a schematic diagram of an integrated system for femtosecond laser machining and measurement.
FIG. 2 is a block diagram of the photocurrent intensity decoding I of the present invention AM And an axial depth Z.
FIG. 3 is a schematic view of the construction of the three-dimensional topography of the surface of the processing element of the present invention.
1-femtosecond laser emitter; 2-plane mirror; a 3-polarizing beam splitter; a 4-quarter wave plate; 5-a first unpolarized beam splitter; a 6-spatial light modulator; 7-4f systems; 8-a second unpolarized beam splitter; 9-focusing an objective lens; 10-XYZ three-coordinate linear displacement platform; 11-a computer; 12 a-a second mid-gray mirror; 12 b-a second focusing lens; 13-a third unpolarized beam splitter; 14 a-a first mid-gray mirror; 14 b-a first focusing lens; 15-a first needle plate; 16-a first photodetector; 17-a second photodetector; 18-a second perforated plate; 19—femtosecond laser reflected by the processing point; a 20-femtosecond laser beam; 21-a workpiece to be processed;
71-a third focusing lens; 72-a third perforated plate; 73-fourth focusing lens.
Detailed Description
The following describes the embodiments of the present invention in further detail with reference to the accompanying drawings.
The three-dimensional surface morphology and online measurement method for femtosecond laser processing comprises the following steps:
(1) Positioning the femtosecond laser beam to a processing point of an element to be processed in a non-processing state;
(2) Entering a processing state, focusing a femtosecond laser beam on a designated position of an element to be processed to perform ablation processing;
(3) In the processing process, receiving the femtosecond laser beam reflected by the element to be processed, dividing the femtosecond laser beam into two laser beams, and respectively transmitting the two laser beams to the first photoelectric detector and the second photoelectric detector;
the first photodetector converts the detected optical signal into a photocurrent signal I 1 ；
The second photodetector converts the detected optical signal into a photocurrent signal I 2 ；
Decoding I for light current intensity AM ＝(I 1 -I 2 )/(I 1 +I 2 )；
(4) Decoding I according to photocurrent intensity calibrated in advance AM And a corresponding coefficient a and a corresponding coefficient b between the axial depth Z, obtaining an axial depth z=i of the machining point surface AM * a+b; the "×" in the formula is the multiplier; the corresponding coefficients a and b are constants determined in advance, and relate to parameters of the optical system used, including laser wavelength, numerical aperture of the focusing lens, focal length material, and the like.
Photocurrent intensity decoding I AM Linear relation with axial depth Z of the surface of the processing element;
(5) The processing element is displaced in the XY direction to realize point-by-point scanning of the XY plane, and the axial depth Z of each point of the XY plane is obtained;
(6) And summarizing the coordinate information and the axial depth Z of the processing element in real time, and drawing the three-dimensional morphology of the surface of the processing element.
The high spatial coherence and high stability of the femtosecond laser light source make it an ideal light source for three-dimensional online measurement systems.
Overview of depth measurement principle and three-dimensional topography construction: as shown in fig. 2, the laser beam is focused on the surface of the processing element by the focusing objective lens, and the femtosecond laser reflected from the processing point is focused on the first photodetector and the second photodetector by the focusing lens after passing through the beam splitter and the middle gray mirror, respectively. The first and second photodetectors receive and convert axially responsive photocurrent signals I 1 And photocurrent signal I 2 。
By the invention is providedSignal processing method I of (2) AM Using photocurrent signals I detected during processing 1 And photocurrent signal I 2 Decoding of axial depth Z and photocurrent of a machining point of the machining element is achieved, and finally depth information Z of the machining point of the machining element can be achieved 1 ，Z 2 …Z n And (5) performing real-time monitoring.
And then realizing point-by-point scanning of the XY plane through a three-coordinate displacement platform to obtain depth information of each point of the XY plane, and finally summarizing all the depth information and the coordinate information to draw the three-dimensional shape of the surface of the processing element.
As shown in fig. 3, each machining point P of the surface of the machining element 1 ，P 2 ，P 3 ，…，P n From the above description, a photocurrent signal I can be obtained 1 (x 1 ，y 1 )，I 2 (x 1 ，y 1 )，I 1 (x 2 ，y 2 )，I 2 (x 2 ，y 2 )，I 1 (x 3 ，y 3 )，I 2 (x 3 ，y 3 )，…，I 1 (x n ，y n )，I 2 (x n ，y n ) The depth information Z of each measuring point can be obtained by decoding the signal processing mode, the depth and the photocurrent intensity 1 (x 1 ，y 1 )，Z 2 (x 2 ，y 2 )，Z 3 (x 3 ，y 3 )，…，Z n (x n ，y n )。
And finally summarizing all the depth information and the coordinate information to draw the three-dimensional shape of the surface of the processing element.
The method is suitable for processing metal or nonmetal materials with hard and brittle characteristics, such as: silicon wafer, the melting point of monocrystalline silicon is 1693K.
The embodiment selects: under the conditions of 1040nm laser wavelength, 0.42 aperture of focusing objective lens and N-SF11 focusing material, the corresponding coefficient a is 3.894 and the corresponding coefficient b is 0.7445;
the data in group 0 of the following table are room temperature conditions (300K), first photodetector and second photodetector in non-processing statePhoto-current signals (i.e., photo-current signal I) 0 ) The method comprises the steps of carrying out a first treatment on the surface of the Starting from group 1 data, the machining is actually performed, and the photocurrent signals I detected by the first and second photodetectors 1 And photocurrent signal I 2 The method comprises the steps of carrying out a first treatment on the surface of the The point-by-point processing on the surface of a silicon wafer is actually detected as follows:
the integrated system for femtosecond laser processing and measurement comprises
The XYZ three-coordinate linear displacement platform is used for fixing the processing element and controlling the displacement of the processing element in the XYZ direction; by adjusting displacement in the XYZ direction, the femtosecond laser beam can be focused on a designated position for ablation processing and measurement;
a femtosecond laser emitter 1 for emitting a laser beam; the emergent parallel light source is reflected by the plane mirror 2 to change the emergent direction of laser, and then passes through the polarization beam splitter 3 and the quarter wave plate 4;
a polarizing beam splitter 3 and a quarter wave plate 4 for modulating the laser beam into circularly polarized light and then transmitting to a first unpolarized beam splitter 5;
a first unpolarized beam splitter 5 reflecting the incident laser beam into a spatial light modulator 6;
the spatial light modulator 6 changes the polarization direction of the incident laser beam and the energy distribution of the laser according to the requirement, and the polarization state of the laser emitted by the spatial light modulator 6 is regulated and combined with the polarization beam splitter 3 and the quarter wave plate 4, so that the laser can be prevented from being retroreflected into the laser resonant cavity of the femtosecond laser transmitter 1, and the femtosecond laser component can be protected while the cross influence is avoided; the femtosecond laser beam emitted by the spatial light modulator 6 passes through the first unpolarized beam splitter 5 and then is transmitted to the 4f system 7; the design mainly utilizes a spatial light modulator to modulate the phase and polarization state of initial laser so as to be suitable for different processing requirements; the laser beam coming out of the spatial light modulator 6 is half transmitted through the first non-polarizing beam splitter 5 to enter the 4f system, and the other half is reflected by the first non-polarizing beam splitter 5 to reach the quarter wave plate again, at this time, the combination of the quarter wave plate and the polarizing beam splitter can effectively prevent the half of the laser beam from returning to the resonant cavity to affect the light source.
4f system 7, which performs low-pass filtering to the received laser beam and then transmits the laser beam to a second unpolarized beam splitter 8;
a second unpolarized beam splitter 8 for splitting the laser beam into N Shu Chushe light again and transmitting the light to a focusing objective 9 in a set manner;
a focusing objective lens 9 for focusing the incident laser beam on a specified position on the processing element to perform ablation processing;
a third unpolarized beam splitter 13 for receiving the laser beam reflected from the element to be processed, dividing the beam into at least two laser beams, and transmitting the two laser beams to a first photodetector 16 and a second photodetector 17 respectively;
before processing, the first photodetector 16 and the second photodetector 17 obtain a photocurrent signal I from the initially detected optical signal 0 ；
During processing, the first photodetector 16 converts the detected optical signal into a photocurrent signal I 1 ；
During processing, the second photodetector 17 converts the detected optical signal into a photocurrent signal I 2 ；
A computer 11 for generating a photocurrent signal I 0 Photocurrent signal I 1 And photocurrent signal I 2 And calculating and drawing the three-dimensional shape and distribution of the surface of the processing element by combining preloaded software.
Preferably, a first middle gray mirror 14a and a first focusing lens 14b are arranged between the third unpolarized beam splitter 13 and the first photodetector 16, and a second middle gray mirror 12a and a second focusing lens 12b are arranged between the third unpolarized beam splitter 13 and the second photodetector 17. The damage to the photoelectric detector caused by the too high energy of the femtosecond laser pulse can be effectively avoided, the ablation threshold of the femtosecond laser pulse can be effectively improved without worrying about the influence on the photoelectric detector, and the application range of the processing and measuring integrated platform is improved.
Preferably, the detection end of the first photodetector 16 is closely attached to the first pinhole plate 15, and the pinhole of the first pinhole plate 15 corresponds to the focal point of the first focusing lens 14 b; the detection end of the first photodetector 16 is located at the focal plane of the first focusing lens 14b and is offset from the center of the focal point of the first focusing lens 14b by an off-axis distance v d The method comprises the steps of carrying out a first treatment on the surface of the Therefore, the defocused scattered light can be more effectively blocked, and the signal-to-noise ratio of measurement is improved; in practice, the spot on the focal plane of the first focusing lens 14b is not a point, but a spot of several microns; distance v of off axis d The range of the value of the light source is 100-200 microns, and the design can isolate more scattered light on the basis of not changing the structure of the optical system, so that the noise ratio is improved.
The detection end of the second photodetector 17 is closely attached with a second pinhole plate 18, the pinhole of the second pinhole plate 18 corresponds to the focus of the second focusing lens 12b, the center of the detection end of the second photodetector 12b is aligned with the focus center of the second focusing lens and has a defocus distance u from the focus plane d . This defocus distance u d The adjustable range of (2) is 100-200 micrometers, and the defocus distance u is adjusted d Can optimize I AM A larger measuring range and better linearity of the light intensity and depth are achieved as much as possible.
Preferably, the center of the detection end of the second photodetector 12b is offset from the center of the focus of the second focusing lens 12b by an off-axis distance v d2 The method comprises the steps of carrying out a first treatment on the surface of the Further more scattered light is isolated, thereby increasing the noise ratio.
Preferably, the 4f system includes a third focusing lens 71, a third pinhole plate 72, and a fourth focusing lens 73, which are sequentially arranged;
the third focusing lens 71 and the fourth focusing lens 73 cooperate to focus and diffuse the incident laser beam first and then emit the laser beam to the second unpolarized beam splitter 8; a third needle plate hole is provided on the focal plane between the third focusing lens 71 and the fourth focusing lens 73, and a needle hole of the third needle plate hole corresponds to the focal center of the third focusing lens. The passage of the light spot through the pinhole of the third pinhole plate 72 corresponds to passing through a low pass filter in the frequency domain, which not only eliminates the high frequency noise of the light spot, but also makes the femtosecond laser beam smoother to facilitate subsequent processing and measurement.
The integrated processing and measuring platform designed by the invention can realize real-time measurement of the depth of a processing point of a processing element and real-time online measurement of the surface morphology of the processing element. Compared with the problems that the time and the labor are consumed when repeatedly searching the processing point during the traditional offline measurement, the repeated clamping and positioning precision requirements on the processing element are high, the processing quality cannot be ensured and the like, the processing and three-dimensional online morphology measurement method combining the femtosecond laser and the confocal microscopy provided by the invention combines the advantages of no thermal damage of the femtosecond laser processing technology and the three-dimensional imaging advantage of high axial chromatography of the confocal microscopy, and is a feasible technical approach for realizing the femtosecond laser processing and the three-dimensional online nondestructive detection.
The foregoing has shown and described the basic principles and main features of the present invention and the advantages of the present invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and that the above embodiments and descriptions are merely illustrative of the principles of the present invention, and various changes and modifications may be made without departing from the spirit and scope of the invention, which is defined in the appended claims. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (8)
1. The three-dimensional surface morphology measuring method for femtosecond laser processing is characterized by being suitable for silicon wafer materials; the method comprises the following steps:
(1) Positioning the femtosecond laser beam to a processing point of an element to be processed in a non-processing state;
(2) Entering a processing state, focusing a femtosecond laser beam on a designated position of a processing element to perform ablation processing;
(3) In the processing process, receiving the femtosecond laser beam reflected by the element to be processed, dividing the femtosecond laser beam into two laser beams, and respectively transmitting the two laser beams to the first photoelectric detector and the second photoelectric detector;
the first photodetector records the detected optical signal as a photocurrent signal I 1 ；
The second photodetector records the detected optical signal as a photocurrent signal I 2 ；
Decoding I in real time for light current intensity AM ＝(I 1 -I 2 )/(I 1 +I 2 )；
(4) Decoding I according to photocurrent intensity calibrated in advance AM And a corresponding coefficient a and a corresponding coefficient b between the axial depth Z, obtaining an axial depth z=i of the machining point surface AM *a+b；
Photocurrent intensity decoding I AM Linear relation with axial depth Z of the surface of the processing element;
(5) The processing element is displaced in the XY direction to realize point-by-point scanning of the XY plane, and the axial depth Z of each point of the XY plane is obtained;
(6) And summarizing the coordinate information and the axial depth Z of the processing element in real time, and drawing the three-dimensional morphology of the surface of the processing element.
2. The method for measuring the three-dimensional surface topography by femtosecond laser machining according to claim 1, wherein the corresponding coefficient a is 3.894 and the corresponding coefficient b is 0.7445.
3. The integrated system for femtosecond laser processing and measurement is characterized by comprising
The XYZ three-coordinate linear displacement platform is used for fixing the processing element and controlling the displacement of the processing element in the XYZ direction;
a femtosecond laser emitter for emitting a laser beam;
the polarization beam splitter and the quarter wave plate are used for receiving the laser beam of the femtosecond laser transmitter, modulating the laser beam into circularly polarized light and transmitting the circularly polarized light to the first unpolarized beam splitter;
a first unpolarized beam splitter that reflects an incident laser beam into the spatial light modulator;
the spatial light modulator changes the polarization direction of an incident laser beam and the energy distribution of laser according to the requirement, and the incident laser beam is emitted to the first unpolarized beam splitter and then transmitted to the 4f system;
4f, the system carries out low-pass filtering on the received laser beam and then transmits the laser beam to a focusing objective lens;
focusing objective lens to focus the laser beam on the appointed position of the processing element to process ablation;
a third unpolarized beam splitter for receiving the laser beam reflected by the element to be processed, dividing the laser beam into at least two laser beams, and transmitting the two laser beams to the first photoelectric detector and the second photoelectric detector respectively;
before processing, the first photodetector and the second photodetector cooperate to record the initially detected optical signal as a photocurrent signal I 0 ；
In the processing process, the first photoelectric detector converts the detected optical signal into a photoelectric current signal I 1 ；
In the processing process, the second photoelectric detector converts the detected optical signal into a photocurrent signal I 2 ；
Computer according to photocurrent signal I 0 Photocurrent signal I 1 And photocurrent signal I 2 And calculating and drawing the three-dimensional shape of the surface of the processing element by combining preloaded software.
4. The integrated femtosecond laser machining measurement system according to claim 3, wherein a second unpolarized beam splitter is provided between the 4f system and a focusing objective lens; the second unpolarized beam splitter splits the laser beam into N Shu Chushe light again before passing to the focusing objective in a set manner.
5. The integrated femtosecond laser machining measurement system according to claim 3, wherein a first middle gray mirror and a first focusing lens are arranged between the third unpolarized beam splitter and the first photodetector, and a second middle gray mirror and a second focusing lens are arranged between the third unpolarized beam splitter and the second photodetector.
6. The integrated system of claim 5, wherein the detection end of the first photodetector is closely attached to a first pinhole plate, and the pinhole of the first pinhole plate corresponds to the focal point of the first focusing lens; the detection end of the first photodetector is positioned on the focal plane of the first focusing lens and is offset by an off-axis distance v relative to the focal center of the first focusing lens d ；
The detection end of the second photoelectric detector is tightly attached with a second pinhole plate, the pinhole of the second pinhole plate corresponds to the focus of the second focusing lens, the center of the detection end of the second photoelectric detector is aligned with the focus center of the second focusing lens and has a defocusing distance u from the focus plane d 。
7. The integrated femtosecond laser machining measurement system of claim 6, wherein a center of a detection end of the second photodetector is offset from a center of a focus of the second focus lens by an off-axis distance v d2 。
8. The integrated femtosecond laser machining measurement system according to claim 3, wherein the 4f system includes a third focusing lens, a third pinhole plate, and a fourth focusing lens arranged in sequence;
the third focusing lens and the fourth focusing lens are matched to focus and diffuse the incident laser beam, and then the incident laser beam is emitted to the second unpolarized beam splitter; a third needle plate hole is arranged on a focal plane between the third focusing lens and the fourth focusing lens, and a needle hole of the third needle plate hole corresponds to a focal point of the third focusing lens.
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