On-line detection device and method for laser drilling

Abstract

The present invention provides an online detection device and method for laser drilling. The online detection device for laser drilling includes: a laser processing component for emitting processing laser pulses; a laser lighting component for emitting illumination laser pulses and transmitting them to a workpiece to illuminate the microholes of the workpiece, including a laser illumination light source, a beam expansion unit, a second beam splitter unit, a first beam splitter unit and an objective lens; a gated imaging component for receiving the illumination laser signal reflected from the workpiece to obtain image information of the microholes of the workpiece, including an imaging lens, a gated camera and an image processing unit; the illumination laser pulse is reflected by the beam expansion unit, the second beam splitter unit and the first beam splitter unit, and then converged on the surface of the workpiece by the objective lens; the illumination laser signal reflected from the workpiece enters the imaging lens after being reflected by the objective lens, the first beam splitter unit and transmitted by the second beam splitter unit, and the gated camera opens the shutter at a set delay time to transmit the image information to the image processing unit.

Description

Technical Field

[0001] The present invention relates to the field of laser processing technology, and in particular to an online detection device and method for laser drilling. Background Art

[0002] Laser drilling is the process of machining micro-holes in materials using a high-energy-density laser beam. It is widely used in industrial manufacturing, especially in the fields of precision machining and micro-machining. The transparency of micro-holes is crucial to the machining quality, so it is necessary to monitor the status of micro-holes online through imaging.

[0003] During the micro-hole processing process, the laser interacts with the material to quickly ablate the workpiece surface and generate plasma with high-intensity light radiation. Depending on the processing material, the duration of plasma luminescence is generally between 10 nanoseconds and 100 microseconds. Plasma radiation runs through the entire drilling process, seriously interfering with imaging. The exposure time of ordinary cameras is usually in the millisecond level. In addition to receiving the illumination signal, they also receive a large amount of plasma radiation, which greatly suppresses the signal-to-noise ratio and interferes with imaging. Although the ultra-dynamic camera can enhance weak signals and suppress strong signals through algorithms, the plasma signal is not eliminated, and there is no significant improvement in the imaging effect. Summary of the invention

[0004] The embodiment of the present invention provides an online detection device and method for laser drilling, which uses a gated camera to selectively receive signals arriving at a specific time, greatly suppress noise signals, improve the signal-to-noise ratio, and enhance the quality of micropore images.

[0005] An embodiment of the present invention provides an online detection device for laser drilling, comprising:

[0006] A laser processing component for emitting processing laser pulses to process micro holes on a workpiece;

[0007] A laser illumination assembly is used to emit illumination laser pulses and transmit the illumination laser pulses to the workpiece to illuminate the microholes of the workpiece; the laser illumination assembly includes a laser illumination light source, a beam expansion unit, a second light splitting unit, a first light splitting unit and an objective lens;

[0008] A gated imaging component selectively receives the illumination laser signal reflected from the workpiece and obtains image information of the micropores of the workpiece according to the signal; the gated imaging component includes an imaging lens, a gated camera and an image processing unit;

[0009] The first spectroscopic unit is arranged in front of the laser processing component, the objective lens is arranged in front of the first spectroscopic unit, the processing laser pulse emitted by the laser processing component is transmitted from the first spectroscopic unit, and the objective lens converges the processing laser pulse transmitted from the first spectroscopic unit on the surface of the workpiece to perform micro-hole processing; the illumination laser pulse emitted by the laser illumination light source is expanded by the beam expansion unit, reflected by the second spectroscopic unit and the first spectroscopic unit, and then converged on the surface of the workpiece by the objective lens; the second spectroscopic unit, the imaging lens and the gated camera are arranged in sequence to form a confocal optical path; the illumination laser signal reflected from the workpiece passes through the objective lens, is reflected by the first spectroscopic unit and transmitted by the second spectroscopic unit, and then enters the imaging lens, the gated camera receives the reflected illumination laser signal, controls the shutter of the gated camera to open at the set delay time, and transmits the image information to the image processing unit, and the image processing unit displays the captured image of the micro-holes of the workpiece.

[0010] Preferably, the gated camera includes an imaging module, a gating module, a gain module and a timing control module; the gated camera is connected to the laser illumination light source; the imaging module acquires an image formed by focusing the illumination laser signal reflected from the workpiece; the gating module controls the opening and closing of a shutter; the gain module is used for gain amplification of the illumination laser signal reflected from the workpiece; the imaging module includes an image sensor, after receiving a shooting signal, the image sensor starts to expose and sends an exposure signal, the timing control module sends a synchronization trigger signal to the laser illumination light source and a gating pulse signal to the gating module, and after a set delay time, the gating module controls the shutter to open, so that the shutter opening signal is synchronized with the illumination laser signal reflected from the workpiece.

[0011] Preferably, a filter is provided between the second light splitting unit and the imaging lens, the filter is a narrowband filter, the bandwidth of the filter is less than or equal to 5 nm, and the filter only allows light with the same wavelength as the illumination laser pulse to pass through.

[0012] Preferably, the first spectroscopic unit comprises a spectroscopic prism or a dichroic mirror; the processing laser emitted by the laser processing component and the illumination laser emitted by the laser illumination light source have different wavelengths, the processing laser is transmitted from the first spectroscopic unit to the workpiece, and the illumination laser is reflected from the first spectroscopic unit to the workpiece.

[0013] Preferably, the beam expansion unit is used to expand the diameter of the illumination laser pulse and reduce the divergence angle of the illumination laser pulse to form a uniform illumination laser pulse, and the beam expansion unit includes at least one lens or a reflector.

[0014] Preferably, the objective lens is used to converge parallel processing laser pulses and illumination laser pulses onto the workpiece, and the objective lens includes at least one lens.

[0015] Preferably, the second beam splitter unit is a beam splitter prism, which splits the incident light beam into two parts, one part is transmitted through the beam splitter prism, and the other part is reflected; part of the illumination laser pulse emitted by the laser illumination light source is reflected to the first beam splitter unit through the second beam splitter unit; part of the illumination laser signal reflected back by the workpiece is transmitted through the second beam splitter unit and enters the imaging lens; the ratio of the transmitted light beam to the reflected light beam is set by selecting the model of the beam splitter prism.

[0016] Based on the same concept, the present invention also provides an online detection method for laser drilling, using the above-mentioned online detection device for laser drilling, comprising the following steps:

[0017] The processing laser pulse emitted by the laser processing component is transmitted from the first beam splitting unit and converged on the surface of the workpiece through the objective lens to perform micro-hole processing;

[0018] After receiving the shooting signal, the image sensor starts to expose and sends an exposure signal, the timing control module sends a synchronization trigger signal to the laser illumination light source, and the gate control module sends a gate pulse signal;

[0019] The illumination laser pulse emitted by the laser illumination light source is expanded by the beam expansion unit, reflected by the second beam splitting unit and reflected by the first beam splitting unit, and then converged on the surface of the workpiece by the objective lens; the illumination laser signal reflected back by the workpiece enters the imaging lens after being reflected by the objective lens, the first beam splitting unit and transmitted by the second beam splitting unit;

[0020] After a set delay time, the gating module controls the shutter to open, so that the gating is synchronized with the illumination laser signal reflected back from the workpiece;

[0021] The image sensor superimposes the image information acquired in the multiple gated pulse signals within the exposure time to output a frame of image, and transmits it to the image processing unit;

[0022] The image processing unit displays the captured micropore image of the workpiece, observes the details at the bottom of the micropore, and determines whether the micropore is opened; if the micropore is opened, a dark spot area will appear on the image; if not, a bright spot area will appear on the image.

[0023] Preferably, the gating frequency of the gated pulse signal is the same as the frequency of the illumination laser pulse emitted by the laser illumination light source; the gating width of the gated pulse signal is close to the pulse width of the illumination laser pulse emitted by the laser illumination light source; and the set delay time is calculated by the following formula:

[0024] ,

[0025] in, is the set delay time; The distance that the illumination laser travels from the emission to the workpiece and from the reflection from the workpiece back to the gated camera; The speed of light.

[0026] Compared with the prior art, the technical solution of the embodiment of the present invention has beneficial effects.

[0027] For example, the online detection device and method for laser drilling provided by the present invention adopts a gated camera to select to open the gated camera at a set time, thereby physically avoiding the plasma signal; the shutter exposure time of the gated camera can be as short as nanoseconds, and combined with a synchronized illumination pulse signal, the door is opened to receive the signal within a set time range, and the shutter is quickly closed after receiving the signal; through this gating method, the signal arriving at a specific time is selectively received, thereby greatly suppressing the noise signal and improving the signal-to-noise ratio and micropore image quality.

[0028] For another example, a laser illumination assembly including a laser illumination light source, a beam expansion unit, a second beam splitting unit, a first beam splitting unit and an objective lens is set, so that the illumination laser pulse is reflected twice by the second beam splitting unit and the first beam splitting unit and reaches the surface of the workpiece processed by the processing laser pulse. The second beam splitting unit, the imaging lens and the gated camera are sequentially arranged to form a confocal optical path, and the illumination laser signal reflected by the workpiece is reflected by the first beam splitting unit and transmitted by the second beam splitting unit and then reaches the gated camera, thereby realizing real-time online acquisition of the processed microhole image.

[0029] For another example, a narrow-band filter is disposed between the second light splitting unit and the imaging lens to allow only light with the same wavelength as the illumination laser pulse to pass through, thereby shielding part of the background noise in the frequency domain. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a principle diagram of the online detection device of laser drilling of the present invention;

[0031] Figure 2 It is a schematic diagram of the structure of the gated camera of the present invention;

[0032] Figure 3 It is a working schematic diagram of the gate-controlled camera of the present invention;

[0033] Figure 4 This is a schematic diagram of the multi-pulse accumulation imaging principle of the present invention.

[0034] Description of reference numerals:

[0035] 100-laser processing assembly; 200-laser lighting assembly; 300-gated imaging assembly; 400-workpiece;

[0036] 210 - laser illumination light source; 220 - beam expansion unit; 230 - second light splitting unit; 240 - first light splitting unit; 250 - objective lens;

[0037] 310-imaging lens; 320-gated camera; 330-image processing unit; 340-filter;

[0038] 321 - imaging module; 322 - timing control module; 323 - gain module; 324 - gating module; 3211 - image sensor. DETAILED DESCRIPTION

[0039] In order to make the purpose, features and beneficial effects of the present invention more obvious and understandable, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. It is understood that the specific embodiments described below are only used to explain the present invention, rather than to limit the present invention. In addition, the same or similar reference numerals may be used in the figures to refer to the same or similar elements in different embodiments, and the description of the same or similar elements in different embodiments and the description of the prior art elements, features, effects, etc. may be omitted.

[0040] Reference Figures 1 to 4 , an embodiment of the present invention provides an online detection device and method for laser drilling.

[0041] Specifically, the laser drilling online detection device provided by the embodiment of the present invention includes:

[0042] The laser processing assembly 100 is used to emit processing laser pulses to process micro holes on the workpiece 400;

[0043] The laser illumination assembly 200 is used to emit illumination laser pulses and transmit the illumination laser pulses to the workpiece 400 to illuminate the microholes of the workpiece 400; the laser illumination assembly 200 includes a laser illumination light source 210, a beam expansion unit 220, a second light splitting unit 230, a first light splitting unit 240 and an objective lens 250;

[0044] The gated imaging component 300 selectively receives the illumination laser signal reflected from the workpiece 400 and obtains the image information of the micropores of the workpiece 400 according to the signal; the gated imaging component 300 includes an imaging lens 310, a gated camera 320 and an image processing unit 330;

[0045] The first beam splitter unit 240 is arranged in front of the laser processing component 100, and the objective lens 250 is arranged in front of the first beam splitter unit 240. The processing laser pulse emitted by the laser processing component 100 is transmitted from the first beam splitter unit 240, and the objective lens 250 converges the processing laser pulse transmitted from the first beam splitter unit 240 to the surface of the workpiece 400 for micro-hole processing; the illumination laser pulse emitted by the laser illumination light source 210 is expanded by the beam expansion unit 220, reflected by the second beam splitter unit 230 and the first beam splitter unit 240, and then converged by the objective lens 250 on the surface of the workpiece 400. The surface of the workpiece 400; the second beam splitting unit 230, the imaging lens 310 and the gated camera 320 are sequentially arranged to form a confocal optical path; the illumination laser signal reflected from the workpiece 400 passes through the objective lens 250, is reflected by the first beam splitting unit 240 and transmitted by the second beam splitting unit 230, and then enters the imaging lens 310, the gated camera 320 receives the reflected illumination laser signal, controls the shutter of the gated camera 320 to open at the set delay time, and transmits the image information to the image processing unit 330, and the image processing unit 330 displays the captured image of the workpiece micropores.

[0046] In some embodiments, the gated camera 320 includes an imaging module 321, a gating module 324, a gain module 323 and a timing control module 322; the gated camera 320 is connected to the laser illumination light source 210; the imaging module 321 obtains the image formed by focusing the illumination laser signal reflected from the workpiece 400; the gating module 324 controls the opening and closing of the shutter; the gain module 323 is used for gain amplification of the illumination laser signal reflected from the workpiece 400; the imaging module 321 includes an image sensor 3211, after receiving the shooting signal, the image sensor 3211 starts to expose and send an exposure signal, the timing control module 322 sends a synchronization trigger signal to the laser illumination light source 210 and the gated module 324 sends a gated pulse signal, after the set delay time, the gated module 324 controls the shutter to open, so that the shutter opening signal is synchronized with the illumination laser signal reflected from the workpiece.

[0047] In some embodiments, a filter 340 is arranged between the second spectroscopic unit 230 and the imaging lens 310. The filter 340 is a narrow-band filter. The bandwidth of the filter 340 is less than or equal to 5 nm. The filter 340 only allows light with the same wavelength as the illumination laser pulse to pass through, thereby shielding part of the background noise in the frequency domain.

[0048] In some embodiments, the first beam splitter unit 240 includes a beam splitter prism or a dichroic mirror; the processing laser emitted by the laser processing component 100 and the illumination laser emitted by the laser illumination light source 210 have different wavelengths, the processing laser is transmitted from the first beam splitter unit 240 to the workpiece 400, and the illumination laser is reflected from the first beam splitter unit 240 to the workpiece 400; the processing laser and the illumination laser emitted by the laser processing component 100 and the laser illumination light source 210 respectively arranged at different positions are synchronously irradiated to the same position of the workpiece 400, thereby realizing synchronous processing and detection.

[0049] In some embodiments, the beam expansion unit 220 is used to expand the diameter of the illumination laser pulse and reduce the divergence angle of the illumination laser pulse to form a uniform illumination laser pulse. The beam expansion unit 220 includes at least one lens or a reflector.

[0050] In some embodiments, the objective lens 250 is used to converge parallel processing laser pulses and illumination laser pulses onto the workpiece 400 , and the objective lens 250 includes at least one lens.

[0051] In some embodiments, the second beam splitter unit 230 is a beam splitter prism, which splits the incident light beam into two parts, one part is transmitted through the beam splitter prism, and the other part is reflected; part of the illumination laser pulse emitted by the laser illumination light source 210 is reflected to the first beam splitter unit 240 through the second beam splitter unit 230; part of the illumination laser signal reflected back from the workpiece 400 is transmitted through the second beam splitter unit 230 and enters the imaging lens 310; the ratio of the transmitted light beam to the reflected light beam is set by selecting the model of the beam splitter prism; a 50:50 beam splitter prism is usually selected, that is, half of the incident light beam is transmitted and half is reflected.

[0052] In some embodiments, the imaging lens 310 collects the laser illumination signal returned from the workpiece 400 and focuses it onto the photosensitive surface of the gate control camera 320. The imaging lens 310 is composed of a plurality of lenses, which are convex lenses, concave lenses or aspherical lenses.

[0053] The present invention also provides an online detection method for laser drilling, which uses the above-mentioned online detection device for laser drilling and includes the following steps:

[0054] The processing laser pulse emitted by the laser processing assembly 100 is transmitted through the first beam splitting unit 240 and converged on the surface of the workpiece 400 through the objective lens 250 to perform micro-hole processing;

[0055] After receiving the shooting signal, the image sensor 3211 starts to expose and sends an exposure signal, the timing control module 322 sends a synchronization trigger signal to the laser illumination light source 210, and the gate control module 324 sends a gate pulse signal;

[0056] The illumination laser pulse emitted by the laser illumination light source 210 is expanded by the beam expansion unit 220, reflected by the second beam splitting unit 230 and reflected by the first beam splitting unit 240, and then converged on the surface of the workpiece 400 by the objective lens 250; the illumination laser signal reflected back by the workpiece 400 enters the imaging lens 310 after being reflected by the objective lens 250, the first beam splitting unit 240 and transmitted by the second beam splitting unit 230;

[0057] After the set delay time, the gate control module 324 controls the shutter to open, so that the shutter opening signal is synchronized with the illumination laser signal reflected by the workpiece. The specific timing process is as follows: Figure 3 As shown;

[0058] The image sensor 3211 superimposes the image information acquired in the multiple gated pulse signals within the exposure time to output a frame of image, and transmits it to the image processing unit 330;

[0059] The image processing unit 330 displays the captured image of the micropores of the workpiece, observes the details of the bottom of the micropores, and determines whether the micropores are opened; if the micropores are opened, dark spots appear on the image; if not, bright spots appear on the image.

[0060] In some embodiments, the gated frequency and gated width of the gated pulse signal are the same as the frequency and pulse width of the illumination laser pulse emitted by the laser illumination light source 210; the set delay time is calculated by the following formula:

[0061] ,

[0062] in, is the set delay time; The distance that the illumination laser travels from being transmitted to the workpiece 400 and reflected from the workpiece 400 to reaching the gated camera 320; The speed of light.

[0063] In some embodiments, the gating frequency of the gated pulse signal and the frequency of the illumination laser pulse emitted by the laser illumination light source 210 are higher than the processing laser pulse frequency emitted by the laser processing assembly 100, so that in one emission cycle of the processing laser pulse, there are multiple gated pulse signals (Gate1, Gate2, Gate3, Gate4...Gate n), and multiple cumulative imaging shots are achieved in one emission cycle of the processing laser pulse; the specific timing process is as follows: Figure 4 As shown in the figure, the plasma radiation lasts for a long time, while in the case of gated control, the illumination pulse signal can be received only by opening the door for a short exposure time. In this short time, only a small amount of plasma signal is received, which suppresses the influence of plasma signal. Accumulating multiple pulses can significantly improve the signal-to-noise ratio.

[0064] In a specific implementation, the laser processing component 100 emits a processing laser to process a microhole on the workpiece 400. The diameter of the microhole is hundreds of microns, and the aspect ratio is greater than 10:1. The minimum gate width of the gate module 324 of the gate camera 320 is less than 3ns, the maximum gain of the gain module 323 is greater than 1000 times, and the jitter of the imaging module is less than 100ps. The laser processing component 100 emits processing laser pulses at a fixed frequency and converges on the surface of the workpiece 400 to process the microhole. After receiving the shooting signal, the image sensor 3211 starts to expose and send an exposure signal. The timing control module 322 simultaneously sends a synchronization trigger signal to the laser illumination light source 210 and a gated pulse signal to the gate module 324. The laser illumination light source 210 uses an 860nm pulse laser with a frequency of 1kHz and a pulse width of 10ns. It converges on the microhole through the objective lens 250 (focal length f=100mm). The microhole has a depth of 3mm and a diameter of 300um. The illumination laser signal returned by the workpiece 400 enters the gated imaging component. After the set delay time, the gate module 324 controls the shutter to open, accurately synchronizes the returned illumination laser signal with the shutter opening signal, so that the camera captures each illumination laser pulse signal. The gated camera uses an image-enhanced sCMOS (i.e., IsCMOS) camera with a gate frequency of 1kHz and a gate width of 10ns; the image sensor 3211 has an exposure time of 10ms and a frame rate of 98FPS.

[0065] like Figure 3 As shown, during the exposure time of a single frame image of the image sensor 3211, an illumination laser pulse train is emitted at time T0, which includes 8 laser pulses (Burst=8). After a delay of ΔT, the returned illumination laser signal reaches the gated camera 320, and the gated camera 320 opens the shutter 8 times in succession at the same frequency (corresponding to Figure 4 In the example, Gate1, Gate2, Gate3, ..., Gate n, n=8), the gate width is close to the pulse width, and 8 pulse signals are received respectively. The signals are superimposed on the image sensor 3211 and then a frame of image is output.

[0066] When processing microholes, plasma radiation fills the entire drilling process. If a non-gated camera is used for imaging, all signals reaching the camera will be received during the entire exposure time of a frame of image. The intensity of the accumulated plasma signal far exceeds the illumination laser signal, which results in a poor signal-to-noise ratio. However, after using a gated camera, the effective exposure time (i.e., the total shutter opening time, corresponding to 3211) is much shorter than the single exposure time of the image sensor. Figure 4In the example, the shutter time of the gate 1, gate 2, gate 3, gate n, n=8) is 10ns×8=80ns, and the shutter is closed for the rest of the time and does not receive signals. Compared with the millisecond exposure time of the non-gated camera, the gated camera can reduce the exposure time by about 6 orders of magnitude. In addition, the 860nm filter 340 filters out the plasma noise signals in other bands, and the noise suppression rate can reach 10 -2 Even higher. The ultra-short shutter combined with frequency domain filtering can significantly suppress background noise by about 8 orders of magnitude while fully receiving the illumination signal, thus improving the signal-to-noise ratio and imaging quality of the image.

[0067] The illumination laser signal returned from a micro-hole with a depth-to-diameter ratio of 10:1 is usually weak. The gated camera 320 used can provide high optical gain to greatly enhance the weak signal, thereby presenting a clear micro-hole image.

[0068] Although specific embodiments have been described above, these embodiments are not intended to limit the scope of the present disclosure, even when only a single embodiment is described with respect to specific features. The feature examples provided in the present disclosure are intended to be illustrative rather than limiting, unless otherwise stated. In specific implementations, the technical features of one or more dependent claims may be combined with the technical features of the independent claim, based on actual needs and where technically feasible, and may be derived from the technical features of the corresponding independent claim in any appropriate manner rather than simply through the specific combination listed in the claims.

[0069] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. An online detection device for laser drilling, characterized in that: include: A laser processing component for emitting processing laser pulses to process micro holes on a workpiece; A laser illumination assembly is used to emit illumination laser pulses and transmit the illumination laser pulses to the workpiece to illuminate the microholes of the workpiece; the laser illumination assembly includes a laser illumination light source, a beam expansion unit, a second light splitting unit, a first light splitting unit and an objective lens; A gated imaging component selectively receives the illumination laser signal reflected from the workpiece and obtains image information of the micropores of the workpiece according to the signal; the gated imaging component includes an imaging lens, a gated camera and an image processing unit; Wherein, the first spectroscopic unit is arranged in front of the laser processing component, the objective lens is arranged in front of the first spectroscopic unit, the processing laser pulse emitted by the laser processing component is transmitted from the first spectroscopic unit, and the objective lens converges the processing laser pulse transmitted from the first spectroscopic unit on the surface of the workpiece to perform micro-hole processing; the illumination laser pulse emitted by the laser illumination light source is expanded by the beam expansion unit, reflected by the second spectroscopic unit and the first spectroscopic unit, and then converged on the surface of the workpiece by the objective lens; the second spectroscopic unit, the imaging lens and the gated camera are sequentially arranged to form a confocal optical path; the illumination laser signal reflected from the workpiece passes through the objective lens, is reflected by the first spectroscopic unit and transmitted by the second spectroscopic unit, and then enters the imaging lens, the gated camera receives the reflected illumination laser signal, controls the shutter of the gated camera to open at the set delay time, and transmits the image information to the image processing unit, and the image processing unit displays the captured image of the micro-holes of the workpiece; The gated camera includes an imaging module, a gated module, a gain module and a timing control module; the gated camera is connected to the laser illumination light source; the imaging module obtains an image formed by focusing the illumination laser signal reflected from the workpiece; the gated module controls the opening and closing of the shutter; the gain module is used for gain amplification of the illumination laser signal reflected from the workpiece; the imaging module includes an image sensor, after receiving a shooting signal, the image sensor starts to expose and sends an exposure signal, the timing control module sends a synchronization trigger signal to the laser illumination light source and a gated pulse signal to the gated module, and after a set delay time, the gated module controls the shutter to open, so that the shutter opening signal is synchronized with the illumination laser signal reflected from the workpiece.

2. The online detection device for laser drilling according to claim 1, characterized in that: A filter is arranged between the second light splitting unit and the imaging lens. The filter is a narrow-band filter with a bandwidth of less than or equal to 5 nm. The filter only allows light with the same wavelength as the illumination laser pulse to pass through.

3. The online detection device for laser drilling according to claim 1, characterized in that: The first spectroscopic unit includes a spectroscopic prism or a dichroic mirror; the processing laser emitted by the laser processing component and the illumination laser emitted by the laser illumination light source have different wavelengths, the processing laser is transmitted from the first spectroscopic unit to the workpiece, and the illumination laser is reflected from the first spectroscopic unit to the workpiece.

4. The online detection device for laser drilling according to claim 1, characterized in that: The beam expansion unit is used to expand the diameter of the illumination laser pulse and reduce the divergence angle of the illumination laser pulse to form a uniform illumination laser pulse. The beam expansion unit includes at least one lens or a reflector.

5. The online detection device for laser drilling according to claim 1, characterized in that: The objective lens is used to converge parallel processing laser pulses and illumination laser pulses onto a workpiece, and the objective lens includes at least one lens.

6. The online detection device for laser drilling according to claim 1, characterized in that: The second beam splitter unit is a beam splitter prism, which splits the incident light beam into two parts, one part is transmitted through the beam splitter prism, and the other part is reflected; part of the illumination laser pulse emitted by the laser illumination light source is reflected to the first beam splitter unit through the second beam splitter unit; part of the illumination laser signal reflected back by the workpiece is transmitted through the second beam splitter unit and enters the imaging lens; the ratio of the transmitted light beam to the reflected light beam is set by selecting the model of the beam splitter prism.

7. An online detection method for laser drilling, characterized in that: The online detection device for laser drilling according to any one of claims 1 to 6 comprises the following steps: The processing laser pulse emitted by the laser processing component is transmitted from the first beam splitting unit and converged on the surface of the workpiece through the objective lens to perform micro-hole processing; After receiving the shooting signal, the image sensor starts to expose and sends an exposure signal, the timing control module sends a synchronization trigger signal to the laser illumination light source, and the gate control module sends a gate pulse signal; The illumination laser pulse emitted by the laser illumination light source is expanded by the beam expansion unit, reflected by the second beam splitting unit and reflected by the first beam splitting unit, and then converged on the surface of the workpiece by the objective lens; the illumination laser signal reflected back by the workpiece enters the imaging lens after being reflected by the objective lens, the first beam splitting unit and transmitted by the second beam splitting unit; After a set delay time, the gate control module controls the shutter to open, so that the shutter opening signal is synchronized with the illumination laser signal reflected back from the workpiece; The image sensor superimposes the image information acquired in the multiple gated pulse signals within the exposure time to output a frame of image, and transmits it to the image processing unit; The image processing unit displays the captured micropore image of the workpiece, observes the details at the bottom of the micropore, and determines whether the micropore is opened; if the micropore is opened, a dark spot area will appear on the image; If it is not opened, bright spots will appear on the image.

8. The online detection method of laser drilling according to claim 7, characterized in that: The gated frequency of the gated pulse signal is the same as the frequency of the illumination laser pulse emitted by the laser illumination light source; the gated width of the gated pulse signal is close to the pulse width of the illumination laser pulse emitted by the laser illumination light source; the set delay time is calculated by the following formula: ， in, is the set delay time; The distance that the illumination laser travels from the emission to the workpiece and from the reflection from the workpiece back to the gated camera; The speed of light.

Images