CN209841188U - Laser focus searching device - Google Patents
Laser focus searching device Download PDFInfo
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- CN209841188U CN209841188U CN201920660917.2U CN201920660917U CN209841188U CN 209841188 U CN209841188 U CN 209841188U CN 201920660917 U CN201920660917 U CN 201920660917U CN 209841188 U CN209841188 U CN 209841188U
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Abstract
The utility model discloses a laser focus searching device, including the human-computer interaction interface that connects gradually, microcontroller, step motor driver connects electric lift platform, connect electric rotating platform on the electric lift platform, connect the metal target on the electric rotating platform, set up photoelectric sensor on the metal target, photoelectric sensor connects the ADC module, electric lift platform bottom perpendicular electric lift platform bottom is upwards connected fixed stay post, connect the grating chi displacement sensor who measures electric lift platform removal on the fixed stay post, grating chi displacement sensor, ADC module all connect microcontroller, connect the laser fixing frame on the fixed stay post; the ultraviolet photoelectric sensor, the signal amplifier, the ADC module, the microcontroller, the electric lifting table, the electric rotating table and the grating ruler displacement sensor form a closed-loop control system, so that accurate measurement of the focal position is ensured; still have simple structure, with low costs, advantage that degree of automation is high.
Description
Technical Field
The utility model belongs to the technical field of laser parameter measuring equipment, concretely relates to device is look for to laser focus.
Background
In recent years, science and technology are rapidly developed, and laser engraving and cutting technologies are widely applied to industrial processing due to the characteristics of small laser spot, high energy density and high cutting speed. With the continuous development of the technology, the requirement on the precision of material processing in the industry is higher and higher, and the precision of laser processing has a close relationship with the focal position of laser, so that the accurate finding of the focal position of the laser is a key technology for improving the precision of material processing.
In practical engineering, the focal position of the laser is measured, and the position with the smallest spot cross-sectional area in the beam propagation direction is found. For a nearly circular spot, the spot radius can be converted to reflect its size. Currently, in the field of laser processing, there are three main methods for measuring the position of a laser focus, which are specifically as follows:
1.a conventional measurement method. Such as a cauterization method, a sensitization method, etc. The burning method determines the focus position by observing the position with the minimum laser burning trace, and has the problems of inconvenient manual operation, low measurement precision and the like; the sensitization method is to use the sensitization material to record the spot size of different positions, and determine the focus position according to the position with the minimum spot area, and has the problems that the focus position of the high-power laser cannot be measured, the measurement precision is low, and the like. The applicability and the accuracy of the measuring method are difficult to grasp, the requirement on an operator is high, and the measuring error is large.
2. Beam analyzers (Chengni, Zhenggajin, Weinwei, et al.) based on Charge Coupled Devices (CCD) for measuring laser beam quality M based on CCD2[J]The method comprises the steps of obtaining image display of laser spots by a CCD (charge coupled device) of an electronic imaging device, and analyzing laser by a computer to obtain beam shape parameters, wherein the image display is carried out on the laser spots by the CCD of the electronic imaging device, and the beam shape parameters are obtained by the computer. The main bottleneck is the difficulty in measuring high power laser beams. The company Cinogy, germany, introduced a beam analyzer specifically for measuring high-power laser light. The beam analyzer is also a CCD-based measurement method, but at a higher cost.
3. The laser focus is directly measured by using a metal probe (Liqiang, Jinjiang Hua, Wang Chiongong, etc.. high-power laser beam spot diagnostic instrument and the test principle thereof [ J ] laser technology, 1999,23(6): 375-: the method comprises the steps of sampling by utilizing a high-speed rotating probe, sending sampled light to a detector through an internal light path, determining the energy of each sampling, recording the angle position and the plane position of the probe, synthesizing corresponding data through a computer to obtain light intensity distribution information of sections corresponding to different positions, and further determining the focus information of the whole light beam. This method has extremely high requirements on the probe selected to be able to withstand the high power density laser, and has high requirements on the movement control and time synchronization measurement of the probe, resulting in an excessively high cost of the measurement method.
The three methods can measure the position of the laser focus, but have the problems of incapability of measuring the position of the high-power laser focus, low measurement precision, high cost and inconvenient manual operation.
SUMMERY OF THE UTILITY MODEL
The utility model aims at providing a device is look for to laser focus has solved the unable accurate problem of measuring high-power laser focus of current equipment.
The utility model provides a technical scheme who adopts is, a laser focus seeks device, human-computer interaction interface including connecting gradually, microcontroller, the step motor driver, the electric lift platform is connected to the step motor driver, connect electric rotary table on the electric lift platform, connect the metal target on the electric rotary table, set up photoelectric sensor on the metal target, photoelectric sensor connects the ADC module that can gather the signal of telecommunication, the perpendicular electric lift platform bottom of electric lift platform bottom upwards connects the fixed stay post, connect the grating chi displacement sensor who measures the electric lift platform and remove on the fixed stay post, grating chi displacement sensor, microcontroller is all connected to the ADC module, connect the laser instrument mount on the fixed stay post.
The utility model discloses a characteristics still lie in:
and a signal amplifier is connected between the photoelectric sensor and the ADC module.
The electric lifting platform is also connected with a telescopic sensor fixing device which is fixedly connected with a photoelectric sensor.
The electric lifting platform is internally provided with a stepping motor for controlling lifting.
The electric rotating platform is internally provided with stepping motors for controlling rotation.
The surface of the metal target material is smooth and flat.
The utility model has the advantages that:
the utility model relates to a laser focus searching device, which utilizes an ultraviolet photoelectric sensor, a signal amplifier, an ADC module, a microcontroller, an electric lifting platform, an electric rotating platform and a grating ruler displacement sensor to form a closed-loop control system, thereby ensuring the accurate measurement of the focus position; still have simple structure, with low costs, advantage that degree of automation is high.
Drawings
Fig. 1 is a schematic structural view of a laser focus searching device of the present invention;
FIG. 2 is a schematic diagram of the circuit connection relationship of the laser focus searching device of the present invention;
fig. 3 is a waveform of an output signal of an ADC module after filtering according to an embodiment of the present invention;
fig. 4 is a diagram illustrating the focus positioning effect in an embodiment of the laser focus searching device of the present invention.
In the figure, 1, a human-computer interaction interface, 2, a microcontroller, 3, a stepping motor driver, 4, a sensor fixing device, 5, an electric lifting table, 6, an electric rotating table, 7, a metal target, 8, a signal amplifier, 9, a grating ruler displacement sensor, 10, a photoelectric sensor, 11, an ADC module, 12, a fixed support column and 13, a laser fixing frame.
Detailed Description
The present invention will be described in detail with reference to the accompanying drawings and specific embodiments.
The utility model provides a laser focus searching device, as shown in figure 1, comprising a human-computer interaction interface 1, a microcontroller 2 and a stepping motor driver 3 which are connected in sequence, wherein the stepping motor driver 3 is connected with an electric lifting platform 5, the electric lifting platform 5 is connected with an electric rotating platform 6, the electric rotating platform 6 is connected with a metal target 7, the metal target 7 is provided with a photoelectric sensor 10, the photoelectric sensor 10 is connected with an ADC module 11 which can collect electric signals, the bottom end of the electric lifting platform 5 is vertical to the bottom end of the electric lifting platform 5 and is upwards connected with a fixed supporting column 12, the fixed supporting column 12 is connected with a grating ruler displacement sensor 9 which measures the movement of the electric lifting platform 5, the grating ruler displacement sensor 9 and the ADC module 11 are both connected with the microcontroller 2, the microcontroller 2 forms a closed-loop control system with the electric lifting platform 5 and the stepping motor driver 3 according to displacement feedback signals collected, the fixed support column 12 is connected with a laser fixing frame 13.
As shown in fig. 2, the photoelectric sensor 10 collects the ultraviolet radiation signal 12 and converts the ultraviolet radiation signal into a corresponding electrical signal, and a signal amplifier 8 is connected between the photoelectric sensor 10 and the ADC module 11, and is capable of amplifying the electrical signal in the photoelectric sensor 10, and finally collected by the ADC module 11, and converts the analog signal into a digital signal and transmits the digital signal to the microcontroller 2.
The electric lifting platform 5 is also connected with a telescopic sensor fixing device 4 which can be stretched back and forth, the sensor fixing device 4 is fixedly connected with a photoelectric sensor 10, the photoelectric sensor 10 can be moved to any position above the surface of the metal target 7, and the photoelectric sensor is manually adjusted and fixed at a proper position before the fixed focus measurement is started, so that the sensor fixing device 4 is ensured not to shield a laser path and absorb ultraviolet radiation of a large proportion.
The electric lifting platform 5 is internally provided with a stepping motor for controlling lifting.
The electric rotating platform 6 contains stepping motors for controlling rotation.
The surface of the metal target 7 is smooth and flat and is fixed on the electric rotating table 6; the electric rotating table 6 is driven by a step motor driver 3 controlled by the microcontroller 2, and the position of the laser irradiated on the metal target 7 is updated by rotating a certain angle, so that the surface characteristics of the metal target 7 can be ensured to be consistent during each laser 14 ablation; the electric rotating platform 6 is fixed on the table top of the electric lifting platform 5, and the electric lifting platform 5 is driven by the step motor driver 3 controlled by the microcontroller 2 and can move up and down in the z direction.
The man-machine interaction interface 1 comprises parameter setting of the system, starting of keys, display of focal position information and the like.
The utility model relates to a laser focus seeks device's theory of operation does:
for industrial laser, the energy density of light spots at different positions is different along the propagation direction of a light beam, wherein the energy density of a focus position is the largest, when the metal target 7 is ablated by laser, plasma can be induced to generate on the surface of metal, the plasma sends out an ultraviolet radiation signal, and the larger the energy density of the light spots is, the stronger the generated ultraviolet radiation signal is. At different positions in the propagation direction, the ultraviolet radiation signals generated by laser ablation of the same metal target 7 are different, and by using the photoelectric sensor 10 which is sensitive to ultraviolet wave bands and insensitive to visible light, the size of the energy density of the light spot can be reflected by collecting the ultraviolet radiation signals at different positions. Therefore, as long as the position where the ultraviolet radiation signal is maximum is found, the focal position of the laser can be determined.
The utility model relates to a laser focus seeks device's application method does:
s1: adjusting the electric lifting platform 5 to move downwards through the human-computer interaction interface 1 until the position is obviously lower than the focus position, and adjusting the position of the photoelectric sensor 10 to the laser irradiation position;
s2: fixing a laser on a laser fixing frame 13, starting the laser to emit continuous laser, setting an electric lifting platform 5 to move upwards through a human-computer interaction interface 1, continuously ablating a metal target 7 by the laser to generate an ultraviolet radiation signal (a light radiation signal containing an ultraviolet frequency band), acquiring the ultraviolet radiation signal by a photoelectric sensor 10 and converting the ultraviolet radiation signal into an electric signal, converting the electric signal into a digital signal through an ADC (analog-to-digital converter) module 11, transmitting the digital signal to a microcontroller 2, receiving the digital signal by the microcontroller 2, comparing the digital signal with the digital signal acquired at the previous time, when the digital signal is judged to enter a descending trend, continuing to move the electric lifting platform 5 upwards by a distance L, stopping moving the electric lifting platform 5, positioning the metal target 7 above a laser focus, ending a coarse adjustment stage, stopping emitting the laser by a laser source, wherein the distance of the upward movement is reasonably set according to actual, can be set to 0-1 mm.
S3: setting the electric lifting platform 5 to move downwards with the step length not less than 500 mu m through the human-computer interaction interface 1, setting the rotation angle theta and the rotation time interval delta t of the electric rotating platform 6, and starting the laser source 13;
s4: the microcontroller 2 controls the rotation angle theta of the electric rotating table 6 at intervals of time delta t, the laser ablates the metal target 7 to generate an ultraviolet radiation signal, the photoelectric sensor 10 collects the ultraviolet radiation signal 12 and converts the ultraviolet radiation signal into an electric signal, the electric signal is converted into a group of digital signals through the ADC module 11 and transmits the digital signals to the microcontroller 2, the microcontroller 2 adopts a sliding average filtering algorithm to filter the group of digital signals to obtain a group of signal values, the maximum value in the group of signal values is selected, the average value of the former n signal values is subtracted from the maximum value to obtain a measured value corresponding to a certain step length, and the measured value is stored in the microcontroller 2;
meanwhile, when the electric lifting platform 5 is moved according to the set step length, the grating ruler displacement sensor 9 measures the displacement information of the electric lifting platform 5, and feeds the displacement information back to the microcontroller 2 through the displacement feedback signal of the grating ruler, and the microcontroller 2 calibrates the moving step length according to the displacement information;
s5: controlling the electric lifting platform 5 to move downwards by a step length m through the microcontroller 2, feeding back position information of the electric lifting platform 5 to the microcontroller 2 by the grating ruler displacement sensor 9, and repeating the step 4 until the moving distance of the electric lifting platform 5 is twice L;
s6: and (3) according to the measured value stored by the microcontroller 2, making an ultraviolet light signal intensity curve in the Z coordinate direction, carrying out interpolation processing by adopting a cubic spline method, and finding out the maximum value of the measured value in the interpolation curve through an extreme value search algorithm, wherein the position on the Z coordinate corresponding to the maximum value is the focal position of the laser beam.
The parameters can be set and then stored in the measurement system software as default parameters, and then the laser focus is searched again to realize the whole-process automation.
Examples
GSS-Fib fiber laser marking machine is selected as an experimental object, the laser wavelength is 1064nm, and the beam quality M2<2, the minimum line width is 0.01mm, the average power is set to be 5W, and the repeated working frequency is 20 kHz; the photoelectric sensor selects a GaN Schottky diode (type GUVA-S12SD), and the signal amplifier selects a semiconductor chip LMV 358; the metal target material is a 304 stainless steel plate with a smooth surface, and the thickness of the steel plate is 8 mm; the microcontroller selects an STM32F407ZGT6, and the ADC module selects an ADC module in an STM32F407ZGT 6; the step motor driver selects Rayleigh DM 432C; the displacement sensor of the grating ruler is SINOKA 300.
At first start the utility model discloses the device, move down at man-machine interface control electric lift platform, adjust the plane to lower position, then open laser marking machine system, set up laser marking machine parameter on its operation interface of dispatching from the factory, make marking machine launch laser pulse ablation metal target always, produce lasting ultraviolet radiation signal, microcontroller control electric lift platform rebound, it is 1.5cm/s to set up coarse adjusting moving speed this moment, photoelectric sensor gathers this signal and converts the signal of telecommunication into, the signal of telecommunication passes through ADC module transmission to microcontroller (it is once every 1ms to set up this digital analog conversion sampling), microcontroller receives the signal of telecommunication and judges the change of electric signal amplitude, get every 10 sampling calculation average values, continue rebound 0.5mm after the signal of telecommunication average value begins to diminish again.
Then, the duration of each laser pulse sequence output by the laser marking machine is set to be 21ms, the interval time is set to be 3s, the moving step length m of the electric translation stage is set to be 100 mu m, the rotation angle theta of the electric rotation stage is set to be 10 degrees, and the rotation interval time delta t is set to be 3 s. So that the laser marking machine can be ablated again at the position where the metal target material has not been ablated. Operating in step 4, the typical signal waveform (after filtering) collected by the ADC module is as shown in fig. 3, where n is 30, and the measured value is stored in the microcontroller.
Finally, after step 5 is executed, ultraviolet radiation signals of different positions in the z direction are obtained. And (5) analyzing the collected data by the microcontroller according to the step 6, carrying out cubic spline interpolation processing, and finally finding out that the maximum value of the signal in the interpolation curve is 1574mV and the position corresponding to the maximum value of the signal is 150.99mm by an extremum searching algorithm. The interpolated curve of the signal value of the photosensor as a function of the measurement position is shown in fig. 4.
In order to prove this the utility model relates to a laser focus seeks device is accurate effectual, places every ablation pit diameter size that this metal target material measured pulse power laser ablation left under optical microscope, and statistics ablation pit average diameter is along with the change curve of z direction measuring position, sees figure 4. As is known in the art of conventional laser marking machines, the closer the metal target is to the laser focal point, the smaller the average diameter of the ablation pits. The minimum ablation pit diameter position at z 151.00mm was substantially consistent with the present system focus measurement (at z 150.99 mm), indicating that the results of the present laser focus position measurement scheme are reliable.
The utility model relates to a laser focus searching device, which utilizes an ultraviolet photoelectric sensor, a signal amplifier, an ADC module, a microcontroller, an electric lifting platform, an electric rotating platform and a grating ruler displacement sensor to form a closed-loop control system, thereby ensuring the accurate measurement of the focus position; still have simple structure, with low costs, advantage that degree of automation is high.
Claims (6)
1. The utility model provides a device is look for to laser focus, its characterized in that, including human-computer interaction interface (1), microcontroller (2), step motor driver (3) that connect gradually, electric lift platform (5) are connected in step motor driver (3), connect electric rotating platform (6) on electric lift platform (5), connect metal target (7) on electric rotating platform (6), set up photoelectric sensor (10) on metal target (7), ADC module (11) that can gather the signal of telecommunication are connected in photoelectric sensor (10), fixed support post (12) are upwards connected to electric lift platform (5) bottom perpendicular electric lift platform (5) bottom, connect grating chi displacement sensor (9) of measuring electric lift platform (5) removal on fixed support post (12), grating chi displacement sensor (9), The ADC modules (11) are connected with the microcontroller (2), and the fixed support columns (12) are connected with the laser fixing frames (13).
2. The laser focus searching device according to claim 1, wherein a signal amplifier (8) is further connected between the photoelectric sensor (10) and the ADC module (11).
3. The laser focus searching device according to claim 1, wherein a telescopic sensor fixing device (4) is further connected to the electric lifting table (5), and the sensor fixing device (4) is fixedly connected to the photoelectric sensor (10).
4. The laser focus searching device according to claim 1, wherein the electric lifting platform (5) contains a stepping motor for controlling lifting.
5. The apparatus according to claim 1, wherein the electric rotary table (6) contains a stepping motor for controlling rotation.
6. The laser focus searching apparatus according to claim 1, wherein the surface of the metal target (7) is smooth and flat.
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| CN201920660917.2U CN209841188U (en) | 2019-05-09 | 2019-05-09 | Laser focus searching device |
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| CN201920660917.2U CN209841188U (en) | 2019-05-09 | 2019-05-09 | Laser focus searching device |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115488494A (en) * | 2021-06-18 | 2022-12-20 | 中国科学院上海光学精密机械研究所 | Method for confirming focus of ultrafast laser micro-nano processing platform |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115488494A (en) * | 2021-06-18 | 2022-12-20 | 中国科学院上海光学精密机械研究所 | Method for confirming focus of ultrafast laser micro-nano processing platform |
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Granted publication date: 20191224 Termination date: 20210509 |