KR20230006388A - Laser control apparatus and laser pulse extraction method - Google Patents

Abstract

The present invention relates to a laser control apparatus capable of enhancing energy utilization efficiency of laser pulses. A laser oscillator outputs a pulse laser beam. The pulse laser beam enters a cutting optical system. The cutting optical system starts to cut a portion of the laser pulse of the pulse laser beam at the time of passing a certain operational delay time after a cutting command is input. The laser control apparatus outputs the cutting command to the cutting optical system at a point in time prior to the rising point of the laser pulse, and also outputs the cutting command such that the time of passing the operational delay time from the point when the cutting command was output falls after the rising point of the laser pulse.

Description

Laser control device and laser pulse cutting method {LASER CONTROL APPARATUS AND LASER PULSE EXTRACTION METHOD}

This application claims priority based on Japanese Patent Application No. 2021-110774 filed on July 2, 2021. The entire content of that application is incorporated herein by reference.

The present invention relates to a laser control device and a laser pulse cutting method.

BACKGROUND ART A laser processing device that performs punching processing on a printed board or the like with a laser beam is known (see Patent Document 1). The laser processing device disclosed in Patent Literature 1 includes a laser oscillator that outputs a pulse laser beam, and an acousto-optical modulator that cuts out a part of the laser pulse. After the rise (or generation) of the laser pulse, by giving a cutting command to the acousto-optic modulator, a portion is cut from the laser pulse. The cut laser pulse is incident on the object to be processed, and the remaining laser pulse is input to the beam damper.

Patent Document 1: Japanese Unexamined Patent Publication No. 2017-159317

In a cutting optical system such as an acousto-optical modulator, an operation delay occurs after a cutting command is input until the laser pulse is actually cut. Therefore, the energy of the laser pulse in the period from the rise of the laser pulse to the input of the cutting command and the period from the input of the cutting command to the actual cutting is unnecessary. In other words, the utilization efficiency of laser pulse energy is lowered.

An object of the present invention is to provide a laser control device and a laser pulse cutting method capable of increasing the energy utilization efficiency of a laser pulse.

According to one aspect of the present invention,

A laser oscillator for outputting a pulsed laser beam;

A laser control device for controlling a cutting optical system having a characteristic of starting to cut a part of the laser pulse of the pulsed laser beam when a predetermined operation delay time elapses after the pulsed laser beam is incident and a cutting command is input. as,

The cutting command is output to the cutting optical system at a point in time prior to the rising (or generating) point of the laser pulse, and a point in time when the operation delay time has elapsed from the point of outputting the cutting command is A laser control device for outputting the cutting command to be later than the rising point is provided.

According to another aspect of the present invention,

A laser pulse cutting method in which a laser pulse is output from a laser oscillator and entered into a cutting optical system, and a part of the laser pulse is cut out,

The cutting optical system has a characteristic of starting cutting of a part of the laser pulse at a time when a predetermined operation delay time has elapsed after a cutting command is input,

At a time point prior to the rising point of the laser pulse, the cutting command is output to the cutting optical system, and a time point that has elapsed by the operation delay time from the time point of outputting the cutting command is after the rising point of the laser pulse. As much as possible, a laser pulse cutting method for outputting the cutting command is provided.

When the cutting command is output under the above conditions, the time from the rise of the laser pulse to the start of cutting is shorter than the operation delay time. For this reason, the energy utilization efficiency of the laser pulse can be increased.

1 is a schematic diagram of a laser processing machine equipped with a laser control device according to an embodiment.
Fig. 2 is a diagram showing an example of relationship information stored in a storage unit.
3 is a graph showing another example of relationship information stored in a storage unit.
4A and 4B of FIG. 4 are timing charts of the oscillation command trg, the laser pulse LP0, the cutting command chp, and the laser pulse LP1 when the laser control device according to the present embodiment and comparative example operates, respectively.
Fig. 5 is a flowchart showing the laser pulse cutting procedure executed by the laser control device according to the present embodiment.
Fig. 6 is a flowchart showing a procedure for determining the pulse output delay time td.
7 is a schematic diagram of a laser processing machine equipped with a laser control device according to another embodiment.
Fig. 8 is a timing chart of the oscillation command trg, the laser pulse LP0, the path selection command sel, the cutting command chp, and the laser pulses LP1 and LP2 when the laser control device according to another embodiment is operated.

Referring to Figures 1 to 6, a laser control device and a laser pulse cutting method according to an embodiment will be described.

1 is a schematic diagram of a laser processing machine equipped with a laser control device 40 according to the present embodiment. This laser processing machine is used, for example, for punching of printed circuit boards.

The laser oscillator 10 receives the oscillation command trg from the laser control device 40 and outputs a pulsed laser beam. As the laser oscillator 10, a gas laser oscillator such as a carbon dioxide gas laser oscillator is used, for example. The pulsed laser beam output from the laser oscillator 10 is split into two paths in the beam splitter 11 . As the beam splitter 11, a partially reflecting mirror is used, for example.

One of the two pulsed laser beams diverged from the beam splitter 11 enters the cutting optical system 14 via the irradiation optical system 12 and the aperture 13, and the other enters the photodetector 20. . The irradiation optical system 12 changes at least one of the divergence angle and the beam diameter of the pulsed laser beam. As the irradiation optical system 12, a beam expander is used, for example. The aperture 13 shapes the beam cross section of the pulsed laser beam.

The photodetector 20 outputs a detection signal det during the period in which the laser pulse is incident. As the photodetector 20, a photovoltaic element capable of high-speed response is used, for example. The detection signal det output from the photodetector 20 is input to the laser control device 40 .

The cutting optical system 14 cuts a part on the time axis from the incident laser pulse LP0 based on the cutting command chp input from the laser controller 40 and generates the laser pulse LP1 used for processing. A certain operation delay occurs from the input of the cutting command chp until the laser pulse LP1 is cut. The time from the input of the cutting command chp until the laser pulse LP1 is cut is referred to as an operation delay time tdo. Of the laser pulse LP0, parts other than the laser pulse LP1 are incident on the beam damper 15. The laser pulse LP1 cut from the laser pulse LP0 propagates along the machining path. As the cutting optical system 14, an acousto-optical modulator (AOM) is used, for example.

The laser pulse LP1 cut by the cutting optical system 14 is incident on the object to be processed 60 via the reversing mirror 16, the scanning optical system 17, and the lens 19. The scanning optical system 17 changes the traveling direction of the pulsed laser beam to a two-dimensional direction based on the control signal sig1 from the laser control device 40. As the scanning optical system 17, for example, a galvano scanner including a pair of movable mirrors 18X and 18Y is used. The lens 19 condenses the pulsed laser beam whose traveling direction is changed by the scanning optical system 17 onto the surface of the object 60 . As the lens 19, an fθ lens is used, for example. By operating the scanning optical system 17, a pulsed laser beam can be incident at an arbitrary position within a part of the surface of the object 60 (scan area).

The object to be processed 60 is, for example, a printed circuit board, and is supported horizontally on the stage 30 . Based on the control signal sig2 from the laser control device 40, the moving mechanism 31 moves the stage 30 in two directions that are parallel to the horizontal plane and orthogonal to each other. By moving the stage 30, an arbitrary area on the surface of the object 60 can be arranged within a scan area scannable by the scanning optical system 17.

The laser control device 40 controls the laser oscillator 10, the cutting optical system 14, the scanning optical system 17, and the moving mechanism 31. The function to control them is realized by a combination of software and hardware. The laser control device 40 includes a storage unit 41 for storing programs and various data for realizing these functions. Hereinafter, the function of the laser control device 40 will be briefly described. However, detailed functions of the laser control device 40 will be described later with reference to the timing chart of 4A in FIG. 4 and the flow charts in FIGS. 5 and 6.

Various parameters defining laser irradiation conditions are input to the laser control device 40 from the input device 50 . Parameters defining the laser irradiation conditions include the pulse repetition frequency f of the pulsed laser beam output from the laser oscillator 10, the pulse width (hereinafter referred to as the original pulse width pw0), and the laser pulse LP1 cut from the laser pulse LP0. including the pulse width of As the input device 50, for example, a keyboard, a touch panel, a pointing device, a communication device, a removable media reader, and the like are used.

The laser control device 40 receives the detection signal det from the photodetector 20 and detects the rise and fall of the laser pulse. An oscillation command trg is output to the laser oscillator 10 based on the information defining the pulse repetition frequency f and the original pulse width pw0. For example, the rise and fall of the oscillation command trg correspond to the oscillation start and oscillation stop commands, respectively, and the time from the rise to the fall corresponds to the original pulse width pw0. The frequency at which the oscillation command trg is output corresponds to the pulse repetition frequency f.

In addition, the delay time from the time of outputting the oscillation command trg to the time of detecting the rise of the laser pulse is measured. This delay time is referred to as "pulse output delay time td". The laser control device 40 further stores, in the storage unit 41, relational information associating the pulse repetition frequency f and the original pulse width pw0 with the pulse output delay time td.

2 is a chart showing an example of relational information stored in the storage unit 41. As shown in FIG. A pulse output delay time td is associated with each combination of pulse repetition frequency f and original pulse width pw0. For example, when the pulse repetition frequency f=f ₁ and the original pulse width pw0=pw ₁ , the pulse output delay time td=td ₁₁ .

3 is a graph showing another example of the relationship information stored in the storage unit 41 . The horizontal axis represents the pulse repetition frequency f, and the vertical axis represents the pulse output delay time td. The curve in the graph shows the relationship between pulse repetition frequency f and pulse output delay time td when the original pulse width pw0 is constant. The pulse output delay time td is defined as a function of pulse repetition frequency f under the condition that the original pulse width pw0 is constant. The definition expression of this function is stored in the storage unit 41 .

In the example shown in Fig. 3, when the original pulse width pw0 is constant, the pulse output delay time td becomes shorter as the pulse repetition frequency f increases. Also, when the pulse repetition frequency f is constant, the pulse output delay time td becomes shorter as the original pulse width pw0 increases.

The laser control device 40 (FIG. 1) outputs the cutting command chp after a certain time elapses from the time point at which the start command trg is output. The time from when the starting command trg is output to when the cutting command chp is output is referred to as "cutting command delay time tdc". The laser control device 40 calculates the cutting command delay time tdc based on the pulse output delay time td and the like.

The laser control device 40 further outputs a control signal sig1 to the scanning optical system 17 to position the incident position of the pulsed laser beam. In addition, the control signal sig2 is output to the moving mechanism 31 to move the object 60.

4A of FIG. 4 is a timing chart of the oscillation command trg, the laser pulse LP0, the cutting command chp, and the laser pulse LP1. At time t0, the laser controller 40 outputs an oscillation command trg. For example, the rise of the oscillation command trg corresponds to a command to start oscillation, and the fall corresponds to a command to end oscillation. The elapsed time from the rising to the falling of the start command trg corresponds to the original pulse width pw0.

The laser oscillator 10 outputs the laser pulse LP0 (time t2) after a certain period of time elapses from the rise of the oscillation command trg (time t0). The elapsed time from the rise of the oscillation command trg to the rise of the laser pulse LP0 corresponds to the pulse output delay time td (Figs. 2 and 3). When the oscillation command trg falls (time t6), the intensity of the laser pulse LP0 starts to decrease, and then the laser pulse LP0 completely falls (time t7).

The laser control device 40 outputs the cutting command chp at a time point (time t1) elapsed by the cutting command delay time tdc from the rising point of the start command trg (time t0). The rise of the cutting command chp corresponds to the command to start cutting, and the fall (time t4) corresponds to the command to end cutting. The elapsed time from the rise of the cutting command chp to the fall is assumed to be the cutting pulse width pw1.

Due to the operation delay of the cutting optical system 14 (FIG. 1), cutting from the laser pulse LP0 is started at the time when the operation delay time tdo elapses (time t3) from the rise of the cutting command chp (time t1), and the laser Pulse LP1 rises. Similarly, at a time point (time t5) that has elapsed by the operation delay time tdo from the fall of the cutting command chp (time t4), the cutting from the laser pulse LP0 ends, and the laser pulse LP1 falls.

Fig. 5 is a flowchart showing the laser pulse cutting procedure executed by the laser control device according to the present embodiment.

First, the repetition frequency f and the original pulse width pw0 (4A in FIG. 4) of the pulses of the pulsed laser beam output from the laser oscillator 10 by the laser control device 40, and the relationship stored in the storage unit 41 Based on the information (FIGS. 2 and 3), the pulse output delay time td (4A in FIG. 4) is calculated (step SA1). Information specifying the pulse repetition frequency f and the original pulse width pw0 is previously input to the laser control device 40 from the input device 50 (FIG. 1).

The laser control device 40 outputs the cutting command chp from the output time point (time t0) of the oscillation command trg based on the pulse output delay time td and the operation delay time tdo of the cutting optical system 14 calculated in step SA1. The cutting command delay time tdc (4A in Fig. 4) up to the point in time (time t1) is calculated (step SA2). For example, the cutting command delay time tdc is longer than the value obtained by subtracting the operation delay time tdo from the pulse output delay time td (td-tdo <tdc), and is shorter than the pulse output delay time td (tdc <td), Determines the cutting command delay time tdc.

After that, or in parallel, the control signal sig1 is output to the scanning optical system 17 so that the laser pulse is incident on the target position of the object 60, and the control signal sig2 is output to the moving mechanism 31 (step SA3).

The laser control device 40 outputs an oscillation command trg to the laser oscillator 10 (step SA4). Then, it waits until the cutting command delay time tdc elapses (Step SA5). When the cutting command delay time tdc elapses, the laser control device 40 determines whether or not the positioning of the incident position of the laser pulse by the scanning optical system 18 and the moving mechanism 31 has been completed (Step SA6).

If the positioning is not completed, the start command trg is stopped after a time corresponding to the original pulse width pw0 has elapsed from the time of outputting the start command trg (step SA13).

When the positioning is completed, the laser control device 40 outputs a cutting command chp to the cutting optical system 14 (step SA7). Then, it waits until the time corresponding to the cutting pulse width pw1 (4A in Fig. 4) elapses (Step SA8). After waiting, the cutting command chp is stopped (Step SA9). Specifically, the cutting command chp is lowered. After that, the start command trg is stopped (Step SA10). More specifically, the oscillation command trg is lowered when the original pulse width pw0 elapses from the output of the oscillation command trg.

It is determined whether or not machining of all processing points of the object 60 has been completed (Step SA11). When processing of all the processing points is completed, the process ends. When unprocessed points remain, the laser control device 40 controls the scanning optical system 18 and the moving mechanism 31 (step SA12). However, when it is not necessary to move the object 60, it is not necessary to drive the moving mechanism 31.

After step SA12 or step SA13, the process waits for a time corresponding to the pulse repetition frequency f (step SA13). The starting point of this waiting time is the point at which the start command trg is output in Step SA4. After waiting for the time corresponding to the pulse repetition frequency f, the oscillation command trg is output (Step SA4), and the procedures from Step SA5 are repeated. As a result, the waveforms of the oscillation command trg, the laser pulses LP0 and LP1, and the cutting command chp shown in 4A of FIG. 4 are repeated at a constant frequency. However, the cutting command chp is not output in a cycle in which positioning is not completed.

Next, with reference to Fig. 6, a method of determining the pulse output delay time td (Figs. 2 and 3) stored in the storage unit 41 (Fig. 1) will be described. Fig. 6 is a flowchart showing a procedure for determining the pulse output delay time td.

First, the values of pulse repetition frequency f and original pulse width pw0 are determined (step SB1). These values are input from the input device 50. The laser control device 40 outputs an oscillation command trg to the laser oscillator 10 under the conditions of the pulse repetition frequency f and the original pulse width pw0 determined in step SB1 (step SB2). When the laser pulse LP0 (FIG. 1) rises, the detection signal det from the photodetector 20 is input to the laser control device 40. The delay time from the output of the oscillation command trg until the detection signal det is received is measured (step SB3).

The average value of the measured delay time from the output of the oscillation command trg to the reception of the detection signal det from the point in time when the predetermined plurality of laser pulses LP0 is output is calculated (step SB4). This average value corresponds to the pulse output delay time td. The pulse output delay time td is stored in the storage unit 41 in association with the pulse repetition frequency f and the original pulse width pw0 determined in step SB1 (step SB5).

Next, the excellent effect of this embodiment will be described in comparison with the comparative example shown in Fig. 4B.

4B of FIG. 4 is a timing chart of the oscillation command trg, the laser pulse LP0, the cutting command chp, and the laser pulse LP1 in the comparative example. In the comparative example, the cutting command chp is output at the time point (time t1) when a certain cutting command delay time tdc1 elapses from the time point at which the rise of the laser pulse LP0 is detected (time t2). At the time when the operation delay time tdo elapses from the output of the cutting command chp (time t3), cutting from the laser pulse LP0 is started, and the laser pulse LP1 rises.

Among the laser pulses LP0, the laser energy of the time until the laser pulse LP1 rises is wasted unnecessarily. In the comparative example, the time tw during which the laser energy is unnecessarily wasted is longer than the operation delay time tdo of the cutting optical system 14.

In contrast, in the above embodiment, since the cutting command chp is output prior to the rising point of the laser pulse LP0 (time t2), the time tw from the rising of the laser pulse LP0 to the start of cutting of the laser pulse LP1 is the cutting optical system 14 ) is shorter than the operation delay time tdo. For this reason, it is possible to reduce unnecessarily wasted laser energy and increase the utilization efficiency of the laser pulse LP0.

Further, in the above embodiment, since the pulse output delay time td is stored in the storage unit 41 for each pulse repetition frequency f and original pulse width pw0, the pulse repetition frequency f and original pulse used for actual processing Even when the pulse width pw0 is changed, in step SA2 (FIG. 5), the cutting command delay time tdc can be calculated using an appropriate pulse output delay time td according to actual processing conditions.

If the pulse output delay time td corresponding to the repetition frequency f and the original pulse width pw0 of the pulse used for actual processing is not stored in the storage unit 41, according to the procedure shown in FIG. 6, the pulse output delay time td can be obtained. However, when the pulse output delay time td corresponding to the repetition frequency f and the original pulse width pw0 of the pulse used for actual processing is not stored in the storage unit 41, the already stored pulse output delay time td The pulse output delay time td may be obtained by performing interpolation using

Next, a modified example of the above embodiment will be described.

In the above embodiment, relational information relating both the pulse repetition frequency f and the original pulse width pw0 and the pulse output delay time td (FIG. 2, FIG. 3) is stored in the storage unit 41 (FIG. 1). . For example, when the pulse output delay time td hardly changes even when the original pulse width pw0 is changed, the pulse output delay time td may be related only to the pulse repetition frequency f. Conversely, if the pulse output delay time td hardly changes even when the pulse repetition frequency f is changed, the pulse output delay time td may be related only to the original pulse width pw0.

Next, a laser pulse cutting method based on the procedure of the laser control device 40 (FIG. 1) according to the above embodiment will be described.

As shown in 4A of FIG. 4, the cutting optical system 14 (FIG. 1) has a characteristic of starting cutting of a part of the laser pulse LP0 at the time when the operation delay time tdo has elapsed after the cutting command chp is input. I have it. At a time point prior to the rising point of the laser pulse LP0, a cutting command chp is output to the cutting optical system 14. At this time, the cutting command chp is output so that the time point at which the operation delay time tdo has elapsed from the time point at which the cutting command chp is output is later than the rising point of the laser pulse LP0.

In this way, by controlling the output timing of the cutting command chp, it is possible to reduce unnecessarily wasted laser energy and increase the utilization efficiency of the laser pulse LP0.

Next, a laser control device according to another embodiment will be described with reference to FIGS. 7 and 8 . Hereinafter, descriptions of configurations common to the embodiments described with reference to FIGS. 1 to 6 will be omitted.

Fig. 7 is a schematic diagram of a laser processing machine equipped with a laser control device according to the present embodiment. In the embodiment shown in Fig. 1, there is only one machining path. In contrast, in this embodiment, there are two machining paths. The cutting optical system 14 converts the laser pulse LP1 cut from the laser pulse LP0 into one machining path, and converts the laser pulse LP2 into the other machining path. In each of the two machining paths, a reversing mirror 16, a scanning optical system 17, a lens 19, a stage 30, and a moving mechanism 31 are disposed.

In addition to the cutting command chp, the path selection command sel is input from the laser control device 40 to the cutting optical system 14. The path selection command sel commands a machining path to be selected from two machining paths. The cutting optical system 14 cuts the laser pulse toward the commanded machining path.

Fig. 8 is a timing chart of the oscillation command trg, the laser pulse LP0, the path selection command sel, the cutting command chp, and the laser pulses LP1 and LP2. Similar to the embodiment shown in 4A of Fig. 4, the laser pulse LP0 rises at the time point (time t2) when the pulse output delay time td elapses from the rise of the oscillation command trg (time t0). The laser control device 40 outputs the first cutting command chp at a time point (time t1) when the cutting command delay time tdc has elapsed since the start command trg rises. At this time, the path selection command sel selects the path of the laser pulse LP1. For this reason, the laser pulse LP1 is cut from the laser pulse LP0 at the time when the operation delay time tdo elapses (time t3) from the time of outputting the cutting command chp for the first time.

After the fall of the laser pulse LP1 (time t5), the laser control device 40 switches the path selection command sel to select the processing path of the laser pulse LP2 (time t6). Also, the second cutting command chp is output (time t7). At the time when the operation delay time tdo elapses (time t8) from the time of outputting the second cutting command chp, the laser pulse LP2 is cut from the laser pulse LP0. After the fall of the laser pulse LP2 (time t10), the output of the oscillation command trg is stopped (time t11). Further, the route selection command sel is switched to select the route of the laser pulse LP1 (time t12).

Next, excellent effects of the embodiment shown in Figs. 7 and 8 will be described. Also in this embodiment, since the first cutting command chp is output prior to the rise of the laser pulse LP1, waste laser energy can be reduced and the utilization efficiency of the laser pulse LP0 can be increased.

Each embodiment described above is an example, and it goes without saying that partial substitution or combination of configurations shown in different embodiments is possible. The same operation effect by the same configuration of a plurality of embodiments is not separately mentioned for each embodiment. In addition, the present invention is not limited to the above-described embodiment. For example, it will be apparent to those skilled in the art that various changes, improvements, combinations, and the like are possible.

10 Laser Oscillator
11 Beamsplitter
12 Irradiation optical system
13 Aperture
14 cutting optical system
15 Beam damper
16 reversing mirror
17 scanning optical system
18X movable mirror
18Y movable mirror
19 lens
20 photodetector
30 stages
31 Mobility
40 Laser control device
41 storage unit
50 input devices
60 processing object
trg start command
chp cutting command
det detection signal
sel path selection command
sig1, sig2 control signal

Claims (4)

A laser oscillator for outputting a pulsed laser beam;
A laser control device for controlling a cutting optical system having a characteristic of starting to cut a part of the laser pulse of the pulsed laser beam when a predetermined operation delay time elapses after the pulsed laser beam is incident and a cutting command is input. as,
At a time point before the rising point of the laser pulse, the cutting command is output to the cutting optical system, and a time point that has elapsed by the operation delay time from the time point of outputting the cutting command is later than the rising point of the laser pulse. A laser control device for outputting the cutting command so that According to claim 1,
The laser oscillator outputs the laser pulse in synchronism with input of an oscillation command;
also,
Outputting the oscillation command to the laser oscillator;
storing relational information associating at least one of a repetition frequency and a pulse width of a pulse commanded by the oscillation command with a pulse output delay time;
Based on at least one of the repetition frequency and pulse width of the pulse commanded by the oscillation command, the pulse output delay time obtained from the relation information, and the operation delay time, which is shorter than the pulse output delay time, and which is shorter than the pulse output delay time, Determining a cutting command delay time so as to be longer than a value obtained by subtracting the operation delay time from the delay time;
Based on the determined cutting command delay time, the laser control device outputs the cutting command to the cutting optical system by delaying it from an output point of the oscillation command. According to claim 2,
also,
Receiving a detection signal from a photodetector for detecting the laser pulse output from the laser oscillator;
Measuring a delay time from outputting the oscillation command to inputting the detection signal, and obtaining the pulse output delay time based on the measured value of the delay time;
A laser control device that stores, as the relationship information, a relationship between at least one of a pulse repetition frequency and a pulse width of a pulse commanded by the oscillation command and the pulse output delay time obtained based on a measurement value of the delay time. A laser pulse cutting method in which a laser pulse is output from a laser oscillator and entered into a cutting optical system, and a part of the laser pulse is cut out,
The cutting optical system has a characteristic of starting cutting of a part of the laser pulse at a time when a predetermined operation delay time has elapsed after a cutting command is input,
At a time point prior to the rising point of the laser pulse, the cutting command is output to the cutting optical system, and a time point that has elapsed by the operation delay time from the time point of outputting the cutting command is after the rising point of the laser pulse. As possible, a laser pulse cutting method for outputting the cutting command.

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