JPS5845838B2 - Pulse laser hatch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pulsed laser oscillation device that can easily obtain a laser pulse with a steep falling edge.

A pulsed laser oscillation device is used to focus a laser beam to drill holes in a workpiece or remove a specific object.

In these applications, there is a close relationship between the laser waveform and processing characteristics; when the laser waveform exceeds a certain power level, it contributes to the processing characteristics, but when the power is below a certain level, it increases the temperature of the workpiece. This will only increase the thermal influence around the caloes, resulting in many disadvantageous aspects to the processing characteristics.

In a pulsed laser oscillation device for optical excitation using a flashlamp, the problem can be solved by controlling the discharge waveform of the flashlamp, and one example of this is Japanese Patent Publication No. 48-29437.

This uses a waveform shaping circuit consisting of a capacitor and inductance to increase the pulse discharge current over time and control the laser waveform into an upward slope.

However, this flashlamp discharge waveform control method not only requires a complicated waveform shaping circuit, but also fails to provide a laser waveform with a steep fall as intended in the present application.

The present invention has been made in view of the above points.
To provide a laser pulse oscillation device that easily obtains a steeply falling pulse waveform with a simple circuit configuration, thereby reducing the thermal influence around the processing part of a workpiece and improving processing characteristics compared to conventional ones. It is.

The present invention will be described in detail below with reference to the drawings.

In Figure 1, charging control circuit 1 has a built-in DC power supply, etc.
A first charge/discharge capacitor 2 is connected to the capacitor 2, and a series circuit of a first discharge lamp 3, such as a flash lamp, and a waveform shaping coil 4 for controlling the discharge waveform of this lamp 3 is connected to the capacitor 2. There is.

3a is a trigger electrode that excites and controls the discharge lamp 3.

Further, a second charging/discharging capacitor 6 is connected to the charging control circuit 1 via a diode 5.

If the capacitance of the first charging/discharging capacitor 2 is C2, and the capacitance of the second charging/discharging capacitor 6 is C6, then, for example, if the capacitance C6 of the second charging/discharging capacitor 6 is sufficiently small, C6<C
Set the relationship of 2.

A second discharge lamp 7, such as a flash lamp, is connected to both ends of the second charge/discharge capacitor 6 through a resistor 8.

7a is a trigger electrode of the second discharge lamp 7.

Reference numeral 9 denotes a switch element having a trigger electrode 9a for controlling the discharge currents of the first and second charge/discharge capacitors 2 and 6, and for example, Cyrisk is used.

Thus, the first discharge lamp 3 and the second discharge lamp 7 are arranged with a desired spacing between them, and a laser substance 10 that generates a laser pulse is arranged between these lamps 3 and 7. ,
The configuration is such that the discharge energy of the discharge lamps 3 and 7, that is, the excitation light of the laser material, is focused on the laser material 10.

1L12 is a resonator mirror.

Next, the operation of the pulsed laser oscillation device shown in FIG. 1 will be explained.

The voltage obtained by the charging control circuit 1 is charged to the second charging/discharging capacitor 6 via the first charging/discharging capacitor 2 and the diode 5 .

The charging voltage of the capacitors 2 and 6 is assumed to be V as shown in FIG. 2a.

After charging is completed, the trigger electrode 3a, ? If a trigger pulse is given to a, the first charging/discharging capacitor 2
The voltage passes through the waveform shaping coil 4 and is discharged in the discharge lamp 3, and the voltage drops from the part A in FIG. 2A.

On the other hand, the voltage of the second charging/discharging capacitor 6 passes through the resistor 8 and is discharged in the discharge lamp 7, but due to the resistor 8, the discharge characteristic gradually drops as shown in the opening in FIG. 2a.

When a trigger pulse is applied to the trigger electrode 9a of the switch element 9 at time 12, the voltage of the second charge/discharge capacitor 6 is supplied to the discharge lamp T through the switch element 9 with a small resistance value, and then The voltage of the charging/discharging capacitor 2 of No. 1 is also applied to the discharge lamp 7 through the diode 5 and the switch element 9.

Therefore, the voltage of the first charging/discharging capacitor 2 is discharged in parallel in the first and second discharge lamps 3' and 7, resulting in a steep discharge characteristic as shown in c in Fig. 2a. .

/Z is a case where the switching element 9 is not made conductive and the charging/discharging capacitor 2 is substantially discharged only by the discharge lamp 3.

Note that the discharge waveform varies greatly depending on the capacitor capacity, but as mentioned above, for example, if the capacity of the second charge/discharge capacitor 6 is made sufficiently smaller than the capacity of the first charge/discharge capacitor 2, the The time it takes for the first charge/discharge capacitor 2 to finish discharging is significantly shorter than when only the first discharge lamp 3 is used because the impedance of the discharge circuit becomes less than 1 when the second discharge lamp 7 starts discharging. can.

FIG. 2C shows the discharge source waveforms of the first discharge lamp 3 and the second discharge lamp 7.

That is, in FIG. 2, 2 is the current waveform of the discharge lamp 3 when the second discharge lamp 7 is lit, and 21 is a similar waveform when the second discharge lamp 7 is not lit.

Further, E in FIG. 2C is the discharge source waveform of the second discharge lamp T when the switch element 9 is turned on at time 12.

In addition, FIG. 2d shows the laser output waveform generated from the laser material 10, when only the first discharge lamp 3 is triggered, and when the second discharge lamp 7 is triggered at time 12 and the first and second discharge lamps are triggered. It is a figure when both the discharge lamps 3 and 7 are lit and discharged.

The resistor 8 is used to set the second discharge lamp 7 in a preliminary discharge state when a trigger pulse is applied to the trigger electrodes 3a and 7a.

Further, the constants of the resistor 8, the second charge/discharge capacitor 6, and the second discharge lamp 7 are such that the discharge duration is longer than the discharge pulse width determined by the first discharge lamp 3, the waveform shaping coil 4, and the first charge/discharge capacitor 2. Select according to the time.

Therefore, in the pulsed laser oscillation device of the present invention as shown in FIG. 1, a laser waveform as shown in FIG. By discharging the second discharge lamp 7, the discharge can be made steep.

This makes it possible to increase the peak output at the rear of the laser waveform and to make the fall of the waveform steeper.

Therefore, by using the above-described pulsed laser waveform, even when drilling a hole in a workpiece, the influence of heat around the workpiece can be reduced, and the machining finish characteristics can be improved.

Note that in the above explanation, the second charging/discharging capacitor 6 has a smaller capacity than the first charging/discharging capacitor 2, but the capacitor 6 is not limited to this, and even if the capacitor 6 has a large capacity, the output at the rear of the laser waveform may vary depending on the relationship with other elements. can be increased, and processing characteristics can be improved.

Next, FIG. 3 shows another embodiment of the present invention, in which a switch element 1 constitutes another discharge circuit in the discharge circuit of the charge/discharge capacitor 2.
5. If necessary, a low impedance load 16 such as a resistor or a flash lamp is provided.

The operating characteristics will be explained below with reference to FIG.

As shown in FIG. 4a, when a trigger pulse is applied to the trigger electrode 3a of the discharge lamp 3 at time 41, the voltage of the charging/discharging capacitor 2 is discharged slowly as shown in FIG.
If the switching element 15 is controlled to be conductive at time t2, a discharging circuit is added to the charging/discharging capacitor 2, and discharge occurs in a steep manner as shown in FIG.

This is the case when the switch element 15 is kept in the cut-off state.

Fig. 4 shows the discharge source waveform of the discharge lamp 3, and when the switch element 15 is conductive, the switch element 15 shows the waveform.
This is the case when the system is turned off.

Further, FIG. 4C shows a discharge source waveform flowing through the switch element 15, and the conduction of the switch element 15 causes the charging/discharging capacitor 2 to be discharged in a short time.

FIG. 4d shows the laser waveform obtained by the laser material 10, and when the switching element 15 is turned on, the waveform becomes as shown in FIG.
When it is in the cut-off state, a waveform similar to a nohi is obtained.

That is, the conduction of the switch element 15 allows the laser waveform to fall steeply.

As described in detail above, the present invention (accordingly, the charging control circuit)
This first charging/discharging circuit and a separate second charging/discharging circuit or discharging circuit for variable impedance are provided, and the first charging/discharging circuit is mainly used for optical excitation of the discharge lamp, and the second charging/discharging circuit is used at a certain timing. Since the operation of the charging/discharging circuit or the discharging circuit is controlled so that the voltage of the second charging/discharging circuit is discharged in parallel, the peak output can be increased at the rear of the laser waveform, and the falling In this case, a steep discharge waveform can be obtained.

Therefore, if such a waveform is used for laser processing, only a heating effect will be applied to the workpiece without evaporating the workpiece.
Since it is not necessary to irradiate large laser energy, the thermal effect on the workpiece can be sufficiently reduced, and it is possible to obtain a workpiece with superior processing finish characteristics compared to the conventional method.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a pulsed laser oscillation device according to the present invention,
Figure 2 a = d is a waveform diagram showing the characteristics of the circuit in Figure 1;
FIG. 3 is a circuit diagram of a pulsed laser oscillation device illustrating another embodiment of the present invention, and FIG. 4 a=d is a waveform diagram showing characteristics of the circuit of FIG. 3. 1... Charging control circuit, 2... Charging/discharging capacitor, 3... Discharging lamp, 4...
Waveform shaping coil, 5... Diode, 6...
...charging/discharging capacitor, 7...discharging lamp,
8...Resistor, 9...Switch element, 1
0... Laser substance, 15... Switch element, 16... Low impedance load.

Claims (1)

[Claims] 1. A charging/discharging capacitor connected to a charging control circuit, a discharge lamp connected to this capacitor and discharging charging voltage in response to a trigger signal, a laser substance optically excited by this discharge lamp, and a laser substance connected to the charging/discharging capacitor, and a discharge circuit that discharges the voltage of the charge/discharge capacitor without passing through the discharge lamp during discharge of the discharge lamp.