JPH04349677A - Pulse laser power source - Google Patents

Abstract

PURPOSE:To obtain a pulse laser power source having a high power source efficiency by reducing energy loss even when a power source impedance is not matched to a discharge impedance. CONSTITUTION:Excess energy due to reverse charging of a capacitor C2 of a pulse width compressing circuit is input to an inverter 30 through a series circuit of a diode Dr, a transformer Tr and a capacitor Cr to be connected in parallel with it, and recovered.

Description

[Detailed description of the invention]

[Purpose of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulsed laser power source with improved power efficiency.

0002

BACKGROUND OF THE INVENTION In recent years, there has been an increasing industrial demand for pulsed lasers that use pulsed laser light to precisely process objects and to separate isotopic elements. To excite a pulsed laser, it is necessary to apply an extremely short pulse voltage of microseconds or less to the laser device to generate a discharge, but it is difficult to directly create such a short pulse voltage with a switch. For this reason, a so-called magnetic pulse compression circuit is often used, which generates a primary pulse using a semiconductor switch or the like to charge a capacitor, and further compresses the pulse width by utilizing the saturation characteristics of a saturable inductor. FIG. 3 is a block diagram of a conventional pulse laser power source. In FIG. 3, initially the DC charging power source 10
When the semiconductor switch SW is turned on, the charge charged in the capacitor C1 is discharged through the discharge reactor LD, and transferred to the second capacitor C2, where pulse charging is performed. The voltage of capacitor C2 is saturable reactor SL
is pulse excited. When the saturable reactor SL is saturated due to this excitation action, the inductance value is drastically reduced and the charge of the capacitor C2 is transferred to the peaking capacitor CP. At this time, since the inductance value of the saturable reactor SL at saturation is extremely small, the peaking capacitor C
The charging of P is accelerated and a so-called pulse compression effect is performed. Furthermore, due to charging of the peaking capacitor CP, the voltage between the electrodes of the laser discharge gap 20 increases, the insulation between the electrodes is broken, and the peaking capacitor CP
The charges accumulated in the laser medium flow through the circuit inductance LH, and the laser is excited.

0003

[Problems to be Solved by the Invention] Such a capacitance transfer type pulse charging circuit has the feature of being able to obtain a high-speed pulse voltage with a relatively simple circuit, but it is difficult to process reflected energy from the load. There were some points that were not sufficient. This will be explained with reference to FIG.

In FIG. 3, the peaking capacitor CP
The ratio of the energy stored in the laser discharge gap and the energy injected into the discharge section changes depending on the ratio of the discharge impedance ZD of the laser discharge gap, the peaking capacitor CP, and the circuit impedance ZC determined by the circuit inductance LH. Assuming that the discharge impedance ZD is approximately equal to the circuit impedance ZC, almost all the energy is injected into the discharge section with one pulse of current because the impedances are matched. However, in reality, the value of discharge impedance is extremely small, and impedance matching in this portion cannot be achieved sufficiently in most cases. Assuming that the typical values of CP, LH, and ZD are 20nF, 10nH, and 0.1Ω, respectively,
The energy injected into the discharge section is only 35% of the energy stored in the peaking capacitor CP. In such a case, since the discharge impedance is smaller than the circuit impedance, the voltage of the peaking capacitor CP is reversed due to discharge. A part of this energy charged with opposite polarity is transferred to peaking capacitor CP and capacitor C.
2. The current becomes a closed circuit current in the saturable reactor SL, and charges the capacitor C2 with the opposite polarity to the initial polarity. The direction of the current at this time is the same as when initially charging the peaking capacitor CP, and the saturated saturable reactor is further saturated, so the inductance remains small and can flow easily. Furthermore, the energy charged in capacitor C2 is transferred to capacitor C2, capacitor C1, semiconductor switch SW, and discharge reactor LD.
A resonant current is passed through a closed circuit consisting of The current flowing through this closed circuit is attenuated by the internal resistance of the semiconductor switch SW. In other words, this current increases the loss generated in the semiconductor switch SW. Furthermore, when operating this laser at high repetition rates, the semiconductor switch SW must be turned off as quickly as possible after discharge in order to shorten the pulse interval. At that time as well, it is necessary to cut off this resonant current, resulting in turn-off loss of the semiconductor switch SW. Such an increase in loss in the semiconductor switch SW causes the temperature of the semiconductor switch SW to rise excessively, resulting in a loss of reliability. An object of the invention is to provide a highly reliable pulsed laser power source with high power efficiency by regenerating surplus energy into a power source. [Structure of the invention]

[0005]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a pulse generator comprising a saturable inductor connected in series to a charging power source and a capacitor connected in parallel to the charging power source. A pulsed laser power supply for repeatedly discharging and exciting a laser load connected to an output end of the pulse width compression circuit, comprising a width compression circuit and a switching means for intermittently connecting a charging power supply to the pulse width compression circuit. It is configured with an energy regeneration circuit that is connected in parallel to the power supply and regenerates surplus energy stored in the capacitor to the charging power supply.

More specifically, the energy regeneration circuit consists of a series circuit consisting of a diode, a transformer, and a regeneration capacitor connected in parallel with the capacitor in a direction that does not affect the charging of the capacitor; It consists of a conversion means that converts surplus power stored in a regenerative capacitor connected in parallel into AC power.

[0007]

[Operation] By equipping this energy regeneration circuit,
The surplus energy recharged to the capacitor C2 in the form of a reverse voltage can be quickly discharged and the energy can be regenerated into the power supply, so no post-voltage is applied to the load, and the surplus energy can be It can be used effectively.

[0008]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a pulsed laser power source according to the present invention. In FIG. 1, the same numbers as in FIG. 3 indicate the same components. In FIG. 1, the diode Dr and transformer Tr are connected in a direction that does not affect the charging of the capacitor C2.
and a capacitor Cr are connected in parallel to the capacitor C2, and an inverter 30 is connected in parallel to the capacitor Cr.
is connected, and the output of the inverter 30 is connected to the output of the AC power supply 1. Next, the operation of this pulsed laser power source will be explained.

The process is as described above up to the point where capacitor C2 is reversely charged due to the mismatch between the source impedance and the discharge impedance. On the way, semiconductor switch SW
Even when the capacitor 2 is charged by conducting, there is no effect at all because the polarity of the diode is the polarity that maintains the charging voltage of the capacitor 2. Next, when capacitor C2 is reverse charged, this reverse voltage is in the direction of forward biasing diode Dr, so capacitor C2
The surplus energy stored in the regenerative capacitor Cr is quickly discharged into the regenerative capacitor Cr by a circuit including the capacitor C2, the transformer Tr, and the regenerative capacitor Cr. The electric power accumulated in the regeneration capacitor Cr is transferred to the inverter 30
The AC power is converted into AC power and regenerated to the AC power supply 1.

[0011] In this way, surplus energy is transferred to the AC power supply 1.
Since an energy regeneration circuit has been added to regenerate energy, surplus energy can be used effectively and power efficiency can be improved. In addition, excess energy prevents unnecessary oscillating current from flowing to the switch SW, and
loss can be reduced.

On the other hand, although this embodiment has described a pulse laser power source that regenerates surplus energy into an AC power source as AC power, the invention is not limited to this embodiment. For example, as shown in FIG. 2, by connecting a rectifier 31 to the output of an inverter 30, it is converted into DC power and regenerated to a smoothing capacitor Cs with a DC charging current of 10.
Of course, the effect is effective.

[0013]

As described above, according to the present invention, by providing an energy regeneration circuit that quickly discharges surplus energy recharged in the form of reverse voltage in the capacitor C2 and regenerates it to the power supply, the switch Oscillatory current caused by excess energy is prevented from flowing through the switching means, thereby reducing loss generated in the switching means, and providing a highly reliable pulsed laser power source with high power supply efficiency.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a pulsed laser power source of the present invention.

FIG. 2 is a configuration diagram showing another embodiment of the pulsed laser power source of the present invention.

FIG. 3 is a configuration diagram of a conventional pulse laser power source.

[Explanation of symbols]

1...AC power supply, 30...Inverter

Claims (2)

[Claims] 1. A pulse width compression circuit comprising a saturable inductor connected in series to a charging power source and a capacitor connected in parallel to the charging power source, and the charging power source is connected to the pulse width compression circuit. a pulse laser power source for repeatedly discharging and exciting a laser load connected to the output end of the pulse width compression circuit, the pulse laser power source comprising a switch means for intermittently connecting the pulse width compression circuit in parallel with the charging power source;
A pulsed laser power source comprising an energy regeneration circuit that regenerates surplus energy accumulated in the capacitor to the charging power source. 2. The energy regeneration circuit includes a series circuit including a diode, a transformer, and a regeneration capacitor connected in parallel with the capacitor in a direction that does not affect charging of the capacitor, and the regeneration capacitor. and converting means connected in parallel to the regenerative capacitor for converting surplus power accumulated in the regeneration capacitor into alternating current power.