CN1797875A - Pump arrangement in long pulse for transverse energized carbon-dioxide laser - Google Patents

Abstract

The Pump arrangement is composed of two power sources of capacity charge in high voltage, two high voltage discharge switches, and pulse forming network, an energy storage capacity in high voltage, a charging diode in high voltage, and a high voltage discharge resistance. Two power sources are in use respectively for controlling energy stored in the energy storage capacity in high voltage and the pulse forming network. Two high voltage discharge switches are in use respectively for constituting discharge loop to make the said stored energy inject to transverse energized carbon-dioxide laser so as to reach purpose of outputting laser pulses with each pulse width, especially, long pulse (pulse width from a few micro second to hundred micro second). The Pump arrangement is applicable to laser processing and laser radar.

Description

Pump arrangement in long pulse for transverse energized carbon-dioxide laser

Technical field

The present invention relates to a kind of laser pulse pumping, relate to a kind of pump arrangement in long pulse for transverse energized carbon-dioxide laser particularly.

Background technology

Transversely excited (Transversely Excited) carbon dioxide laser (hereinafter to be referred as: TE-CO ₂Laser) is 20th century a kind of CO of growing up of the seventies ₂Laser.This laser has certain application because its output peak power height, pulse energy are big, advantage that can high repetition frequency work in fields such as industrial processes, defence and militaries.

Typical TE CO ₂Laser basic structure as shown in Figure 1.Comprise laser shell 1, a pair of main discharge electrode 2, main discharge electrode high pressure input 3, preionization spark array 4, main discharge electrode earth terminal 5, heat exchanger 6, blower fan 7, water conservancy diversion air channel 8 etc.The typical pump pump circuit device of this laser is made up of an energy-storage capacitor Cs, high-voltage switch gear G and a bypass resistance (or inductance) Rp as shown in Figure 2.High voltage source is used for charging to energy storage capacitor Cs.Charging finishes, the in good time conducting of high-voltage switch gear G, and the electric energy among the energy storage capacitor Cs injects laser working gas by high-voltage switch gear G, forms laser output.Typical output laser pulse waveform is a pulsewidth less than the hangover that to add a length be 1～2us of the spike of 100ns as shown in Figure 3, and wherein Tuo Wei energy accounts for 30～50% of laser gross energy.

As can be seen from Figure 2, common TE-CO ₂The pump arrangement of laser mainly is made up of a high-voltage discharging switch and an energy storage capacitor.Lasing energy all derives from the energy in the energy-storage capacitor.The output waveform of laser is the characteristic of laser itself basically, concerns little with the size of energy storage capacitor Cs and the height of charging voltage.

Therefore, in the existing technology, a TE-CO ₂The width of the output laser pulse of laser almost is constant, and the shape of laser pulse shape also almost is uncontrollable.This makes this laser be restricted in some applications.In some application scenarios, need the laser that pulse energy is big, pulse duration is wide (as tens microseconds), it is impossible adopting pump arrangement as shown in Figure 2.

For at TE-CO ₂Obtain Long Pulse LASER output in the laser, also the someone attempts changing the capacitor C s among Fig. 2 into pulse forming network and (please refer to Y.Okita, K.Yasuoka, et al, " Long-pulse, high repetition rate transversely excited CO ₂Laser for materialprocessing ", SPIE Vol.2118 1994:22-11), and has obtained Long Pulse LASER output.But this way is to the designing requirement strictness of laser, and only is applicable to the situation that laser working gas air pressure is lower, is not suitable for the TE-CO than hyperbar ₂Laser (is TEA CO ₂Laser), therefore, has limitation.

Summary of the invention

The object of the present invention is to provide a kind of TE-CO ₂The long pulse pump arrangement of laser.Pump arrangement of the present invention can be controlled TE-CO ₂The output pulse width of laser and shape obtain the Long Pulse LASER output of several microseconds even microseconds up to a hundred.

For achieving the above object, at TE-CO provided by the invention ₂In the laser long pulse pump arrangement, employing is with lasing energy separated into two parts and adopt two measures such as high-voltage discharging switch, has realized TE-CO ₂The control of laser output pulse waveform.

Because at common TE-CO ₂In the laser diode pump pump apparatus, lasing energy comes from an energy-storage capacitor, and is disposable injection laser.Therefore, the waveform of laser pulse by the characteristic of laser itself (as working gas form, air pressure, cavity length or the like) decision, and little with the magnitude relationship of injecting energy.And the present invention will encourage TE-CO ₂The energy separated into two parts of laser, a part is provided by energy storage capacitor Cs, and another part is provided by a pulse forming network, thereby reaches control TE-CO ₂The purpose of the output laser pulse waveform of laser.

Specifically, TE-CO of the present invention ₂Laser long pulse pump arrangement mainly is made up of two high-voltage capacitor charging power supplys, two high-voltage discharging switch, pulse forming network (Pulse FormingNetwork-PFN), an energy storage capacitor, a bypass resistance and high-voltage charging diodes etc.The present invention by controlling two high voltage source charging intervals and charging voltage, two high-voltage switch gears conduction mode and select suitable pulse forming network parameter, can make the output laser pulse waveform of the TE-CO2 laser that is encouraged controlled, realize that pulse duration reaches the laser output of a few microsecond to tens microseconds.

Description of drawings

Fig. 1 is TE-CO ₂Laser basic structure schematic diagram.

Fig. 2 is typical TE-CO ₂The pump circuit schematic diagram of laser.

Fig. 3 is typical TE-CO ₂Laser pulse waveform schematic diagram.

Fig. 4 is TE-CO of the present invention ₂Laser long pulse pump arrangement schematic diagram.

Fig. 5 is TE-CO of the present invention ₂Laser long pulse output waveform schematic diagram.

Fig. 6 is the switchable TE-CO of pulse duration of the present invention ₂Laser long pulse pump arrangement schematic diagram.

Embodiment

See also Fig. 4, be TE-CO of the present invention ₂Laser long pulse pump arrangement schematic diagram.Among Fig. 4 CCPS1 and CCPS2 for the high-voltage capacitor charging power supply that adopts the current constant mode charging (for sake of convenience, dividing these two high-voltage capacitor charging power supplys of another name is A and B), G1 and G2 are high-voltage discharging switch (for sake of convenience, dividing these two high-voltage discharging switch of another name is C and D), Cs is the high pressure energy storage capacitor, D1 is the high-voltage charging diode, and Rp is a laser discharge bypass resistance, Li, Ci (i=1,2 ..., n) for forming the inductance and the electric capacity of pulse forming network.

Circuit of the present invention connects: the high-voltage output end of high-voltage capacitor charging power supply CCPS1 is connected with the anode of the end of energy storage capacitor Cs and high-voltage discharging switch G1; The other end of energy storage capacitor Cs is connected to TE-CO ₂Laser main discharge electrode high voltage input terminal; An end and the TE-CO of the anode of high-voltage charging diode D 1 and laser discharge bypass resistance Rp ₂Laser main discharge electrode high voltage input terminal is connected; The other end of the negative electrode of high-voltage charging diode D1 and laser discharge bypass resistance Rp then with TE-CO ₂Laser main discharge electrode earth terminal is connected, that is high-voltage charging diode D1 and the equal and TE-CO of laser discharge bypass resistance Rp ₂The laser parallel connection.The high-voltage output end of high-voltage capacitor charging power supply CCPS2 is connected with an end (can be described as the input of pulse forming network) and the anode of high-voltage discharging switch G2 of capacitor C 1 in the pulse forming network; An end of inductance L 1 (can be described as the output of pulse forming network) is connected to TE-CO in the pulse forming network ₂Laser main discharge electrode high voltage input terminal; The high pressure output earth terminal of two high-voltage capacitor charging power supplys (CCPS1 and CCPS2) and the negative electrode of two high-voltage discharging switch (G1 and G2) all are connected to TE-CO2 laser main discharge electrode earth terminal by lead, and are connected to safety line.

In the pulse forming network in Fig. 4, all inductance value, capacitance are generally equal, i.e. L ₁=L ₂=...=Ln, C ₁=C ₂=...=Cn, wherein, n is an integer, and n 〉=4.The characteristic impedance of pulse forming network is pressed following formula (1) and is calculated:

$Z_{\mathrm{pfn}}=\sqrt{\frac{L_i}{C_i}}---\left(1\right)$

The time width of pulse forming network is pressed following formula (2) and is calculated:

$T=2\·n\·\sqrt{L_i\·C_i}---\left(2\right)$

Wherein the selection of inductance, capacitance size will be according to TE-CO in the pulse forming network ₂The impedance discharge of laser and needed laser pulse width decide.Theory requires both impedances to equate, that is:

Z _pfn＝Z _laser (3)

In the actual design work, require the characteristic impedance of pulse forming network to be slightly larger than the impedance discharge of laser, generally get:

Z _pfn＝(110％～130％)·Z _laser (4)

Adopt long pulse pump arrangement of the present invention, can make TE-CO ₂The output pulse of laser can become long pulse form as shown in Figure 5.In Fig. 5, " protuberance " behind the laser pulse spike become the major part of whole pulse energy, and be different with the typical TE-CO2 laser pulse waveform that Fig. 3 provides, and the laser energy shown in Fig. 3 almost is to divide equally in spike and hangover.

Adopt long pulse pump arrangement of the present invention, TE-CO ₂The laser pulse waveform can be controlled flexibly.In two parts energy, energy among the energy storage capacitor Cs is mainly contributed the spike part in pulse, the energy of pulse forming network then " protuberance " part of paired pulses works, therefore, as long as control impuls forms the charging voltage (being the energy in the pulse forming network) on the network, just can control the amplitude of " protuberance " part in the laser pulse shape.For example, during not conducting of Fig. 4 mesohigh switch G2, typical TEA CO in the long pulse pump arrangement regression figure 2 of the present invention ₂The laser diode pump pump apparatus.Therefore, in fact pump arrangement of the present invention has comprised the given device of Fig. 2, and versatility is better.

As an expansion of the present invention, can design pump arrangement shown in Figure 6.Among Fig. 6, all pulse forming networks (PFN1, PFN2 ... characteristic impedance PFNn) is identical, but pulse duration (calculating by formula 2) difference.The effect of diverter switch (SW) is to switch between different pulse forming networks, but once only allows a pulse forming network to connect.Like this, make a TE-CO ₂Laser can be exported the laser pulse with different pulse durations.In addition, because high voltage charging power supply CCPS1 and CCPS2 adopt constant current charge, controllability is good, and in the process that switch switches, can make on the diverter switch (SW) does not have electric current and voltage, realizes zero-voltage and zero-current switch, not only safety but also the change of switching side.

In sum, TE-CO provided by the invention ₂The pump arrangement of laser by energy storage capacitor of Energy distribution and the pulse forming network with pump laser, has been realized TE-CO ₂The control of laser output pulse waveform makes common TE-0CO ₂Laser can be exported the pulse laser of several microseconds to microseconds up to a hundred.Adopt the present invention, can under the prerequisite of optical system of not changing the TE-CO2 laser and mechanical structure, make its output have the laser pulse shape of different pulse durations.

Claims (9)

1. a pump arrangement in long pulse for transverse energized carbon-dioxide laser is made up of two high-voltage capacitor charging power supplys, two high-voltage discharging switch, pulse forming network, energy storage capacitor, bypass resistance and high-voltage charging diodes, wherein:

The high-voltage output end of high-voltage capacitor charging power supply A is connected with the anode of an end of energy storage capacitor and high-voltage discharging switch C; The other end of energy storage capacitor is connected to TE-CO ₂Laser main discharge electrode high voltage input terminal; The anode of high-voltage charging diode and TE-CO ₂One end of laser discharge bypass resistance is connected with TE-CO2 laser main discharge electrode high voltage input terminal; The negative electrode of high-voltage charging diode and TE-CO ₂The other end of laser discharge bypass resistance then with TE-CO ₂Laser main discharge electrode earth terminal is connected;

The high-voltage output end of high-voltage capacitor charging power supply B is connected with the anode of pulse forming network input and high-voltage discharging switch D; The output of pulse forming network is connected to TE-CO ₂Laser main discharge electrode high voltage input terminal; The high pressure output earth terminal of two high-voltage capacitor charging power supply A, B and the negative electrode of two high-voltage discharging switch C, D all are connected to TE-CO ₂Laser main discharge electrode earth terminal;

Inductance value in the described pulse forming network equates;

Capacitance in the described pulse forming network equates.

2. the pump arrangement of claim 1 is characterized in that, earth terminal is connected to safety line.

3. the pump arrangement of claim 1 is characterized in that, the high-voltage capacitor charging power supply of using in the pump arrangement is the current constant mode charging, and it allows charging interval, the charging interval of forbidding and charging voltage is controlled.

4. the pump arrangement of claim 1 is characterized in that, two high-voltage discharging switch are independent mutually, and its conducting zero-time is controlled respectively.

5. claim 1 or 4 pump arrangement is characterized in that high-voltage discharging switch is high-pressure thyratron, high pressure trigger tube or smash crack.

6. the pump arrangement of claim 1 is characterized in that, its characteristic impedance of the pulse forming network in the pump arrangement and TE-CO ₂The laser impedance discharge is complementary.

7. the pump arrangement of claim 1 is characterized in that, the bypass resistance in the pump arrangement is non-pure resistive.

8. the pump arrangement of claim 1 is characterized in that, the pulse forming network that has a plurality of different pulse durations in the pump arrangement is used for a TE-CO ₂Laser by diverter switch control, makes the different laser pulse width of TE-CO2 laser output.

9. the pump arrangement of claim 8 is characterized in that, diverter switch is once only connected a pulse forming network.

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