JP2583719B2 - Gas controlled output stabilized gas laser system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas laser apparatus capable of stabilizing a gas laser output without using a power supply system control as a laser output adjustment method for a whole gas laser.

[0002]

2. Description of the Related Art In a gas laser, a decrease in laser output for a long time and a fluctuation in the laser output in a short time occur. The cause of the laser output decrease over a long period of time is caused by gas deterioration due to a decrease in a specific component of the laser gas. Therefore, as a method of stabilizing the laser output by gas control, for example, in the case of an excimer laser, a method disclosed in Japanese Patent Application No. 2-24
As in a halogen gas injection type output stable excimer laser apparatus described in Japanese Patent No. 1642, there is an apparatus which attempts to stabilize by injecting a halogen gas.

FIG. 16 shows an example of a conventional halogen gas injection type output stable excimer laser device. In FIG. 16, a laser tube 101 is connected to a laser gas exhaust system 103, a rare gas / buffer gas filling system 104, and a halogen gas injection system 105 by a gas pipe. The gas injection system 105 includes a gas flow controller 118, an electromagnetic valve 119, and a halogen gas cylinder 120. Laser tube 10
1 is filled with a laser gas 106, output windows 108 are provided at both ends of the laser tube, and a total reflection mirror 109 and an output mirror 110 are disposed with the pair of output windows interposed therebetween. Take out. The laser beam 107 is split into two by a beam splitter 111, one is used for laser processing, and the other is incident on a laser power meter 112 and transmitted to an excimer laser output controller 113 via a laser output signal line 114. Is done. A signal is sent from the laser output control device 113 to the laser power supply 115 via the laser power control line 116, and the laser output is controlled by the laser output control line 117. On the other hand, a control signal is transmitted from the laser output control device 113 to the gas flow controller 118 by a gas flow control signal line 121 and a control signal to the solenoid valve 119 by a solenoid valve control signal line 122, respectively. Accordingly, a halogen gas is injected into laser tube 101.

However, this gas control can only improve the deterioration of the laser gas (improve the laser output), and cannot reduce the laser output, and it takes a long time before the laser control is affected by the gas control. I know that. Therefore, in order to suppress the fluctuation of the laser output in the gas laser for a short time, at present, it is necessary to rely on a power supply system control capable of high-speed control. However, especially in the power system control in the pulse oscillation laser, it can not be changed only every step there is the control parameter of the power supply system, can only be controlled for each value [Delta] P _L step, which is also the laser output P _L.
Therefore, there is a problem that the stability of the laser output is determined by the steps of the control parameters of the power supply system. of course,
Although the control steps of the power supply system can be reduced, the configuration of the power supply system becomes complicated, and the power supply system itself becomes larger and more expensive than the laser tube main body, and the practicality is lost. Therefore, it can be estimated that it is difficult to stabilize the laser output with high accuracy by controlling the power supply system.

[0005]

The conventional power supply system control is as follows.
This is control at high voltage or large current. Particularly, in the case of a pulsed high pressure gas laser such as an excimer laser, in order to stabilize the laser output with high accuracy within ± 1%, for example, a change in charging voltage is required. The width must be reduced, which complicates the configuration of the control power supply system, which causes not only a problem that the power supply system becomes expensive but also a problem that maintenance and inspection become difficult.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems by stabilizing the gas laser output without using a dedicated power supply control system for stabilizing the laser output.

[0007]

The present invention focuses on the fact that the gain of a laser gas as a laser medium in a gas laser device that performs laser oscillation depends on the pressure (density) of the laser gas near an operating point of laser oscillation. The method adopts a method of adjusting the laser gas pressure to change the density of the laser gas to increase or decrease the gain, thereby stabilizing the laser output to a predetermined output.

Accordingly, the laser output stabilization method can be applied to any of solid, liquid, and gas lasers having similar density / gain characteristics, but is most suitable for a gas laser whose density change is easy and whose density change is wide. It can be said that there is.

Next, a method of adjusting the pressure of a laser gas as a laser medium is described. A gas chamber (for example, cylinder type,
A bellows type, balloon type, bag type, etc.) are provided, and the volume of the variable volume gas chamber is changed, for example, by adjusting the amount of gas introduced into the variable volume gas chamber. The location of the variable volume gas chamber may be either inside or outside the laser tube as long as the pressure (density) of the laser gas can be changed. The number of variable volume gas chambers may be one or more in accordance with the purpose of controlling the pressure (density) of the laser gas or injecting a specific gas component. The gas introduced into the variable volume gas chamber may be air, but if it leaks into the laser tube, it may damage the laser device itself, so one component of the rare gas or the gas constituting the laser gas or A plurality of components are desirable, and ideally the laser gas itself.

When the laser gas or a gas of one gas component or a plurality of gas components constituting the laser gas is introduced into the variable volume gas chamber, a mechanism capable of discharging the introduced gas into the laser tube is provided by a variable volume gas chamber. In addition to stabilizing the laser output, the gas in the volume-variable gas chamber is positively discharged into the laser tube, and the laser output stabilized for a long time can be easily achieved by supplementing the laser gas consumed by the laser oscillation.

In the case of a plurality of variable volume gas chambers,
If one is used for adjusting the pressure (density) of the laser gas and the other is used for replenishing the gas in the laser tube, there is no need to interrupt stabilization of the laser output. As means for supplying various gases to these variable volume gas chambers, a method using a high pressure gas of a gas cylinder, a method using a gas pump, replenishing a gas cylinder with a gas pump, and then from the gas cylinder to the variable volume gas chamber. A supply method is conceivable.

In addition, as means for changing the volume of the variable volume gas chamber, a gas is sealed in the variable volume gas chamber, heat is allowed to enter and exit from the outside, and the variable volume gas chamber is expanded and contracted by thermal energy. A method is conceivable. In this case, the variable volume gas chamber has a heat insulating structure, and a heat generating / cooling unit or a heat exchanging unit is provided in the laser chamber so that the laser gas in the laser tube is not thermally affected. What is necessary is just to make the structure which can supply and discharge. Further, if the outer shell of the variable volume gas chamber is made of a shape memory alloy, heat can be supplied and discharged between the variable volume gas chamber and the outside of the laser tube by the same method as described above, and the volume of the variable volume gas chamber can be changed. Further, when a gas having high thermal conductivity is used in these variable volume gas chambers, there is an advantage that the volume change rate of expansion and contraction of the variable volume gas chambers can be increased.

When the temperature control range is previously limited due to the mechanical characteristics of the material of the variable volume gas chamber and the like, a structure that allows gas to enter and exit from the outside instead of a sealed variable volume gas chamber is adopted. In addition, the output can be stabilized even if gas does not frequently enter and exit the variable volume gas chamber.

Further, there are two methods of exhausting the gas introduced into the variable volume gas chamber, such as exhausting the gas only once, or using the gas pump and the gas cylinder in combination. When expensive gas is used as the introduced gas, the latter will be more advantageous in terms of operating cost. further,
Considering the case of handling gas such as corrosive laser gas,
The material of the variable volume gas chamber must be made of a corrosion-resistant gas-resistant material.

As another means for changing the volume of the variable volume gas chamber, a structure in which a motor and a feed mechanism are combined is used. If connected, the volume of the variable volume gas chamber can be changed by moving a part of the variable volume gas chamber by the rotational motion of the motor. Further, since the gas chamber in the laser tube is exposed to the gas circulating wind, it is necessary to provide a protective partition.

[0016]

The gain of the laser gas as a laser medium depends on the laser gas density, and the laser gas density is proportional to the laser gas pressure if the laser gas is sealed. Therefore,
The laser output can be controlled by adjusting the laser gas pressure. In the present invention, as a means, a variable volume gas chamber is provided at a place communicating with the laser gas in the laser tube, and by changing the volume of the variable volume gas chamber, the pressure (density) of the laser gas in the laser tube is adjusted. Also, the laser output can be stabilized with high accuracy without using the power supply system control. Various forms can be used as the variable volume gas chamber,
In addition to adjusting the density of the laser gas by changing the volume, a configuration in which the laser gas component is emitted from the variable volume gas chamber to the laser tube is also possible, so that the laser gas component can be replenished at the same time.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an overall configuration of a gas controlled output stabilized gas laser device according to a first embodiment of the present invention.

Inside the laser tube 1, two main electrodes 2,
A circulating fan 3 and a variable volume gas chamber 4 are provided outside with a laser gas supply / discharge device 6 for supplying / exhausting a laser gas 5 and a gas pressure gauge 7 for measuring the pressure of the laser gas 5. In the laser tube 1, a pair of transmission windows 8 are provided on a line passing between the two main electrodes 2. A laser power supply 9 for injecting power for laser oscillation is connected to the main electrode 2 by a high-voltage wire 10. The circulation fan 3
The rotational motion of a circulating fan motor 12 supported by a bearing support 11 inside the laser tube 1 and installed outside the laser tube 1 is transmitted via a magnetic coupling 13 to a power shaft 14.
As a result, the rotational motion is transmitted, and the laser gas 5 is forcibly circulated to the discharge portion 15 between the two main electrodes 2.

A gas pressure gauge 7 for monitoring the gas pressure inside the variable volume gas chamber 4 is installed in the variable volume gas chamber 4 in order to avoid overload (excess of internal stress). The method of changing the volume will be described later. Further, a gas chamber volume control device 16, for example, a gas supply / exhaust control device, is connected to the variable volume gas chamber 4 by a gas chamber volume control transmission system 17, for example, a gas supply / exhaust pipe. Changes the volume of the variable volume gas chamber 4 in response to the command signal, and consequently changes the volume of the laser gas.
The laser output can be controlled by changing the pressure (density) of the laser.

A total reflection mirror 19 and an output mirror 20 are provided outside the laser tube 1 with a pair of transmission windows 8 on the optical axis 18 of the discharge portion 15 between the two main electrodes 2 interposed therebetween. Then, the laser beam 21 generated in the discharge unit 15 is amplified and extracted. The laser beam 21 is split into a laser beam 21 ′ and a laser beam 21 ″ by a beam splitter 22, and the laser beam 21 ′ is incident on a laser power meter 23 for measuring laser output, and the other laser beam 2
1 ″ is used for laser processing or the like. The laser gas supply / discharge device 6 and the laser tube 1 are connected by a laser gas supply / discharge gas tube 24 so that the laser gas can be supplied / discharged therebetween.

Further, the laser gas supply / discharge device 6, gas pressure gauge 7, laser power supply 9, circulating fan motor 12,
The gas chamber volume control device 16 and the laser power meter 23
Laser gas control signal line 25, gas pressure signal line 2 respectively
6. The power supply control signal line 27, the circulation fan motor rotation control signal line 28, the gas chamber volume control signal line 29 and the laser output signal line 30 are connected to a laser output control device 31 which controls the entire laser device.

Next, a method of stabilizing the laser output will be described. Laser output is detected by laser power meter 2
It starts by detecting the laser beam 21 'at 3. The detected output is transmitted to the laser output control device 31 via the laser output signal line 30 according to the arrow 32 indicating the signal flow. The laser output control device 31 calculates the output of the laser beam 21 using the received laser output signal of the laser beam 21 ′, the sensitivity of the laser power meter 23, and the laser beam distribution ratio of the beam splitter 22, and achieves the target stabilization. A deviation from the output value is determined, and if a deviation equal to or more than a predetermined value is detected between the two, the volume of the variable volume gas chamber 4 is sent to the gas chamber volume control device 16 via the gas chamber volume control signal line 29. Send a command to change.

In accordance with the command from the laser output control device 31 received, the gas chamber volume control device 16 controls the volume as indicated by an arrow 33 so that the deviation between the laser output and the target stabilization output is equal to or less than a predetermined value. By giving a physical action to the variable gas chamber 4 and changing the volume of the variable volume gas chamber 4 to change the pressure of the laser gas 5 inside the laser tube 1, gain control of the laser gas 5 as a laser medium is performed. Thus, the output of the laser beam 21 is stabilized.

When the laser output stabilization control by the variable volume gas chamber 4 is continued for a long time, it becomes difficult to stabilize the laser output only by the variable volume gas chamber 4 due to the deterioration of the laser gas 5 finally. At that time, the laser output control device 31 operates the laser gas supply / discharge device 6 via the laser gas control signal line 25, and exchanges the laser gas 5 in the laser tube 1 according to the arrow 34 indicating the flow of the laser gas 5. Furthermore, long-term laser output stabilization control can be realized.

Therefore, according to this embodiment, the laser gas 5
Pressure (density) can be continuously changed, so the stepless control of the laser output of the high-voltage pulse gas laser device, which was very difficult with the power supply system control that controls the charging voltage in the past, It has the advantage that it can be easily realized without using it.

[0027] FIG. 2 is a characteristic curve showing the relationship between the charging voltage Vs and the laser output P _L of the gas laser device representing the basic principle of the laser output control method applied in the present invention. FIG.
Is an example of a XeCl excimer laser with high pressure pulsed gas lasers, which shows the relationship between the charging voltage Vs and the laser output P _L pressure p of the laser gas 5 as a parameter. For example, as shown by the vertical dashed line at the charging voltage Vs = 25 kV, when the laser gas pressure p is increased (p ₁ <p ₂ <p ₃ ) for the same charging voltage Vs, the normalized laser output P
It can be seen that _L increases (P _L1 <P _L2 <P _L3 ). Of course, in general, in a gas laser device, there is an appropriate pressure (density) range of the laser gas 5 which does not cause abnormality in the energy injection into the laser gas 5 due to electric discharge or the like. Therefore, the present invention can be applied to any gas laser device capable of controlling the gain by changing the pressure (density) of the laser gas 5 within the range of the pressure (density) of the laser gas 5.

As described above, the basic principle of the laser output stabilization control of the present invention is to control the pressure of the laser gas 5 as a laser medium to change its density and control the gain for laser oscillation of the laser gas 5. It is in. Therefore, as a method of controlling the pressure of the laser gas 5, a method such as temperature control of expanding and contracting by directly applying heat to the laser gas 5 can be considered. In this method, even if the pressure of the laser gas 5 is changed, the laser tube 1 can be used. Since the density of the laser gas 5 cannot be changed as long as it is sealed, it is not suitable as the laser output control method of the present invention. In FIG. 2, the charging voltage Vs is shown as being continuously variable. However, the charging voltage Vs is actually discontinuous and the amount of discontinuity ΔVs depends on the power supply of the laser device.

FIG. 3 shows a section of the variable volume gas chamber 4 for controlling the pressure (density) of the laser gas 5 in the gas controlled output stabilized gas laser device of the present invention. (A) piston type, (b) bellows type,
(C) Balloon type and (d) Bag type. Various power sources for changing the volume of the variable volume gas chamber 4 are conceivable.
When gas is sent and exhausted, cylinder 3
Assuming that the frictional force at the contact surface between the piston 5 and the piston 36 is negligibly small, the pressure of the gas sent and exhausted by the gas delivery / exhaust control device 16 ′ through the gas delivery / exhaust pipe 17 ′ becomes the pressure of the laser gas 5 in the laser tube 1. It only needs to be the same as the pressure. On the other hand, the bellows type and the balloon type depend on the constituent materials of the outer shell of the bellows 37 and the balloon 38, but the restoring force may be applied by the amount of deformation from the original stable shape. In comparison, it must be taken into account that the pressure condition of the gas to be sent and exhausted may be different from the pressure of the laser gas.
Further, in the case of the bag type, up to the maximum volume of the bag 39, the gas can be sent and exhausted while the pressure of the laser gas and the pressure of the gas to be sent and exhausted are perfectly balanced. Therefore, by monitoring the pressure of the gas to be sent and exhausted, the pressure of the laser gas 5 can be simultaneously monitored. The arrow 40 in FIG. 3 indicates the direction of the volume change type of the variable volume gas chamber 4.

FIG. 4 shows an example of a method for controlling the volume of the variable volume gas chamber 4. The shape of the variable volume gas chamber 4 to be controlled is a piston type for simplicity of description, and the piston 36 in the cylinder 35 is formed by sending and discharging gas to and from the variable volume gas chamber 4 by the gas sending and exhausting control device 16 ′. It is a method of controlling the pressure (density) of the laser gas 5 in the laser tube 1 by moving and increasing or decreasing the volume of the variable volume gas chamber 4.

The laser beam 21 oscillated by the predetermined energy injection by the laser power supply 9 is split by the beam splitter 22 on the optical axis 18 after being emitted from the laser tube 1, and the laser power is also set on the optical axis 18. Meter 23
The laser output signal is converted to a laser output signal and sent to a laser output control device 31 via a laser output signal line 30. In the laser output control apparatus 31 calculates a laser output P _L from the laser output signal received, the deviation between the target value P _LO laser output
ΔP _L is determined by, for example, Equation 1, and the variable volume gas chamber 4 is set to a gas transmission / exhaust control device 16 ′ (corresponding to the gas chamber volume control device 16 in FIG. 1) so as to cancel the deviation ΔP _L. On the other hand, the gas is sent and exhausted through a gas sending and discharging pipe 17 '(corresponding to the gas chamber volume control transmission system 17 in FIG. 1).

ΔP _L = P _L −P _LO (Equation 1) When there is a relationship between the laser gas pressure p (density) and the laser output P _L as already shown in FIG. 2, the laser output P _L Is lower than the target output (ΔP _L <0), the gas is supplied to the variable volume gas chamber 4 as indicated by an arrow 33 ′ indicating the direction of gas supply and exhaust, and the volume of the variable volume gas chamber 4 is increased. raising the pressure of the laser gas 5 (density) Te increases the laser output P _L. Conversely, if the laser output P _L is higher than the target output (0 <ΔP _L ), the arrow 3 indicating the direction of gas supply and exhaust is used.
3 was evacuated variable volume gas chamber 4 of the gas as' reducing the pressure of the laser gas 5 (density) by reducing the volume of the variable volume gas chamber 4, it lowers the laser output P _L.

FIG. 5 shows the configuration of a gas supply / exhaust control device 16 ′ (corresponding to the gas chamber volume control device 16 in FIG. 1) for controlling the pressure (density) of the laser gas 5 using the variable volume gas chamber 4. . The gas supply / exhaust control device 16 ′ includes a gas supply source 41 serving as a driving force for changing the volume of the variable volume gas chamber 4, a gas pump 42, an electromagnetic valve 43, a mass flow controller 44, and a gas processing device 45 as necessary. Here, according to the command of the laser output control device 31 not shown,
The gas is supplied to the variable volume gas chamber 4 by a combination operation of the gas supply source 41 and the gas pump 42 or an operation of only the gas supply source 41. In consideration of the gas components used in the gas control type output stabilized gas laser apparatus of the first embodiment of the present invention, the gas of the gas supply source 41 is a laser gas, a gas composed of one or a plurality of laser gas components. Instead, it may be a rare gas or air. In the case of air, the gas supply source 41 becomes the atmosphere and only the gas pump 42 may be used.
Further, the exhaust gas is discharged to the atmosphere through an exhaust pipe 46 through a gas processing device 45. The gas processing device 45 is not required for non-hazardous gases such as rare gas and air.

In sending and discharging gas to and from the variable volume gas chamber 4,
With devices of the opening and closing operations only such as an electromagnetic valve, giving an abrupt change in the pressure of the laser gas 5 (density) by the gas pressure, resulting in, can on the laser output P _L adverse effects (fluctuation of the output) Therefore, using a device having a flow rate adjusting function such as the mass flow controller 44 is more suitable for the gas controlled output stabilized gas laser device of the first embodiment of the present invention.

Although not shown in FIG. 5, the gas introduced into the variable volume gas chamber 4 has, for example, a buffer cylinder in addition to a gas supply source cylinder. The gas can be pressurized and collected in a buffer cylinder using a gas pump, and can be used many times. Further, a gas sending / exhausting control device 1 is provided for supplying an inexpensive gas such as air or nitrogen.
When used at 6 ', after supplying an inexpensive gas to the variable volume gas chamber 4, this gas can be exhausted directly into the atmosphere to lower the pressure (density) of the laser gas 5.

FIG. 6 shows a first embodiment of the present invention.
Another volume control method of the variable volume gas chamber 4 will be described. this is,
This is a method utilizing expansion and contraction of the gas inside the variable volume gas chamber 4 due to heat. In this case, the variable volume gas chamber 4 is covered with a heat insulating material 47 or is constituted by the heat insulating material 47 itself so as not to thermally affect the laser gas. In FIG. 6, (a) has a structure having a heating unit 48 and a cooling unit 49 inside the variable volume gas chamber 4, or (b) has a heat exchange unit 50. In response to a command from the laser output control device 31 that has detected a change in the laser output, the internal gas of the variable volume gas chamber 4 is heated or cooled by the heat flowing in and out of the variable volume gas chamber 4 and the outside of the laser tube 1. Inflate or deflate the internal gas. The volume of the variable volume gas chamber 4 changes in accordance with the expansion and contraction of the gas, and the pressure (density) of the laser gas 5 in the laser tube 1 can be controlled. As a result, the laser output can be stabilized. A heater and a cooling unit 49 are used as the heating unit 48.
It is only necessary to provide a cooling pipe 51 for flowing a coolant such as water in the variable volume gas chamber 4. Alternatively, a heat control device 52 having a heating unit 48 and a cooling unit 49 is installed outside the variable volume gas chamber 4, and a heat exchange unit 50 is provided inside the variable volume gas chamber 4, and a heat medium pipe 53 is provided. The same effect can be obtained even if the heat is transmitted and received by the heat medium through the heat source.

FIG. 7 shows a first embodiment of the present invention.
Another method of controlling the volume of the variable volume gas chamber 4 using heat will be described. Since the energy source of the volume change is heat, the outside of the variable volume gas chamber 4 must have a hermetically sealed heat-insulating structure that does not adversely affect the laser gas 5, as in the case of FIG. In the example of FIG. 7, the piston inner surface 54 inside the piston type variable volume gas chamber 4 and the cylinder end surface 55 are shown.
Then, a spring 57 made of a shape memory alloy 56 is attached, and the piston 36 is moved by expansion and contraction of the spring 57 made of the shape memory alloy 56 by temperature control to change the volume of the variable volume gas chamber 4. It is. 7A shows a heating unit 48 and a cooling unit 49 in the variable volume gas chamber 4, and FIG.
Is a structure having an exchange unit 50. In addition, although not shown here, the sealed variable volume gas chamber 4 itself having a heat insulating structure is formed of a shape memory alloy 56 having a predetermined shape.
There is a method of controlling the temperature and changing the volume of the variable volume gas chamber 4 by utilizing the balance between the restoring force depending on the temperature of the shape memory alloy 56 and the pressure of the laser gas 5. Therefore, similarly to the embodiment shown in FIG. 6, the heating section 48 and the cooling section 49 or the heat exchange section 5 are provided inside the variable volume gas chamber 4.
0, heats the gas in the variable volume gas chamber 4 or heats or changes the volume of the variable volume gas chamber 4 by the flow of heat between the laser tube 1 and the outside according to a command from the laser output control device 31 which has detected a change in the laser output. After cooling, the shape of the spring 57 made of the shape memory alloy 56 in the variable volume gas chamber 4 or the shape of the variable volume gas chamber 4 itself is changed. However, in the case of this method, for example, when the heating is performed, the volume is increased by overcoming the pressure of the laser gas 5, and when cooled, the volume is reduced by losing the pressure of the laser gas 5 so that the volume is reduced. It is necessary to select a shape memory alloy 56 having power.

In the first embodiment of the present invention shown in FIGS. 6 and 7, the gas used in the variable volume gas chamber 4 in the volume control method of the variable volume gas chamber 4 using heat includes: Helium, which has a large heat transfer coefficient, has an advantage that the pressure (density) control speed of the laser gas 5 can be increased because heat is transferred quickly.

Further, in FIGS. 6 and 7, the variable volume gas chamber 4 is not made to be of a sealed type, and the pressure of the gas in the variable volume gas chamber 4 can be adjusted by the gas chamber volume control device 16. If the gas temperature control by 52 and the gas sending and exhausting by the gas sending and exhausting control device 16 'can be combined, there is an advantage that the pressure (density) control range of the laser gas 5 can be widened.

FIG. 8 shows a first embodiment of the present invention.
Another volume control method of the variable volume gas chamber 4 will be described. In the present volume control method, a gas chamber volume control motor 58 is used as a power source for changing the volume of the variable volume gas chamber 4. A gear 60 is attached to a rotation output shaft 59 of the gas chamber volume control motor 58, and a screw 62 is engraved on the outer peripheral portion of the rotation force of the gas chamber volume control motor 58 via a reduction gear 61. Is transmitted to the rotating shaft 63 for controlling the volume of the gas chamber. The reduction gear 61 has a structure 6 that can slide in the axial direction of the rotation shaft.
4, even if the gas chamber volume control rotary shaft 63 moves in the axial direction for volume control of the variable volume gas chamber 4, the rotational force of the gas chamber volume control motor 58 is reliably used for the gas chamber volume control. The structure can be transmitted to the rotating shaft 63. On the outer wall 65 of the laser tube 1, a set screw 66 fixed to the rotating shaft 63 for controlling the volume of the gas chamber is fixed. The rotary shaft 63 for controlling the volume of the gas chamber is provided with a set screw 66, an inner wall 67 of the laser tube 1, and an end face 68 of the bellows 37 in contact with the laser tube 1.
6, through a rotatable structure 70 inside the end face 69 of the bellows 37 on the laser gas side. The set screw 66 has a screw formed on the inner periphery like a nut, and is paired with the screw 62 on the outer periphery of the gas chamber volume control rotary shaft 63 to rotate the gas chamber volume control rotary shaft 63. The feed mechanism 71 is constituted by the feed mechanism 71.

The bellows 37 is airtight with respect to the laser gas 5, and has a volume control rotating shaft 63 by a feed mechanism 69.
The movement by the feed mechanism in the bellows 37 is transmitted to the end face 68 of the bellows connected by a rotatable structure to change the axial length of the bellows 37. Therefore, the laser tube 1
, The end face 69 of the bellows 37 moves as indicated by an arrow 73, the volume of the bellows 37 changes, and the pressure (density) of the laser gas 5 is controlled. When the rotation amount of the gas chamber volume control motor 58 is used as the control amount as in the present embodiment, a motor having a holding force at the time of stoppage, such as a stepping motor, is used as the gas chamber volume control motor 58. Is suitable.

As a second embodiment of the present invention, a laser tube 1
FIG. 9 shows a gas control type output stabilizing gas laser device in which a variable volume gas chamber 4 is installed outside of FIG. In this embodiment, the variable volume gas chamber 4 is connected to the laser gas conduit 7 communicating with the laser tube 1.
3, and is provided in another gas container 83.
The pressure (density) of the laser gas 5 is controlled through the laser gas conduit 73 by changing the volume of the variable volume gas chamber 4 in the gas container 83. The second embodiment has basically the same device configuration as that of the first embodiment shown in FIG. 1, and the laser output control method is completely the same.

FIG. 10 shows a laser gas partial exchange method as an application example of the use of the variable volume gas chamber 4 in the first embodiment or the second embodiment of the gas controlled output stabilized gas laser device of the present invention. Although the first embodiment in which the variable volume gas chamber 4 is incorporated in the laser tube 1 is used for explanation, the principle of the laser gas partial exchange method is the same in the second embodiment. For simplicity of explanation, the laser tube 1, the variable volume gas chamber 4 (piston type with the piston 36 and the cylinder 35), the laser gas 5, the laser gas supply / discharge device 6, the gas tube 24, the gas supply / exhaust control device 16 'and the gas supply Only the exhaust pipe 17 'is shown in FIG.
0 is shown.

First, it is assumed that the piston 36 in the variable volume gas chamber 4 before the first replacement is at the position shown in FIG. Next, the laser output control device 31 not shown here, based on the laser output, the laser gas pressure in the laser tube 1 and the pressure data in the variable volume gas chamber 4, ′, And a command to the laser gas supply / discharge device 6 to discharge the laser gas.

The gas supply / exhaust control device 16 ′ receives a command from the laser output control device 31 as shown in FIG.
The gas is sent to the variable volume gas chamber 4 in the direction of the arrow 33 ′ through the gas supply / discharge pipe 17 ′, and the piston 36 in the cylinder 35 is pushed toward the laser gas 5. At the same time, the laser gas supply / discharge device 6 also evacuates a part of the laser gas 5 from the laser tube 1 through the gas tube 24 as indicated by an arrow 34 in response to an exhaust command from the laser output control device 31. The gas supply and exhaust are performed while maintaining the balance between the gas supply and the exhaust so as to keep the laser output constant.

Next, when the volume of the variable volume gas chamber 4 reaches the maximum as shown in FIG. 4C, the laser output control device 31 sends the gas supply / discharge control device 16 'and the laser gas supply / discharge device 6 to stop the supply and discharge. Issue a command. Subsequently, the laser gas supply / discharge device 6
First, a gas supply instruction of the laser gas 5 is transmitted to the gas supply / exhaust control device 1.
6 ', a laser gas is supplied to the laser tube 1 as shown in FIG.
Exhaust gas inside. At this time, similarly to (b), the air supply and the exhaust are balanced so as to keep the laser output constant.

When the variable volume gas chamber 4 is used for partial replacement of the laser gas 5, the conventional method without the variable volume gas chamber 4
In order to keep the laser output constant, the pressure (density) of the laser gas 5 in the laser tube 1 should not be changed.
The supply and exhaust of the laser gas 5 must be performed simultaneously.
Therefore, there is a problem that the exhaustion of a part of the newly supplied laser gas 5 is unavoidable and the utilization efficiency of the laser gas 5 is poor. However, when the variable volume gas chamber 4 is used for the partial replacement of the laser gas 5 as in this embodiment, the utilization efficiency of the partially replaced laser gas 5 becomes 100%, and there is an advantage that the operating cost of the gas laser is reduced.

FIG. 11 shows a method of replenishing gas components using a piston type gas chamber as another application example of the variable volume gas chamber 4. In this application example, the laser gas 5 itself or a component gas of the laser gas is referred to as a variable volume gas chamber 4 ′, which is distinguished from the single function variable volume gas chamber 4 that only sends and exhausts the gas so far.
An electromagnetic valve 74 for gas release or a gas discharge port 75 that can be remotely controlled by the mass flow controller 44 or the like is provided outside the piston 36 or the cylinder 35 of the variable volume gas chamber 4 to change the volume of the variable volume gas chamber 4. The gas filled therein can be emitted into the laser tube 1.

When the variable volume gas chamber 4 'having the gas discharge port 75 is used, the supply of the laser gas 5 or the gas constituting the laser gas 5 to the variable volume gas chamber 4' and the inside of the variable volume gas chamber 4 ' Of the laser gas 5 or the gas constituting the laser gas 5 into the laser tube 1 at the same time. Therefore, while adjusting the laser output, the components of the laser gas 5 consumed by producing a compound or the like in the laser tube at the time of laser oscillation can be replenished in the laser tube 1, so that the laser output control device 16 'alone controls the laser output. There is an advantage that laser output stabilization can be maintained for a longer time than performing. However, in the piston type variable volume gas chamber 4, the laser gas 5 or the component gas of the laser gas 5 in the variable volume gas chamber 4 ′ flows out into the laser tube 1 by diffusion only by opening the gas discharge port 75. Therefore, it is expected that it will take some time to replenish the laser tube 1 with the laser gas 5 or the component gas of the laser gas 5.

Therefore, as a countermeasure example in this application,
As shown in FIG. 12, the variable volume gas chamber 4 'is desirably a balloon-shaped device having the property that its volume is reduced when there is no external force. Although the gas discharge solenoid valve 74 is attached to the tip of the balloon 38 here, a structure in which a branch is provided inside the laser tube 1 of the gas supply / discharge pipe 17 ′ and the gas discharge solenoid valve 74 is attached is also used. good. In general, when a balloon type or a bag type is adopted as the variable volume gas chamber 4, a partition wall 76 for fixing the balloon 38 or the bag 39 so as not to be affected by the laser gas 5 circulating in the laser tube 1. It is necessary to provide. In the case of the piston type, a spring 77 for attracting the piston 36 may be provided between the piston 36 inside the cylinder 35 and the inner wall of the variable volume gas chamber 4 'as shown in FIG.

FIG. 13 shows a third embodiment of the present invention. The present embodiment is a gas controlled type output stabilized gas laser device in which two variable volume gas chambers 4′a and 4′b are incorporated in a laser tube 1 as an example having a plurality of variable volume gas chambers. The configuration of the apparatus is the same as that of the first embodiment except that the number of variable volume gas chambers 4 and the type of gas used in the gas supply / exhaust control device 16 ′ are two types. When a plurality of variable volume gas chambers 4'a and 4'b are provided, there is an advantage that control of the pressure (density) of the laser gas 5 and replenishment of a specific component of the laser gas 5 consumed by laser oscillation can be separately performed. .

Referring to FIG. 14, the variable volume gas chamber 4'a,
The method of controlling the pressure (density) of the laser gas 5 and the method of replenishing the components of the laser gas 5 at 4′b are shown. Hereinafter, for the sake of simplicity, two variable volume gas chambers 4 are defined as a gas chamber 4'a and a
The gas chamber 4'a is used for controlling the pressure (density) of the laser gas 5, and the gas chamber 4'b is used for replenishing a specific component of the laser gas 5.

First, the process is started from the state (a) in which the gas is not filled in the gas chamber 4'b. In order to supply the replenishment component of the laser gas 5 to the gas chamber 4'b, while monitoring the laser output so that the laser output does not change, the gas pressure in the gas chamber 4'a is adjusted as shown in FIG. At the same time as (arrow 33) and evacuation (arrow 78), a gas that is a supplementary component of the laser gas is supplied to the gas chamber 4'b (arrow 79). And
As shown in (c), when a predetermined amount of the replenishment component gas is filled in the gas chamber 4′b, the gas chamber 4′b
By shutting off the supply source of the replenishing gas component in 6 ′ and monitoring the laser output, the gas discharge solenoid valve 74 of the gas chamber 4′b is opened as shown in FIGS. The replenishment component gas filled in the gas chamber 4 ′ b is discharged from the discharge port 75 into the laser tube 1 as needed. In some cases, air is supplied to gas chamber 4'a to suppress laser output fluctuation (arrow 80).
Should be combined.

According to the above method, the shortage gas component can be quickly replenished without lowering the laser output.
The deficiency of a specific gas component of the laser gas can be recovered. Further, by operating the gas supply / discharge device 6 in combination with the partial replacement of the laser gas 5, it is possible to further stabilize the laser output for a longer time.

FIG. 15 shows a variable volume gas chamber 4 ″ having a double structure.
Is shown. This is because when the gas for changing the volume of the variable volume gas chamber 4 is used as a replenishing gas for the laser gas as shown in the third embodiment of the present invention, the gas chamber in the bag type or piston type is used. In order to cope with the fact that the gas inside the variable volume gas chamber 4 is not quickly discharged into the laser gas 5 even when the gas discharge solenoid valve 74 is opened, there is no restoring force to return to the original shape. Things. (A)
Is a variable volume gas chamber 4 ″ having a double bag structure. This problem can be solved by using one bag 39a for controlling the pressure (density) of the laser gas 5 and for purging out the laser gas component from the gas chamber, and using the other bag 39b for replenishing the laser gas component. That is, if the bag 39b is filled with the predetermined laser gas component 81, and then the gas 82 for changing the volume of the gas chamber is sent to the bag 39a by the gas supply / exhaust pipe 17 ', the replenishment gas component 81 in the bag 39b is It will be pushed out. In the case of the piston type, as shown in FIG.
As shown in FIGS. 4A and 4B, another cylinder 35a for operating to push out the replenishment gas component 81 in the gas chamber may be provided on the side of the piston in contact with the laser gas 5. Therefore, in the case of (b), another variable volume gas chamber 4 ″ a is required for controlling the pressure (density) of the laser gas 5. However, in both (a) and (b), when the replenishment gas component 81 is expelled, care must be taken so that the pressure (density) of the laser gas 5 fluctuates and the laser output does not become unstable. In addition, when the variable volume gas chamber itself has a restoring force, such as a bellows type or balloon type,
The gas chamber does not need to be doubled, and the gas in the gas chamber can be discharged into the laser tube using the restoring force. At this time as well, care must be taken so that the pressure (density) of the laser gas 5 does not fluctuate.

[0056]

According to the present invention, in particular, the deficiencies of the prior art which can only be controlled for each value [Delta] P _L steps that the laser output P _L denotes a power system control in a pulsed laser, by adjusting the pressure of the laser gas, Since continuous high-speed control of the laser output is possible, high-precision output stabilization of the gas laser can be realized at relatively low cost.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration (first embodiment) of a gas controlled output stabilized gas laser device according to the present invention.

FIG. 2 is a characteristic curve diagram showing a relationship between laser gas pressure (density) and laser output applied in the present invention.

FIG. 3 is a sectional view showing a shape of a variable volume gas chamber used in the present invention.

FIG. 4 is a diagram showing a method of controlling the volume of a variable volume gas chamber by sending and discharging gas.

FIG. 5 is a configuration diagram showing a gas supply / exhaust control device.

FIG. 6 is a diagram showing a method of controlling the volume of a variable volume gas chamber by expansion and contraction of gas by heat.

FIG. 7 is a diagram showing a method of controlling the volume of the variable volume gas chamber by deforming the shape memory alloy by heat.

FIG. 8 is a diagram showing a method of controlling the volume of a variable volume gas chamber by mechanical movement of a motor.

FIG. 9 is a diagram showing an overall configuration (second embodiment) of a gas controlled output stabilized gas laser device.

FIG. 10 is a cross-sectional view showing a method for partially exchanging a laser gas using a variable volume gas chamber.

FIG. 11 is a sectional view showing a variable volume gas chamber provided with a gas discharge port.

FIG. 12 is a cross-sectional view showing a measure for increasing the speed of high-speed gas release from the variable volume gas chamber.

FIG. 13 is a diagram showing an overall configuration (third embodiment) of a gas controlled output stabilized gas laser device including two variable volume gas chambers.

FIG. 14 is a sectional view showing a laser gas component replenishment method using two variable volume gas chambers.

FIG. 15 is a sectional view showing a variable volume gas chamber having an internal gas purging mechanism.

FIG. 16 is an overall configuration diagram showing a conventional example of a halogen gas injection type output stable excimer laser device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Laser tube, 2 ... Main electrode, 3 ... Circulation fan, 4 ... Variable volume gas chamber, 5 ... Laser gas, 6 ... Laser gas supply / discharge device, 7 ... Gas pressure gauge, 8 ... Transmission window, 9 ... Laser power supply, 1
0: High-voltage electric wire, 11: Bearing support, 12: Motor for circulation fan, 13: Magnetic coupling, 14: Power shaft, 15
... discharge unit, 16 ... gas chamber volume control device, 16 '... gas sending and discharging control device, 17 ... gas chamber volume control transmission system, 17' ...
Gas supply / exhaust piping, 18: optical axis, 19: total reflection mirror, 20
... Output mirror, 21, 21 ', 21''... Laser beam, 22
… Beam splitter, 23… Laser power meter, 24
… Laser gas supply / discharge gas pipe, 25… Laser gas control signal line, 26… Gas pressure signal line, 27… Power control signal line, 2
8 ... circulation fan motor rotation control signal line, 29 ... gas chamber volume control signal line, 30 ... laser output signal line, 31 ... laser output control device, 32 ... arrow showing signal flow, 33 ...
Arrows indicating the operation of the gas chamber volume control device, 33 '... Arrows indicating the direction of gas sending and discharging, 34 ... Arrows indicating the flow of laser gas, 35 ... Cylinders, 36 ... Pistons, 37 ... Bellows, 38 ... Balloons, 39 ... bag, 40 ... arrow indicating the direction of deformation of the variable volume gas chamber, 41 ... gas supply source, 42 ... gas pump, 43 ... solenoid valve, 44 ... mass flow controller, 45 ... gas processing device, 46 ... exhaust pipe, 47 ... Insulation material, 48 heating unit, 49 cooling unit, 50 heat exchange unit, 5
DESCRIPTION OF SYMBOLS 1 ... Cooling pipe, 52 ... Heat control device, 53 ... Heat medium piping,
54: piston inner surface, 55: cylinder end surface, 56: shape memory alloy, 57: spring made of shape memory alloy, 58: volume control motor, 59: rotary output shaft of volume control motor, 60: gear, 61 ... Reduction gear, 62 ... screw, 63 ...
Rotating shaft for gas chamber volume control, 64 ... Slidable structure,
65: outer wall of laser tube, 66: set screw, 67: inner wall of laser tube, 68: end face of bellows in contact with laser tube, 6
9: End face of bellows on the laser gas side, 70 rotatable structure, 71: Rotation of rotating shaft for gas chamber volume control, 72: Feeding mechanism, 73: Laser gas conducting tube, 74: Solenoid valve for gas release, 75: Gas release Outlet, 76 ... partition wall, 77 ... spring, 78
... arrows indicating exhaust from the gas chamber, 79 ... arrows indicating gas supply to the laser tube, 80 ... arrows indicating air supply to the gas chamber,
81: replenishing gas component, 82: gas for changing the volume of the gas chamber,
83: gas container, 101: laser tube, 102: gas pipe, 103: laser gas exhaust system, 104: rare gas / buffer gas filling system, 105: halogen gas injection system, 106
... Laser gas, 107 ... Laser beam, 108 ... Output window, 109 ... Total reflection mirror, 110 ... Output mirror, 11
DESCRIPTION OF SYMBOLS 1 ... Beam splitter, 112 ... Power meter, 113
... excimer laser output control device, 114 ... laser output signal line, 115 ... laser power supply, 116 ... laser power control line, 117 ... laser output control line, 118
... gas flow controller, 119 ... solenoid valve, 120 ... halogen gas cylinder, 121 ... gas flow controller control signal line,
122: solenoid valve control signal line.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yukio Kawakubo 4026 Kuji-cho, Hitachi City, Ibaraki Prefecture Within Hitachi Research Laboratory, Hitachi, Ltd. (56) References JP-A-59-47786 (JP, A) 201960 (JP, U)

Claims (2)

(57) [Claims] 1. A laser tube, a laser gas supply / exhaust device for supplying a laser gas into the laser tube and exhausting the laser gas from the laser tube, a laser power meter for monitoring a laser output, and a portion in contact with the laser gas in the laser tube. A variable volume gas chamber provided to change the volume by displacing at least a part of the partition wall; calculating a laser output based on an input from the laser power meter; and calculating the calculated laser output. In a method of exchanging a laser gas in a gas laser device comprising: a laser output control device that controls the laser output by operating the variable volume gas chamber so that the deviation from the target output falls within a preset value or less. First, the laser gas is evacuated from the laser tube, and the volume of the variable volume gas chamber is reduced. Performing a first procedure, and then supplying a laser gas into the laser tube, and performing a second procedure for expanding the volume of the variable volume gas chamber. Exhausting and reducing the volume of the laser gas in the first procedure and the second procedure. The volume reduction of the variable gas chamber, and the supply of the laser gas and the volume expansion of the volume variable gas chamber are controlled and controlled so that the deviation between the calculated laser output and the target output does not exceed the set value. And a method of exchanging the laser gas in the laser tube partially while maintaining a constant laser output during operation of the gas laser device. 2. A laser tube, a laser gas supply / exhaust device, a laser power meter for monitoring a laser output, a variable volume gas chamber provided in a portion of the laser tube communicating with the laser gas, and a variable volume gas chamber. Means for changing the volume of the variable volume gas chamber, and a laser output control device for controlling the laser output by controlling the volume of the variable volume gas chamber. And changing the volume of the variable volume gas chamber, the laser output control device calculates a laser output based on the output of the laser power meter, and the calculated laser output and the predetermined target output In the meantime, if a deviation exceeding a preset value occurs, via the means for changing the volume of the variable volume gas chamber, operate the volume of the variable volume gas chamber, In the laser device for controlling a laser output, the laser output control device instructs the laser gas supply / exhaust device to exhaust the laser gas from inside the laser tube at the time of laser gas exchange, and sets the volume of the volume variable gas chamber to the deviation. Reducing the volume of the variable volume gas chamber by means of changing the volume of the variable volume gas chamber so as to be less than the value,
And, while instructing the laser gas supply and exhaust device to supply the laser gas into the laser tube, the volume of the variable volume gas chamber,
A gas laser apparatus characterized in that a part of the variable volume gas chamber is enlarged by means for changing the volume of the variable volume gas chamber so as to control the partial replacement of the laser gas so that the deviation falls within a set value or less.