JPH0927649A - Laser beam oscillation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To feed a stabilized quality laser beam in a long term by a method wherein the positional deviation of the laser beam is detected and the position on at least one side of the positions of an output mirror and a reflecting mirror is controlled so that the position of the laser beam becomes a reference position. SOLUTION: The vertical and horizontal intensity distribution signals measured by a beam monitor 22a are taken in by a controller 23. Whether the position of a laser beam 5 is within a beam position variation allowable range or not and whether it is due to an adjustment error or not that the position of the beam 5 is not within the allowable range are judged on the basis of these taken-in intensity distribution signals. In the case where it is judged that the cause is not due to the adjustment error, actuators 24a and 24b of a reflecting mirror 3 are controlled to adjust the position of the beam 5 so that the beam position of the beam 5 becomes a reference position. That is, a laser beam oscillation device controls the positions of the mirror 3 and an output mirror 4 on the basis of the beam position of the beam 5 and the balance of the intensity of the beam 5 to correct the positional deviation of the beam 5 and guarantees the quality of the beam 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser beam oscillating device which monitors a laser beam, prevents the output of the laser beam from deteriorating, becomes unstable, and vibrates at an oscillation wavelength, and performs stable control at all times.

[0002]

2. Description of the Related Art In a laser beam oscillating device, there is a problem that the quality of the laser beam is deteriorated due to deterioration of the laser medium, such as reduction of output of the laser beam, instability, fluctuation of oscillation wavelength.

In order to solve these problems, in the conventional laser beam oscillator, the output of the laser beam,
The quality of the laser beam is maintained by controlling the oscillation wavelength.

FIG. 5 is a diagram showing the structure of a conventional laser beam oscillator. As shown in the figure, the laser discharge unit 1
On one end side of the reflection mirror 3 via the laser narrow band resonator 2.
Is provided. An output mirror 4 is provided on the other end side of the laser discharge unit 1.

A laser beam 5 emitted from the output mirror 4
A beam splitter 6 is provided on the laser optical path of, and a beam splitter 7 is provided on the reflected optical path of the laser beam 5 reflected by the beam splitter 6.

Among the laser beams 5 incident on the beam splitter 7, an energy monitor 8 for monitoring the output of the incident laser beam is provided on the laser optical path of the laser beam 5 reflected by the beam splitter 7. A wavelength monitor 9 for monitoring the wavelength of the incident laser light is provided on the laser optical path of the laser beam 5 that has passed through the splitter 7.

The output side of the energy monitor 8 and the output side of the wavelength monitor 9 are connected to the input side of a controller 10, and the output side of the controller 10 is connected to the narrow band laser resonator 2 and the power supply 11. ing. The output side of the power supply 11 is connected to the electrode of the laser discharge unit 1.

Next, the operation of the laser beam oscillator constructed as described above will be described. First, the laser light generated in the laser discharge unit 1 is reflected between the reflecting mirror 3 and the output mirror 4 via the laser narrow band resonator 2, and then the laser beam 5 having a predetermined wavelength is output from the output mirror 4. Is emitted as.

The laser beam 5 emitted from the output mirror 4 is
A part of the laser beam 5 is reflected by the beam splitter 6, the laser beam 5 reflected by the beam splitter 6 is incident on the beam splitter 7, and a part thereof is reflected.

The laser beam 5 reflected by the beam splitter 7 enters the energy monitor 8 and its output is measured. The laser beam 5 that has passed through the beam splitter 7 is incident on the wavelength monitor 9 and its wavelength is measured.

The output of the laser beam 5 measured by the energy monitor 8 and the wavelength of the laser beam 5 measured by the wavelength monitor 9 are output to the controller 10. Based on the output of the laser beam 5 measured by the energy monitor 8 and the wavelength of the laser beam 5 measured by the wavelength monitor 9, the controller 10 outputs the resonance frequency of the laser narrow band resonator 2 and the power supply 11 from the power source 11. Laser discharge part 1
Control the voltage applied to the electrodes.

That is, in the conventional laser beam oscillator, the quality of the laser beam is improved by controlling the power supply 11 or the laser narrow band resonator 2 and controlling the output and oscillation wavelength of the laser beam. .

[0013]

However, in the conventional laser beam oscillator, as described above, only the output of the laser beam 5 and the oscillation wavelength are monitored and the laser beam 5 is emitted.
Since the stabilization control is performed, the positional deviation of the laser beam caused by the positional deviation of the laser narrow band resonator 2 cannot be detected, and as a result, the laser beam output is reduced due to the positional deviation. It was not possible to detect wavelength fluctuations and changes in spectral width.

Therefore, in the conventional laser beam oscillating device, erroneous control irrelevant to the direct cause is performed, so that the quality of the laser beam 5 cannot be guaranteed.

For example, when the output of the laser beam is reduced due to the displacement of the laser narrow band resonator 2 during the stabilization control of the laser beam, the controller 10 controls the power supply 11 to increase the laser beam output. The voltage applied to the electrode of the laser discharge part 1 is increased.

However, since the reduction of the laser beam output is not the reduction of the output due to the gas deterioration, the output hardly recovers even if such control is performed.
Further, even if the output of the laser beam is restored, erroneous control is continued, which not only results in a poor quality laser beam, but also shortens the life of parts such as electrodes.

The present invention has been made in view of the above circumstances, and by detecting the positional deviation of the laser beam, the quality of the laser beam, which is the most important element of the laser beam, can be stably supplied for a long period of time. An object is to provide a laser beam oscillator.

[0018]

Therefore, first, in order to achieve the above object, in the invention according to claim 1, the laser light generated from the laser light generating means is reflected between the output mirror and the reflecting mirror. In the laser beam oscillation device which later emits as a laser beam from the output mirror, the positional deviation amount detecting means for detecting the positional deviation amount of the position of the laser beam emitted from the output mirror with respect to the reference position, and the positional deviation amount detecting means. Laser beam position control for controlling the position of at least one of the output mirror and the reflecting mirror so that the position of the laser beam emitted from the output mirror becomes the reference position based on the amount of positional deviation detected by Means and means are provided.

According to a second aspect of the present invention, in the laser beam oscillator according to the first aspect, the positional deviation amount detecting means calculates a beam intensity distribution of at least one cross section of the laser beam, and the calculation is performed. It is characterized in that it is performed based on the obtained beam intensity distribution.

According to the first aspect of the present invention, the positional deviation amount detecting means detects the positional deviation amount of the position of the laser beam emitted from the output mirror with respect to the reference position, and the laser beam position control means detects the positional deviation amount detecting means. Of the output mirror and the reflecting mirror, the position of the laser beam emitted from the output mirror becomes the reference position based on the amount of positional deviation detected in
Since at least one position is controlled, the quality of the laser beam, which is the most important element of the laser beam, can be stably supplied for a long period of time.

According to the second aspect of the present invention, the amount of positional deviation is detected by calculating the beam intensity distribution of at least one cross section of the laser beam and based on the calculated beam intensity distribution.

[0022]

FIG. 1 is a diagram showing the configuration of a laser beam oscillator according to an embodiment of the present invention. Note that the same parts as those in FIG.
As shown in the figure, a reflecting mirror 3 is provided on one end side of the laser discharge unit 1 via a laser narrow band resonator 2.
An output mirror 4 is provided on the other end side of the laser discharge unit 1.

Laser beam 5 emitted from the output mirror 4
A beam splitter 6 is provided on the laser optical path of, and a beam splitter 7 is provided on the reflected optical path of the laser beam 5 reflected by the beam splitter 6.

Among the laser beams 5 incident on the beam splitter 7, an energy / wavelength monitor 20 is provided on the laser optical path of the laser beam 5 reflected by the beam splitter 7, and the laser beam passing through the beam splitter 7 is provided. A beam splitter 21 is provided on the laser optical path 5.

A beam monitor 22a is provided on the laser optical path of the laser beam 5 that has passed through the beam splitter 21, and a beam monitor 2 is provided on the laser optical path of the laser beam 5 reflected by the beam splitter 21.
2b is provided.

The output sides of the energy / wavelength monitor 20 and the beam monitors 22a and 22b are connected to the input side of a controller 23. The output side of the controller 23 is connected to the laser band-band resonator 2, the power source 11, Reflector actuators 24a, 24b, output mirror actuator 25
a and 25b are connected.

Next, referring to FIG. 2, the beam monitor 22
The configuration of a will be described. As shown in the figure, the beam monitor 22a includes a slit 31, a line sensor 32, a drive circuit 33, and a power supply 34.

The slit 31 is constructed so as to substantially coincide with the vertical beam diameter of the laser beam 5 in order to clearly detect the beam fluctuation. The line sensor 32 detects the vertical beam intensity of the laser beam 5 that has passed through the slit 31.

The drive circuit 33 drives the line sensor 32, and the drive power is supplied from the power supply 34. Regarding the configuration of the beam monitor 22b, the beam monitor 22a is different from the configuration of the beam monitor 22a except that the slit and the line sensor are configured to detect the beam intensity in the lateral direction.
The configuration is the same as that described above.

When the beam diameter of the laser beam 5 is large, the lens 35 is provided on the beam optical path of the laser beam 5 to reduce the beam diameter of the laser beam 5, as shown by the broken line in FIG. Good.

Next, the operation of the laser beam oscillator constructed as described above will be described. First, the laser light generated in the laser discharge unit 1 is reflected between the reflecting mirror 3 and the output mirror 4 via the laser narrow band resonator 2 and then emitted from the output mirror 4 as a laser beam 5.

Laser beam 5 emitted from this output mirror 4
Is partially reflected by the beam splitter 6. The laser beam 5 reflected by the beam splitter 6 is
It is incident on the beam splitter 7 and a part thereof is reflected.

The laser beam 5 reflected by the beam splitter 7 is incident on the energy / wavelength monitor 20, and the output of the incident laser beam 5 and its wavelength are measured by the energy / wavelength monitor 20. It is output to the controller 23.

The controller 23 applies the resonance frequency of the laser narrow band resonator 2 and the power source 11 to the electrode of the laser discharge section 1 based on the output and wavelength of the laser beam 5 measured by the energy / wavelength monitor 20. Control the voltage applied.

The laser beam 5 that has passed through the beam splitter 7 is partially reflected by the beam splitter 21. The reflected laser beam 5 is transmitted to the beam monitor 2
2b is output.

On the other hand, the laser beam 5 which has passed through the beam splitter 21 enters the beam monitor 22a. As shown in FIG. 2, the laser beam 5 incident on the beam monitor 22 a passes through the slit 31 and then the vertical beam intensity is detected by the line sensor 32, and the detected beam intensity is output to the controller 23. It

The beam intensity in the horizontal direction of the laser beam 5 incident on the beam monitor 22b is detected, and the detected beam intensity is output to the controller 23.
FIGS. 3A and 3B are diagrams showing intensity distribution waveforms in the vertical direction and the horizontal direction when the laser beam 5 is at the reference position.

The controller 23 uses the above-mentioned waveform in advance.
For example, based on the intersection of the intensity distribution waveform when 20% of the maximum value of the intensity distribution waveform is used as a threshold value, the vertical beam position (x ₁ , x ₂ ) and the horizontal beam position (y ₁ , y ₂ ),
The strength balances Ax and Ay are obtained.

The positional deviation of the laser beam 5 can be determined based on the beam position and intensity balance. For example, as shown in FIG. 3C, when the beam position (x ₁ ′, x ₂ ′) in the vertical direction (x direction) changes, the vertical actuator 24 a of the reflecting mirror 3 is controlled to Correct the positional deviation of the laser beam.

As shown in FIG. 3D, when the intensity balance Ay 'in the lateral direction (y direction) changes, the lateral actuator 25b of the output mirror 4 is controlled to control the laser beam. Correct the misalignment.

Further, the beam position (x
₁ ″, x ₂ ″) and the intensity balance Ax ″ change, the actuator 24a in the vertical direction of the reflecting mirror 3
After controlling, the beam intensity distribution is taken in and the beam position is reviewed and adjusted again.

The operation of the laser oscillator will be described below with reference to the flowchart of FIG. First, the controller 23 captures the vertical intensity distribution signal measured by the beam monitor 22a (step).
1).

Next, it is determined whether or not the laser beam 5 is within the beam position fluctuation allowable range based on the captured vertical intensity distribution signal (step 2). st
If it is determined in ep2 that the beam position variation is not within the allowable range, it is determined whether there is an adjustment error (s
step3). If it is determined that the adjustment error occurs in the processing of step 3, error processing is performed (step
4), the process ends.

If it is determined in step 3 that there is no adjustment error, the vertical actuator 24a of the reflecting mirror 3 is controlled to adjust the beam position of the laser beam 5 to the reference position (step 5). ), St
Return to the processing of ep1.

On the other hand, when it is determined in the processing of step 2 that the beam position variation is within the allowable range, the controller 23 causes the intensity balance of the intensity distribution signals in the vertical direction measured by the beam monitor 22a to vary. It is determined whether or not it is within the allowable range (step
6).

If it is determined in step 6 that the intensity balance of the intensity distribution signal in the vertical direction is not within the intensity balance fluctuation allowable range, it is determined whether or not there is an adjustment error (step 7). In the processing of step 7, if it is determined that there is an adjustment error, error processing is performed (step 8) and the processing ends.

When it is determined in step 7 that there is no adjustment error, the vertical actuator 24a on the output mirror 4 side is controlled to adjust the beam position of the laser beam 5 to the reference position ( step9), s
Return to step 1 processing.

On the other hand, when it is determined in step 6 that the intensity balance of the intensity distribution signals in the vertical direction is within the intensity balance variation allowable range, the controller 23
Thus, the lateral intensity distribution signal measured by the beam monitor 22b is captured (step 10).

Next, it is judged whether or not the laser beam 5 is within the beam position fluctuation allowable range based on the captured lateral intensity distribution signal (step 11). s
If it is determined in step 11 that the beam position variation is not within the allowable range, the adjustment error is determined (step 12). When it is determined that the adjustment error occurs in the processing of step 12, error processing is performed (step 13) and the processing ends.

If it is determined in step 12 that there is no adjustment error, the lateral actuator 24b of the reflecting mirror 3 is controlled to adjust the beam position of the laser beam 5 to the reference position (step 14). ),
It returns to the processing of step 10.

On the other hand, when it is determined in the processing of step 11 that the beam position variation is within the allowable range, the controller 23 causes the intensity balance of the lateral intensity distribution signal measured by the beam monitor 22b to vary. It is determined whether or not it is within the allowable range (ste
p15).

In the processing of step 15, when it is determined that the intensity balance of the intensity distribution signal in the lateral direction is not within the intensity balance fluctuation allowable range, it is determined whether or not there is an adjustment error (step 16). In the processing of step 16, if it is determined that there is an adjustment error, error processing is performed (step 17) and the processing ends.

When it is determined in step 16 that there is no adjustment error, the lateral actuator 24b on the output mirror 4 side is controlled to adjust the beam position of the laser beam 5 to the reference position ( step1
8) Return to step 10 processing.

On the other hand, if it is determined in step 15 that the intensity balance of the intensity distribution signal in the lateral direction is within the intensity balance variation allowable range, the process returns to step 1.

That is, the laser beam oscillator of the present embodiment controls the positions of the reflecting mirror 3 and the output mirror 4 based on the beam position and intensity balance of the laser beam 5 to determine the amount of positional deviation of the laser beam 5. Correction to ensure the quality of the laser beam, the beam monitor 22a,
22b can also be used as an energy monitor. When the beam monitors 22a and 22b are used as energy monitors, a switching mechanism for optical components in the beam monitor or an integrating circuit for a line sensor in the beam monitor is added.

Since the intensity distribution of the laser beam can be constantly observed by the beam monitors 22a and 22b, it can be used as a guide for beam quality diagnosis and manual alignment. Further, in the above-described embodiment, the vertical direction (x
Direction) and the lateral direction (y direction) based on the intensity distribution, the positions of the reflecting mirror 3 and the output mirror 4 are controlled to correct the positional deviation amount of the laser beam 5, but the intensity distribution is only in one direction. You may perform control based on.

Therefore, according to the laser beam oscillator of the present embodiment, the positional deviation of the laser beam 5 is corrected, and then the laser output control and the oscillation wavelength are controlled, so that the quality of the laser beam 5 is improved. Can be stabilized.

Further, since optimum control can be performed without performing unnecessary laser output control and oscillation wavelength control, taking the case of an excimer laser device as an example, it is also effective in extending the life of the laser gas. .

[0059]

As described above in detail, according to the present invention,
By detecting the positional deviation of the laser beam, it is possible to provide a laser beam oscillation device that can stably supply the quality of the laser beam, which is the most important element of the laser beam, for a long term.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a laser beam oscillator according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a beam monitor of the laser beam oscillator according to the same embodiment.

FIG. 3 is a diagram showing an output waveform of a beam monitor of the laser beam oscillator according to the same embodiment.

FIG. 4 is a flowchart for explaining the operation of the laser beam oscillator according to the same embodiment.

FIG. 5 is a diagram showing a configuration of a conventional laser beam oscillator.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Laser discharge part, 2 ... Laser narrow band resonator, 3 ... Reflector, 4 ... Output mirror, 5 ... Laser beam, 6, 7 ... Beam splitter, 11 ... Power supply, 20 ... Energy / wavelength monitor,
21 ... Beam splitter, 22a, 22b ... Beam monitor, 23 ... Controller, 24a, 24b ... Reflector actuator, 25a, 25b ... Output mirror actuator,
31 ... Slit, 32 ... Line sensor, 33 ... Sensor drive circuit, 34 ... Power supply.

Claims (2)

[Claims] 1. A laser beam oscillating device which emits a laser beam from a laser beam generating means as a laser beam after reflecting the laser beam from an output mirror and a reflecting mirror. The position deviation amount detecting means for detecting the position deviation amount of the beam position with respect to the reference position, and the position of the laser beam emitted from the output mirror is based on the position deviation amount detected by the position deviation amount detecting means. A laser beam oscillator comprising: a laser beam position control means for controlling the position of at least one of the output mirror and the reflecting mirror so that the reference position is reached. 2. The position shift amount detecting means calculates a beam intensity distribution of at least one cross section of the laser beam, and the calculation is performed based on the calculated beam intensity distribution. Laser beam oscillator.