JPH04162787A - Laser device - Google Patents

Abstract

PURPOSE:To make small energy loss by equipping it with a polarizing plate, which removes the polarized light components of the laser beam disordered during amplification, and a correction means, which detects the polarized light components of the output beam of a multistage laser amplifier and corrects the polarization of the laser beam that the multistage amplifier receives on the basis of that result. CONSTITUTION:One part of the laser beam outputted from a multistage laser amplifier 2 is separated, and this laser beam is made to enter a rotary polarizing plate 6, and the light whose quantity of light corresponds to the rotation of the rotary polarizing plate 6 enters a photodetector 8, and the photodetector 8 converts the incident light into an electric signal, and outputs this electric signal into a controller 9 as information of the quantity of light. On the other hand, the polarized light components disordered during laser beam amplification are removed by the polarization plate 3. This way, the polarization of the seed layer beam, which is input to this multistage laser amplifier 2 according to the polarization of the laser beam outputted from the multistage laser amplifier 2, is corrected. Accordingly, the quantity of the polarized light, which are contained in the laser beam outputted from the multistage laser amplifier 2 and are to be removed, become the minimum. Hereby, energy loss can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a high-output laser device, and particularly relates to a laser device that is equipped with multi-stage laser amplifiers and can specify arbitrary polarization for output light. .

[Prior Art] FIG. 2 is a schematic diagram showing a conventional laser device of this type.

A conventional high-output laser device includes a laser oscillator 1, a multistage laser amplifier 2, a polarizing plate 3, and a quarter-wave plate 4.

The laser oscillator 1 outputs a linearly polarized seed laser beam.

The multi-stage laser amplifier 2 amplifies the weak seed laser beam output from the laser oscillator 1 and outputs a high-energy laser beam. By passing this laser light through the polarizing plate 3, polarized light components that are disturbed during amplification by the multistage laser amplifier 2 are removed.

Then, the quarter-wave plate 4 converts the linearly polarized laser light that has passed through the polarizing plate 3 into arbitrary polarized light (in this case, circularly polarized light) and outputs it.

[Problem to be Solved by the Invention] However, in the conventional laser device, as described above, the polarized light components that are disturbed during amplification by the multi-stage laser amplifier 2 are removed by the polarizing plate 8; All polarized light components result in energy loss. Therefore, conventional laser devices have the drawback of large energy loss.

The present invention has been made in view of such problems, and includes:
It is an object of the present invention to provide a laser device with lower energy loss than conventional laser devices.

[Means for Solving the Problems] A laser device according to the present invention includes a laser oscillator that outputs linearly polarized laser light, and a multistage laser amplifier that inputs the laser light output from the laser oscillator and amplifies the laser light. , a polarizing plate that removes the polarization component of the laser light that is disturbed during amplification by the multistage laser amplifier, and a polarization plate that detects the polarization component of the output light of the multistage laser amplifier and, based on the result, controls the input laser light to the multistage laser amplifier. It is characterized by having a correction means for correcting polarization.

[Operation] In the present invention, the correction means detects the polarization component of the laser beam output from the multistage laser amplifier, and corrects the polarization of the laser beam that enters the multistage laser amplifier based on the result. That is, in the present invention, the polarization of the laser light incident on the multistage laser amplifier is corrected in advance so that the laser light output from the multistage laser amplifier becomes the closest to linearly polarized light.

As a result, the polarized light component removed by the polarizing plate after being output from the multi-stage laser amplifier is significantly reduced compared to the prior art. Therefore, the laser device according to the present invention has extremely low energy loss.

The correction means can be composed of, for example, a reflection plate, a rotating polarizing plate, a photodetector, a control means, a voltage application means, and a Pockels cell. That is, the Pockels cell is placed between the laser oscillator and the multistage laser amplifier. Further, a part of the amplified laser light output from the multi-stage laser amplifier is separated by a reflection plate, and this amplified laser light is made incident on a rotating polarizing plate. The photodetector receives the laser beam that has passed through the rotating polarizing plate and detects the polarized component of the amplified laser beam.

The control means outputs a control signal to make the output of the multistage laser amplifier linearly polarized light based on the detection result of the photodetector. The voltage applying means applies a predetermined voltage to the Pockels cell based on this control signal. Thereby, the polarization of the laser light incident on the multistage laser amplifier can be corrected, and the output light of the multistage laser amplifier can be made to be close to linearly polarized light. Therefore, the amount of polarized components of the amplified laser light to be removed by the polarizing plate can be reduced compared to the conventional method, and energy loss can be reduced.

[Embodiments] Next, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a schematic diagram showing a laser device according to an embodiment of the present invention.

A Pockels cell 11 is disposed between the laser oscillator 1 and the multistage laser amplifier 2. Further, a reflection plate 5 is disposed between the multistage laser amplifier 2 and the polarizing plate 3,
A portion of the laser light output from the multistage laser amplifier 2 is separated by a reflection plate 5. Most of the laser light output from the multi-stage laser amplifier 2 passes through this reflecting plate 5 and reaches the polarizing plate 3. This polarizing plate 3 removes the polarized light component that is disturbed when the laser light is amplified by the multistage laser amplifier 2, and allows only the linearly polarized laser light to be input.
/4 wavelength plate 4. The quarter-wave plate 4 arbitrarily polarizes this linearly polarized laser light (in this case, circularly polarizes it) and outputs it.

On the other hand, the laser beam separated by the reflection plate 5 is made to enter a rotating polarizing plate 6. This rotating polarizing plate e is driven and rotated by a driving device 7.

The drive device 7 also outputs rotation angle information synchronized with the rotation of the rotating polarizing plate 6 to the controller 9.

The light that has passed through the rotating polarizing plate 6 is incident on a photodetector 8 . This photodetector 8 converts the incident light into an electrical signal (light amount information) and outputs this electrical signal to the controller 9. Controller 9
is the rotation angle information input from the drive device 7 and the photodetector 8
Generates a feedback signal based on the electrical signal input from the The high voltage amplifier 10 amplifies this feedback signal and outputs a high voltage for driving and controlling the Pockels cell 11. The Pockels cell 11 polarizes the laser light passing through the Pockels cell 11 due to the electro-optic effect based on this high voltage.

Next, the operation of the laser device according to this embodiment will be explained.

A laser oscillator 1 outputs a linearly polarized seed laser beam. This laser light passes through the Pockels cell 11 and is input to the multistage laser amplifier 2. The multistage laser amplifier 2 amplifies the weak seed laser beam input from the laser oscillator 1 and outputs a high-energy laser beam.

The reflection plate 5 separates a portion of the laser light output from the multistage laser amplifier 2 and causes the laser light to enter the rotating polarizing plate 6 . This rotating polarizing plate 6 is driven and rotated by a driving device 7, and the amount of light corresponding to the rotation of the rotating polarizing plate 6 is incident on the photodetector 8. The photodetector 8 converts the incident light into an electrical signal, and outputs this electrical signal to the controller 9 as light amount information. On the other hand, the driving device 7 outputs rotation angle information of the rotating plate 6 to the controller 9 as the rotating polarizing plate 6 rotates.

The controller 9 calculates the polarization component of the output light of the multistage laser amplifier 2 from this rotation angle information and light amount information, and generates a feedback signal based on the result. This feedback signal is then output to the high voltage amplifier 10. The high voltage amplifier 10 amplifies this feedback signal to a voltage that drives the Pockels cell 11 and applies this voltage to the Pockels cell 11. Then, the Pockels cell 11 polarizes the seed laser beam output from the laser oscillator 1 due to the electro-optic effect. In this way, the polarization of the seed laser beam is controlled so that the output light of the multistage laser amplifier 2 becomes close to linearly polarized light.

The seed laser light polarized by the Pockels cell 11 is input to the multistage laser amplifier 2, and the multistage laser amplifier 2 outputs a high-output laser light.

In this case, the laser light output from the multistage laser amplifier 2 is close to linearly polarized light. A portion of this laser light is separated by the reflection plate 5 and used to control the polarization of the seed laser light as described above.

In addition, most of the laser light output from the multistage laser amplifier 2 passes through the reflection plate 5 and reaches the polarizing plate 3, and the polarized components that are disturbed during laser light amplification by the multistage laser amplifier 2 are removed. be done. The linearly polarized laser light that has passed through the polarizing plate 3 is arbitrarily polarized (circularly polarized in this case) by a quarter-wave plate 4 and output.

In this way, in this embodiment, the multistage laser amplifier 2
The seed laser beam input to this multistage laser amplifier 2 is polarized and corrected according to the polarization of the laser beam output from the multistage laser amplifier 2. Therefore, the amount of polarized components to be removed contained in the laser light output from the multi-stage laser amplifier 2 can be minimized, and energy loss can be significantly reduced compared to the conventional method. Further, even if the number of stages of the multistage laser amplifier 2 is reduced compared to the conventional one, the same output energy as that of the conventional laser device can be obtained, so the cost of the laser device can be reduced.

[Effects of the Invention] As explained above, according to the present invention, the control means detects the polarization component of the laser light output from the multistage laser amplifier and corrects the polarization of the laser light input to the multistage laser amplifier based on the result. is provided, the laser light output from the multistage laser amplifier can be made to be close to linearly polarized light. This makes it possible to minimize the amount of polarized components to be removed that are included in the laser light output from the multi-stage laser amplifier. Therefore, the laser device according to the present invention has extremely low energy loss compared to conventional laser devices. Further, even if the number of stages of the multi-stage laser amplifier is reduced, the same output energy as the conventional laser device can be obtained, so there is also an effect that the device cost can be reduced.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a laser device according to an embodiment of the present invention, and FIG. 2 is a schematic diagram showing a conventional laser device. 1; Laser oscillator, 2; Multi-stage laser amplifier, 3; Polarizing plate, 4; 1/4 wavelength plate, 5; Reflector, 6; Rotating polarizing plate, 7
; Drive device, 8; Photodetector, 11; Pockels cell

Claims (2)

[Claims] (1) A laser oscillator that outputs linearly polarized laser light;
a multi-stage laser amplifier that inputs and amplifies the laser light output from the laser oscillator; a polarizing plate that removes the polarization component of the laser light that is disturbed during amplification by the multi-stage laser amplifier; and an output light of the multi-stage laser amplifier. A laser device comprising: a correction means for detecting a polarization component of the laser beam and correcting the polarization of the laser beam input to the multistage laser amplifier based on the result. (2) The correction means includes a Pockels cell disposed between the laser oscillator and the multistage laser amplifier, and a reflection plate that separates a part of the output light of the multistage laser amplifier;
a rotating polarizing plate into which the output light of the multi-stage laser amplifier separated by the reflecting plate enters; a photodetector which receives the laser beam that has passed through the rotating polarizing plate and detects the polarized component of the amplified laser beam; A control means for outputting a control signal to linearly polarize the polarization component of the amplified laser beam based on the detection result of the photodetector, and a voltage application means for applying a predetermined voltage to the Pockels cell based on the control signal. The laser device according to claim 1, characterized in that it is comprised of: