JPH0511146A - Optical fiber incidence correction device for solid laser device - Google Patents

Abstract

PURPOSE:To automatically align a laser beam with the center of the photodetection opening of a fiber. CONSTITUTION:The laser device makes the laser beam, outputted by a laser oscillator 3 equipped with a laser medium l and an exciting light lamp 2 for guiding exciting light to the laser medium 1, incident on the photodetection opening 10 of the optical fiber 5 through a condenser lens 4. The laser beam emitted by the laser oscillator 3 is branched and made incident on a condenser lens 7 for correction which has the same characteristics with the condenser lens 4, a detection part 8 receives the laser beam passed through the lens 7 for correction and detects the deviation of the laser optical axis from an orthogonal plane, and a 1st actuator 9 which moves the detection part and condenser lens 7 for correction at right angles to the optical axis is put in operation to obtain a correction direction and distance information; and then the photodetection opening 10 of the optical fiber and the condenser lens are moved by a 2nd actuator 11 by the same movement quantity at right angles to the optical axis.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for correcting deviation of a laser beam due to a thermal lens effect or output fluctuation in a solid-state laser device.

[0002]

2. Description of the Related Art Generally, in a laser resonator in which a laser medium is excited by a pump lamp to oscillate a laser beam, a laser beam may be displaced due to a thermal effect. This phenomenon is caused by the fact that the laser medium expands due to heat, which causes the position of the laser medium to shift. The laser beam may shift due to such a thermal effect or other disturbance factors, and the beam irradiation position on the irradiation plane may change with time.

If the beam irradiation position on the irradiation plane fluctuates, the transmission of the laser light to the optical fiber becomes insufficient, which causes a problem that it cannot be used efficiently. For this reason, in the past, the output was suppressed or the cooling device for the laser medium was improved to prevent overheating of the laser medium and stabilize the irradiation position of the laser beam. There is a problem such as not being able to do it or making the device large. Moreover, although the fluctuation range can be reduced by these methods, it cannot be completely stabilized, so that it is necessary to constantly adjust the optical system in response to the fluctuation.

[0004]

However, this adjustment is extremely troublesome, and there is a problem in that a dedicated engineer must constantly monitor the laser device while it is in operation.

The present invention has been made in view of the above-mentioned matters, and an optical fiber capable of automatically entering the laser beam at the center of the optical fiber even if the irradiation position on the plane of the laser beam changes. It is a technical object to provide an incident correction device.

[0006]

In order to solve the above technical problems, the present invention has the following constitution. That is, the present invention relates to a laser device in which a laser beam output from a laser oscillator equipped with a laser medium and an excitation lamp for introducing excitation light into the laser medium is incident on a light receiving port of an optical fiber through a condenser lens. That is, a branching device for branching a part of the laser beam output from the laser oscillator, a converging lens for correction having the same characteristics as the condensing lens provided in the next stage of the branching device, Detection unit for receiving the laser beam that has passed through the optical condensing lens,
A first actuator that moves the detection unit and the correction condensing lens in a direction orthogonal to the optical axis; a second actuator that moves the light receiving port and the condensing lens of the optical fiber in a direction orthogonal to the optical axis; And a calculation unit that receives the signal from the detection unit and controls the first and second actuators,
When the irradiation position of the laser beam irradiated on the detection unit by the correction condenser lens is displaced, the arithmetic unit detects the displacement and moves the detection unit and the correction condenser lens in the direction orthogonal to the optical axis. The optical fiber incidence correction apparatus in the solid-state laser device is configured to move the condenser lens and the light receiving port of the optical fiber by the same amount as the movement amount of the detection unit and the correction condenser lens at this time. Is.

The first and second actuators each have a moving means for two channels in the X and Y directions. Further, a bandpass filter can be inserted between the correction condenser lens and the branching device.

[0008]

The detector detects the deviation of the laser beam on the light receiving surface, and based on the data, the first actuator is operated to move the positions of the correction condenser lens and the detector, and the center position of the detector. Make the laser beam hit. In this case, the moving distance between the correcting condensing lens and the detection unit is obtained as the coordinates in the X and Y directions.

Then, the arithmetic unit operates the second actuator based on this data to move the condenser lens and the light receiving port of the optical fiber. At this time, it is moved by the same distance as the coordinates in the X and Y directions obtained by the first actuator.

As a result, the center of the laser beam is accurately incident on the center of the light receiving port of the optical fiber, and the light-converging property on the optical fiber can always be automatically adjusted to the optimum state. Therefore, the end face of the light receiving port of the optical fiber is not burned or the coupling efficiency is not deteriorated.

Incidentally, the meaning of moving the condenser lens and the light receiving port of the optical fiber by the same amount as the movement amount of the detecting portion and the correcting condenser lens is that the moving direction and the moving distance are the same. is there.

[0012]

Embodiments of the present invention will be described with reference to FIGS. An excitation lamp 2 for injecting excitation light is arranged in the vicinity of a rod-shaped laser medium 1, and a total reflection mirror 20a and a semi-transmission mirror 20b are arranged on both ends of the laser medium 1. .. Then, a laser beam is generated from the laser medium 1 excited by the excitation lamp 2 and is repeatedly reflected between the total reflection mirror 20a and the semi-transmission mirror 20b, whereby the laser oscillator 3 in which the light is amplified is configured. There is.

A beam splitter 6 as a branching device is installed on the laser transmitting side of the semi-transmissive mirror 20b so that the laser beam output from the laser oscillator 3 is divided into a straight traveling direction and a right-angled direction. ing. Then, the laser beam branched in the right angle direction is focused by the condenser lens 4
Light enters the light receiving port 10 provided at the tip of the optical fiber 5 via. The light receiving port 10 is supported integrally with the condenser lens 4 by a support arm 22. The condenser lens 4 is supported by the second actuator 11 and is configured to be movable on the XY plane orthogonal to the optical axis.

The second actuator 11 is a stepping motor 11 for moving the condenser lens 4 in the X direction.
a and a stepping motor 1 for moving in the Y direction
It consists of 1b. The stepping motor 11a is attached to the frame 11c.
The condenser lens 4 is slidably supported on the.
The condenser lens 4 and the stepping motor 11a are connected by a rack and pinion mechanism. The stepping motor 11b is attached to the fixed frame 11d,
The frame 11c is slidably provided on the fixed frame 11d. And this frame 11c
The stepping motor 11b and the stepping motor 11b are connected by a rack and pinion mechanism.

On the other hand, a bandpass filter 2 for passing only a specific wavelength is provided on the back surface of the beam splitter 6.
1 is provided, and its passing wavelength is set to 1.06 μm so as to remove visible light. A correcting condenser lens 7 having the same characteristics as the condenser lens 4 is provided at the next stage of the bandpass filter 21.

A two-dimensional photodiode array as a detector 8 for receiving the laser beam that has passed through the correcting condenser lens 7 is provided in the subsequent stage of the correcting condenser lens 7. The correction condenser lens 7 is an arm 23.
It is fixed to the detection unit 8 via the, and can be moved integrally with the detection unit 8. The detector 8 is supported by the first actuator 9 and is movable in the direction orthogonal to the optical axis. That is, this first actuator 9
Comprises a stepping motor 9a for moving the detecting section 8 in the X direction and a stepping motor 9b for moving the detecting section 8 in the Y direction.

The stepping motor 9a is attached to a frame 9c, and the detection unit 8 is attached to the frame 9c.
Is slidably supported. The detection unit 8 and the stepping motor 9a are connected by a rack and pinion mechanism. Stepping motor 9b is fixed frame 9d
The fixed frame 9d is slidably provided with the frame 9c. And
The frame 9c and the stepping motor 9b are connected by a rack and pinion mechanism.

The output signal of the detection unit 8 is input to the calculation unit 12, and the position of the laser beam irradiated on the detection unit 8 on the XY coordinates is digitized. Then, it is calculated how much the detector 8 should be moved in which direction to move the position of the laser beam to the center of the detector 8 (including a predetermined specific position), and the first actuator 9 Is configured to operate.

The first actuator 9 and the second actuator
The actuator 11 can use a servo motor or a linear stepping motor in addition to the stepping motor, and the driving amount thereof is controlled by a command from the arithmetic unit 12.

Further, a potentiometer, a rotary encoder, a linear encoder, etc. are attached to each actuator as moving amount detecting means, and the moving amount of the actuator is sent to the calculating unit 12 with the center of the detecting unit 8 as an absolute position. It can be output.

When the actuator is a stepping motor, the control amount when the correction lens is moved to adjust the irradiation position can be used as it is as the movement amount, so that the actuator itself constitutes the movement amount detecting means.

Further, as the detecting section 8, a photodiode array, a MOS image sensor, a CCD image sensor, other image pickup plates or image pickup tubes can be used. Hereinafter, an operation example will be described.

During the operation of the laser oscillator 3, the laser beam is split in the right angle direction by the beam splitter 6, and the light receiving port 10 of the optical fiber 5 is passed through the condenser lens 4.
Incident on. On the other hand, the laser beam transmitted through the beam splitter 6 irradiates the detection unit 8 via the bandpass filter 21 and the correction condenser lens 7. Then, the detector 8 detects the irradiation position of the laser beam.

This information is input to the arithmetic unit 12. Then, the calculation unit 12 determines whether or not the deviation of the incident light from the reference position is within a prescribed range, and when the irradiation position is deviated from the reference position of the detection unit 8, a signal for driving the actuator 9 is output. The detector 8 is moved so that the irradiation position is the reference position. Here, the calculation unit 12 stores this movement amount as a distance on the XY coordinates.

Subsequently, the arithmetic unit 12 drives the second actuator 11 based on this storage by the same distance in the same direction as the moving direction and moving distance of the first actuator 9. Since the condenser lens 4 and the correcting condenser lens 7 have the same characteristics, the irradiation position of the condenser lens 4 is the optical fiber 5
Coincides with the center position of the light receiving port 10.

By the above operation, energy can be concentrated and highly efficient coupling can be achieved.

[0027]

According to the present invention, the detecting section detects the deviation in the plane orthogonal to the laser optical axis, operates the first actuator based on the data, and obtains the distance information to be corrected. Since the second actuator is actuated by this distance information and the irradiation position is aligned with the center of the light receiving port of the optical fiber, the coupling with the optical fiber can always be in the best state.

[Brief description of drawings]

FIG. 1 is a side view showing an embodiment of the present invention.

FIG. 2 is a perspective view of a main part showing an embodiment of the present invention.

FIG. 3 is a perspective view of an essential part showing an embodiment of the present invention.

[Explanation of symbols]

 1 Laser Medium 2 Excitation Lamp 3 Laser Oscillator 4 Condensing Lens 5 Optical Fiber 6 Beam Splitter 7 Corrective Condensing Lens 8 Detecting Section 9 First Actuator 10 Light Receiving Port 11 Second Actuator 12 Computing Section

Front Page Continuation (72) Inventor Kazuyoshi Sudo 3 Miyachi Technos Co., Ltd. at 95 Futatsuka, Noda City, Chiba Prefecture

Claims (1)

Claim: What is claimed is: 1. A laser beam output from a laser oscillator comprising a laser medium and an excitation lamp for introducing excitation light into the laser medium is received by an optical fiber through a condenser lens. In the laser device incident on the mouth, a branching device for splitting a part of the laser beam output from the laser oscillator, and a correcting condensing lens having the same characteristics as the condensing lens provided in the next stage of the branching device. A detection unit that receives the laser beam that has passed through the correction condenser lens; a first actuator that moves the detection unit and the correction condenser lens in a direction orthogonal to the optical axis; a light receiving port of the optical fiber; A second actuator that moves the condenser lens in a direction orthogonal to the optical axis; and an arithmetic unit that receives the signal from the detection unit and controls the first and second actuators. The calculating unit detects when the irradiation position of the laser beam irradiated on the detecting unit by the correcting condenser lens is deviated, and moves the detecting unit and the correcting condenser lens in the direction orthogonal to the optical axis. An optical fiber incidence correction apparatus in a solid-state laser device, which is configured to move the condenser lens and the light receiving port of the optical fiber by the same amount as the movement amount of the detection unit and the correction condenser lens at this time.