JP2666592B2 - Gas laser oscillator - 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 oscillator for reducing microwave leakage from a microwave waveguide.

[0002]

2. Description of the Related Art FIG. 2 shows a configuration of a conventional gas laser oscillator using microwave excitation. In FIG. 2, 1 is a magnetron that generates microwaves, 2 is a copper plate that constitutes a part of a microwave resonator, 3 is a stub that matches the output impedance of the magnetron 1 to the impedance of the microwave resonator, and 4 is a discharge stub. A discharge tube for exciting the laser medium, 5 is a microwave waveguide for guiding microwaves to the discharge tube 4, 6 is a rear mirror, 7 is an output mirror, and two mirrors, a rear mirror 6 and an output mirror 7, are opposed to each other. To form an optical resonator. Reference numeral 11 denotes a laser beam emitted from the output mirror 7.

Next, the operation of the laser oscillator will be described with reference to FIG. The microwave generated by the magnetron 1 is matched in the stub 3 with the impedance of the discharge tube 4 and the output impedance of the magnetron 1, guided to the waveguide 5 so that there is almost no reflected power, and injected into the discharge tube 4. The laser medium is ionized by the microwave power injected into the discharge tube 4, and atoms or molecules of the laser medium repeat collisions to excite the laser medium while receiving energy from an electric field generated by the microwave. The excited laser medium emits energy as photons, and is optically amplified by an optical resonator including a rear mirror 6 and an output mirror 7 to generate a laser beam 11. A part of the amplified laser light 11 is emitted from the output mirror 7 and the rest is turned back inside the optical resonator to contribute to the optical amplification. Although the emitted laser beam 11 has a certain divergence angle, it is almost parallel and light with good coherence can be obtained.

[0004]

In the above conventional example, when the laser output becomes large, it is necessary to increase the beam diameter of the laser beam due to the problem of durability of the output mirror. Therefore, when the beam diameter is increased, the diameter of the discharge tube increases, and a large hole is formed in the copper plate located at the end of the waveguide. If a large hole is formed in the copper plate, microwaves leak from the hole, and if a face is brought close to the hole, there is a risk of causing blindness or cataracts.

An object of the present invention is to minimize leakage of microwaves from a microwave resonator and to ensure the safety of a human body.

[0006]

SUMMARY OF THE INVENTION To achieve the above object, the present invention provides an optical resonator having a shield cover provided so as to cover a rear mirror and an output mirror from a copper plate located at the end of a waveguide. A beam opening is provided on the intersection of the optical axis and the shield cover such that the circumference of the hole is less than 1/4 of the wavelength of the microwave, and the curvature of the output mirror is adjusted to output from the optical resonator. After setting the focal point of the laser beam near the beam opening and extracting the laser beam, the optical system and the shield cover for extracting the laser beam from the laser oscillator by using the beam diameter correction lens to make the laser beam almost parallel are provided. It was done.

[0007]

According to the above means, the microwave leaked from the copper plate located at the end face of the waveguide is stopped in the shield cover because the hole in the shield cover is sufficiently smaller than the wavelength of the microwave. Leakage to the outside can be prevented, and safety of the human body can be ensured.

[0008]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the gas laser oscillator of the present invention.

In FIG. 1, reference numeral 8 denotes a shield cover for preventing microwaves leaking from the microwave resonator from escaping to the outside, and reference numeral 9 denotes a hole whose size is such that the length around the hole is 1/1 / the wavelength of the microwave. A beam aperture manufactured to be less than 4 is a beam diameter correcting lens, and 11 is a laser beam. Laser light 11 is emitted from beam opening 9. Since the laser beam 11 emitted from the beam opening 9 has a large divergence angle, the laser beam 11 is adjusted by the beam diameter correcting lens 10 to be substantially parallel. Other symbols are the same as those of the conventional example.

Next, the operation of the gas laser oscillator of the present invention will be described. The microwave generated by the magnetron 1 is matched in the stub 3 with the impedance of the discharge tube 4 and the output impedance of the magnetron 1, guided to the waveguide 5 so that there is almost no reflected power, and injected into the discharge tube 4. The laser medium is ionized by the microwave power injected into the discharge tube 4, and atoms or molecules of the laser medium repeat collisions to excite the laser medium while receiving energy from an electric field generated by the microwave. The excited laser medium emits energy as photons, and is optically amplified by an optical resonator including a rear mirror 6 and an output mirror 7 to generate a laser beam 11. A part of the amplified laser light 11 is emitted from the output mirror 7 and the rest is turned back inside the optical resonator to contribute to the optical amplification. Unlike the conventional example, the emitted laser beam 11 has a focal point near the optical resonator due to the curvature of the output mirror 7, and the position of the focal point and the position of the beam port 9 provided on the shield cover 8. The positions are almost the same. Since the beam port 9 is provided near the focal point of the laser beam 11, the beam port 9 does not need to be a large hole, and the length around the hole can be made less than １ ／ of the wavelength of the microwave. Therefore, it does not leak from the shield cover 8 due to the nature of the microwave,
Human body safety can be ensured. Since the laser light 11 condensed in the vicinity of the beam opening 9 has a large divergence angle, it is shaped into a substantially parallel light beam using the beam diameter correction lens 10. Through the above process, a laser beam substantially similar to a conventional laser beam is obtained.

[0011]

As is apparent from the above description, according to the present invention, it is possible to greatly reduce microwave leakage from the microwave resonator and to ensure the safety of the human body.
The effect is great.

[Brief description of the drawings]

FIG. 1 is a perspective view of an embodiment of a gas laser oscillator according to the present invention.

FIG. 2 is a perspective view of a conventional gas laser oscillator.

[Explanation of symbols]

 2 Copper plate 4 Discharge tube 5 Microwave waveguide 6 Rear mirror 7 Output mirror 8 Shield cover 9 Beam port 10 Beam diameter correction lens 11 Laser beam

Claims (1)

(57) [Claims] 1. An optical resonator having one or more discharge tubes, a microwave resonator formed of a microwave waveguide and a copper plate on the outer periphery of the discharge tubes, and a rear mirror and an output mirror provided before and after the discharge tubes. And a shield cover that covers the rear mirror and the output mirror from a copper plate that forms part of the microwave resonator, and the length around the hole provided at the intersection of the optical axis of the optical resonator and the shield cover is equal to the microwave. A beam opening having a wavelength less than 1/4 of the wavelength, and adjusting the curvature of the output mirror to set the focal point of the laser beam emitted from the optical resonator in the vicinity of the beam opening. A gas laser oscillator that makes the laser light almost parallel using a beam diameter correction lens after taking out the laser beam.