JP2658975B2 - External mirror type 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 an external mirror type laser oscillator and, more particularly, to an inner diameter adjusting mechanism having an aperture structure disposed in the oscillator.

[0002]

2. Description of the Related Art An aperture mechanism is sometimes provided in a laser oscillator for controlling an oscillation mode or adjusting a laser output. FIG. 4 is a cross-sectional view of an external mirror type laser oscillator having such a diaphragm mechanism. As shown in the figure, Brewster windows 302a, 30
A pair of optical resonator mirrors 303 and 304 are disposed on the left and right sides of the laser tube 301 having the laser beam 2b, and on the optical axis between the Brewster window 302b on the emission side of the laser light 305 and the optical resonator mirror 303 on the output side. An aperture part 306 for regulating the output of the laser light 305 is provided.

FIG. 5 is a diagram showing a diaphragm component for controlling a laser oscillation mode disclosed in Japanese Utility Model Laid-Open Publication No. 63-136368 and Japanese Patent Laid-Open No. 2-12983.
5A and 5B are front views showing a closed state and an open state of the diaphragm, respectively, and FIG. 5C is a sectional view. As shown in FIG. 5, the diaphragm component 306 has a plurality of movable fins 307, and is a diaphragm similar to a so-called iris diaphragm used for a shutter portion of a camera. The structure is such that the hole diameter at the center can be varied by external control means.

In the external mirror type laser oscillator, the diffraction loss is adjusted by the aperture portion 306 with respect to the oscillation mode of the laser light determined by the configuration of the optical resonator mirror, the resonator length, and the shape of the laser tube. , T
EM ₀₀ mode (lateral single mode) or higher order mode (multi mode) can be selected. In the iris squeezing method, a laser beam is directly blocked by a movable portion perpendicular to the optical axis.

FIG. 6 is a sectional view showing a state of an output section of a laser having a diaphragm section proposed in Japanese Patent Application Laid-Open No. 58-79787. As shown in the figure, in this conventional example, a pair of condenser lenses 30 are disposed between a Brewster window 302 of a laser tube 301 and an output-side optical resonator mirror 303.
8, 309, a diaphragm part 310 having tapered grooves formed on both sides facing the condenser lens, and a diaphragm part 3
It has a driving unit 311 for changing the relative position between the focusing lens 10 and the focal point of the condenser lens, and the laser output can be changed by sliding the diaphragm component 310 on the optical axis. ing. In this method, a part of the laser beam is deflected by a groove tapering with respect to the optical axis.

[0006]

In the first conventional example shown in FIG. 5, a plurality of thin fins (made of metal, commercially available,
Black-dyed steel is generally used to change the hole diameter at the center, and lubricating oil is usually injected into the movable part and the fin-finished part.

Here, as is well known, in the external mirror type laser oscillator, the space between the Brewster window and the optical resonator has a dust-proof structure to prevent dust and the like from entering, and is used for the dust-proof structure. For each part that is used, materials that do not generate gas due to the use environment temperature, laser light, laser tube discharge light, etc. are selected and subjected to such thermal and chemical treatments. I have.

However, in the diaphragm parts shown in FIG. 5, the lubricating oil is a gas generation source inside the dustproof structure, and further, when the discharge light of the laser tube or the laser light is reduced, the temperature of the fins increases. The fins may oxidize with time and rust may occur. These generated gases, oxides, rust, and the like adhere to the Brewster window and the inner surface of the output mirror, causing a problem of causing a decrease in laser output and deterioration of optical components.

In addition, with respect to the iris diaphragm mechanism shown in FIG.
In order to suppress outgassing and oxidation / rust generation due to lubricating oil, for example, a metal that is not easily oxidized (for example, stainless steel, nickel-plated copper, etc.) is used for the fin material, and the fin thickness is increased. Although it is conceivable to increase the heat capacity and smooth the surface of the fins so that the lubricating oil can be eliminated, these countermeasures result in special iris diaphragm parts, which make the diaphragm mechanism very expensive. Would. Further, in the iris-type diaphragm component, as shown in FIG. 5C, the internal laser light 312 is reflected by the fins 307, and the reflected light 313 matching the optical axis of the internal laser light is returned to the laser tube. There are drawbacks that increase the noise of the laser beam and cause output instability.

In the diaphragm part shown in FIG. 6, the shape of the diaphragm part has a taper angle larger than the converging angle of the laser beam condensed by the pair of condenser lenses. The structure is such that the reflected light does not coincide with the laser optical axis, so that the influence of the reflected light can be suppressed. However, this method requires a pair of lenses, and thus has the disadvantage of increasing the size of the apparatus. Was. In addition, there is a problem in that the adjustment of the distance between the lenses is required, so that the number of steps for the adjustment increases.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to prevent generation of gas or foreign matter in the dust-proof structure, and to reduce the output and the like. An object of the present invention is to provide a diaphragm mechanism that can easily perform adjustment without increasing the size of the apparatus.

[0012]

According to the present invention, a Brewster window is provided at both ends disposed between a pair of optical resonator mirrors and between the pair of optical resonator mirrors. An external mirror type laser oscillator comprising: a laser tube provided; and a stop mechanism for reducing the diameter of laser light disposed between one of the optical resonator mirrors and the Brewster window. A drawing part having a drawing part having a trapezoidal shape and a plurality of crevices formed at a tip thereof, and a guide part having a pressing part for pressing the drawing part and holding the drawing part, wherein the drawing part and The external mirror type laser is characterized in that the aperture is adjusted by changing the relative position of the laser light in the optical axis direction with respect to the guide component and changing the pressing force of the pressing section against the aperture section. The oscillator, is provided.

[0013]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing a schematic configuration of an external mirror type laser oscillator according to a first embodiment of the present invention. As shown in the figure, Brewster windows 102a, 1
A pair of optical resonator mirrors 103 and 104 are disposed on both sides of the laser tube 101 provided with the laser tube 02b, and an aperture is provided between the Brewster window 102b on the side from which the laser light 105 is emitted and the optical resonator mirror 103. A mechanism 106 is provided. The aperture mechanism 106 includes an aperture component 107 and a guide component 108 that accommodates the aperture component 107.

FIG. 2A is a front view of the aperture mechanism 106 used in the first embodiment, and FIG.
Is a sectional view thereof. FIG. 2C shows the drawing part 10.
FIG. 7 is a perspective view of FIG. The aperture component 107 has a screw portion 107a having a cylindrical shape with a screw formed on the outer peripheral surface thereof, and an aperture portion 107b having a hollow truncated cone shape having a plurality of crevices 107c formed therein. The guide part 108 has a rectangular parallelepiped outer shape. The screw part 108a in which a screw that meshes with the screw part 107a of the drawing part is cut.
And a pressing portion 108b that presses the button 07b.

Here, the guide part 108 is fixed to the apparatus main body by a fixing member (not shown), and the screw part 108a and the pressing part 108b of the drawing part 10
7 is supported. When the stop part 107 is rotated about the optical axis of the laser beam, the guide part 1 of the stop part 107 is rotated.
The penetration into 08 changes, so that the aperture can be adjusted. That is, when the diaphragm part 107 is rotated and pushed to the right in FIG. 2B, the diaphragm part 107b of the diaphragm part 107 receives a pressing force from the pressing part 108b of the guide part 108, and the crevices 107c are formed. And the inner diameter is reduced. Conversely, drawing part 1
07 is pulled out to the left side of FIG.

The aperture 107b of the aperture component 107 is
Since the inner diameter of the tip portion is changed using elastic deformation, and it should not be easily oxidized by environmental temperature, laser light and laser tube discharge light, stainless steel or nickel plating is used. It is preferred to be formed of copper or the like. The guide component 108 is also preferably formed using the same material from the viewpoint of oxidation resistance.

Since the throttle mechanism of the present embodiment does not use lubricating oil, generation of gas can be prevented. Also, in the iris-type diaphragm shown in FIG. 5, the diaphragm component that blocks the laser light is almost perpendicular to the optical axis of the laser light, whereas in the diaphragm mechanism according to the present invention, the diaphragm component 1
Since the stop portion 107b of 07 is tapered with respect to the laser light, it is possible to prevent the reflected light at the laser light blocking portion from returning to the laser optical axis, prevent noise characteristics from deteriorating, and stabilize the output. Can be achieved.

Here, when the oscillation mode (single mode or multi mode) of the laser is selected by changing the inner diameter by using the friction 107c provided in the diaphragm 107b, a level that does not oscillate with respect to the higher mode. The desired mode can be selected even if the shape of the tip of the narrowed portion is not necessarily a perfect circle and there is a gap in the rubbed portion. In this case, since the oscillation threshold value of the higher-order mode differs depending on the type and configuration of the laser, it is necessary to set the number and width of the friction of the aperture portion according to each characteristic.

FIG. 3A is a sectional view showing the structure of the aperture mechanism 206 used in the second embodiment of the present invention, and FIG. 3B is a partially enlarged view of FIG. FIG. 3 (a),
As shown in (b), the pressing portion 2 of the guide component 208
08b is provided at the tip of the aperture part 207b of the aperture part 207.
A metal packing 209 is provided in order to suppress the contact resistance between the metal member and the guide component 208 so that the movement can be performed smoothly.

The screw part 207a of the stop part 207 is directly connected to a driven gear 212 driven by a driving gear 211. The drive gear 211 is driven by a drive unit 210 controlled by a control unit (not shown). Driven gear 21
2 can slide left and right with respect to the drive gear 211, and when rotated by the drive unit 210, moves with the stop part 207 left and right in the figure. According to the present embodiment, by combining with a laser power meter and a beam diameter measuring device, the aperture diameter of the aperture mechanism can be easily adjusted while monitoring the laser output and the beam diameter.

In the above-described embodiment, the guide component is fixed and the aperture component is movable. However, the guide component is reversed and the aperture component side is fixed to the apparatus main body, and the guide component is rotated to move left and right. Is also good. Also, the diaphragm 107b,
A light absorbing film can be formed on at least the inner surface of 207b.

[0022]

As described above, according to the present invention, the pressing force of the pressing portion of the guide component with respect to the drawing portion of the drawing component is adjusted by moving the drawing component with respect to the guide component, thereby reducing the inner diameter of the tip. Since it is changed, it is not necessary to use lubricating oil for the throttle mechanism, and generation of gas can be prevented. In addition, since it is possible to select a material that does not easily oxidize (for example, stainless steel, nickel-plated copper, or the like) as the material of the drawing mechanism, it is possible to suppress the occurrence of an oxide film or rust on the drawing part body. it can.

Therefore, according to the present invention, gas, oxide,
It is possible to reduce the laser output and the deterioration of optical components caused by the generation of foreign substances such as rust in the dust-proof structure without complicating and increasing the size of the device, increasing the number of assembly steps, and reducing the cost. This can be prevented by using a material.

Further, since the stop portion for directly blocking the laser beam has a tapered shape, the reflected light of the laser beam at the stop component can be deviated from the optical axis of the laser beam. It is possible to prevent a phenomenon in which light noise is generated or output is unstable due to interference with light itself.

[Brief description of the drawings]

FIG. 1 is a sectional view of a laser oscillator according to a first embodiment of the present invention.

FIG. 2 is a front view and a sectional view of a diaphragm mechanism used in a first embodiment of the present invention, and a perspective view of a diaphragm part.

FIG. 3 is a sectional view of a diaphragm mechanism used in a second embodiment of the present invention.

FIG. 4 is a cross-sectional view of a conventional laser oscillator.

FIG. 5 is a front view and a sectional view of a conventional drawing part.

FIG. 6 is a sectional view of another conventional example.

[Explanation of symbols]

101, 301 Laser tube 102a, 102b, 302a, 302b Brewster window 103, 104, 303, 304 Mirror for optical resonator 105, 305 Laser beam 106, 206 Throttle mechanism 107, 207 Throttle part 107a, 207a Screw part 107b, 207b Throttle Part 107c Friction 108, 208 Guide part 108a, 208a Screw part 108b, 208b Press part 209 Metal packing 210 Drive part 211 Drive gear 212 Follower gear 306, 310 Aperture part 307 Fin 308, 309 Condenser lens 311 Drive part 312 Internal laser Light 313 reflected light

Claims (3)

(57) [Claims] 1. A pair of optical resonator mirrors, a laser tube having Brewster windows at both ends disposed between the pair of optical resonator mirrors, one optical resonator mirror and the Brewster window, An external mirror type laser oscillator, comprising: a diaphragm mechanism for narrowing the diameter of laser light disposed between the diaphragm parts; wherein the diaphragm mechanism has a diaphragm portion having a hollow truncated cone shape and a plurality of crevices formed. And a guide part having a pressing part for pressing the stop part and holding the stop part, wherein the pressing is performed by changing the relative position of the stop part and the guide part in the optical axis direction of the laser light. An external mirror type laser oscillator, wherein the diaphragm is adjusted by changing a pressing force of the part on the diaphragm. 2. An outer peripheral surface of the aperture component and an inner wall surface of the guide component are carved with screws that mesh with each other, and one of the aperture component and the guide component is fixed to an apparatus body, 2. The external mirror type laser oscillator according to claim 1, wherein the relative position between the two is changed by rotating one of the other. 3. The diaphragm component of the diaphragm mechanism is made of stainless steel or copper, and has a surface plated with nickel.
The external mirror type laser oscillator as described in the above.