JPS5855663Y2 - Laser oscillation device - Google Patents

Description

[Detailed Description of the Invention] Technical Field of the Invention The present invention relates to a laser oscillation device in which the characteristics of a resonator can be changed.

Technical background of the invention and its problems In recent years, laser oscillation devices with unstable resonators have been attracting attention as devices capable of generating high-output, relatively well-focused laser beams.

However, since unstable resonators have a short history of development, there are almost no examples of their application to actual laser oscillation devices.

On the other hand, most of the resonators of conventional laser oscillation devices have been of stable type.

However, the stable resonator uses Zn5e as the output mirror.
An expensive semiconductor mirror such as GaAs or GaAs must be used.

Therefore, there is a drawback that the cost of changing the characteristics of the resonator depending on the intended use of the laser oscillator is extremely high.

On the other hand, an unstable resonator is composed of only a metal mirror, which is much cheaper than the semiconductor mirror mentioned above, as a reflecting mirror, so it is possible to change the characteristics of the resonator by using a reflecting mirror with a different curvature. can be done relatively cheaply.

However, in the past, no laser oscillation device having the above-mentioned unstable resonator has been developed in which the characteristics of the resonator can be easily changed.

In addition, the output mirror of a stable resonator is a plane mirror, and the laser beam emitted from this output mirror is a plane wave, but the beam diameter increases as the distance increases due to diffraction.

If this happens, it will not fit into the processing lens with a small diameter, resulting in the disadvantage of having to use an expensive large diameter lens. A problem arises in that a beam transmission system is required.

OBJECT OF THE INVENTION The object of the present invention is to provide a laser oscillation device in which the characteristics of an unstable resonator, that is, the reflecting mirror can be easily changed to one with a different curvature.

Summary of the invention A pair of reflecting mirror housings are arranged to face each other through an excitation space formed by the main body of the oscillator, and a plurality of reflection mirrors with different curvatures that can be slid into the reflecting mirror housings by external operation are provided. This laser oscillation device is provided with a movable body holding a mirror, and by manipulating these movable bodies, the curvature of a pair of opposing reflecting mirrors constituting an unstable resonator can be changed.

Examples of ideas An embodiment of the present invention will be described below with reference to the drawings.

First, Figure 1 shows an outline of a general unstable resonator.
In the figure, 1 is an excitation space.

A concave reflecting mirror 2 and a convex reflecting mirror 3 made of metal mirrors are arranged to face each other with the excitation space 1 interposed therebetween.

In the vicinity of the convex reflecting mirror 3, a combined reflecting mirror 5 having a through hole 4 is provided at an inclination angle of 45°.

Therefore, the laser beam L excited by the concave reflector 2 and the convex reflector 3 is reflected by the combined reflector 5, and from the output window 6 provided in the direction of reflection, a laser beam having an annular cross-section is emitted. It becomes L and emits.

In such an unstable resonator, the curvature of the concave reflector 2 is R1, and the curvature of the convex reflector 3 is R, as shown in FIG.
2. The distance between these reflecting mirrors 2 and 3 is l, and the concave reflecting mirror 2
Let a be the steady-state curvature of the wavefront of the light inside the resonator produced by the convex reflecting mirror 3, and b be the curvature of the wavefront of the light produced by the convex reflecting mirror 3.

By solving equations (1) and (2) simultaneously, a,
l) is determined, and furthermore, the magnification rate M is determined by.

Then, the distance a from the concave reflecting mirror 2 to the minimum diameter of the laser beam L and the equivalent degree of coupling determined by the above equations (1), (2), and (3) are determined.

The degree of coupling usually has an optimum value for each laser oscillation device, and when it deviates significantly from this optimum value, the oscillation efficiency becomes extremely poor.

In an unstable resonator, the degree of coupling is determined by the magnification factor M, as described above.

Therefore, when changing the characteristics of the resonator depending on the purpose of use, the concave reflector 2 and the convex reflector 3 are arranged so that the magnification factor M is kept almost constant and only the distance a that provides the minimum beam diameter is changed.
curvature R], the combination pregnancy of R2 must be determined.

A specific example of the resonator of the present invention made from this point of view is shown in FIGS. 3 and 4.

That is, numeral 11 in the figure is the main body of the oscillation device forming the excitation space 1.

At both ends of the main body 11, there is provided a first reflecting mirror housing 13 in which a plurality of concave reflecting mirrors 2 with different curvatures are built in via bellows 12°]2, and a plurality of concave reflecting mirrors 2 with different curvatures are built in. A second reflecting mirror housing section 14 in which convex reflecting mirrors 3 are incorporated is provided so as to face it.

These first. The second reflecting mirror storage section 13,14 is constructed as shown in FIG.

That is, a pair of guide shafts 16.16 are installed in the housing 15 so as to be spaced apart from each other in the vertical direction, with both ends fixed to inner surfaces of both sides of the housing 15.

A movable body 17 is slidably provided on these guide shafts 16,16.

A pair of mounting holes 18.18 are formed in this movable body 17 in a direction perpendicular to the axial direction of the guide shaft 16.16,
These mounting holes 18 and 18 are provided with the concave reflector 2 or convex reflector 3 having different curvatures, respectively.
... is maintained.

Further, the movable body 17 is provided with a drive shaft 19 connected at one end so as to be parallel to the guide shaft 16.16.

The other end of the drive shaft 19 protrudes airtight from an insertion portion 20 provided on one side outer surface of the housing 15 via an O-ring 21.

Therefore, the housing 15 of this drive shaft 19. If the moving body 17 is moved by pushing and pulling the protruding end,
A desired curvature of the concave reflecting mirror 2 and the convex reflecting mirror 3 provided in the first reflecting mirror housing 13 and the second reflecting mirror housing 14, respectively. can be opposed to each other with the excitation space 1 interposed therebetween.

A stopper 22 for positioning the movable body 17 is provided at the end of the guide shaft 16.16, and a scale 23 is attached to the end protruding from the insertion portion 20 of the drive shaft 19. 22 and scale 23, it is possible to position the concave reflecting mirror 2 and the convex reflecting mirror 3.

Further, in the main body 11, a coupled reflector 5 is provided at an end on the second reflector housing 14 side at an inclination angle of 45°, and an output window 6 is formed in the direction of reflection. There is.

Note that the movable body 17 has a cooling water supply pipe made of a flexible tube for cooling the reflecting mirrors 2...3... held in the mounting holes 18.18. 24a and discharge pipe 24b are connected.

According to the resonator configured in this way, when changing the characteristics of the resonator, that is, the distance a that provides the minimum beam diameter, depending on the purpose of use of the laser beam L, the first. A drive shaft 19 protruding from one side of the second reflector housing 13.14.
19 and slide each movable body 17.17, the concave reflecting mirrors 2 and 17 facing each other across the excitation space 1 are moved.
. . . and the convex reflecting mirror 3 . . . may be changed to ones with different curvatures.

Such an operation is performed in the first step. The driving shaft 19.19, which protrudes airtight from the second reflector housing 13.14, allows this to be carried out easily and quickly without breaking the vacuum state of the excitation space 1.

Moreover, according to the unstable resonator having the above configuration, inexpensive metal mirrors can be used for the concave reflecting mirror 2 and the convex reflecting mirror 3. In order to be able to change the characteristics of each reflector housing 13
．． 14 with multiple reflecting mirrors 2...3...
Even if it is provided, it can be constructed at low cost without causing a significant increase in cost.

Furthermore, since the resonator of the present invention is unstable, the laser beam L output from the output window 6 does not spread unlike in the case of a stable resonator.

Therefore, it is not necessary to use a processing lens with a large diameter according to the spread of the laser beam L, or to use a special transmission system such as a collimator lens to collimate the laser beam L.

Furthermore, if the excitation method of the laser medium can be changed in the same laser (for example, C
It is also possible to switch the resonator configuration to obtain the optimum coupling ratio for each excitation method (such as switching between W mode and pulsed mode).

Effects of the invention As described above, according to the invention, the reflector constituting the unstable resonator can be easily and quickly changed to one with a different curvature without breaking the vacuum of the excitation space, and the characteristics of the resonator, that is, the laser beam can be improved. The distance at which the beam has the minimum diameter and the coupling rate can be adjusted depending on the purpose of use.

In addition, since it is an unstable resonator, an inexpensive metal mirror can be used as the above-mentioned reflector, so even if multiple reflectors are used to change the characteristics of the resonator, there is no significant cost. It does not cause high fever.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIGS. 1 and 2 are explanatory diagrams of an unstable resonator, FIG. 3 is a schematic configuration diagram, and FIG. 4 is a partially broken perspective view of the reflector housing. It is a diagram. 1...Excitation space, 2...Concave reflecting mirror,
3...Convex reflecting mirror, 11...Main body, 1
3.14...Reflector storage section, 17...
Moving body, 19... Drive shaft.

Claims (1)

[Scope of utility model registration request] A main body of an oscillation device that forms an excitation space, a pair of reflecting mirror housings arranged to face the main body through the excitation space, and a pair of reflecting mirror housings that are provided in the reflecting mirror housings so as to be slidable by an operation from the outside. 1. A laser oscillation device comprising: a movable body; and a plurality of reflecting mirrors each having a different curvature, each of which is held by the movable body.