JPS62165985A - Laser oscillator stabilized at diverging angle of laser beam - Google Patents

Abstract

PURPOSE:To stabilize a beam diverging angle by a simple controller by composing a solid state laser oscillator of a curvature variable reflecting mirror for forming a resonator, a laser beam detector for detecting the diverging angle of an emitted beam, and a controller for controlling the curvature of the mirror in response to the output of the detector. CONSTITUTION:A curvature variable full-reflecting mirror 1 which uses a piezo element is provided at one side of a laser medium 2, and a partial transmission reflecting mirror 3 is provided at the other side. In this structure, the diverging angle theta of a laser beam emitted from the mirror 3 is determined by the curvatures of the mirrors 1, 3 and the thermal lens effect of the medium 2, and the lens effect is varied by an exciting energy to thereby cause the diverging angle theta to alter. Accordingly, the beam is branched by a beam splitter 4, the variation of the diverging angle is detected by a beam detector 5 to be converted into an electric signal, which is input to a controller 6 to control the curvature of the mirror 1 by the output of the controller.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a solid-state Raded oscillator, and particularly to stabilization of the divergence angle of an emitted beam. [Prior Art] In a conventional solid-state Raded oscillator, the laser beam The spread angle of the beam is sometimes controlled by an additional L beam expander outside the laser oscillator.

[Problem that the invention seeks to solve]

However, when controlling the beam expansion angle using a shear beam expander, variations in the beam diameter are unavoidable. Moreover, it requires two or more lenses that are difficult to control. However, if the excitation energy to the Laser medium changes, a thermal lensing effect of the laser medium will occur, and as a result, it is difficult to fully stabilize the variation of the beam divergence angle.

[Means for solving problems]

According to the invention, in a solid state laser oscillator.

A variable curvature reflector serving as a reflector constituting a resonator, a laser beam detection device that detects all nine angles of spread of the emitted beam, and controlling the curvature of the variable curvature reflector according to the output of the laser beam detection device. A laser oscillator with a stabilized divergence angle is obtained, characterized by having a control circuit that controls □□.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 shows a laser oscillator according to one embodiment of the invention.

The illustrated laser oscillator includes a variable curvature total reflection mirror 1 using a piezo element sound, a laser medium 2, and a two-part transmission reflection mirror 3. The laser beam output from the partially transmitting reflector 3 has a total divergence angle θ. This expansion angle θ is caused by the curvature of the reflecting mirrors 1 and 3 and the thermal lens effect of the laser medium 2.

Here, the curvature of the reflecting mirror 3 is uniquely determined by the lens focal length. On the other hand, the thermal lens effect of the laser medium 2 varies depending on the excitation energy. Therefore, if there is a change in the excitation energy for the Rade medium 2, there is a possibility that the spread angle θ of the laser beam will also change.

In view of the above, the laser oscillator shown in FIG. 2 further includes a laser beam detection device that detects a nine-angle variation in laser beam expansion. This laser beam detection device includes a beam splitter 4 that is designed to split all of the laser beams, and a precise laser beam detector 5 that detects variations in the divergence angle of the laser beam split by the beam splitter 4. have. The laser beam detector 5 outputs an electric signal representing the variation in the divergence angle of the laser beam. The output signal of the detector 5 is input to the control circuit 6. The control circuit 6 changes the curvature of the variable curvature total reflection m1 depending on its output. That is, the control circuit 6 performs feedback control to stabilize the nine-angle variation in the spread of the laser beam. Note that the radius of curvature of the reflecting mirror 1 can be arbitrarily changed within a range from infinity to several meters.

Next, we will explain the principle of a variable curvature total reflection mirror using piezo elements in the second section.
The explanation will be given with reference to FIG. 3 and the entire circumference of FIG.

In FIG. 2, numeral 11 is a material made by pasting together two piezo elements, and electrodes are attached to the piezo elements so that electric fields are directed in opposite directions. Here, a dielectric is completely vapor-deposited on one end surface.

It is a total reflection mirror. Now, when a spot field is applied to the piezo elements by the control circuit 12, stresses in mutually opposite directions are applied to the two piezo elements as shown in FIG. 3, resulting in a radius of curvature approximated by 5 curvatures and R.

〔Effect of the invention〕

As explained above, the present invention does not require any other optical system such as a beam exosender other than a laser oscillator, and has the effect that the spread angle of the laser beam can be fully stabilized by a simple control circuit.

[Brief explanation of drawings]

FIG. 1 is a configuration explanatory diagram showing one embodiment of the present invention. FIG. 2 is a diagram illustrating the control principle of the variable curvature total reflection mirror used in the same embodiment, and FIG. 3 is a diagram illustrating the principle of changing the curvature of the variable curvature total reflection mirror. 1... Curvature variable total reflection mirror, 2... Laser medium, 3...
・Partially transmitting reflector, 4...Beam splitter-95
...Laser beam detector, 6...Control circuit. Figure 2 Figure 3

Claims (1)

[Claims] 1) In a solid-state laser oscillator, a variable curvature reflector as a reflector constituting a resonator, a laser beam detector that detects the divergence angle of the emitted beam, and a variable curvature reflector that detects the divergence angle of the emitted beam according to the output of the laser beam detector. 1. A laser oscillator that stabilizes the spread angle of a laser beam, comprising a control circuit that controls the curvature of a mirror.