JPH0624266B2 - Laser equipment - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a laser device having a laser beam position detecting means.

<Prior Art> A conventional laser device of this type is shown in FIG.

In FIG. 1 (a), 1 is an AC high voltage power source, 2 and 3 are electrodes arranged opposite to each other, 4 is each electrode 2,
Silent discharge generated between 3, 5 is a partial reflection mirror, 6 is a total reflection mirror, 7 is an aperture for mode selection arranged near the partial reflection mirror 5, and 8 is a gas flow of a laser medium gas. Yes, it is flowing in a direction perpendicular to the plane of the paper as shown in FIG. Reference numeral 9 is a laser beam to be generated. In FIGS. 1 (b) and 1 (c), reference numeral 70 is an aperture member that constitutes the aperture 7, and a circular opening 71 is provided on the laser optical axis which is the center of the aperture member. Aperture member 70 is provided with a groove 72 extending in the diametrical direction on the outer periphery of opening 71, and a thermocouple 73 as a temperature detecting element is provided in groove 72. Reference numeral 74 denotes cooling water which flows through the passage 75 in the aperture member 70 to cool the aperture member 70 and has a flow indicated by an arrow in FIG. 1 (c).

Next, the operation of FIG. 1 will be described. First, an AC high voltage is applied from the power source 1 between the electrodes 2 and 3 to
Silent discharge 4 is generated during 3. On the other hand, a gas flow 8 of the laser medium gas is caused to flow between the electrodes 2 and 3, and the laser medium gas is excited by the silent discharge 4 to generate laser light. If the partial reflection mirror 5 and the total reflection mirror 6 are arranged to face each other across the silent discharge 4 and the aperture 7 having the circular opening 71 is arranged in the vicinity of the partial reflection mirror 5, the circular reflection mirror 5 and the total reflection mirror 6 are circular. The laser beam 9 can be taken out. In this case, if the positions where the partial reflection mirror 5 and the total reflection mirror 6 are opposed to each other are adjusted, that is, if the alignment is poor, the mode symmetry of the laser beam 9 is broken, so that the temperature of each part of the aperture member 70 is reduced. Distribution occurs. Therefore, in order that the output from the thermocouple 73 provided on the aperture member 70 becomes uniform,
By appropriately adjusting the position of each of the partial reflection mirrors 5 and the total reflection mirror 6 facing each other, for example, by adjusting the angle of each of the mirrors 5 and 6, the laser optical path is made appropriate. It is possible to correct the deviation of the laser beam from the optical axis and generate the laser beam 9 in a mode with good symmetry. Here, the cooling water 74 is flown in order to suppress an increase in the temperature level of the aperture member 70.

Since such a conventional laser device uses a means for detecting a temperature rise of the aperture member 70 as a laser beam position detecting means, it generally requires a response time of several seconds and suppresses a temperature level rise of the aperture member 70.
It is necessary to cool the aperture member 70. In addition, due to the influence of heat diffusion to the surrounding atmosphere, accurate temperature detection cannot be performed, the laser beam position detection accuracy is poor, and the aperture member 70 is upsized due to its structure, which adversely affects the laser beam quality. There were various inconveniences.

<Summary of the Invention> In view of the above-mentioned conventional circumstances, the present invention has a structure in which a laser beam is directly detected at a point sufficiently distant from the center of the laser beam. It is an object of the present invention to provide a laser device capable of eliminating the conventional drawbacks such as not adversely affecting the laser.

<Embodiment of the Invention> An embodiment of the present invention will be described below with reference to FIGS. 2 to 6. Note that, in FIG. 2 (a), the same elements as those in FIG. 1 (a) are included. The same reference numerals are attached.

That is, in FIG. 2 (a), reference numeral 80 denotes a laser beam position detecting means provided on the front side of the aperture 7 for mode selection so as to face each other, and as shown in FIG. It is composed of an aperture member having an opening 85A having an opening diameter A on the optical axis, and a plurality of laser beam detection elements mounted on the inner peripheral portion of the aperture member 85 at equal intervals in the circumferential direction. The laser beam detection element 84 is the aperture member 8
5 is arranged along the circle having a diameter not smaller than the opening diameter A of the aperture member 85 on the front side. Here, the front surface side of the aperture member 85 means the side on which the laser light excited and generated by the silent discharge 4 is incident, that is, the side facing the center side in FIG. 2 (a).

Here, in the case of a Co ₂ laser having a TEMoo mode of 1 kW output, the reflectance of the partial reflection mirror 5 is 40%,
The rightward power at the position of the optical laser beam detection element 84 of the laser internal standing wave is 2.5 kW, and the leftward power is 1 kW.

The 1 / e ₂ intensity diameter w of the standing wave is about 13 mm, and the aperture diameter φa of the aperture 7 for mode selection is 1.
7w, 22mm, aperture diameter A of aperture member 85
Is 32 mm, and the light receiving area of each laser beam detection element 84 is 4 mm ₂ .

Next, the operation will be described.

The standing waves of the laser formed in the resonator are rightward (toward the partial reflection mirror 5) and leftward. The shape of the rightward standing wave is determined by the aperture 7 for mode selection, enters the partial reflection mirror 5, emits 1 kW of power to the outside, and the reflected light of 1.5 kW is reflected by the total reflection mirror 6. Return to Aperture 7. In this process, the right-handed standing wave receives optical amplification and becomes a power of 2.5 kW, and at the same time, it has a beam shape with a long skirt.
The end is cut (cut at the foot) with the aperture 7.

The power to cut off with Aperture 7 is 1 of the total power to the right.
%, That is, several W to several tens W, the intensity distribution is the third
The light intensity distribution is approximately equal to the normal distribution shown in the figure.

Therefore, a part of the power of the rightward standing wave is directly incident on the laser beam detecting element 84 installed in the front direction of the aperture 7, and the incident power is several mW.

The laser beam detection element 84 may detect the power as described above, and a thermopile, a thermocouple, a pyroelectric element, a thermistor, a bolometer, an infrared photodiode, or the like may be used.

Next, when the center of the laser beam does not coincide with the center of the aperture member 85, the output of the laser beam detecting element 84 shows a clear imbalance. That is, FIG. 4 shows the detected power when the center of the laser beam and the center of the opening 85A of the aperture member 85 deviate by ± 1 mm, where 1 is the case when the centers of both are the same. In the figure, the case where the laser beam is displaced far away from the laser beam detecting element of interest is defined as the negative shift amount.

Here, the detectability of the laser beam detecting element is expressed by the following equation.

What can be seen from such detectability is that the position of the laser beam can be detected with an accuracy of 0.03 mm by using a laser beam detecting element capable of detecting a power deformation of 10%, for example.

As is clear from the above description, the laser beam position detection means 80 uses the aperture member 85 and the laser beam detection element 84 to directly detect the laser beam position at a point sufficiently distant from the center of the laser beam. Since the detection is performed by detecting the laser beam, the laser beam can be quickly responded to the axis deviation, the response is good, and the quality of the laser beam is not adversely affected, so that a stable laser beam can be obtained. Therefore, by driving the total reflection mirror 6 or the partial reflection mirror 5 so that the difference between the signals from the laser beam detection element 84 is minimized, stable single-mode oscillation with good axial symmetry can be obtained. be able to.

According to the above-mentioned embodiment, the laser beam position detecting means 8
Although the aperture member 85 of 0 and the aperture 7 for mode selection are separately formed, they may be integrally formed as shown in FIG. In this case, an aperture 86A having an aperture diameter φa for mode selection is provided in the aperture member 86, and further, a laser beam detecting element 84 is provided at a portion having a diameter A coaxially, which is a position sufficiently distant from the aperture diameter φa. Install by embedding.

Further, as shown in FIG. 6, a laser beam reflecting portion 88 is provided on the front peripheral portion of the aperture member 87, and the reflecting portion 88 is provided.
It may be configured to detect the reflected light by the detecting element 84 installed at another position. The point is that it is arranged in the optical path of the generated laser beam and has an opening on the optical axis of the laser beam. An aperture member and a plurality of laser beam detection elements for detecting an incident laser beam are provided on the front surface side of the aperture member at a plurality of positions along a circle having a diameter equal to or larger than the opening diameter of the aperture member. Good.

The positional relationship between the laser beam position detecting means 80 and the mode selection aperture 7 is shown in FIG. 7, FIG. 8, and FIG. 9 in addition to the embodiment of the present invention shown in FIG. There is. In FIG. 7, the difference from the embodiment of FIG. 2 is that the laser beam position detecting means 80 is attached to the total reflection mirror 6 side. FIG. 8 is an inversion of the arrangement of FIG. FIG. 9 shows the beam position detecting means 80 in the embodiment of FIG. 8 which is placed outside the resonator region surrounded by the partial reflection mirror 5 and the total reflection mirror 6. In any case of FIG. 7, FIG. 8 and FIG. 9, the laser beam cut off by the mode selection aperture 7 becomes a shape with a widened skirt as it propagates, and the laser power of the skirt is increased. The function of directly detecting the beam position by the beam position detecting means 80 does not change, and the same effect as that of the embodiment shown in FIG. 2 can be exhibited.

<Effects of the Invention> As described above, according to the present invention, the laser beam position can be detected by directly detecting the laser beam at a point sufficiently distant from the center of the laser beam by the aperture member and the laser beam detecting element. With this configuration, it is possible to detect the position of the laser beam with good response and to obtain a stable laser beam because it does not adversely affect the laser beam quality. Further, there is an advantage that a cooling means is not required unlike the conventional device, and the device can be simplified and downsized.

[Brief description of drawings]

FIG. 1 (a) is a schematic front view showing a conventional laser device,
(b) and (c) are a front view and a side view of an aperture in the same apparatus, FIG. 2 (a) is a schematic front view showing an embodiment of the laser apparatus according to the present invention, and FIG. FIG. 3 is a front view of the laser beam position detecting means in the example, FIG. 3 is a graph showing the light intensity distribution of the laser beam incident on the laser beam detecting element, and FIG. 4 is a diagram for explaining the position detectability with respect to the axis deviation of the laser beam. Graphs, FIGS. 5 and 6 are views showing other embodiments of the present invention, respectively. (A) is a front view, (b) is a side sectional view, and FIGS. 7 to 9 are the present invention. It is a schematic front view which shows the structure principal part of another Example. 80 ... Laser beam position detecting means, 84 ... Laser beam detecting element, 85, 86, 87 ... Aperture member,
85A, 86A ... Opening

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical indication location H01S 3/097 (72) Inventor Shuji Ogawa 8-1-1 Tsukaguchihonmachi, Amagasaki-shi, Hyogo Sanbishi Electric Equipment Co., Ltd. Applied Equipment Research Laboratory (72) Inventor Masaki Kuzumoto 8-1-1 Tsukaguchi Honcho, Amagasaki City, Hyogo Sanryo Electric Co., Ltd. Applied Equipment Research Laboratory (56) Reference JP-A-58-93294 (JP, A) Japanese Patent Publication Sho 57-19584 (JP, B2)

Claims (2)

[Claims] 1. An aperture member disposed in the optical path of a generated laser beam and having an opening on the optical axis of the laser beam, and a diameter equal to or larger than the diameter of the opening of the aperture member on the front side of the aperture member. It is arranged in multiple parts along the circle of
A laser device comprising: a laser beam position detecting means including a plurality of laser beam detecting elements for detecting the power of an incident laser beam. 2. The laser device according to claim 1, wherein the laser beam detecting element outputs to the means for adjusting the resonator mirror angle so that the mutual output difference is minimized.