JPH0249543B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a laser device equipped with a laser beam position detector for detecting the axial position of a laser beam.

[Prior Art] A conventional device of this type is shown in FIG. 3. In the figure, 1 is a total reflection mirror, 2 is a partial reflection mirror, 3 is a laser medium, 4 is an aperture member arranged in a laser resonator and has an opening on the optical axis of the laser beam, and 5 is an opening of this aperture member. A photodetecting element, for example, a thermocouple, is installed at a position on the outer periphery of the opening at a distance from the periphery of the opening. 6
60 is the laser beam taken out to the outside, 60 is the optical axis of the laser beam, 61 is the diffracted light generated when the laser beam is cut off by the aperture member, 62 is the light traveling to the left inside the resonator, 63 is the light This light travels to the right inside the resonator and is the main beam. Further, FIG. 4 shows a front view of the aperture member 4. 41 is an opening.

Next, the operation will be explained. The two mirrors 1 and 2 constitute a resonator. The light traveling back and forth between both mirrors is amplified by a laser medium 3, and when it reaches a certain intensity, it is taken out as a laser beam 6.
Light 63 traveling to the right inside the resonator spreads while reaching the aperture member 4 from the total reflection mirror 1, is cut off by the opening 41 installed in the aperture member 4, is reflected by the partial reflection mirror 2, and becomes light 62. head towards the total reflection mirror. Diffracted light 61, which is a part of the light cut out in this process, enters the photodetecting element 5 installed at the outer periphery of the opening of the aperture member 4. Assuming that the laser beam is in a symmetric mode, such as TEMoo mode, and the photodetection elements are arranged axially symmetrically, the output difference between each photodetection element will be minimum only when the two axes match. .
Furthermore, if the central axis of the laser beam deviates due to misalignment of either mirror 1 or 2 constituting the resonator, a difference in output is generated between the respective photodetecting elements, and the deviation can be detected based on this difference in output.

[Problem that the invention seeks to solve]

Conventional laser devices such as those described above detect only a part of the cut laser beam, are therefore affected by the local distribution of the cut light, and can only be applied to axially symmetric laser beams. There were other problems.

The present invention was made to solve this problem, and an object of the present invention is to provide a laser device that can stably detect the position of an asymmetric laser beam.

[Means for solving problems]

In the laser device according to the present invention, an aperture member is provided at a position on the outer periphery of the opening of the aperture member at a distance from the periphery of the opening, and
The laser beam incident on the outer periphery of the opening of the aperture member is divided into regions, and a photodetector element detects the laser beam integrated within each region, and the output of the photodetector element in each region is compared. The means for detecting the position constitutes a laser beam position detector.

[Effect]

The photodetecting element of this invention detects the diffracted light, which is the cut-off light by the aperture, over almost the entire area on the outer periphery of the aperture, thereby detecting the laser beam even when the cut-off light has a local distribution. Detects positional deviations stably.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a front view showing the main parts of a laser beam position detector according to an embodiment of the present invention. It is a photodetecting element that divides the diffracted light incident on the outer peripheral position of the aperture into regions and detects the laser beam integrated within each region. For example, for a Co ₂ laser, the shape shown in Fig. 1 is used. It consists of a light receiving plate made of metal such as Al, and by measuring the temperature rise, the integrated output in each region is detected.

Next, the operation will be explained. In this invention, the aperture 4 shown in FIG. 1 is inserted in place of the aperture 4 shown in FIG. 4. The diffracted light cut off by the aperture 41 is divided into four areas on the circumference and detected by the photodetecting element 5. By comparing the output signals from the four regions using the laser beam position detection means, the power center of the laser beam,
Misalignment with the center axis of the opening can be detected.
For a well-symmetrical mode like TEMoo, the resonator mirror 1,
By driving the mirrors 2, movement of the mirrors 1 and 2 of the resonator due to thermal expansion or the like can be corrected. For modes with poor symmetry, mirrors 1 and 2 of the resonator are similarly set by memorizing the output ratio between each detection element and driving the mirrors 1 and 2 of the resonator to the initial settings.
2 movement can be corrected.

The mirrors 1 and 2 are driven by manual angle control using a micrometer, for example, or by automatic feedback control.

In the above embodiment, the photodetecting elements that equally integrate the cut-off light on the outer periphery of the opening 41 may be arranged as shown in FIG. 2, and each point may be weighted to a certain degree.

Further, in the above embodiment, the photodetecting element is constructed of a metal light receiving plate, but thermocouples, photodiodes, etc. may be arranged in an array and the outputs thereof may be added for each region.

〔Effect of the invention〕

As explained above, the present invention divides the diffracted light generated by being cut off by the aperture into regions, and transmits the diffracted light integrated within each region to the outer peripheral position of the aperture of the aperture member. Since the beam is detected by a photodetecting element provided at a distance from the surrounding area, the position of the beam can be stably detected without being affected by the local strength of the beam.

[Brief explanation of the drawing]

FIG. 1 is a front view showing the main parts of a laser beam position detector according to one embodiment of the invention, and FIG. 2 is a front view showing the main parts of a laser beam position detector according to another embodiment of the invention. , FIG. 3 is a cross-sectional configuration diagram showing a conventional laser device, and FIG. 4 is a front view showing main parts of a conventional laser beam position detector. 4...Aperture member, 5...Photodetection element, 6
. . . Laser beam, 41 . . . Aperture, 60 . . . Optical axis, 61 .

Claims (1)

[Claims] 1. An aperture member disposed within a laser resonator and having an opening on the optical axis of the laser beam, provided at a position on the outer periphery of the aperture of this aperture member at a distance from the periphery of the aperture, and at a position on the outer periphery of the aperture. a photodetecting element that divides the diffracted light generated when the laser beam incident on the laser beam is cut off by the aperture member into regions and detects the diffracted light integrated within each region; and the light of each of the regions. A laser device comprising a laser beam position detector comprising means for comparing outputs of detection elements and detecting the position of the laser beam.