JP2602154Y2 - Laser focal length measuring device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser focal length measuring apparatus for measuring a focal length of a laser torch for condensing a laser beam from an optical fiber and irradiating the laser beam on a material or the like to perform laser processing. .

[0002]

_2. Description of the Related Art Welding and cutting of metal materials and the like are performed by laser light from a high-power (several KW) laser such as a gas laser (Ar gas laser, CO ₂ gas laser) or a solid-state laser (YAG laser). Have been done. When performing such laser processing, a laser torch is used. This laser torch is for performing laser processing by receiving a laser beam from a high-power laser via an optical fiber, condensing the laser beam, and then irradiating a material such as metal with the laser beam.

[0003] High power laser light is often ultraviolet light, so that the optical axis cannot be visually confirmed.
Even when the laser light is in the visible light range, irradiating the material as it is will change the spot diameter of the laser light and cause poor welding or cutting, so the focal length of the laser light must be adjusted before emitting the laser light. Need to measure.

In order to determine the focal length, a laser having a low output (about several mW which does not generate heat even when irradiated to a material) and a wavelength in the visible light region, that is, a He-Ne (helium neon) laser (aiming laser) Is used.

[0005] Usually, the focal length is measured by irradiating a spot of the condensed laser light by irradiating an He-Ne laser beam onto an optical fiber of a laser torch onto a target paper and moving the target paper along the optical axis. The measurement is performed by measuring the distance when the diameter of the spot becomes minimum on a scale. After the measurement of the focal length is completed, the laser processing is performed by injecting a high-power laser beam into the optical fiber of the laser torch.

[0006]

However, in the above-mentioned conventional method, however, the measurer must move the paper along the scale while keeping the paper perpendicular to the optical axis to visually determine the position where the spot diameter becomes minimum. Therefore, the paper is shaken or distorted, so that it takes a lot of time and effort to perform the alignment. In addition, an error occurs in the size of the spot diameter due to individual differences of the measurers, and the accuracy of the focal length is reduced.

Further, if laser processing is performed after measuring the focal length of the laser torch, the focal length changes due to fogging of the mirror in the laser torch or adhesion of dust or dirt, so that the focal length must be measured again. There is a problem.

Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide a laser focal length measuring device capable of accurately measuring a focal length with a simple operation.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention measures a focal length of a laser torch for condensing a laser beam from an optical fiber and irradiating the laser beam on a material or the like to perform laser processing. In a laser focal length measuring device for the optical surface plate, a holding table provided on one side of the optical surface plate and holding a laser torch so as to emit laser light along the optical surface plate, A pinhole filter that allows laser light of a predetermined diameter to pass therethrough, an optical sensor that is provided on the back side of the pinhole filter and detects laser light that has passed through the pinhole filter, and supports the pinhole filter on an optical platen, Adjust the position of the pinhole filter so that the pinhole filter coincides with the optical axis of the laser beam, and move the pinhole filter along the optical axis after the optical axis coincides. Filter position adjustment / movement means, movement detection means for detecting movement of the pinhole filter on the optical axis, output from the optical sensor is input, and the movement value of the movement detection means is input, and the focal length is calculated from both outputs. And an XY recorder for detection.

[0010]

According to the above construction, after the optical axis of the pinhole filter is adjusted by the pinhole filter position adjusting / moving means, the pinhole filter can be moved along the optical axis without blurring. The pinhole filter passes only the laser beam of a predetermined diameter and is detected by the optical sensor. By moving this pinhole filter back and forth along the optical axis, the position of the pinhole sensor is detected by the movement detecting means. Then, the energy intensity of the laser beam per unit with respect to the moving position can be detected by the optical sensor. When the output from the optical sensor, the movement value of the movement detecting means, and the energy intensity are input to the XY recorder, the distance from the laser torch to the pinhole filter is defined as the X axis, and the energy intensity per unit of the laser light is defined as the Y axis. Is drawn on the XY recorder, and the peak value in this graph coincides with the focal length, so that the focal length of the laser torch can be accurately and easily obtained.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a schematic side view of an embodiment of the laser focal length measuring apparatus of the present invention, and FIG. 2 is a plan view of the optical system of the laser focal length measuring apparatus shown in FIG. still,
FIGS. 1 and 2 show a laser torch as an object to be measured for convenience of explanation.

In FIGS. 1 and 2, reference numeral 1 denotes an optical surface plate, and a holding table 3 for holding a cylinder 2a of a laser torch 2 on the optical surface plate 1 so as to emit laser light along the optical surface plate.
Is attached. A groove 3a having a substantially V-shaped cross section is formed on the upper surface of the holding table 3 so as to prevent rolling when the cylinder 2a is placed.

An α-axis stage 4 is attached to the center of the optical platen 1. The α-axis stage 4 is a plate-shaped fixed base 4 a having a hinge 5 provided on one side (right side in the figure).
A rotatable platform 4b having one side connected to the hinge 5 and rotatable; and a bolt 6 penetrating near the other side of the rotatable platform 4b and having a threaded portion in contact with the fixing platform 4a. And by rotating the head of the bolt 6,
The turntable 4b can turn around an α-axis (the center axis of the hinge and perpendicular to the paper surface) at an angle corresponding to the number of rotations of the bolt 6. That is, for example, when the bolt 6 is turned clockwise, the tilt angle of the turntable 4b increases, and when the bolt 6 is turned counterclockwise, the tilt angle of the turntable 4b decreases.

On the rotary table 4b of the α-axis stage 4, X
The axis stage 7 is attached. The X-axis stage 7 is provided with a plate-shaped fixed base 7a and a guide (not shown) provided on the fixed base 7a via an X-axis (perpendicular to the paper surface) parallel to the fixed base 7a and along the fixed base 7a. And a plate-shaped moving table 7b that can move in the direction of

On the X-axis stage 7, a θ-axis stage 8
Is attached. The θ-axis stage 8 includes a plate-shaped fixed base 8a and a rotation axis (θ
(Axle) 15 and a plate-shaped rotary base 8b parallel to the fixed base 8a and rotatable around the rotation axis.

On the θ-axis stage 8, a Y-axis stage 9
Is attached. The Y-axis stage 9 is provided with a plate-shaped fixed base 9a and a guide (not shown) on the fixed base 9a via a guide (not shown). The Y-axis stage 9 is parallel to and along the fixed base 9a.
A plate-like movable table 9 that can move in the axis (parallel to the paper) direction
b. The Y-axis stage 9 is provided with a linear scale (built in the Y-axis stage 9) and a Z-axis stage 10.

The linear scale is, for example, a predetermined voltage is applied to both ends, and is a substantially linear resistor (not shown) mounted along the Y axis on a fixed base 9a of the Y axis stage 9.
And the moving table 9 while moving on the resistor along the resistor.
and a sliding terminal (not shown) connected to the sliding terminal b and generates an output voltage proportional to the position of the moving table 9b between one end of the resistor and the sliding terminal. It is supposed to. By detecting this output voltage, the position of the movable base 9b, that is, the distance between the laser torch 2 and a pinhole filter 11 described later can be known. The output voltage of the linear scale is input to an X-axis terminal of the XY recorder 12 described later. In the present embodiment, the resistance linear potentiometer is used for the linear scale. However, the present invention is not limited to this. If the distance can be detected, another distance measuring device such as a magnescale may be used. A fixed base 10a having a side surface perpendicular to the Y-axis stage 9, and a guide (not shown) provided on the side surface of the fixed base 10a via a guide (not shown); ) And a plate-like movable table 10b that can be moved in the direction. Z axis stage 10
Can adjust the vertical direction of the pinhole filter 11.

A pinhole filter 11 is mounted on the movable base 10b of the Z-axis stage 10 so that the surface thereof is along the Z-axis.

The pinhole filter 11 has a pinhole 11a having a diameter smaller than the maximum beam diameter of the laser beam, and an optical sensor 13 is mounted on the back side (left side in the figure) of the pinhole 11a.

The optical sensor 13 receives the laser beam passing through the pinhole 11a and converts it into an electric signal. The electric signal from the optical sensor 13 is input to the optical power meter 14.

The optical power meter 14 amplifies the electric signal from the optical sensor 13 and causes the pointer (both not shown) of the indicator to fluctuate, and displays the light intensity at that angle. The output of the meter 14 is the Y of the XY recorder 12
Connected to shaft terminal.

The XY recorder 12 uses a voltage input to the X-axis terminal 12a as an X-axis and a voltage input to the Y-axis terminal 12b as a Y-axis, and displays the graph on a recording paper (not shown) in a rectangular coordinate system. It is designed to be visible.

The pinhole filter position adjusting / moving means comprises an α-axis stage 4, an X-axis stage 7, a θ-axis stage 8, a Y-axis stage 9 and a Z-axis stage 10, and the movement detecting means is a linear scale. It is formed with.

The laser torch 2 has an optical fiber 17 at one end.
Is provided substantially coaxially, and is provided with a substantially cylindrical container 2a having an opening at a side surface, and a laser beam emitted from an end face of an optical fiber 17 provided in the container 2a substantially in a radial direction of the container. A reflecting mirror (not shown) and a condenser lens 16 provided on the optical axis on the exit side of the mirror and condensing the laser beam and exiting from the container window through the opening (see FIG. 3A) And formed.

The aiming laser light incident on the optical fiber 17 of the laser torch 2 is, for example, He-Ne laser light of 760 nm and several mW, and the processing laser light is 1.06 μm.
m, several kilowatts of YAG (yttrium aluminum garnet) laser light.

The optical fiber 1 of the laser torch 2
7, a focal length when He-Ne laser light is incident,
Since the wavelengths of the two laser beams are different from the focal length when the YAG laser beam is incident, they are not the same but have a constant ratio. That is, the focal length of the YAG laser light is 1.04 times the focal length of the He-Ne laser light. The value obtained by multiplying the focal length obtained by the laser focal length measuring apparatus of this embodiment by 1.04 is the focal length of the YAG laser light (when other processing laser light is used, it is obtained from the wavelength. Multiply by a factor).

Next, the operation of the embodiment will be described.

As shown in FIG. 1, first, a cylinder 2a of a laser torch 2 is placed on a holding table 3, and an opening is provided with a pinhole filter 1a.
1 and facing the optical fiber 17 with He-N
e-laser light is incident. The vertical axis of the optical axis formed by the pinhole filter 11 and the optical sensor 13 is adjusted by the α-axis stage 4, the horizontal direction of the pinhole filter 11 is adjusted by the X-axis stage 7, and the pin angle is adjusted by the θ-axis stage 8. The rotation angle of the Hall filter 11 is adjusted, and the Y-axis stage 9
The vertical direction of the pinhole filter 11 is sequentially adjusted by the Z-axis stage 10 so that the optical axis including the focal point of the laser beam coincides with the pinhole 11a of the pinhole filter 11. Is done. The laser beam condensed by the condenser lens 16 has a smaller beam diameter as it approaches the focal point, and a larger beam diameter as it moves away from the focal point (see FIG. 3A).
When the pinhole filter 11 is moved back and forth along the Y axis after the optical axis 1a coincides with the optical axis, only the laser beam of a predetermined diameter is passed by the pinhole filter 11 regardless of the position in the Y axis direction. The energy intensity of the laser light per unit is detected by the optical sensor 13. At the same time, the moving position in the X-axis direction is detected by a linear scale (moving position detecting device). When the output of the linear scale is input to the X-axis terminal 12a of the XY recorder 12, and the output of the optical sensor 13 is input to the Y-axis terminal 12b of the XY recorder 12 via the optical power meter 14, the upper part of FIG. ) Is drawn. Since the value of the Y-axis of the XY recorder 12 when this curve takes the peak value coincides with the focal point of the laser torch 2, the focal length of the laser torch 2 can be obtained accurately and easily. FIG. 3A shows the relationship between the condenser lens and the laser beam, and FIG. 3B shows the relationship between the distance from the condenser lens and the energy per unit area. The distance and the vertical axis indicate the energy per unit area.

By multiplying the focal length of the aiming laser beam thus obtained by a predetermined coefficient, the focal length of the processing laser beam can be obtained.

As described above, according to the present embodiment, the optical base 1 and the holder 3 provided on one side of the optical base 1 for holding the laser torch 2 so as to emit laser light along the optical base 1. A pinhole filter 11 for passing a laser beam having a predetermined diameter with respect to the emitted laser beam, an optical sensor 13 provided on the back side of the pinhole filter 11 for detecting the laser beam passing through the pinhole filter 11, The filter 11 is supported on the optical surface plate 1, and the position of the pinhole filter 11 is adjusted so that the pinhole filter 11 coincides with the optical axis of the laser beam. Pinhole filter position adjusting / moving means 4, 7, 8, 10 for moving along the axis; movement detecting means for detecting movement of the pinhole filter 11 on the optical axis;
Since the output from the optical sensor 13 is input and the movement value of the movement detection means is input and the XY recorder 12 for detecting the focal length from both outputs is provided, the focal length can be accurately measured by a simple operation. A laser focal length measuring apparatus can be realized.

[0032]

[Effects of the Invention] In summary, according to the present invention, the following excellent effects are exhibited.

(1) The focal length of the laser torch can be accurately measured by a simple operation.

[Brief description of the drawings]

FIG. 1 is a schematic side view of one embodiment of a laser focal length measuring apparatus of the present invention.

FIG. 2 is a plan view of an optical system of the laser focal length measuring device shown in FIG.

3A is a diagram illustrating a relationship between a condenser lens and a laser beam, and FIG. 3B is a diagram illustrating a relationship between a distance from the condenser lens and energy per unit area.

[Explanation of symbols]

 Reference Signs List 1 optical surface plate 2 laser torch 3 holding table 3a groove 4 α-axis stage 4a, 7a, 8a, 9a, 10a fixing table 4b, 7b, 8b, 9b, 10b moving table 5 hinge 6 bolt 7 X-axis stage 8 θ-axis stage 9 Y axis stage 10 Z axis stage 11 Pinhole filter 11a Pinhole 12 XY recorder 12a X axis terminal 12b Y axis terminal 13 Optical sensor 14 Optical power meter 15 Rotation axis

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Kenji Hirano 1 Shin-Nakahara-cho, Isogo-ku, Yokohama-shi, Kanagawa Pref. Ishikawajima-Harima Heavy Industries Co., Ltd. (56) References JP-A-58-169007 (JP, A) JP-A-5-203445 (JP, A) JP-A-62-262917 (JP, U) JP-T-Hei 4-5055653 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G01B 11/00-11/30 102 G01C 3/00-3/32 B23K 7/10 501 B23K 26/00

Claims (1)

(57) [Scope of request for utility model registration] 1. A laser focal length measuring device for measuring a focal length of a laser torch for condensing a laser beam from an optical fiber and irradiating the laser beam on a material or the like to perform laser processing, comprising: an optical surface plate; A holder provided on one side of the optical surface plate for holding a laser torch so as to emit laser light along the optical surface plate, and a pinhole filter for passing laser light having a predetermined diameter with respect to the emitted laser light And an optical sensor provided on the back side of the pinhole filter for detecting laser light passing through the pinhole filter; supporting the pinhole filter on the optical platen; A pinhole filter that adjusts the position of the pinhole filter so that it coincides with the optical axis, and moves the pinhole filter along the optical axis after the optical axis coincides Position adjustment / movement means, movement detection means for detecting movement of the pinhole filter on the optical axis, an output from the optical sensor is input, and a movement value of the movement detection means is input, and a focus is obtained from both outputs. A focal length measuring apparatus for a laser, comprising: an XY recorder for detecting a distance.