JPH0726711U - Laser focal length measuring device - Google Patents

Abstract

(57) [Summary] [Purpose] To be able to accurately measure the focal length with a simple operation. [Structure] An optical surface plate 1 and a laser torch 2 provided on one side of the optical surface plate 1 so as to emit laser light along the optical surface plate 1.
A holding table 3 for holding a pinhole filter, a pinhole filter 11 for passing a laser beam having a predetermined diameter to the emitted laser beam, and a pinhole filter provided on the back side of the pinhole filter 11.
An optical sensor 13 that detects the laser light that has passed through 11 and a pinhole filter 11 are supported on the optical surface plate 1, and the position of the pinhole filter 11 is adjusted so that the pinhole filter 11 matches the optical axis of the laser light. The pinhole filter position adjusting / moving means 4, 7, 8 and 10 for moving the pinhole filter 11 along the optical axis after the adjustment and the optical axes match, and the movement of the pinhole filter 11 on the optical axis. The movement detection means for detection and the output from the optical sensor are input, and the movement value of the movement detection means is input to detect the focal length from both outputs.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a laser focal length measuring device for measuring the focal length of a laser torch that collects laser light from an optical fiber and irradiates it onto a material or the like for laser processing.

[0002]

[Prior art]

BACKGROUND ART Welding and cutting of metal materials and the like are performed with laser light from high-power (several KW) lasers such as gas lasers (Ar gas lasers, CO ₂ gas lasers) and solid-state lasers (YAG lasers). A laser torch is used when performing such laser processing. This laser torch receives laser light from a high-power laser through an optical fiber, collects it, and irradiates it on a material such as metal for laser processing.

By the way, since the high-power laser beam is often an ultraviolet ray, the optical axis cannot be visually confirmed. Even if the laser light is in the visible light range, if the material is directly irradiated, the spot diameter of the laser light will change, causing welding defects and cutting defects. Needs to be measured.

Therefore, in order to obtain this focal length, a laser having a low output (a few mW that does not generate heat even when irradiated with a material) and a wavelength in the visible light region, that is, a He-Ne (helium neon) laser (aiming laser) Is used.

Usually, the measurement of the focal length is performed by irradiating a spot of the laser light, which is obtained by making He—Ne laser light incident on the optical fiber of the laser torch, onto the target paper and moving the target paper along the optical axis. , It is performed by measuring the distance when the spot diameter becomes the minimum with a scale. After the measurement of the focal length is completed, a high-power laser beam is incident on the optical fiber of the laser torch for laser processing.

[0006]

[Problems to be solved by the device]

 However, in the above-mentioned conventional method, the measurer must move the paper along the scale while keeping the paper perpendicular to the optical axis to visually find the position where the spot diameter becomes the minimum, so that the paper to be shaken However, the alignment becomes very troublesome, and the accuracy of the focal length becomes low due to an error in the spot diameter due to the individual difference of the measurer.

If laser processing is performed after measuring the focal length of the laser torch, the mirror in the laser torch becomes fogged or dust adheres to change the focal length. Therefore, the focal length must be measured again. There is a problem that it does not become.

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

[0009]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention provides a laser focal length measuring device for measuring the focal length of a laser torch that collects laser light from an optical fiber and irradiates it onto a material or the like for laser processing. An optical surface plate, a holding table which is provided on one side of the optical surface plate and holds a laser torch so as to emit a laser beam along the optical surface plate, and a laser beam having a predetermined diameter with respect to the emitted laser light. A pinhole filter that allows the light to pass through, an optical sensor that is provided on the back side of the pinhole filter to detect the laser light that has passed through the pinhole filter, and the pinhole filter is supported on an optical surface plate and the pinhole filter Adjust the position of the pinhole filter so that it coincides with the optical axis, and move the pinhole filter along the optical axis after the optical axis coincides. Moving means, movement detecting means for detecting movement of the pinhole filter on the optical axis, output from the optical sensor, and movement value of the moving detecting means are inputted to detect the focal length from both outputs. It is provided with an XY recorder.

[0010]

[Action]

 According to the above configuration, after adjusting the optical axis of the pinhole filter by the pinhole filter position adjusting / moving means, the pinhole filter can be moved along the optical axis without shaking. Since the pinhole filter allows only the laser beam of a predetermined diameter to pass and is detected by the optical sensor, by moving this pinhole filter back and forth along the optical axis, the movement detection means detects the position of the pinhole sensor. However, it becomes possible to detect the energy intensity per unit of laser light with respect to this moving position with an 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 taken as the X axis, and the energy intensity per unit of laser light is calculated. A graph with the Y axis is drawn on the XY recorder, and the peak value in this graph matches the focal length, so the focal length of the laser torch can be accurately and easily obtained.

[0011]

【Example】

 Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

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

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

An α-axis stage 4 is attached to the central part of the optical surface plate 1. The α-axis stage 4 has a plate-like fixed base 4a having a hinge 5 provided on one side (right side in the figure) and a plate-like turntable having one side connected to the hinge 5 so as to be rotatable. It is formed by a base 4b and a bolt 6 that penetrates the vicinity of the other side of the rotary base 4b and has a threaded portion that comes into contact with the fixed base 4a. The table 4b is rotatable about the α axis (the central axis of the hinge and perpendicular to the plane of the drawing) at an angle according to the number of rotations of the bolt 6. That is, for example, when the bolt 6 is rotated to the right, the tilt angle of the turntable 4b is increased, and when it is turned to the left, the tilt angle of the turntable 4b is decreased.

An X-axis stage 7 is mounted on the rotary table 4 b of the α-axis stage 4. The X-axis stage 7 is provided on a plate-shaped fixed base 7a and a guide (not shown) on the fixed base 7a and is parallel to the fixed base 7a and along the fixed base 7a along the X-axis (perpendicular to the paper surface). It is formed by a plate-shaped moving table 7b that is movable in the (axis) direction.

A θ-axis stage 8 is attached on the X-axis stage 7. The θ-axis stage 8 is a plate-shaped fixed base 8a, a rotary shaft (θ-axis) 15 provided perpendicularly to the fixed base 8a, and a plate parallel to the fixed base 8a and rotatable about this rotary shaft. It is formed of a rotary table 8b.

A Y-axis stage 9 is attached on the θ-axis stage 8. The Y-axis stage 9 is provided on a plate-shaped fixed base 9a and a guide (not shown) on the fixed base 9a, and is parallel to the fixed base 9a and along the Y-axis (on the paper surface). It is formed of a plate-shaped moving table 9b that is movable in the directions of parallel axes). 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 includes, for example, a substantially linear resistor (not shown) mounted along the Y-axis on the fixed base 9 a of the Y-axis stage 9 with a predetermined voltage applied to both ends, and a resistor. It is formed by a resistance linear potentiometer consisting of a sliding terminal (not shown) that moves on the antibody along the resistor and is connected to the moving base 9b, and between the one end of the resistor and the sliding terminal. In addition, an output voltage proportional to the position of the moving table 9b is generated. By detecting this output voltage, the position of the movable table 9b, that is, the distance between the laser torch 2 and the pinhole filter 11 described later can be known. The output voltage of the linear scale is input to the X-axis terminal of the XY recorder 12 described later. Although the resistance linear potentiometer is used for the linear scale in the present embodiment, the present invention is not limited to this, and other distance measuring devices such as a magnet scale may be used if the distance can be detected. , 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, parallel to the side surface and along the side surface along the Z-axis (parallel to the paper surface). It is formed of a plate-shaped moving base 10b that is movable in the (axis) direction. The Z-axis stage 10 can adjust the pinhole filter 11 in the vertical direction.

A pinhole filter 11 is attached to the moving 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 light, and an optical sensor 13 is attached to the back side (left side in the figure) of the pinhole 11a.

The optical sensor 13 receives the laser light that has passed 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 to oscillate a pointer (not shown) of the indicator, and displays the light intensity at that angle. The output of the meter 14 is connected to the Y-axis terminal of the XY recorder 12.

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

The pinhole filter position adjusting / moving means is composed of 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. The movement detecting means is a linear scale. Is formed by.

The laser torch 2 has a substantially cylindrical container 2 a having an optical fiber 17 penetrating at one end so as to be coaxial and having an opening formed on a side surface thereof, and an optical fiber 17 provided inside the container 2 a. A mirror (not shown) that reflects the laser light emitted from the end face of the container in the radial direction of the container, and a laser beam that is provided on the optical axis on the emitting side of the mirror and collects the laser light from the container window through the opening. It is formed by a condenser lens 16 (see FIG. 3A) that emits light.

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

By the way, the focal length when the He—Ne laser light is incident on the optical fiber 17 of the laser torch 2 is not the same as the focal length when the YAG laser light is incident because the wavelengths of both laser lights are different. It has 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 numerical value obtained by multiplying the focal length obtained by the laser focal length measuring device of this embodiment by 1.04 is the focal length of the YAG laser light (when other laser light for processing is used, it is determined from the wavelength). Multiply the coefficient).

Next, the operation of the embodiment will be described.

As shown in FIG. 1, first, the cylinder 2a of the laser torch 2 is mounted on the holding table 3 so that the opening faces the pinhole filter 11, and the He-Ne laser light is supplied to the optical fiber 17. Incident. The α-axis stage 4 adjusts the vertical tilt of the optical axis formed by the pinhole filter 11 and the optical sensor 13, the X-axis stage 7 adjusts the left-right direction of the pinhole filter 11, and the θ-axis stage 8 adjusts it. The rotation angle of the pinhole filter 11 is adjusted, the longitudinal direction of the pinhole filter 11 is adjusted by the Y-axis stage 9, and the vertical position of the pinhole filter 11 is sequentially adjusted by the Z-axis stage 10, so that the laser light is adjusted. The optical axis including the focal point of is aligned with the pinhole 11a of the pinhole filter 11. 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 departs from the focal point (see FIG. 3 (a)). When the pinhole filter 11 is moved back and forth along the Y-axis after the axes coincide with each other, only the laser beam having a predetermined diameter is passed by the pinhole filter 11 regardless of the position in the Y-axis direction. The energy intensity per unit of light 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, as shown in FIG. ) A substantially mountain-shaped curve is drawn. When this curve has a peak value, the Y-axis value of the XY recorder 12 coincides with the focal point of the laser torch 2, so that the focal length of the laser torch 2 can be accurately and easily obtained. 3A shows the relationship between the condenser lens and the laser light, and FIG. 3B shows the relationship between the distance from the condenser lens and the energy per unit area. Is the distance, and the vertical axis is the energy per unit area.

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

As described above, according to the present embodiment, the light surface plate 1 and the holding table 3 provided on one side of the light surface plate 1 and holding the laser torch 2 so as to emit the laser light along the light surface plate 1. A pinhole filter 11 for passing a laser beam having a predetermined diameter with respect to the emitted laser beam, and 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 pinhole 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 light. Pinhole filter position adjusting / moving means 4, 7, 8, 10 for moving the optical axis along the optical axis, movement detecting means for detecting movement of the pinhole filter 11 on the optical axis, and optical sensor 1. Since the output from 3 and the movement value of the movement detecting means are 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 device can be realized.

[0032]

[Effect of device]

 In short, according to the present invention, the following excellent effects are exhibited.

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

[Brief description of drawings]

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

2 is a plan view of an optical system of the laser focal length measuring device shown in FIG. 1. FIG.

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

[Explanation of symbols]

 1 Optical surface plate 2 Laser torch 3 Holding table 3a Groove 4 α-axis stage 4a, 7a, 8a, 9a, 10a Fixed 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

Claims (1)

[Scope of utility model registration request] 1. A laser focal length measuring device for measuring a focal length of a laser torch for condensing laser light from an optical fiber and irradiating the laser light on a material or the like to perform laser processing. A holding table which is provided on one side of the light surface plate and holds a laser torch so as to emit the laser light along the light surface plate, and a pinhole filter for passing the 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 that has passed through the pinhole filter, and supporting the pinhole filter on the optical surface plate, and the pinhole filter for the laser light. 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. The position adjustment / moving means, the movement detecting means for detecting the movement of the pinhole filter on the optical axis, the output from the optical sensor, and the movement value of the movement detecting means are input to focus on both outputs. A focal length measuring device for laser, comprising: an XY recorder for detecting a distance.