JP3462262B2 - Laser beam incident monitor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for monitoring the position of output light in the invisible wavelength range from a laser light source such as a YAG laser, which is incident on the end face of an optical fiber.

[0002]

2. Description of the Related Art Generally, output light from a laser light source such as a YAG laser, an excimer laser, and an iodine laser is invisible because it is in a non-visible wavelength range, but it is possible to emit extremely strong light as compared with a semiconductor laser. It is used for cutting metal, precision machining such as drilling, and welding.

By the way, in order to guide the output light from the laser light source such as the YAG laser to the processing site through the fiber, the output light is condensed and made to enter the core of the optical fiber with high accuracy. Is essential.

That is, a condenser lens is usually used for condensing the output light from the laser light source, but if the optical axis of this condenser lens and the optical axis of the optical fiber are deviated from each other. Since the output light is not efficiently incident on the core of the optical fiber, the output light is converted into heat and the end face of the optical fiber is destroyed, or the desired light intensity for processing or welding cannot be obtained. And other inconveniences.

Therefore, it is necessary to accurately monitor whether or not the output light from the laser light source such as the YAG laser is incident on the core of the optical fiber.

Conventionally, in order to monitor the position where the output light from the laser light source is incident on the end face of the optical fiber, the following procedure is performed.

As shown in FIG. 5, the output light a from the laser light source is condensed by the condenser lens b, is incident on one end of the optical fiber c, and is output from the other end of the optical fiber c. The photosensitive paper d is received and the photosensitive paper d is exposed. Then, by observing the exposed pattern, it is determined whether or not both optical axes of the condenser lens b and the optical fiber c are coincident with each other.
That is, if the optical axes of both b and c do not match, the photosensitive paper d
May not be fully exposed, or the pattern may be duplicated, so this is used to judge whether the optical axes match or do not match.

However, as described above, in the method using the photosensitive paper d, the incident state of the output light a on the end face of the optical fiber c is not directly observed, but the pattern after being emitted from the optical fiber c is observed. Therefore, it is difficult to objectively judge whether or not the optical axes of the condenser lens b and the optical fiber c are actually coincident with each other, and skill is required to make an accurate judgment. In addition, it is necessary to set and remove the photosensitive paper d, which is troublesome.

Therefore, in the prior art, as shown in FIG. 6, for example, a YAG laser (wavelength: 1
064 nm), which is in the visible wavelength range and has excellent directivity, for example, a He-Ne laser (wavelength: 632.8 nm)
Is used as a monitor light and a wavelength selection mirror
There is an optical system k in which m, a condenser lens c, and an eyepiece lens e are combined so that the incident state of the YAG laser light on the end face of the optical fiber c can be simulated and observed by monitor light.

That is, the above-mentioned wavelength selection mirror m has a wavelength selectivity such that, for example, only a part of the He-Ne laser light is reflected and the rest is transmitted, and the YAG laser light is totally reflected. He-Ne laser light is applied to the wavelength selection mirror m so as to match the optical axis of the YAG laser.

Then, most of the He-Ne laser light passes through the wavelength selection mirror m as it is, but a part of the He-Ne laser light is reflected and condensed by the condenser lens b, and then irradiated on the end face of the optical fiber c. It Then, after a part of the He-Ne laser light applied to the end face of the optical fiber c is reflected by this end face,
It goes through the condenser lens b to the wavelength selection mirror m again,
Most of the light passes through this mirror m and the eyepiece lens e
Is collected at.

Therefore, by directly observing the position and shape of the irradiation pattern of the He—Ne laser light on the end face of the optical fiber c seen through the eyepiece e with the observer g wearing safety glasses h, the optical fiber c Determine whether light is incident on the end face.

[0013]

The optical system k shown in FIG.
Is used, the output light from the laser light source (Y in the above example
The incident state of (AG laser light) on the end face of the optical fiber c can be directly observed by using the monitor light in the visible wavelength range (He-Ne laser light in the above example) in a simulated manner. The quality of the incident state can be determined more easily and more accurately than the method using paper.

However, since the optical system k in FIG. 6 is used for direct observation with the naked eye, the safety glasses are inadvertently inspected.
If you forget to apply h, it will be very dangerous to your eyes.

Therefore, in order to avoid the risk associated with direct observation with the naked eye, a TV camera (not shown) is installed behind the eyepiece lens e, and the TV camera is used to display the irradiation pattern of the monitor light on the end face of the optical fiber c. It has been proposed that the state of incidence of the output light on the end face of the optical fiber c can be indirectly observed by imaging.

However, in the conventional apparatus, the TV camera and the optical system k are provided separately and independently of each other, which not only makes the entire apparatus large but also is inconvenient in handling.

The present invention has been made to solve the above-mentioned problems, and secures the safety of the incident state of the output light in the invisible wavelength range from the laser light source on the end face of the optical fiber. Therefore, it is an object of the present invention not only to make the determination easily and accurately, but also to make the entire device small and lightweight so that it can be handled very easily.

[0018]

The present invention adopts the following constitution in order to solve the above problems.

That is, the laser light incident monitor according to the present invention has a wavelength selective mirror having a wavelength selectivity that reflects only a part of the monitor light in the visible wavelength range and transmits the rest, and totally reflects the output light. On the reflection optical path side of the wavelength selection mirror, a condenser lens for condensing the output light and the monitor light reflected by the wavelength selection mirror on the end face of the optical fiber is a condenser lens sandwiching the wavelength selection mirror. A magnifying lens for magnifying the image of the monitor light reflected by the end face of the optical fiber and transmitted through the wavelength selection mirror, and an optical path returning means for returning the optical path of the monitor light passing through the magnifying lens are respectively arranged at positions facing each other. are, also, an image pickup device for capturing an image of monitor light in the optical fiber end face on the basis of the monitor light emitted from the optical path turn-back means, condenser lens
The optical axis of the lens and the optical axis of the optical fiber core
It is equipped with an optical collimator for adjustment, and these are integrally mounted on the case .

[0020]

In the above construction, the wavelength selective mirror is irradiated with the monitor light in conformity with the optical axis of the output light in the non-wavelength range from the laser light source.

Then, most of this monitor light is transmitted through the wavelength selection mirror as it is, but a part of it is reflected and condensed by the condenser lens, and then is irradiated to the end face of the optical fiber.
Then, a part of the monitor light radiated to the end face of the optical fiber is reflected by this end face and then radiated again to the wavelength selection mirror through the condensing lens, but most of the light is reflected by this mirror. After passing through the magnifying lens, the optical path is folded back by the optical path folding means, the light is incident on the imaging device.

As a result, the image of the monitor light on the end face of the optical fiber is picked up by the image pickup device. Therefore, by observing the position and shape of the irradiation pattern of the monitor light on the end face of the optical fiber, the light incident on the end face of the optical fiber can be detected. You can judge the quality.

Further, since the monitor light transmitted through the wavelength selection mirror is returned by the optical path returning means, the mounting area of the optical system can be small even with the same optical path length, and the wavelength selection mirror, the condenser lens, the magnifying lens, Since the optical path turning-back means, the image pickup device , and the optical collimator are integrally attached to the case, the entire device can be downsized.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a partially cutaway plan view of a laser light incident monitor according to an embodiment of the present invention, and FIG. 2 is a front view of the same. In this example, the output light in the non-visible wavelength range incident on the end face of the optical fiber from the laser light source is the YAG laser light (wavelength: 1064 nm), and the He-Ne laser light (wavelength is the wavelength) as the monitor light in the visible wavelength range. : 632.8 nm) will be described.

Laser light incidence monitor 1 of this embodiment
Is provided with a wavelength selection mirror 4 in one box-shaped case 2.

In this example, the wavelength selection mirror 4 has a protective layer made of Al ₂ O ₃ formed on a glass substrate, and layers of SiO ₂ and ZrO _{2 having} different refractive indexes are alternately laminated on the protective layer. As shown in FIG. 3, it is composed of laminated interference film filters, and as shown in FIG.
Although 0% is transmitted, the remaining about 10% is reflected, and the YAG laser light in the invisible wavelength range has wavelength selectivity of totally reflecting.

In the wavelength selection mirror 4, H
In order to eliminate unnecessary reflection of the e-Ne laser light at the interface between the glass substrate and air, it is more preferable to form an antireflection film such as a multilayer interference film on the back surface side of the glass substrate.

The wavelength selection mirror 4 is made of YAG.
The YAG laser light output from the laser oscillator 6 is arranged at an angle of 45 ° with respect to the incident light path.

A He-Ne laser tube (not shown) is arranged at a rear position of a laser rod (not shown) which constitutes the YAG laser oscillator 6, whereby the He-Ne laser tube is aligned with the optical axis of the YAG laser light. Then, the He-Ne laser light is output.

On the reflection optical path side of the wavelength selection mirror 4, a condenser lens 10 for condensing the YAG laser light and the He-Ne laser light reflected by the wavelength selection mirror 4 on the end face of the optical fiber 8. , And an optical collimator 12 for adjusting so that the optical axis of the condenser lens 10 and the optical axis of the core of the optical fiber 8 coincide with each other.

The condenser lens 10 is fitted in a cylindrical lens holder 14 whose one end is fixed to the case 2,
The focus is set so as to be located on the end face of the optical fiber 8 attached to the optical collimator 12.

The optical collimator 12 includes the lens holder 1
4 has a hollow receptacle holder 16 attached to the other end side thereof, and a receptacle 18 into which one end of the optical fiber 8 is inserted and fitted in the receptacle holder 16 is a surface orthogonal to the optical axis of the condenser lens 10. It is provided so as to slide inside. Then, two pairs of optical axis adjusting screws 20 are screwed into opposing positions on the outer periphery of the receptacle holder 16,
The optical axis adjusting screw 20 is adapted to come into contact with the receptacle 18 through the receptacle holder 16. By adjusting the amount of advance / retreat of the optical axis adjusting screw 20, sliding of the receptacle 18 is regulated, and The optical axis of the optical lens 10 is adjusted so as to match the optical axis of the core of the optical fiber 8.

On the other hand, at a position facing the condensing lens 10 with the wavelength selection mirror 4 sandwiched therebetween, an enlargement for enlarging the image of the He-Ne laser reflected by the end face of the optical fiber 8 and transmitted through the wavelength selection mirror 4 is made. Lens 22 and this magnifying lens 2
Optical path returning means 24 for returning the optical path of the He-Ne laser that has passed through 2 are arranged respectively.

The magnifying lens 22 is provided with its optical axis aligned with that of the condensing lens 10, and its focal length is determined by the relationship with the condensing lens 10 in terms of the magnifying power of the image and the size of the apparatus. It is set in consideration of restrictions.

The optical path folding means 24 is the magnifying lens 4
In order to secure the optical path length so that the light from the optical system is focused on the image pickup position of the image pickup device 26 described later, it is configured by combining a plurality of (three in this example) total reflection mirrors 24a to 24c.

Further, on the side surface of the case 2, an image of the He-Ne laser light at the end face of the optical fiber 8 is picked up based on the He-Ne laser light emitted from the optical path folding means 24.
An image pickup device 26 such as a CD video camera is attached.

Next, in order to monitor whether or not the YAG laser light is surely incident on the core of the optical fiber 8 by using the laser light incidence monitor device 1 having the above-described structure, first, Y
He-Ne laser light is generated in conformity with the optical axis of the YAG laser light from the AG laser oscillator 6, and the He-Ne laser light is applied to the wavelength selection mirror 4 through the transmission opening 2a formed in the case 2. To do.

Then, most of the He-Ne laser light passes through the mirror 4 as it is, but a part of the He-Ne laser light is reflected and collected by the condenser lens 10, and then the transmission port formed in the case 2. It is irradiated toward the end face of the optical fiber 8 attached to the optical collimator 12 through 2b. The He-Ne laser light applied to the end surface of the optical fiber propagates in the optical fiber, but a part of the light is reflected by the end surface of the optical fiber 8, and the reflected light is reflected by the condensing lens 10. Then, the wavelength selection mirror 4 is irradiated again with the light. At this time, most of the He—Ne laser light is transmitted through the mirror 4 and condensed by the magnifying lens 22, and the optical path is folded back by the optical path folding means 24, and then the transmission port 2 formed in the case 2.
It is incident on the image pickup device 26 through c.

As a result, He-N at the end face of the optical fiber 8
An enlarged image of the e-laser light is picked up by the image pickup device 26. Therefore, by observing the position and shape of the irradiation pattern of the He—Ne laser light on the end face of the optical fiber 8, the YAG
Instead of the laser light, it is possible to determine whether or not the light is reliably incident on the core in a pseudo manner by the He—Ne laser light.

When the optical axis of the core of the optical fiber 8 does not coincide with the optical axis of the condenser lens 10, the optical axis adjusting screw of the optical collimator 12 is observed while observing the image of the image pickup device 26. By adjusting the amount of advance / retreat of 20, the receptacle 18 is slid in the plane orthogonal to the optical axis of the condenser lens 10, and the optical axes of both 10 and 8 are adjusted.

As described above, if the optical collimator 12 is integrally provided with the image pickup device 26, the optical axis can be adjusted very easily, which is convenient.

After the optical axis adjustment is completed, if YAG laser light is generated from the YAG laser oscillator 6, this YAG laser light is generated.
The laser light is totally reflected by the wavelength selection mirror 4, condensed by the condenser lens 10, and then incident on the core of the optical fiber 8.

Further, when the light incident on the end face of the optical fiber 8 is monitored, the wavelength selection mirror 4 and the eyepiece lens 22.
Since the He-Ne laser light that has passed through the optical path is turned back by the optical path turning means 24, even when the optical path length necessary for focusing the light focused by the eyepiece lens 22 on the image pickup device 26 is maintained, The mounting area is small. Moreover, since the optical path folding means 24 and the image pickup device 26 are also integrally attached to the case 2, the size of the entire device can be reduced.

In the laser light incident monitor 1 shown in FIGS. 1 and 2, the wavelength selection mirror 4 has a wavelength selectivity for totally reflecting the YAG laser light. For example, as shown in FIG. It can also be configured.

That is, in this apparatus, as the wavelength selection mirror 4 ′, one having a wavelength selectivity such that only a part of the He—Ne laser light is reflected and the rest is transmitted and the YAG laser light is totally transmitted is used. . Then, a laser rod (not shown) that constitutes the YAG laser oscillator 6 is provided at a position on the opposite side of the condenser lens 10 that sandwiches the wavelength selection mirror 4 ', and a He-Ne laser tube (not shown) is provided at a position behind the laser rod. ) Is arranged so that the He-Ne laser light is output in conformity with the optical axis of the YAG laser light, while it is reflected by the end face of the optical fiber 8 and reflected by the wavelength selection mirror 4 '. The magnifying lens 22 and the optical path folding means 24 are arranged on the side of the reflected optical path of the He-Ne laser light.

In this way, the condenser lens 10 for the laser light source, the optical collimator 12, the optical path folding means 24,
Each arrangement configuration of the image pickup device 26 and the like can be different from the arrangement configuration of the device shown in FIG. 1, so that there is more room for selecting a user-friendly one according to the surrounding situation where the device is installed. Is good.

In this embodiment, the case where the output light from the laser light source in the non-visible wavelength range is YAG laser light and the He-Ne laser light is used as the monitor light in the visible wavelength range has been described. The present invention is applicable even if the laser light in the non-visible wavelength range is excimer laser light or iodine laser light, and the monitor light in the visible wavelength range is argon laser light, for example. Is. In this case, it is necessary to set the wavelength selectivity of the wavelength selection mirror 4 so as to match the wavelength of the laser light.

[0048]

According to the present invention, the following effects can be obtained.

(1) It is possible to easily and accurately determine the quality of the incident state of the output light in the invisible wavelength range from the laser light source on the end face of the optical fiber. Moreover, it is safe because the laser light is not directly observed.

(2) Since the optical path of the monitor light that has passed through the magnifying lens is folded back by the optical path folding means and guided to the image pickup apparatus, and each component constituting the apparatus is integrally provided, the apparatus is thus provided. The overall size and weight are reduced, making it extremely easy to handle. Furthermore, with the imaging device
In addition, if an optical collimator is integrated, the optical axis adjustment will be extremely
It can be done very easily.

[Brief description of drawings]

FIG. 1 is a partially cutaway plan view of a light incident monitoring device according to an embodiment of the present invention.

2 is a front view of the device of FIG. 1. FIG.

FIG. 3 is a wavelength selection characteristic diagram showing the relationship between the incident wavelength of laser light and the reflectance of the wavelength selection mirror.

FIG. 4 is a plan view of a light incident monitor device according to another embodiment of the present invention.

FIG. 5 is an explanatory diagram of a conventional method of monitoring a light incident position on an end face of an optical fiber.

FIG. 6 is an explanatory diagram of another conventional method for monitoring the light incident position on the end face of the optical fiber.

[Explanation of symbols]

1 ... Laser light incidence monitor device, 4 ... Wavelength selection mirror, 8
... optical fiber, 10 ... condenser lens, 12 ... optical collimator, 22 ... magnifying lens, 24 ... optical path folding means, 24a ...
24c ... total reflection mirror, 26 ... imaging device.

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01J 1 / 02,1 / 42 H01S 3/00 B23K 26/02-26/04 G01B 11/00

Claims (3)

(57) [Claims] 1. A device for monitoring the incident position of an output light in the non-visible wavelength range from a laser light source on an end face of an optical fiber, wherein only a part of the monitor light in the visible wavelength range is reflected and the rest is transmitted. In addition, the output light is provided with a wavelength selection mirror having a wavelength selectivity for total reflection, and the output light and the monitor light reflected by the wavelength selection mirror are provided on the end face of the optical fiber on the reflection optical path side of the wavelength selection mirror. The condensing lens for condensing the light at the position opposite to the condensing lens that sandwiches the wavelength selection mirror has a magnifying lens for magnifying the image of the monitor light reflected by the end face of the optical fiber and transmitted through the wavelength selection mirror. Optical path returning means for returning the optical path of the monitor light passing through the magnifying lens are arranged respectively, and an image of the monitor light at the end face of the optical fiber is based on the monitor light emitted from the optical path returning means. An image pickup device for imaging the light of the converging lens
Align the optical axis with the optical axis of the optical fiber core.
Equipped with an optical collimator, and these are integrated with each other.
A laser light incident monitor device characterized by being attached to a case . 2. A device for monitoring an incident position of an output light in a non-visible wavelength range from a laser light source on an end face of an optical fiber, wherein only a part of the monitor light is reflected and the rest is transmitted, and
The output light is provided with a wavelength selection mirror having wavelength selectivity that allows all transmission. The output light and the monitor light transmitted through the wavelength selection mirror are condensed on the end face of the optical fiber on the transmission optical path side of the wavelength selection mirror. The condenser lens reflects on the end face of the optical fiber and on the reflection optical path side of the monitor light reflected by the wavelength selection mirror, and passes through a magnifying lens for magnifying the reflected monitor light image and the magnifying lens. optical path turn-back means for folding the optical path of the kite of the monitor light is arranged, also includes an imaging device that captures an image of the monitor light in the optical fiber end face on the basis of the monitor light emitted from the optical path turn-back means, condenser Optical axis of optical lens and optical fiber core
Equipped with an optical collimator that adjusts so that the optical axis of
In addition, the laser light incidence monitor device is configured such that these are integrally attached to the case . 3. The laser light incident monitor device according to claim 1, wherein the optical path returning means is configured by combining a plurality of total reflection mirrors that return the optical path of the monitor light.