JPH103045A - Laser branching device and laser beam intensity adjusting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser beam intensity adjusting device capable of continuously and variably adjusting the laser beam intensity without breaking a laser mode. SOLUTION: A first attenuator plate 18 is coated with a multilayered partial reflection/transmission film 18b on the front or back surface of a substrate 18a made of glass or quartz so that a reflectivity R and a transmissivity T for a YAG laser beam is continuously changed with a first changing rate αin the longitudinal direction X of the substrate. A second attenuator plate 20 has the same constitution as the first attenuator plate and is arranged to have a posture rotated by 180 deg. to the first attenuator plate. Consequently, a transmissivity and reflectivity of a partial reflection/ transmission film 20b with which the substrate 20a of the second attenuator plate is coated are continuously changed with a second changing rate -α whose polarity is opposite to the first changing rate αand the absolute value is the same in the direction X. The positions of both attenuator plates through which a laser beam LB passes are arbitrarily adjusted by means of an attenuator plate position adjusting mechanism.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0010]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser branching device for simultaneously branching one original laser beam into a plurality of laser beams and a laser beam intensity adjusting device for adjusting the light intensity of the laser beam.

[0020]

2. Description of the Related Art A laser branching device branches a laser beam output from a laser oscillator into a plurality of laser beams and directs them to different positions, and is used, for example, in multi-position processing of laser welding.

FIG. 6 shows a multi-position processing system for laser welding. A plurality of, for example, four emission units 102A, 102B,
102C and 102D are optical fibers 104A and 1
The connection is made via the terminals 04B, 104C and 104D. In the laser device main body 100, a laser beam generated by a laser oscillator is branched into four laser beams by a laser branching device, and the four branched laser beams are respectively incident on one end surfaces of the optical fibers 104A to 104D by an incidence unit. Is done. Each branch laser beam transmitted to each of the emission units 102A to 102D through each of the optical fibers 104A to 104D is condensed and radiated toward each workpiece W there. According to such a multi-position processing method, a plurality of (four in this example) workpieces W can be simultaneously welded by one laser device main body 100, so that production efficiency can be improved.

FIG. 7 shows a configuration of a main part of a conventional laser branching device for performing simultaneous four-branch in the multi-position processing system as described above. This laser branching device includes four spectroscopic mirrors 106A and 106 on the optical path of the original laser beam LB0 output from a laser oscillation unit (not shown).
B, 106C and 106D are arranged in this order at a predetermined angle, for example, 45 °.

As the first beam splitting mirror 106A on which the original laser beam LB0 is first incident, a partially reflecting transmission mirror having a reflectance of about 25% and a transmittance of about 75% is used. The next second
A partial reflection / transmission mirror having a reflectance of about 33% and a transmittance of about 67% is used as the spectral mirror 106B. As the third spectral mirror 106B, a partially reflective transmission mirror having a reflectance of about 50% and a transmittance of about 50% is used. A total reflection mirror having a reflectance of about 100% and a transmittance of about 0% is used as the fourth fourth spectral mirror 106D.

The original laser beam LB0 is applied to the first spectral mirror 10
6A, it is about 25% (about 0.25 LB)
0) is reflected and the remaining about 75% (about 0.75 LB0)
) Is transmitted.

When the transmitted light (about 0.75 LB0) from the first spectral mirror 106A enters the second spectral mirror 106B, about 33% (about 0.25 LB0) is reflected there and the remaining about 67%. The minute (about 0.50 LB0) is transmitted.

When the transmitted light (about 0.50 LB0) from the second spectral mirror 106B enters the third spectral mirror 106C, about 50% (about 0.25LB0) is reflected there, and the remaining about 50%. The minute (about 0.25 LB0) is transmitted.

The transmitted light (about 0.25 LB0) from the third spectral mirror 106C enters the fourth spectral mirror 106D and is totally reflected there.

Thus, the four spectral mirrors 106A-1A
From 06D, four branched laser beams LBA to LBD obtained by substantially dividing the laser output of the original laser beam LB0 into four are extracted.

However, in practice, the reflectance and transmittance of the partial reflection / transmission mirror vary, and the reflectance / transmittance characteristics of the oblique (45 °) incidence mirror show large polarization dependence. Spectral mirror 106A-
It is difficult to accurately divide the intensity of the original laser beam LB0 by 106D, and it is inevitable that the split laser beam LBA ~
The output of the LBD varies. In the above-described multi-position processing by simultaneous branching, if the intensities of the branched laser beams LBA to LBD are not uniform, there arises a problem that the processing quality of the workpiece W varies.

Therefore, as shown by the dotted line in FIG.
Branch laser light LB from spectral mirrors 106A to 106D
A to the light energy attenuating means 110A on the optical path of LBD
110D is arranged, and the intensities of the branched laser beams LBA to LBD are attenuated by the attenuating means 110A to 110D, respectively, so as to be equalized.

[0130]

The attenuating means 110 in the conventional laser branching device as described above uses one unit attenuating element having a constant attenuation rate (ε) in order to make the intensities of the branched laser beams LBA to LBD uniform. One or a plurality of them are placed on the optical path or different attenuation factors (ε1, ε2,
... ΕM) are arranged on the optical path by selectively combining a plurality of attenuating elements.

However, in each of these conventional methods, the attenuation rate can be adjusted only in steps, and the intensities of the branched laser beams LBA to LBD are adjusted to exactly the same value.
It was difficult to adjust finely. In addition, if the adjustment pitch of the attenuation rate is to be finely adjusted, a large number or various kinds of attenuation elements must be prepared or incorporated into the device, which results in an increase in the size and complexity of the device, which is troublesome to handle.

The present invention has been made in view of the above-mentioned problems, and has a small and simple device configuration so that the intensity of the branched laser light can be adjusted to exactly the same value without disturbing the laser mode, or the laser mode can be disturbed. It is another object of the present invention to provide a laser branching device capable of accurately adjusting the intensity of each branched laser beam to a desired value.

A further object of the present invention is to provide a laser light intensity adjusting device capable of continuously and variably adjusting the intensity of laser light without breaking a laser mode.

[0170]

In order to achieve the above object, a laser branching device according to the present invention is a laser branching device for generating a plurality of branching laser beams from one original laser beam. One or more spectroscopic mirrors arranged on the optical path and reflecting incident laser light in a predetermined direction at a predetermined reflectance and transmitting at a predetermined transmittance; and reflected light or transmission from the spectroscopic mirror. A first attenuation plate disposed on an optical path of light and having a transmittance with respect to the wavelength of the original laser light that changes substantially continuously at a first rate of change in a predetermined direction; and a light reflected or transmitted from the spectral mirror. It is arranged on the optical path of light, and the transmittance for the wavelength of the laser light changes substantially continuously in the predetermined direction at a second change rate having a polarity opposite to the first change rate and substantially equal in absolute value. And 2 of the damping plate, said first and second
And an attenuating plate position adjusting means for adjusting the positions of the first and / or second attenuating plates so that the laser beams incident on the attenuating plates have the desired transmittances, respectively.

Further, the laser beam intensity adjusting device of the present invention
A first attenuating plate disposed on an optical path of laser light to be intensity-adjusted, and having a transmittance with respect to the wavelength of the laser light that changes substantially continuously at a first rate of change in a predetermined direction;
It is disposed on the optical path of the laser light, and the transmittance for the wavelength of the laser light is substantially continuously at a second change rate having a polarity opposite to that of the first change rate and substantially equal in absolute value in the predetermined direction. The position of the first and / or second attenuating plate is adjusted so that the changing second attenuating plate and the laser light incident on the first and second attenuating plates are each transmitted at a desired transmittance. And an attenuating plate position adjusting means.

[0190]

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

FIG. 1 shows a configuration of a main part of a laser branching device according to an embodiment of the present invention. This laser branch device is applicable to, for example, the multi-position processing system shown in FIG.

In FIG. 1, the original laser light LB0 output from the YAG laser oscillator 10 is repeatedly reflected and amplified between the pair of resonator mirrors 12 (only one of which is shown) and then emitted from the resonator mirror 12. It is supposed to be.

In the laser branching device according to this embodiment, four spectroscopic mirrors 1 are arranged on the optical path of the original YAG laser light LB0.
4A, 14B, 14C and 14D are arranged at fixed positions at the same inclination angle (for example, 45 °) and at regular intervals.

The spectral mirrors 14A to 14D correspond to the spectral mirrors 106A to 106D in the conventional apparatus (FIG. 7).
Respectively. Therefore, a partially reflecting transmission mirror having a reflectivity of about 25% and a transmittance of about 75% is used as the first spectral mirror 14A on which the original laser beam LB0 is first incident. As the second second spectroscopic mirror 14B, a partially reflecting transmission mirror having a reflectivity of about 33% and a transmittance of about 67% is used. The third spectral mirror 14C includes:
A partially reflecting transmission mirror having a reflectance of about 50% and a transmittance of about 50% is used. A total reflection mirror having a reflectance of about 100% and a transmittance of about 0% is used as the fourth fourth spectral mirror 14D.

As described above, the spectral mirrors 14A to 14D
Has a constant reflectance and transmittance for each mirror, and each is fixedly attached to the mirror holding mechanism 16.

The original laser beam LB0 is applied to the first spectral mirror 14
A, and then there is about 25% (about 0.25LB0
) Is reflected and about 75% of the remaining (about 0.75 LB0
) Is transmitted. When the transmitted light (about 0.75 LB0) from the first beam splitting mirror 14A enters the second beam splitting mirror 14B, about 33% (about 0.25 LB0) is reflected there and the remaining about 67% (about 67%). About 0.50 LB0) is transmitted. The transmitted light from the second spectral mirror 14B (about 0.50
When LB0) enters the third spectral mirror 14C, about 50% (about 0.25LB0) is reflected there, and the remaining about 50% (about 0.25LB0) is transmitted. The transmitted light (about 0.25LB0) from the third spectral mirror 14C enters the fourth spectral mirror 14D and is totally reflected there.

Thus, the intensity of the original laser beam LB0 is almost
Four equally divided laser beams LBA to LBD are extracted from the four spectral mirrors 14A to 14D. However, the spectral mirrors 106A to 106D in the conventional device
Similarly to (FIG. 7), the intensity of the original laser beam LB0 is determined only by the spectroscopic mirrors 14A to 14D due to variations in the reflectance and transmittance of the partial reflection / transmission mirror and the polarization dependence of the reflectance / transmittance characteristics at oblique incidence. It is difficult to accurately divide the laser beams, and the intensities of the branched laser beams LBA to LBD vary to some extent.

In the laser branching device of this embodiment, as will be described later, on the optical path of the branched laser beams LBA, LBB, LBC, LBD, the attenuation plate (18A, 20A), (18B, 20B),
By arranging (18C, 20C) and (18D, 20D), the intensities of the branched laser beams LBA to LBD can be accurately adjusted to a constant value without breaking each laser mode.

On the optical paths of the branched laser beams LBA to LBD from the spectroscopic mirrors 14A to 14D, the first attenuating plates 18A to 18D, the second attenuating plates 20A to 20D, the shutters 24A to 24D, and the incident units 26A to 26D are provided, respectively. 26D
Are arranged in a line. First and second damping plates 18
The positions of A to 18D and 20A to 20D, that is, the transmittances are adjusted by the attenuation plate position adjusting mechanisms 22A to 22D, respectively. Optical fibers 104A to 104D are connected to rear ends of the incident units 26A to 26D.

FIG. 2 shows an example of the configuration of a pair of first and second attenuation plates (18, 20). Each damping plate 18, 2
Numeral 0 is composed of partially reflecting transmission plates [18] and [20] whose reflectance and transmittance for the original laser beam (YAG laser beam) LB0 change almost continuously in the X direction.

The partial reflection / transmission plate [18] constituting the first attenuating plate 18 is made of a substrate [18] made of a material such as glass or quartz, which transmits almost 100% of the YAG laser light.
a], and Y or Y on the front or back surface of the substrate [18a].
The reflectance and the transmittance (R, T) for the AG laser light are the first in the X direction parallel to the longitudinal direction of the substrate [18a].
Of the multilayer reflective film [18b] so as to change almost continuously at the rate of change α of. Accordingly, the reflectance becomes the minimum value RMIN and the transmittance becomes the maximum value TMAX on one end (left end) side of the partial reflection / transmission film [18b], and the reflectance becomes the maximum value RMAX and the transmittance becomes the minimum value on the other end (right end) side. It becomes TMIN.

On the other hand, the partial reflection / transmission plate [20] of the second attenuating plate 20 has the same configuration as the partial reflection / transmission plate [18], and is 180 ° smaller than the partial reflection / transmission plate [18].゜ It is arranged in a rotated posture. This allows
The transmittance and the reflectance of the partially reflective transmission film [20b] coated on the substrate [20a] have a polarity opposite to that of the first change rate α in the X direction and a second change rate substantially equal to the absolute value. It will change almost continuously at -α.
Therefore, one end (left end) of the partial reflection / transmission film [20b]
The reflectance becomes the maximum value RMAX and the transmittance becomes the minimum value TMIN on the side, and the reflectance becomes the minimum value RMIN and the transmittance becomes the maximum value TMAX on the other end (right end) side.

In the laser branching device of this embodiment, for example, (RMAX, TMIN) is selected to be about (30%, 70%)
Select (RMIN, TMAX) to about (10%, 90%). Thus, in the first and second attenuating plates (18, 20) of each set, the position (part) of each attenuating plate through which the optical path of the YAG laser light LB passes is adjusted in the X direction, so that the transmitted light LBT is adjusted.
Can be variably adjusted almost continuously within the range of about 49% to 81%. Since the light absorptance of each of the attenuating plates 18 and 20 is very low, it is ignored.

In the laser branching device of this embodiment, X
Since the change rates α and −α at which the transmittance T of the first and second attenuating plates 18 and 20 continuously change in the direction are opposite to each other and have substantially the same absolute value, the YAG laser beam LB is , 20 before and after the laser beam mode is maintained. This mechanism will be described with reference to FIG.

In FIG. 3, a curve [18] T indicates the distribution of the transmittance T of the first attenuation plate 18 in the X direction, and a curve [20] T indicates the transmittance T of the second attenuation plate 20 in the X direction. Is shown. The slopes α and −α of both curves [18] T and [20] T correspond to the rates of change α and −α of the transmittance T of the first and second attenuating plates 18 and 20, respectively. In this example, the change rates α, −α are linear values, and both curves [18] T,
[20] T is represented by a straight line. It should be noted that the change rates α and −α may be curved values.

The laser beam LB before entering the first attenuating plate 18 has a predetermined beam diameter D and mode. First
Is continuously changing at a change rate α in the X direction, when the laser beam LB passes through the first attenuating plate 18, the mode of the transmitted laser beam LBT1, especially the transverse mode, changes. It collapses once in the X direction.

However, since the transmittance T of the second attenuating plate 20 continuously changes at the rate of change -α in the X direction, the laser beam LBT1 from the first attenuating plate 18 is After passing through 20, the collapse of the transmitted laser beam LBT1 in the X direction is compensated, and as a result, the transmitted laser beam LBT2 having a mode substantially equal to that of the original laser beam LB is obtained from the second attenuating plate 20.

FIG. 4 shows an example of the configuration of an attenuation plate position adjusting mechanism 22 for variably adjusting the transmittance (T) of the first and second attenuation plates (for example, 18A and 20A) of each set. In this adjustment mechanism 22, the first and second damping plates 18A,
A pair of vertical support plates 3 each holding 20A vertically
0 and 31 are configured to be independently slidable in the X direction on the common horizontal support plate 32 in a back-to-back posture. Long holes 36, 37 extending in the X direction are formed in horizontal flange portions 34, 35 integrally formed at the lower ends of the vertical support plates 30, 31, and bolts 38, 39 are horizontally passed through the long holes 36, 67. It is screwed into a screw hole (not shown) of the support plate 32. By loosening the bolts 38, 39, the vertical holding plate 32 and the damping plates 18A, 20A can be manually moved or displaced finely in the X direction.

Each set of attenuation plates (18A, 20A) to (18A)
D-20D), the individual branched laser beams LBA-LB
The intensity of BD is 1/4 (LB) of the intensity of the original laser beam LB0.
It varies around 0/4). Therefore, in each damping plate position adjusting mechanism 22, as described above, the damping plate (18)
A, 20A) to (18D to 20D) are displaced in the X direction to variably adjust each transmittance (T), so that the four branched laser beams LBA to LB are maintained without breaking each mode.
The intensity of D can be made the same.

When the branched laser beams LBA to LBD are perpendicularly incident on the attenuating plates (18A, 20A) to (18D to 20D), the attenuating plates (18A, 20A) to (18D)
~ 20D) is reflected by the incident laser light LBR.
There is a possibility that the light may travel in the same optical path as BA to LBD in the opposite direction and interfere with the original laser light LBO. Therefore, in order to prevent the reflected laser beam LBR from overlapping with the incident laser beam LB, each attenuating plate (18, 2)
0) may be inclined slightly (preferably slightly downward for safety) with respect to the optical axis of each of the branched laser beams LBA to LBD.

Thus, the split laser beams LBA to LBA
BD is from the first and second damping plates (18A, 20A) to
(18D-20D), the respective intensities become exactly equal, and then enter the incident units 22A-22D through the shutters 20A-20D, and are condensed by the condensing lens in the incident unit and the optical fiber 104A
To 104D simultaneously.

The branched laser beams LBA to LBD simultaneously incident on one end surfaces of the optical fibers 104A to 104D pass through the optical fibers 104A to 104D and are emitted from the emission unit 10A.
2A to 102D, and the emission units 102A to 102A
Condensed light is simultaneously emitted from 102D toward each workpiece W.

The shutters 20A to 20D selectively or independently control the transmission of each of the branched laser lights LBA to LBD as necessary, thereby enabling multi-time difference branching. As long as the shutters 20A to 20D are open, the branched laser beams LBA to LBD pass through as they are, and do not attenuate here.

As described above, according to the laser branching device of this embodiment, the original laser light LBO is
The light is roughly divided into four equal parts by 4D, and the branched laser lights LBA to LBD from the spectroscopic mirrors 14A to 14D pass through the first and second attenuating plates (18A, 20A) to (18D to 20D), where the branched laser light LBA to Since the strengths of the LBDs are set to exactly the same value, the processing quality of the workpiece W can be made constant in multi-position processing as shown in FIG. 6 and the reliability of laser processing can be improved.

In the laser branching device of this embodiment, each of the attenuating plates (18A, 20A) to (18D to 20D) is capable of continuously adjusting the reflectance and transmittance (R, T).
Composed of a plurality of partial reflection / transmission plates [18] and [20],
Each damping plate (18A,
20A) to (18D to 20D) can be continuously variably adjusted by simply changing the positions in the fixed direction (X direction), so that the laser light intensity can be continuously and variably adjusted. Variable adjustment can be performed finely.

Also, in the laser branching device of the present embodiment, the same partial reflection / transmission plates [18] and [20] of the same model number can be used for all the attenuation plates (18A, 20A) to (18D to 20D). It is also advantageous in terms of inventory management and maintenance costs. Of course, it is also possible to set the reflectance and transmittance ranges (RMAX, TMIN) to (RMIN, TMAX) of the first and second partial reflection / transmission plates [18], [20] to different values.

The fourth incident unit 22D is disposed behind (transmission side) the third spectral mirror 14C, and transmits the transmitted light from the third spectral mirror 14C to the fourth split laser beam LB.
By setting D, the fourth spectral mirror 14D can be omitted.

In the above-described embodiment, the case where four simultaneous branches are performed has been described. However, other simultaneous multiple branches such as three simultaneous branches can be performed. In the above-described embodiment, the intensities of the branched laser beams LBA to LBD are made equal.
The first and second damping plates (18A, 20A) to (18D to 20D) can be made different at any ratio.
It is also possible to adjust to different intensity values for each of the branched laser beams LBA to LBD.

The shape and structure of the first and second attenuation plates (18, 20) of each set in the present embodiment are not limited to those shown in FIG. For example, as shown in FIG. 5, the first attenuation plate 18 has a disc-shaped substrate [18.
a ′] has a transmittance (T) of a multilayer partial reflection / transmission film [18b ′] coated on the front surface or the back surface of the substrate [1].
8a ′] in the circumferential direction (θ direction).
, And the transmittance (T) of the partially reflective transmission film [20b ′] of the multilayer film coated on the front surface or the back surface of the disc-shaped substrate [20a ′] in the second attenuation plate 20.
Is the first in the circumferential direction (θ direction) of the substrate [20a '].
May be changed almost continuously at a second change rate −α having a polarity opposite to that of the change rate α and having substantially the same absolute value. In this case, the substrates [18a '] and [20a'] can be rotationally displaced in the θ direction by an appropriate substrate rotation position adjusting means (not shown).

In the above-described embodiment, the first and second attenuating plates (18A, 20A) to (18D to 20D) are arranged on the optical path of the laser beam LB before the incident units 26A to 26D. It is also possible to attach it near the exit opening of the exit units 102A to 102D (usually between the condenser lens and the protective glass). In this case, regarding the branched laser beams LBA to LBD, not only variations in the light intensity generated by the spectroscopes 14A to 14D but also variations in the light intensity generated by transmission in the optical fibers 104A to 104D are collected in the final stage. Can be corrected by
Each of the workpieces W can be simultaneously irradiated with the branched laser beams LBA to LBD whose light intensities are accurately aligned.

In the above-described embodiment, the first and second attenuating plates (18, 20) are partial reflection transmitting plates which attenuate the intensity by reflecting the incident laser light. However, a partial absorption transmission plate that attenuates the intensity by absorbing the incident laser light may be used. That is, it is only necessary that the transmittance with respect to the wavelength of the laser beam changes at a predetermined rate in a predetermined direction.

Further, the first and second attenuating plates (18, 20) according to the present invention are not limited to the above-described laser branching device, but can continuously and variably adjust the intensity of laser light without breaking the mode. The present invention is applicable to any laser device as a possible laser beam intensity adjusting device.

[0520]

As described above, according to the laser splitting device of the present invention, the original laser light is split into a plurality of split laser lights by the splitting mirror, and each split laser light is transmitted with respect to the wavelength of the original laser light. Sequentially pass through first and second damping plates, which have substantially opposite polarities in a predetermined direction and have substantially the same absolute value at first and second rate of change, and
The position of the first and / or second attenuating plate is adjusted by the attenuating plate position adjusting mechanism so that the laser light incident on the first and second attenuating plates is transmitted at a desired transmittance. It is possible to exactly match the intensities of all the branched laser beams without breaking the laser mode, or to adjust the intensity to a desired value without breaking the laser mode for each of the branched laser beams. Therefore, it is possible to improve the adjustment work and the processing quality.

Further, according to the laser light intensity adjusting apparatus of the present invention, the laser light whose intensity is to be adjusted has a transmittance which is opposite to that of the laser light in a predetermined direction and whose absolute value is substantially equal in a predetermined direction. Sequentially passing through first and second damping plates that change substantially continuously at the first and second rate of change,
Since the position of the first and / or second attenuating plate is adjusted by the attenuating plate position adjusting mechanism so that the laser light incident on the first and second attenuating plates is transmitted at a desired transmittance, the laser is used. The intensity of the laser beam can be continuously variably adjusted without changing the mode.

[Brief description of the drawings]

FIG. 1 is a schematic plan view showing a configuration of a laser branching device according to one embodiment of the present invention.

FIG. 2 is a perspective view showing a configuration of first and second attenuation plates of each set in the embodiment.

FIG. 3 is a diagram for explaining the function of each set of first and second damping plates in the embodiment.

FIG. 4 is a perspective view showing one configuration example of an attenuation plate position adjusting mechanism for variably adjusting the reflectance of each set of first and second attenuation plates in the embodiment.

FIG. 5 is a perspective view showing a modification of the configuration of the first and second attenuation plates of each set in the embodiment.

FIG. 6 is a schematic perspective view showing a laser welding multi-point processing system.

FIG. 7 is a diagram illustrating a configuration example of a conventional laser branching device.

[Explanation of symbols]

Reference Signs List 10 laser oscillator 14A to 14D spectral mirror 18A to 18D first attenuation plate 20A to 20D second attenuation plate [18], [18 '], [20], [20'] Partial reflection transmission plate [18a], [ 18a '], [20], [20']
Substrate [18b], [18b '], [20b], [20b']
Partial reflection / transmission film 22A-22D Attenuation plate position adjustment mechanism

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location H01S 3/00 H01S 3/00 B

Claims (2)

[Claims] 1. A laser branching device that generates a plurality of branched laser beams from one original laser beam, wherein the laser beam splitter is disposed on an optical path of the original laser beam and reflects incident laser light in a predetermined direction at a predetermined reflectance. One or more spectroscopic mirrors for transmitting light at a predetermined transmissivity at the same time, and disposed on an optical path of reflected light or transmitted light from the spectroscopic mirror, wherein the transmissivity with respect to the wavelength of the original laser light is in a predetermined direction. At the first rate of change, which changes almost continuously at the first rate of change.
And an attenuating plate, which is disposed on the optical path of the reflected light or transmitted light from the spectral mirror, and whose transmittance with respect to the wavelength of the laser light is opposite in polarity to the first rate of change in the predetermined direction and has an absolute value. A second attenuating plate that changes substantially continuously at a substantially equal second change rate; and the first and second attenuating plates so that laser light incident on the first and second attenuating plates is transmitted at desired transmittances, respectively. And / or an attenuation plate position adjusting means for adjusting the position of the second attenuation plate. 2. A first attenuator disposed on an optical path of a laser beam to be adjusted for a light intensity, wherein a transmittance for a wavelength of the laser beam changes almost continuously at a first rate of change in a predetermined direction. A plate, disposed on an optical path of the laser light, and having a transmittance with respect to a wavelength of the laser light, which is opposite in polarity to the first change rate in the predetermined direction and substantially equal in absolute value to a second change rate. A continuously changing second attenuating plate; and a position of the first and / or second attenuating plate such that laser light incident on the first and second attenuating plates is transmitted at a desired transmittance, respectively. And an attenuating plate position adjusting means for adjusting the laser beam intensity.