JP2009294397A - Laser converging prism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser beam converging prism which is built in one body and comparatively easy for positioning, can reduce heat generation by a rather simple configuration even if a comparatively large power laser beam is converged. <P>SOLUTION: This prism 30 is composed by assembling and unitizing a first triangular prism 31 having a base of a first isosceles right triangle, a second triangular prism 32 having a base of a second isosceles right triangle of the same shape as the first isosceles right triangle, a third triangular prism 33 having a base of a third isosceles right triangle forming its right angle with oblique sides of the first and second isosceles right triangles, and a reflective and transmissive plate 34 having a polarizing reflective area 34a reflecting the incident laser beam in the incident direction and changing the polarization direction of the return beam and a transmissive area 34b where the incident laser beam passes through. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a laser condensing prism for condensing laser light having a relatively high output.

Conventionally, for example, a high-power laser is obtained by condensing a plurality of laser beams from a semiconductor laser light source in which a plurality of light emitting units that emit laser beams traveling in an elliptical shape are arranged at predetermined intervals in the minor axis direction of the ellipse Various laser oscillators that can be used have been proposed.
Since semiconductor lasers have high oscillation efficiency (˜50%), there is an increasing need to use them as excitation light for solid-state lasers or as direct processing light sources. Also, semiconductor laser manufacturers include semiconductor laser bars in which a plurality of emitters (light emitting portions) are arranged one-dimensionally, and semiconductor laser stacks in which semiconductor laser bars are stacked and a plurality of emitters (light emitting portions) are arranged two-dimensionally. It has been commercialized.
For example, a general semiconductor laser bar is a semiconductor laser chip having an external dimension of about 10 mm in length, about 0.2 mm in thickness, and about 1 mm in width mounted on a heat sink, and about 1 μm in length in the thickness direction. About 10 light emitting portions having a pitch of about 500 μm are integrated in the direction. Then, a laser beam with an output of about 2 W is emitted from one light emitting unit. If these are condensed to increase the power density and used as excitation light or directly as a processing light source, metal welding, drilling, cutting, etc. can be performed.
In this specification, the semiconductor laser bar and the semiconductor laser stack are collectively referred to as a semiconductor laser light source.

In a general semiconductor laser light source, as shown in the example of FIG. 5A (an example in which the light emitting part is one-dimensionally arranged), the laser light L1 emitted from the light emitting parts (12a to 12h) It progresses while spreading in an almost elliptical shape in the axial direction. Further, as shown in the example of FIG. 5B, the major axis direction spread angle θf is about several tens of degrees (for example, 30 to 40 degrees), and the minor axis direction spread angle θs is several degrees (for example, 3 degrees). ~ 4 degrees). Further, as described above, the dimensions of the light emitting portions (12a to 12h) are about 1 μm in the major axis direction and about 100 to 200 μm in the minor axis direction in a general semiconductor laser light source. Further, the laser light at the time of emission has the polarization direction aligned in a predetermined direction (for example, the major axis direction).
The condensing property of the laser light depends on the beam parameter product indicated by “beam diameter * divergence angle”. In the case of the semiconductor laser array as described above, the beam parameter product in the major axis direction is about 0.2 mm · mrad, The beam parameter product in the short axis direction is 200 mm · mrad. For this reason, when condensing, it is relatively easy to condense in the long axis direction, but it is relatively difficult to condense in the short axis direction.

As shown in FIG. 5D, the beam is condensed by emitting a beam having a width (or diameter) D1 and a divergence angle of angle θ1 from the emission side member B1, and collecting it by the condenser lens SL. When light is collected and condensed on the condensing side member B2 so as to have an incident angle of width D2 and angle θ2, the following expression is established.
D2 = (tan θ1 / tan θ2) * D1
In order to collect light smaller, the spread angle θ1 on the exit side is reduced, the incident angle θ2 on the collection side is increased, or the width D1 on the exit side is reduced so that D2 becomes smaller. Good. When an optical fiber is used for the condensing side member B2, the incident angle θ2 on the condensing side is limited by the numerical aperture NA, so it is not preferable to increase the incident angle θ2 on the condensing side.

For example, in the prior art described in Patent Document 1, as shown in FIG. 6A, a laser beam from a semiconductor laser light source 10 in which a plurality of light emitting units 12a to 12h are arranged in the minor axis direction (X axis direction). After converting L1 (P) and L2 (P) into parallel light with respect to the long axis direction (Y-axis direction) using the long-axis direction collimating lens 20, a polarization conversion plate 132 that converts the polarization direction of the laser light. A multiplexing prism 131 that transmits light in a certain polarization direction and reflects light in another polarization direction, and a prism 133 that includes a total reflection surface 133a that reflects laser light toward the multiplexing prism 131. Using a fractional wave unit 130 (corresponding to a laser focusing prism) in which three optical members are integrally assembled, the laser beam is condensed so that the width LWin in the minor axis direction is halved. Thereby, the width LWout on the emission side in FIG. 5D is halved, and the light can be condensed on an optical fiber having a smaller diameter. FIG. 6B shows a state where the split wave unit 130 is separated into optical members.
In the prior art described in Patent Document 2, as shown in FIG. 7, the laser light beams L1 (P) and L2 (P) from the semiconductor laser light source 10 in which a plurality of light emitting portions 12a to 12h are arranged in the short axis direction. ) Is converted into parallel light with respect to the long axis direction using the long axis direction collimating lens 20, and then converted into parallel light with respect to the short axis direction using the short axis direction collimating lens 140. 132, the combining prism 131, and the prism 133 provided with the total reflection surface 133a, the laser beam is condensed so that the width LWin in the minor axis direction is halved. Thereby, the width LWout on the emission side in FIG. 5D is halved, and the light can be condensed on an optical fiber having a smaller diameter.
JP 2007-286481 A JP 2003-103389 A

In the prior art described in Patent Document 2, the long-axis collimating lens, the short-axis collimating lens, the phase difference portion, the multiplexing member, and the propagation member (total reflection surface) are not integrally formed. Positioning is very difficult because it must be positioned.
On the other hand, in the prior art described in Patent Document 1, a laser beam is guided into an integrally assembled laser condensing prism (in the split wave unit 130), so that the divergence angle is relatively small. Positioning is easy because the laser beam is confined in the axial direction, the short-axis collimating lens is omitted, and the long-axis collimating lens and the laser focusing prism are positioned. However, in order to form the laser focusing prism by integrally assembling the phase difference portion, the multiplexing member, and the propagation member, each optical member is fixed with an adhesive. In this case, as shown in FIG. 4A, at the boundary portion Kc, the laser light propagates through the adhesive layer at a relatively long distance, and the adhesive may absorb the laser light and generate heat. Therefore, it is not very suitable for condensing a high-power laser. Note that, when the laser beam crosses the adhesive layer in the thickness direction, the distance that passes through the adhesive layer is short, and thus no heat generation that causes a problem occurs.
The present invention was devised in view of these points, and is a case where a relatively high-power laser beam is condensed in a laser condensing prism that is integrally formed and relatively easy to position. However, it is an object of the present invention to provide a laser condensing prism that can further reduce heat generation with a simpler structure.

As means for solving the above-mentioned problems, a first invention of the present invention is a laser focusing prism as described in claim 1.
The laser focusing prism according to claim 1, wherein a first prism having a triangular prism shape having a first right isosceles triangle as a bottom surface, and a second right isosceles triangle having the same shape as the first right isosceles triangle as a bottom surface. A third prism that has two sides sandwiching a right angle, the second prism having a triangular prism shape, the length of the hypotenuse in the first right isosceles triangle and the length of the hypotenuse in the second right isosceles triangle A triangular prism-shaped third prism having a bottom surface and a plate-like shape, which reflects laser light incident from a direction orthogonal to the plate-shaped surface toward the incident direction and emits laser light in the first polarization direction. A polarization reflection region that converts reflected light into a second polarization direction that is a polarization direction different from the first polarization direction when transmitted, and transmission that transmits laser light incident from a direction orthogonal to the plate-like surface. And having an area A morphism transmission plate, a laser focusing prism constructed by integrally assembling the.
The third prism is a side surface including a third A incident surface that includes one side that sandwiches the right angle of the third right-angled isosceles triangle and a side surface that includes the other side that sandwiches the right-angle of the third right-angled isosceles triangle. The 3B incident surface is formed on a selective reflection surface that transmits the laser light in the first polarization direction and reflects the laser light in the second polarization direction.
A first emission surface, which is a side surface including the hypotenuse of the first right-angled isosceles triangle in the first prism, is fixed to face the third-A incident surface, and the second right-angled isosceles in the second prism. The second emission surface, which is a side surface including the oblique side of the triangle, is fixed so as to face the third B incidence surface, and thus includes one side sandwiching the right angle of the first right isosceles triangle in the first prism. A first incident surface that is a side surface and a second incident surface that is a side surface including one side that sandwiches the right angle of the second right isosceles triangle in the second prism are adjacent to each other in the same direction. Are lined up.
The reflection / transmission plate is fixed so as to cover a third emission surface which is a side surface including the oblique side of the third right-angled isosceles triangle in the third prism, and extends along a direction orthogonal to the bottom surface of the third prism. One surface divided into two is formed in the polarization reflection region, and the other surface is formed in the transmission region.
Then, the laser beam having the first polarization direction incident on the first incident surface and the first incident light incident on the second incident surface from a direction orthogonal to the first incident surface and the second incident surface. The laser beam in the polarization direction is overlapped in the direction in which the first incident surface and the second incident surface are aligned, and is emitted from the transmission region of the reflection / transmission plate.

The second invention of the present invention is a laser focusing prism as described in claim 2.
The laser focusing prism according to claim 2 is the laser focusing prism according to claim 1, wherein the first prism, the third prism, and the first prism are bonded with an adhesive that transmits the laser light. 2 prisms and the third prism, and the third prism and the reflection / transmission plate are bonded together.

The third invention of the present invention is the laser condensing prism as described in claim 3.
The laser focusing prism according to claim 3 is the laser focusing prism according to claim 2, wherein the first incident surface, the second incident surface, and the transmission region of the reflection / transmission plate are in the transmission region. A non-reflective coating for attenuating the reflected light of the laser light is provided on the surface opposite to the surface facing the third prism.

According to a fourth aspect of the present invention, there is provided a laser condensing prism as set forth in the fourth aspect.
The laser condensing prism according to claim 4 is the laser condensing prism according to claim 1, and is a surface on the opposite side to the surface facing the third prism in the reflection / transmission plate. A plate-shaped transmission plate that transmits the laser light is provided to cover the first prism, the third prism, and the second prism with an adhesive that transmits the laser light. The third prism, the third prism and the reflection / transmission plate, and the reflection / transmission plate and the transmission plate are bonded together.
Then, in a region covering at least the transmission region of the first incident surface, the second incident surface, and a surface of the transmission plate opposite to the reflective transmission plate, An anti-reflective coating that attenuates reflected light is applied.

A fifth invention of the present invention is the laser condensing prism as described in the fifth aspect.
The laser focusing prism according to claim 5 is the laser focusing prism according to claim 1, wherein a boundary portion between the first prism and the third prism, and the second prism and the third prism. The first prism, the second prism, and the third prism are spaced apart from each other so that an air layer is formed at the boundary between the first prism and the third prism and the reflection / transmission plate. A prism and the reflection / transmission plate are arranged.
Then, in the holding member, the first prism, the second prism, the third prism, and the reflection / transmission plate travel the laser light incident from the first incident surface and the second incident surface side. From the direction orthogonal to the direction and the direction orthogonal to the direction in which the first incident surface and the second incident surface are aligned, the material is sandwiched and held without using an adhesive.

A sixth invention of the present invention is the laser condensing prism as described in the sixth aspect.
The laser focusing prism according to claim 6 is the laser focusing prism according to claim 1, wherein a spacer member having a predetermined thickness includes a boundary portion between the first prism and the third prism, and the An adhesive is bonded to the boundary between the second prism and the third prism, the boundary between the third prism and the reflection / transmission plate, and a portion off the light guide path of the laser beam. Thus, an air layer is formed and fixed at each boundary portion of the first prism and the third prism, the second prism and the third prism, and the third prism and the reflection / transmission plate. ing.

A seventh invention of the present invention is the laser condensing prism as described in the seventh aspect.
The laser focusing prism according to claim 7 is the laser focusing prism according to claim 1, wherein the first prism and the third prism are bonded with an adhesive applied to a predetermined thickness. At the boundary, the boundary between the second prism and the third prism, the boundary between the third prism and the reflection / transmission plate, and the portion out of the light guide path of the laser light, the adhesive By adhering to each other, an air layer is formed at each boundary portion of the first prism and the third prism, the second prism and the third prism, and the third prism and the reflection / transmission plate. Formed and fixed.

An eighth invention of the present invention is the laser condensing prism as set forth in the eighth aspect.
The laser condensing prism according to claim 8 is the laser condensing prism according to any one of claims 5 to 7, wherein the first incident surface, the first emission surface, and the first prism in the first prism. The second entrance surface and the second exit surface of the two prisms, the third exit surface of the third prism, the surface of the reflection / transmission plate facing the third exit surface, and the transmission of the reflection / transmission plate A non-reflective coating for attenuating the reflected light of the laser light is applied to the surface opposite to the surface facing the third prism in the region.

According to the laser condensing prism of the first aspect, for example, as shown in FIGS. 1A, 3A, and 4A, the optical members (first prism, second prism, first prism, (3 prisms, reflection / transmission plates) integrally formed with each optical member with respect to the light guide path for reflecting or transmitting the laser light guided into the laser light collecting prism in various directions. It is possible to configure so that the boundary portion of is not in the direction along the light guide path.
Thereby, even if each optical member is bonded, an adhesive layer having a relatively long distance along the light guide path of the laser beam is not formed. Heat generation can be reduced as compared with the prior art.

  According to the laser condensing prism of claim 2, each optical member is adhered with an adhesive to form the laser condensing prism, but the adhesive of a relatively long distance along the incident direction of the laser beam is used. Since no layer is formed, even when used for condensing a high-power laser, heat generation of the adhesive layer can be reduced as compared with the conventional case.

  According to the laser condensing prism of the third aspect, the condensing efficiency can be further improved by applying the non-reflective coating to the incident surface and the emitting surface of the laser beam.

According to the laser condensing prism of the fourth aspect, by adding a transmission plate, it is not necessary to provide a total reflection coating and a non-reflection coating on the exit surface side of the reflection / transmission plate. For the plate, it is only necessary to apply the total reflection coating to the polarization reflection region on the emission surface, and for the transmission plate, it is only necessary to apply the non-reflection coating to the region covering the transmission region (of the reflection transmission plate) on the emission surface.
Therefore, since the coating process can be simplified, it is easy to realize.

  According to the laser condensing prism of the fifth aspect of the present invention, when the optical members (first prism, second prism, third prism, reflection / transmission plate) are integrally formed, they are fixed with an adhesive. Instead, each optical member is sandwiched and fixed by a holding member. Thereby, since there is no adhesive layer, heat generation can be reduced even when used for condensing a high-power laser.

  According to the laser condensing prism of the sixth aspect of the present invention, the boundary between the optical members (the first prism, the second prism, the third prism, and the reflection / transmission plate) (where the light guide path is removed). The spacer member is sandwiched and the spacer member is bonded with an adhesive. Thereby, since there is no adhesive layer in the light guide path, heat generation can be reduced even when used for condensing a high-power laser.

  Further, according to the laser condensing prism according to claim 7, an adhesive is applied to a boundary portion of each optical member (a portion where the light guide path is removed) instead of the spacer member to a predetermined thickness, The optical member is bonded and fixed. Thereby, since there is no adhesive layer in the light guide path, heat generation can be reduced even when used for condensing a high-power laser.

  According to the laser condensing prism of claim 8, the non-reflective coating is applied to the surface that is in contact with the air layer and is not coated with any coating, so that when the laser beam is incident or The reflected light at the time of emission can be attenuated, and the laser beam condensing efficiency can be improved.

  The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1A shows the width LWin in the minor axis direction (in this case, the X axis direction) of a laser beam emitted from the light emitting portions 12a to 12h of the semiconductor laser light source 10 using the laser focusing prism 30 of the present invention. The example of the schematic external view of the laser condensing apparatus 1 which condenses by 1/2 is shown. FIG. 1B shows a state in which the laser focusing prism 30 is separated into optical members. Hereinafter, in the drawings in which the X axis, the Y axis, and the Z axis are described, the X axis, the Y axis, and the Z axis are orthogonal to each other, and the Z axis direction is the incident direction of the laser beam incident on the laser focusing prism 30. The X-axis direction indicates the minor axis direction of the laser beam incident on the laser focusing prism 30, and the Y-axis direction indicates the major axis direction of the laser beam incident on the laser focusing prism 30. ing. Note that the Y-axis direction indicates a so-called vertical direction, and the X-axis direction indicates a so-called horizontal direction.

● [Laser focusing prism 30 structure and focusing operation (Fig. 1)]
Next, referring to FIGS. 1A and 1B, the width of the laser light beam emitted from the light emitting portions 12a to 12h of the semiconductor laser light source 10 in the minor axis direction (in this case, the X axis direction) is set as the laser concentration. The operation of condensing light by the optical prism 30 and the configuration (structure) of the laser condensing prism 30 will be described.
As shown in FIG. 1B, the laser condensing prism 30 includes a first prism 31 having a substantially triangular prism shape, a second prism 32, a third prism 33, a flat plate-shaped reflection / transmission plate 34, and a transmission plate 35. It is constructed by assembling integrally. Note that the transmission plate 35 may be omitted, but will be described in an example not omitted in the present embodiment.
The first prism 31 has a substantially triangular prism shape whose bottom surface is a right-angled isosceles triangle (corresponding to a first right-angled isosceles triangle), and the second prism 32 is the same right-angled isosceles triangle (second right-angled triangle) as the bottom surface of the first prism 31. This is a substantially triangular prism shape having a bottom surface corresponding to an isosceles triangle.
The third prism 33 includes two sides sandwiching a right angle, with the length of the hypotenuse of the right isosceles triangle on the bottom surface of the first prism 31 and the length of the hypotenuse of the right isosceles triangle on the bottom surface of the second prism 32. It is a substantially triangular prism shape with the third right-angled isosceles triangle as the bottom. Further, since the bottom surface of the first prism 31, the bottom surface of the second prism 32, and the bottom surface of the third prism 33 are all right-angled isosceles triangles, the angle θb = 45 degrees.
In addition, the boundary of each optical member is filled with the adhesive as shown by the hatched portion in FIG. 2A, and details of the bonding will be described later.

Next, the special surfaces of each optical member (the first prism 31, the second prism 32, the third prism 33, the reflection / transmission plate 34, and the transmission plate 35) and the assembly of each optical member will be described.
The third prism 33 has a third A entrance surface 33Ain (see FIG. 1B) that is a side surface including one side that sandwiches the right angle of the right isosceles triangle, and the other side that sandwiches the right angle of the right isosceles triangle. The 3B incident surface 33Bin (see FIG. 1B), which is a side surface including the light beam, transmits laser light having the first polarization direction (in this case, P-polarized light) and has the second polarization direction (in this case, S-polarized light). It is configured on a selective reflection surface that reflects laser light (PS separation coatings 33a and 33b are provided).
The reflection / transmission plate 34 is fixed so as to cover the third emission surface 33out (see FIG. 1B), which is the side surface including the hypotenuse of the right isosceles triangle on the bottom surface of the third prism 33. One surface divided in half along the direction perpendicular to the bottom surface of the prism 33 is formed in the polarization reflection region 34a, and the other surface is formed in the transmission region 34b. For example, the reflection / transmission plate 34 is a quarter-wave plate, and a total reflection coating 34c (see FIG. 3) is provided on the opposite side of the incident surface in the polarization reflection region 34a. The laser beam incident from the orthogonal direction is reflected toward the incident direction, and the polarization direction of the reflected light is converted. For example, when laser light having a first polarization direction (or second polarization direction) is incident, the reflected light is changed to laser light having the second polarization direction (or first polarization direction). In this case, when P-polarized laser light is incident, the reflected light becomes S-polarized laser light. In the transmission region 34b, the laser beam incident from the direction orthogonal to the incident surface 34in is guided to the output surface 34out.

As shown in FIG. 1B, the first exit surface 31out, which is the side surface including the hypotenuse of the right isosceles triangle of the bottom surface of the first prism 31, is superimposed on the 3A entrance surface 33Ain of the third prism 33. The second emission surface 32out, which is the side surface including the hypotenuse of the right isosceles triangle on the bottom surface of the second prism 32, is superimposed and fixed on the third B incident surface 33Bin of the third prism 33. . Then, the side surface of the first prism 31 and the side surface of the second prism 32 that are aligned in close contact with each other in the same direction become a first incident surface 31in and a second incident surface 32in, respectively.
Further, as described above, the reflection / transmission plate 34 is fixed so that the incident surface 34in faces and covers the third emission surface 33out of the third prism 33, and covers the emission surface 34out of the reflection / transmission plate 34. A transmission plate 35 having an incident surface 35 in oppositely disposed is fixed.
By integrally configuring the laser condensing prism 30 as described above, as shown in FIG. 1A, the light guide path of the laser beams L1 (P) (L1 (S)) and L2 (P) is provided. Along with this, the boundary portions of the optical members are not formed.

As shown in FIG. 1A, the laser light shown in FIG. 5A is emitted from each of the light emitting portions 12a to 12h of the semiconductor laser light source 10, and the laser light is emitted as a collected laser beam. . In the following description, the laser light beams emitted from the light emitting units 12a to 12h are divided into the laser light beam L1 (P) incident on the first incident surface 31in of the first prism 31 and the second incident surface 32in of the second prism 32. The laser beam L2 (P) incident on the laser beam will be described separately.
It is assumed that the polarization direction of each of the laser beams emitted from the light emitting units 12a to 12h of the semiconductor laser light source 10 is P-polarized light (corresponding to the first polarization direction).

The laser beam L1 (P) is converted into parallel light with respect to the long axis direction (in this case, the Y axis direction) by the long axis direction collimating lens 20, and is incident on the first incident surface 31in of the first prism 31. The
The laser beam L2 (P) is converted into parallel light with respect to the long axis direction by the long axis direction collimating lens 20 and is incident on the second incident surface 32in of the second prism 32.

The second prism 32 is made of a glass material (for example, quartz) having a refractive index larger than that of air, and the second incident surface 32in is oriented so as to be orthogonal to the traveling direction of the laser beam L2 (P). The second exit surface 32out of the second prism 32 is set to a predetermined angle θb (45 degrees) with respect to the second entrance surface 32in. Then, the second prism 32 emits the laser beam L2 (P) incident from the second incident surface 32in from the second emission surface 32out without changing the polarization direction (the laser beam L2 (P) is the polarization direction). Is transmitted through the second prism 32 without being converted.)
The side surface 32s is set parallel to the traveling direction of the laser beam L2 (P), and is one of the laser beams L2 (P) guided from the second incident surface 32in toward the second emission surface 32out. The portion serves to confine in the second prism 32 (contain in the short axis direction) so that the portion does not leak from the side surface 32s to the outside of the second prism 32.

The first prism 31 is made of a glass material (for example, quartz) having a refractive index larger than that of air, and the first incident surface 31in is oriented so as to be orthogonal to the traveling direction of the laser beam L1 (P). The first exit surface 31out of the first prism 31 is set to a predetermined angle θb (45 degrees) with respect to the first entrance surface 31in. The first prism 31 emits the laser beam L1 (P) incident from the first incident surface 31in from the first emission surface 31out without changing the polarization direction (the laser beam L1 (P) is the polarization direction). Is transmitted through the first prism 31 without being converted.)
The side surface 31s is set parallel to the traveling direction of the laser beam L1 (P), and is one of the laser beams L1 (P) guided from the first incident surface 31in toward the first emission surface 31out. The portion serves to confine in the first prism 31 (contain in the short axis direction) so as not to leak from the side surface 31s to the outside of the first prism 31.

The third prism 33 is made of a glass material (for example, quartz) having a refractive index larger than that of air.
The laser beam L2 (P) incident from the third B incident surface 3Bin is guided to the portion of the third emission surface 33out facing the transmission region 34b of the reflection / transmission plate 34 without changing the traveling direction. The light passes through the transmission region 34 b of the reflection / transmission plate 34 and passes through the transmission plate 35.
The laser beam L1 (P) incident from the third A incident surface 3Ain is guided to the portion of the third emitting surface 33out facing the polarization reflection region 34a of the reflection / transmission plate 34 without changing the traveling direction. However, the laser beam L1 (S) is reflected by the polarization reflection region 34a, the traveling direction is reversed, and the polarization direction is further changed. The laser beam L1 (S) is reflected toward the third B incident surface 33Bin when reaching the third A incident surface 33Ain, and is reflected toward the third exit surface 33out when reaching the third B incident surface 33Bin. The laser beam L1 (S) that has reached the third emission surface 33out is transmitted through the transmission region 34b of the reflection / transmission plate 34 and is transmitted through the transmission plate 35.
As described above, the laser light flux (laser light flux L1 (P) and laser light flux L2 (P)) having the width LWin in the minor axis direction of the light emitting portions 12a to 12h of the semiconductor laser light source 10 is converted into the laser light flux by the laser focusing prism 30. L1 (P) and laser beam L2 (P) are superposed in the minor axis direction, and condensed by being emitted with the width in the minor axis direction being approximately half the width LWout.
The reflection / transmission plate 34 is made of an optical crystal material (for example, quartz) having a refractive index larger than that of air, and the transmission plate 35 is made of a glass material (for example, quartz) having a refractive index larger than that of air. It is said.

● [Integration of laser focusing prism 30 with adhesive (FIGS. 2 to 4)]
In the present embodiment, the condensing prism 30 is integrally formed by filling each boundary portion in the light guide path with an adhesive. In this structure, the laser beam is transmitted through the adhesive layer, but heat generation of the adhesive layer is suppressed by shortening the distance through which the laser beam passes through the adhesive layer.
Next, the structure of the laser focusing prism 30 in the present embodiment will be described with reference to FIGS. 2 and 3 show the structure of this embodiment, and FIG. 4 shows the prior art disclosed in Japanese Patent Application Laid-Open No. 2007-286481.
In the conventional structure shown in FIGS. 4 (A) and 4 (B), as shown in FIG. 4 (B) disassembled into optical members, a prism 133 having a prismatic shape (the bottom surface is trapezoidal), an angle θ (C) The laser condensing prism 130 is constituted by a quadrangular prism-shaped combining prism 131 having a selective reflection surface 131b therein and a plate-shaped polarization conversion plate 132. The inclined surface of the prism 133 is a total reflection surface 133a.
FIG. 4A shows a state in which the boundary portions of the optical members in FIG. 4B are filled with an adhesive and integrated. In FIG. 4A, the hatched portion is an adhesive layer.
In the configuration shown in FIG. 4A, both the light guide path of the laser beam L1 (P) and the light guide path of the laser beam L2 (P) in FIG. The laser light passes through the adhesive layer at a very long distance at the boundary portion Kc that is the boundary portion between the prism 133 and the combining prism 131. For this reason, when a high-power laser having an output greater than or equal to a predetermined value is used as the laser beam L1 (P) and the laser beam L2 (P), the amount of heat generated in the adhesive layer increases at the boundary Kc, and the adhesive changes in quality. there's a possibility that.
In addition, 131m, 132m, and 133m have shown that the non-reflective coating is given.

On the other hand, in the structure of the present embodiment shown in FIG. 2A, as shown in FIG. 2B disassembled into optical members, a triangular prism-shaped first prism whose bottom surface is a right-angled isosceles triangle. The laser condensing prism 30 is composed of the first prism 32, the third prism 33, the plate-shaped reflection / transmission plate 34, and the transmission plate 35.
FIG. 2A shows a state where the boundary portions of the optical members in FIG. 2B are filled and integrated with an adhesive. In FIG. 2A, the hatched portion is an adhesive layer. In addition, it is preferable to select an adhesive having a refractive index equivalent to the refractive index of each optical member. First prism 31 (first exit surface 31out) and third prism 33 (third A entrance surface 33Ain), second prism 32 (second exit surface 32out) and third prism 33 (third B entrance surface 33Bin) ), Between the third prism 33 (the third exit surface 33out thereof) and the reflection / transmission plate 34 (the entrance surface 34in thereof), between the reflection / transmission plate 34 (the exit surface 34out thereof) and the entrance surface 35in of the transmission plate 35 (boundary portion). ) Is filled with an adhesive and fixed so as to be integrated.

In the configuration shown in FIG. 2A, both the incident direction of the laser beam L1 (P) and the incident direction of the laser beam L2 (P) in FIG. Since it is a distance in the thickness direction of the adhesive and is a sufficiently short distance, the heat generation of the adhesive layer is not problematic. Thus, the shape of each optical member is such that no boundary is formed in the direction along the light guide path (including the path that reflects and changes the traveling direction) of the laser light guided into the laser condensing prism 30. Is determined in consideration.
Note that an adhesive layer is formed at the boundary between the third prism 33 and the reflection / transmission plate 34 in a direction along the laser beam L1 (S) reflected from the third A incident surface 33Ain toward the third B incident surface 33Bin. However, the laser beam L1 (S) is reflected in the direction away from the reflection / transmission plate 34 by the reflection / transmission plate 34 before being reflected in the direction along the boundary portion. There is little laser light transmitted in the direction along, and heat generation is suppressed.
In addition, in the laser condensing prism 30 shown in FIG. 2A, the surfaces to which the antireflection coating is applied are the first incident surface 31in of the first prism 31, the second incident surface 32in of the second prism 32, and the emission of the transmission plate 35. It is the surface 35out. In addition, it is not necessary to apply an anti-reflective coating to the whole area | region about the output surface 35out.
Further, the transmission plate 35 may be omitted. When the transmission plate 35 is omitted, on the emission surface 34out of the reflection / transmission plate 34, the polarization reflection region 34a may be provided with a total reflection coating 34c, and the transmission region 34b may be provided with a non-reflection coating, but the coating process is somewhat complicated. become.

In the laser condensing prism 30 described above, the adhesive layer is along the laser light guide path (parallel) at the boundary between the third prism 33 and the reflection / transmission plate 34, and an example in which this is improved will be described. To do.
FIGS. 3A and 3B show an example in which an adhesive is not included in the laser light guide region at the boundary between the third prism 33 and the reflection / transmission plate 34. The laser condensing prism 30 shown in FIG. 3A uses a spacer member S as shown in FIG. 3B to separate the boundary between the third prism 33 and the reflection / transmission plate 34 by a predetermined distance. The spacer member S is not shown in FIG. 3A.
In addition, the spacer member S is provided at a position away from the light guide region used as a light guide path for the condensed laser beam, and is bonded to each optical member using an adhesive for an optical system such as an ultraviolet curable resin. Has been. In the case of using an ultraviolet curable resin, the spacer member S is preferably formed of a transparent member such as quartz that transmits ultraviolet rays in order to cure the adhesive, but when the adhesive is not an ultraviolet curable resin. The spacer member S can be made of various materials such as quartz and stainless steel.
In the laser condensing prism 30 shown in FIG. 3A, the first incident surface 31in, the second incident surface 32in, the third exit surface 33out, the entrance surface 34in of the reflection / transmission plate 34, and the exit surface 35out of the transmission plate 35 are not present. Reflective coatings 31m, 32m, 33m, 34m, and 35m may be applied. In addition, it is not necessary to apply anti-reflection coating to the whole area | region about the output surface 35out, and what is necessary is just to provide to the area | region which covers the transmissive area | region 34b of the reflective transmission board 34 at least.
Further, the transmission plate 35 may be omitted. When the transmission plate 35 is omitted, on the emission surface 34out of the reflection / transmission plate 34, the polarization reflection region 34a may be provided with a total reflection coating 34c, and the transmission region 34b may be provided with a non-reflection coating, but the coating process is somewhat complicated. become.

In addition, the thickness of the spacer member S is preferably set to about 50 μm which is as thin as possible so that an air layer can be reliably formed.
Thereby, since it can be set as the structure where an adhesive layer does not exist along the light guide path of a laser beam, heat_generation | fever of an adhesive layer can be suppressed.
In addition, although it can be considered that the boundary portion of each optical member is spaced and closely adhered without forming an air layer (no adhesive is used), it can be enlarged even if the flatness of the surface of each optical member is increased. As a result, irregularities are always formed, and there are randomly places where the optical members are in contact with each other and places where an air layer is formed without contacting the optical members. Since various coating designs are designed based on the refractive indexes of two media (optical members), if a random air layer intervenes due to unevenness, the contact portion and non-contact portion of the optical member Since the refractive index changes and the transmission efficiency is lowered, it is not preferable.

In the above description, the example in which the third prism 33 and the reflection / transmission plate 34 are bonded using the spacer member S and an air layer is formed at the boundary between the third prism 33 and the reflection / transmission plate 34 has been described. Instead of the spacer member S, an air layer may be formed by applying an adhesive to a predetermined thickness.
Further, at the boundary portion between the third prism 33 and the reflection / transmission plate 34, the spacer member S is used to form an air layer at the boundary portion, so that the first prism 31, the second prism 32, and the third prism are formed. In place of the first unit bonded 33 and the second unit bonded the reflection / transmission plate 34 and the transmission plate 35 with a small gap therebetween and fixed with an adhesive, the light emitting units 12a to 12h The direction perpendicular to the traveling direction of the emitted laser beam (in this case, the Z-axis direction) and the short-axis direction (corresponding to the direction in which the first incident surface 31in and the second incident surface 32in are aligned, in this case, The first unit and the second unit may be sandwiched and fixed by a fixing jig (corresponding to a holding member) from a direction orthogonal to the X-axis direction (in this case, the Y-axis direction).

Also, an air layer may be formed in the same manner as described above at the boundary between the first prism 31 and the third prism 33 and at the boundary between the second prism 32 and the third prism 33.
For example, the boundary portion between the first prism 31 and the third prism 33, the boundary portion between the second prism 32 and the third prism 33, and the boundary portion between the third prism 33 and the reflection / transmission plate 34 deviate from the light guide region. Each of the optical members is disposed by sandwiching a spacer member S (no adhesive is used) between the portions to form an air layer having a predetermined interval (the reflection / transmission plate 34 and the transmission plate 35 may be bonded). The direction perpendicular to the traveling direction of the laser beam emitted from the light emitting units 12a to 12h (in this case, the Z-axis direction) and the short-axis direction (the first incident surface 31in and the second incident surface 32in are arranged side by side. Each optical member may be sandwiched and fixed by a fixing jig (corresponding to a holding member) from a direction orthogonal to the direction (in this case, the X-axis direction) (in this case, the Y-axis direction).
Alternatively, an adhesive is applied to the spacer member S, and each optical member (the first prism 31, the second prism 32, the third prism 33, and the reflection / transmission plate 34 (the transmission plate 35 is bonded) is adhered to the spacer member S. ))) May be fixed.
Further, instead of the spacer member S, each optical member may be fixed by applying an adhesive to a predetermined thickness so as to have the same thickness as the spacer member S.
In this case, the surface that is in contact with the air layer and is not coated with any coating is applied with an anti-reflection coating to attenuate the reflected light when the laser beam is incident or emitted, thereby collecting the laser beam. Light efficiency can be improved. Accordingly, the surfaces to which the antireflection coating is applied are the first incident surface 31in and the first exit surface 32out, the second entrance surface 32in and the second exit surface 32out, the third exit surface 33out, the entrance surface 34in of the reflection / transmission plate 34, and the transmission. This is a portion corresponding to at least the transmission region 34 b in the emission surface 35 out of the plate 35. When the transmission plate 35 is omitted, the transmission plate 35 is a portion corresponding to at least the transmission region 34b on the emission surface 34out of the reflection / transmission plate 34.

The laser condensing prism 30 of the present invention is not limited to the appearance, configuration, structure, and the like described in the present embodiment, and various modifications, additions, and deletions can be made without changing the gist of the present invention.
In the description of the present embodiment, it has been described that P-polarized light corresponds to the first polarization direction and S-polarized light corresponds to the second polarization direction. However, P-polarized light corresponds to the second polarization direction, and S-polarized light corresponds to the first polarization direction. This may correspond to one polarization direction.
In the description of the present embodiment, the laser beam from the semiconductor laser light source 10 is incident on the laser condensing prism 30, and the laser beams L1 (P) and L2 (P) from the semiconductor laser light source 10 are P-polarized light. However, when the laser light incident on the laser condensing prism 30 is not P-polarized light but S-polarized light, the S-polarized laser light is transmitted through the third A incident surface 33Ain and the third B incident surface 33Bin. Then, the P-polarized laser beam is changed to be reflected, and the polarization reflection region 34a may be changed to be converted to P-polarized light and reflected when the S-polarized laser beam is incident.
The laser condensing prism 30 described in the present embodiment can be applied to a CO ₂ laser that is another high-power laser, or a prism that condenses a YAG laser.
Further, if laser light mixed with P-polarized light and S-polarized light is incident from the transmission region 34b side on the emission surface 35out, it can be used as a beam splitter, and is separated from the first incident surface 31in and the second incident surface 32in. Laser light can be extracted.

The laser condensing device 1 that condenses the laser light beam emitted from the semiconductor laser light source 10 by using the laser condensing prism 30 of the present invention by reducing the width in the short axis direction (in this case, the X axis direction) to ½. It is a figure which shows the example of the schematic external view, and the state which isolate | separated the laser condensing prism 30 into each optical member. It is a figure explaining the structure (assembly state of each optical member) of the laser condensing prism 30. FIG. It is a figure explaining the structure (assembly state of each optical member) of the laser condensing prism 30. FIG. It is a figure explaining the structure (assembly state of each optical member) of the conventional laser condensing prism. 2 is a diagram for explaining laser light emitted from a semiconductor laser light source 10. FIG. An example of a schematic external view of a laser condensing device 100 that condenses the laser beam emitted from the semiconductor laser light source 10 by halving the width in the minor axis direction by using the conventional laser condensing prism 130, and the conventional It is a figure which shows the state which isolate | separated the laser condensing prism 130 into each optical member. It is a figure explaining another example in the conventional laser condensing prism.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser condensing apparatus 10 Semiconductor laser light source 12a-12h Light emission part 20 Long-axis direction collimating lens 30 Laser condensing prism 31 1st prism 31in Incident surface (1st incident surface)
31out exit surface (first exit surface)
31s side surface 32 second prism 32in incident surface (second incident surface)
32out exit surface (second exit surface)
32s side surface 33 third prism 33Ain 3A entrance surface 33Bin 3B entrance surface 33out third exit surface 33a, 33b PS separation coating 34 reflective transmission plate 34in entrance surface 34out exit surface 34a polarization reflection region 34b transmission region 34c total reflection coating 35 transmission Plate 35in Incident surface 35out Output surface 31m, 32m, 33m, 34m, 35m Non-reflective coating S Spacer member Kc Boundary part

Claims (8)

A first prism having a triangular prism shape having a first right isosceles triangle as a bottom surface;
A triangular prism-shaped second prism whose bottom surface is a second right isosceles triangle having the same shape as the first right isosceles triangle;
A triangular prism-shaped third whose bottom surface is a third right-angled isosceles triangle formed of two sides sandwiching a right angle by the length of the hypotenuse in the first right-angled isosceles triangle and the length of the hypotenuse in the second right-angled isosceles triangle. Prism,
It has a plate shape, reflects laser light incident from a direction orthogonal to the plate-shaped surface toward the incident direction, and reflects the reflected light when the laser light having the first polarization direction is incident on the first polarization direction. And a reflection / transmission plate having a polarization reflection region that converts to a second polarization direction that is different from the polarization direction and a transmission region that transmits laser light incident from a direction orthogonal to the plate-like surface. A laser condensing prism constructed and assembled,
The third prism is a side surface including a third A incident surface that includes one side that sandwiches the right angle of the third right-angled isosceles triangle and a side surface that includes the other side that sandwiches the right-angle of the third right-angled isosceles triangle. The 3B incident surface is formed on a selective reflection surface that transmits the laser light in the first polarization direction and reflects the laser light in the second polarization direction,
A first emission surface, which is a side surface including the hypotenuse of the first right-angled isosceles triangle in the first prism, is fixed to face the third-A incident surface, and the second right-angled isosceles in the second prism. The second emission surface, which is a side surface including the oblique side of the triangle, is fixed so as to face the third B incidence surface, and thus includes one side sandwiching the right angle of the first right isosceles triangle in the first prism. A first incident surface that is a side surface and a second incident surface that is a side surface including one side that sandwiches the right angle of the second right isosceles triangle in the second prism are adjacent to each other in the same direction. Lined up
The reflection / transmission plate is fixed so as to cover a third emission surface which is a side surface including the oblique side of the third right-angled isosceles triangle in the third prism, and extends along a direction orthogonal to the bottom surface of the third prism. One surface divided into two is formed in the polarization reflection region, and the other surface is formed in the transmission region,
The laser beam having the first polarization direction incident on the first incident surface and the first polarization direction incident on the second incident surface from a direction orthogonal to the first incident surface and the second incident surface. And the laser beam is superposed in the direction in which the first incident surface and the second incident surface are aligned, and is emitted from the transmission region of the reflection / transmission plate,
Laser focusing prism. The laser focusing prism according to claim 1,
The first prism and the third prism, the second prism and the third prism, and the third prism and the reflection / transmission plate are bonded with an adhesive that transmits the laser light.
Laser focusing prism. The laser focusing prism according to claim 2,
The reflected light of the laser beam is attenuated on the first incident surface, the second incident surface, and the surface of the reflective / transmissive plate opposite to the surface facing the third prism in the transmissive region. Anti-reflective coating is applied,
Laser focusing prism. The laser focusing prism according to claim 1,
Furthermore, a plate-shaped transmission plate that transmits the laser light is provided so as to cover a surface on the opposite side of the surface facing the third prism in the reflection / transmission plate,
With the adhesive that transmits the laser light, the first prism and the third prism, the second prism and the third prism, the third prism, the reflection / transmission plate, the reflection / transmission plate, and the The transmission plate is bonded,
The reflected light of the laser beam is formed in a region covering at least the transmission region of the first incident surface, the second incident surface, and a surface of the transmission plate opposite to the reflection transmission plate. Non-reflective coating is applied to attenuate the
Laser focusing prism. The laser focusing prism according to claim 1,
An air layer is formed at a boundary portion between the first prism and the third prism, a boundary portion between the second prism and the third prism, and a boundary portion between the third prism and the reflection / transmission plate. As described above, the first prism, the second prism, the third prism, and the reflection / transmission plate are arranged at a predetermined minute interval,
In the holding member, the first prism, the second prism, the third prism, and the reflection / transmission plate are arranged in a traveling direction of laser light incident from the first incident surface and the second incident surface. From the direction orthogonal to and the direction orthogonal to the direction in which the first incident surface and the second incident surface are aligned, it is sandwiched and held without using an adhesive, and is fixed.
Laser focusing prism. The laser focusing prism according to claim 1,
A spacer member having a predetermined thickness includes a boundary portion between the first prism and the third prism, a boundary portion between the second prism and the third prism, and a boundary between the third prism and the reflection / transmission plate. The first prism, the third prism, the second prism, the third prism, and the like. An air layer is formed and fixed at each boundary between the third prism and the reflection / transmission plate,
Laser focusing prism. The laser focusing prism according to claim 1,
With an adhesive applied to a predetermined thickness, a boundary portion between the first prism and the third prism, a boundary portion between the second prism and the third prism, and the third prism and the reflection The first prism, the third prism, the second prism, and the first prism are bonded to each other at a boundary portion with the transmission plate and at a position off the light guide path of the laser light. An air layer is formed and fixed at the boundary between each of the three prisms and the third prism and the reflection / transmission plate,
Laser focusing prism. It is a laser condensing prism in any one of Claims 5-7,
The first entrance surface and the first exit surface of the first prism, the second entrance surface and the second exit surface of the second prism, the third exit surface of the third prism, and the reflection / transmission plate Non-reflecting to attenuate the reflected light of the laser beam on the surface facing the third emission surface and the surface opposite to the surface facing the third prism in the transmission region of the reflection / transmission plate Coating is applied,
Laser focusing prism.

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