JP7569873B2 - Laser light source unit and laser light source module - Google Patents

Description

The present invention relates to a laser light source unit and a laser light source module having multiple laser light source units.

Patent document 1 describes a laser diode that has a so-called TO-CAN (TRANSITOR OUTLINE CAN) type package structure and is equipped with a thermoelectric cooling element for cooling. Laser diodes with TO-CAN type packages have excellent reliability because the light-emitting end surface is sealed off from the outside air.

U.S. Pat. No. 9,768,538

In order to obtain a high-output laser with high reliability, it has been considered to construct a laser light source unit using multiple TO-CAN type package or surface-emitting laser diodes, and to construct a laser light source module using multiple such laser light source units. Such a laser light source module uses many laser diodes, so the overall amount of heat generated during operation is very large, and there is a risk that the temperature of the laser diodes will exceed the rated temperature. To address this, it has been considered to suppress the temperature rise of the laser diode by using a laser diode equipped with a thermoelectric cooling element as described in Patent Document 1. However, laser diodes equipped with thermoelectric cooling elements are relatively expensive, so a laser light source module equipped with a large number of them would significantly increase the cost.

Therefore, there is a need for a laser light source unit and a laser light source module that can effectively cool each laser diode with an inexpensive configuration, even when using multiple TO-CAN type packages or surface-emitting laser diodes that do not have a thermoelectric cooling element.

In order to solve the above problems, one embodiment of the present invention has the following configurations 1) and 2).
1) A plurality of light source bases each having a base seat portion formed in a rectangular plate shape and having an extension portion extending from one end by less than half the width of the base seat portion, a fixed wall portion erected on the base seat portion, and a TO-CAN type package or a surface-emitting laser diode that is surrounded by the fixed wall portion and fixed to the fixed wall portion with a first alloy made of a metal element;
a unit base including a plate-like base portion and a stepped base portion having two rows of pedestals on which the light source base can be placed, the first row and the second row being arranged in a stepped shape with a constant height pitch, the two rows being arranged in a first direction such that the difference in height between the first row and the second row is half the height pitch;
A collimating optical system that shapes the laser beam emitted from the laser diode into a parallel beam and emits the parallel beam is fixed to the base seat, and a mirror that changes the traveling direction of the laser beam emitted as the parallel beam from the collimating optical system by reflection is fixed to the extension.
The multiple light source bases are laser light source units in which the bottom surfaces of the base seats are fixed to the pedestals of the first row and the second row of the unit base with the extension portions facing toward the center, and the laser beams reflected by the mirror are aligned in a straight line in the vertical direction and emitted as line laser beams .
2) A laser light source module including: a cooling plate; a base plate having a cooling refrigerant flow path therein and to which the cooling plate is integrally attached; a plurality of laser light source units described in 1) attached to the cooling plate; and a coupling optical system that aligns and arranges a plurality of line laser beams emitted from each of the plurality of laser light source units, and then couples and inputs the line laser beams into a fiber.

According to one aspect of the present invention, it is possible to obtain the effect of being able to effectively cool a laser diode using an inexpensive configuration.

FIG. 1 is a perspective view showing a laser diode 1. As shown in FIG. FIG. 2 is a perspective view showing a light source base 2 on which the laser diode 1 is mounted. FIG. 3 is a perspective view showing a light source block TB included in a laser light source unit LU which is an example of a laser light source unit according to an embodiment of the present invention. FIG. 4 is a plan view of the light source block TB. FIG. 5 is a perspective view showing the unit base 6 provided in the laser light source unit LU. FIG. 6 is a perspective view showing the laser light source unit LU. FIG. 7 is a front view of the laser light source unit LU. FIG. 8 is a perspective view showing the laser beam Ls emitted from the light source block TB. FIG. 9 is a diagram showing the line laser beam BmL outputted from the laser light source unit LU. FIG. 10 is a plan view showing a laser light source module 7 which is an example of a laser light source module according to an embodiment of the present invention. FIG. 11 is a cross-sectional view taken along the line S11-S11 in FIG. FIG. 12 is a diagram showing the combined laser beam BmS output from the laser light source module 7. As shown in FIG. FIG. 13 is a graph for explaining the change over time in temperature of the laser diode 1 in the laser light source module 7. In FIG. FIG. 14 is a graph for explaining the temperature rise width ΔT of the laser diode 1 in the laser light source module 7. In FIG.

(Example)
A laser light source unit LU, which is an example of a laser light source unit according to an embodiment of the present invention, will be described with reference to Figs. 1 to 9. Fig. 1 is a perspective view showing a laser diode 1. Fig. 2 is a perspective view showing a light source base 2 to which the laser diode 1 is attached. Fig. 3 is a perspective view showing a light source block TB included in the laser light source unit LU, which is an example of a laser light source unit according to an embodiment of the present invention. Fig. 4 is a plan view of the light source block TB. Fig. 5 is a perspective view showing a unit base 6 included in the laser light source unit LU. Fig. 6 is a perspective view showing the laser light source unit LU. Fig. 7 is a front view of the laser light source unit LU. Fig. 8 is a perspective view showing a laser beam Ls emitted from the light source block TB. Fig. 9 is a view showing a line laser beam BmL output from the laser light source unit LU.

First, the light source block TB will be described with reference to Figs. 1 to 4. As shown in Fig. 1, the laser diode 1 is configured in a so-called TO-CAN type package and does not include a thermoelectric cooling element. From the outside, the laser diode 1 has a cylindrical base 12 with a pair of terminals 13, 13 extending from one end face, and a circular brim-like flange portion 11 that protrudes radially outward from one edge of the base 12. If an imaginary plane SFb including the axis CL2 of the base 12 and the pair of terminals 13, 13 and an imaginary plane SFa perpendicular to the imaginary plane SFb are set, the laser diode 1 has a first notch portion 11a formed at a position where the imaginary plane SFa intersects, and a pair of second notches 11b, 11b formed 180° apart at a position where the imaginary plane SFb intersects.

A semiconductor laser element (not shown) is housed inside the base 12, and the laser beam Ls generated by the semiconductor laser element is emitted to the outside as a light beam spreading in a cone shape centered on the axis line CL2 from an emission port 12a formed at the center position of the other end face of the base 12. The light beam of the laser beam Ls emitted from the emission port 12a has a fast axis AF along an imaginary plane SFa and a slow axis AS along an imaginary plane SFb and perpendicular to the fast axis AF.

The light source base 2 shown in Fig. 2 is made of a material with excellent thermal conductivity such as copper or a copper alloy. The light source base 2 has a base seat 21 which is a rectangular plate-shaped portion, an extension 23 which extends from one end of the base seat 21 by a width less than half the width of the base seat 21, and a fixed wall 22 which is provided vertically on an upper surface 21a of the base seat 21.
In the vicinity of the connection portion between the base seat portion 21 and the extension portion 23 on the upper surface 21a, a step portion 213 is formed where the extension portion 23 side is thicker. In the center of the extension portion 23, a long hole 25 is formed that penetrates in the thickness direction and extends in the longitudinal direction of the base seat portion 21. In the portion of the base seat portion 21 opposite the extension portion 23, as shown in Figures 3 and 4, a round hole 24 is formed that penetrates in the thickness direction. The fixed wall portion 22 may be erected at the end portion in the longitudinal direction of the base seat portion 21, or may be erected at a middle portion other than the end portion. In other words, the light source base 2 is formed in a T-shape or L-shape when viewed from the side.

The side surface of the fixed wall portion 22 on the extension portion 23 side is formed with a circularly carved accommodating recess 22a and a terminal escape portion 22b carved further in the center of the accommodating recess 22a. A pair of through holes (not shown) are formed in the bottom surface of the terminal escape portion 22b, and an insulating tube 3 is fitted into each of the pair of through holes. A notch portion 22c is formed at the tip portion of the fixed wall portion 22, which removes a portion of the peripheral wall of the accommodating recess 22a.

As shown in Figures 3 and 4, the laser diode 1, the first optical seat 512, and the second optical seat 522 are attached to the light source base 2 to form a light source block TB. The configuration of the first optical seat 512 and the first collimating lens 511 is referred to as the first optical block 51, and the configuration of the second optical seat 522 and the second collimating lens 521 is referred to as the second optical block 52.

The laser diode 1 is attached to the fixed wall 22 with the terminals 13, 13 inserted into the terminal holes 3a of the insulating tube 3 and the flange 11 housed in the housing recess 22a so that it is substantially submerged. In other words, the laser diode 1 is fixed to the fixed wall 22 with an alloy so that it is covered by the fixed wall 22. The orientation of the attachment of the laser diode 1 around the axis CL2 is such that the first cutout 11a of the flange 11 matches the cutout 22c of the housing recess 22a.

The side surface 11c and bottom surface 11d of the flange portion 11 of the laser diode 1 (see FIG. 1) and the inner side surface and bottom surface 22d of the accommodation recess 22a are fixed by the first solder Sd1 as a first alloy. The first melting temperature T1 of the first solder Sd1 is, for example, greater than 200°C and less than 260°C. The laser diode 1 is fixed by accommodating the laser diode 1 in the accommodation recess 22a with the sheet-like first solder Sd1 sandwiched therebetween, maintaining the first solder Sd1 at a temperature higher than the first melting temperature T1 for an extremely short time until it melts, and then returning it to room temperature to harden it.

In the first optical block 51, the first optical pedestal 512 is fixed to the upper surface 21a of the base seat 21 near the base 12 of the laser diode 1, and the first collimating lens 511 is fixed to the upper surface of the first optical pedestal 512 so that the axis CL2 of the laser diode 1 is at the center and perpendicular to the axis CL2. In the second optical block 52, the second optical pedestal 522 is fixed to the extension part of the extension part 23 on the base seat 21 side, and the second collimating lens 521 is fixed to the upper surface of the second optical pedestal 522 so that the axis CL2 is at the center and perpendicular to the axis CL2. When the first optical pedestal 512 and the second optical pedestal 522 are fixed to the light source base 2 by soldering, a sheet-like first solder Sd1 is applied to the joining surfaces of the first optical pedestal 512 and the second optical pedestal 522 with the light source base 2 and then welding, and when they are bonded, an adhesive is applied to the joining surfaces of the first optical pedestal 512 and the second optical pedestal 522 with the light source base 2 and then bonding is performed. The first optical pedestal 512 and the second optical pedestal 522 are formed of copper or a copper alloy with high thermal conductivity, or ceramic or an Fe-Ni alloy with low thermal expansion.

The first collimating lens 511 collimates the light beam that spreads in the fast axis direction, and the second collimating lens 521 collimates the light beam that spreads in the slow axis direction. Details of this collimating action in the light source block TB will be described later with reference to FIG. 8.

Next, the laser light source unit LU will be described with reference to FIGS.
The laser light source unit LU includes a unit base 6 shown in Fig. 5 and 15 light source blocks TB mounted on the unit base 6. In Fig. 5 to Fig. 7, the left/right, up/down, front/rear directions defined for convenience of explanation are indicated by arrows.

As shown in FIG. 5, the unit base 6 is formed as an integral, solid mass of a generally flat base portion 61 and a stepped base portion 612 formed as a generally right-angled triangular prism with a rear surface perpendicular to the base portion 61 on the upper surface side of the base portion 61. The unit base 6 is formed from copper or a copper alloy. A plurality of mounting seats 611 extending outward on each of the left and right edges of the base portion 61 are formed. Each mounting seat portion 611 has a mounting hole 611a that penetrates in the vertical direction.

The slope of the stepped pedestal portion 612 has two rows of pedestal groups 62L and 62R, with the rear side being higher, and is formed in a stepped shape. In this example, the left row of pedestal groups 62L has odd-numbered pedestals arranged in them. Specifically, from the top, there are eight steps: the first pedestal 621, the third pedestal 623, the fifth pedestal 625, the seventh pedestal 627, the ninth pedestal 629, the eleventh pedestal 6211, the thirteenth pedestal 6213, and the fifteenth pedestal 6215. On the other hand, the right row of pedestal groups 62R has even-numbered pedestals arranged in them. Specifically, from the top, there are seven steps: the second pedestal 622, the fourth pedestal 624, the sixth pedestal 626, the eighth pedestal 628, the tenth pedestal 6210, the twelfth pedestal 6212, and the fourteenth pedestal 6214. When no distinction is made between the pedestals, they are referred to as pedestals 621.

The height pitch PL of the eight pedestals in pedestal group 62L and the height pitch PR of the seven pedestals in pedestal group 62R are constant and the same pitch (PL = PR), and the height position of each pedestal in pedestal group 62R is half the height difference of each pedestal in pedestal group 62L. In other words, the height difference ΔP between adjacent pedestals in pedestal group 62L and pedestal group 62R is PL/2.

A positioning pin P24 and a positioning pin P25 are embedded in each pedestal of the pedestal groups 62L and 62R so that they protrude upward and are spaced apart in the left-right direction. The positioning pin P24 is provided near the left and right edges, and the positioning pin P25 is provided in the center of the left-right direction of the unit base 6 so that it is in a straight line in the front-to-rear direction when viewed from above.

Each pedestal is formed as a flat surface with a shape corresponding to the bottom surface 26 of the base seat portion 21 of the light source block TB, allowing the light source block TB to be placed thereon. The positioning pin P24 and the positioning pin P25 engage with the round hole 24 and the long hole 25 of the light source base 2 with almost no play, respectively. This allows 15 light source blocks TB to be placed on the unit base 6 in two stepped rows on the left and right, with their extensions 23 facing toward the center.

To fix the light source block TB to the 15 pedestals of the unit base 6, a sheet-like second solder Sd2 is used before melting. The second melting temperature T2, which is the melting temperature of the second solder Sd2, which is a second alloy, is lower than the first melting temperature T1 of the first solder Sd1. The second melting temperature T2 is, for example, 200°C or lower. The light source block TB is fixed by placing the light source block TB on the pedestal of the unit base 6 with the sheet-like second solder Sd2 sandwiched between them, maintaining the second solder Sd2 at a temperature higher than the second melting temperature T2 and lower than the first melting temperature T1 for a short period of time until it melts, and then returning it to room temperature to harden it.

Figure 6 shows a laser light source unit LU assembled by attaching light source blocks TB to a total of 15 pedestals in the pedestal groups 62L and 62R of the unit base 6. Specifically, the laser light source unit LU has 15 light source blocks TB attached to the unit base 6, and is provided with wiring sections that supply power to each laser diode 1.

This wiring section is composed of a connection wire 63L, a connection wire 63R, a conductive bar 65, a connection terminal 64L, and a connection terminal 64R. The connection wire 63L is connected in series to the terminals 13 of the eight laser diodes 1 in the pedestal group 62L, and the connection wire 63R is connected in series to the terminals 13 of the seven laser diodes 1 in the pedestal group 62R. The conductive bar 65 connects the front ends of the connection wires 63L and 63R in series. The connection terminal 64L is connected to the rear end side of the connection wire 63L, and the connection terminal 64R is connected to the rear end side of the connection wire 63R. The connection terminals 64L and 64R are connected to an external power supply device and a predetermined voltage is applied between the two terminals. As a result, laser beams Ls are output from the 15 laser diodes 1.

In each light source block TB, the third optical block 53 is fixed to the upper surface 21a of the base seat 21 in the light source base 2 by the first solder Sd1. When the third optical block 53 is fixed to the upper surface 21a, the beam path of the laser beam Ls is adjusted. The light source block TB with the third optical block 53 attached will be described with reference to FIG. 8.

As shown in FIG. 8, the laser diode 1 is fixed in the housing recess 22a by the first solder Sd1 in a position where the first cutout 11a of the flange portion 11 faces the cutout portion 22c of the light source base 2. In this position, the laser beam Ls emitted from the base portion 12 has a fast axis AF in the vertical direction.

In the light source block TB, the laser beam Ls emitted from the laser diode 1 first enters the first collimator lens 511 of the first optical block 51. The first collimator lens 511 is a collimator lens that shapes a beam spreading in the fast axis direction into a parallel beam. Therefore, the laser beam Ls becomes a fast deflected beam Lsa whose fast axis direction is parallel by the first collimator lens 511.

The fast deflected beam Lsa then enters the second collimating lens 521 of the second optical block 52. The second collimating lens 521 is a collimating lens that shapes the beam expanding in the slow axis direction into a parallel beam. Therefore, the fast deflected beam Lsa becomes the slow deflected beam Lsb, which is also parallel in the slow axis direction, by the second collimating lens 521. In other words, the light flux of the slow deflected beam Lsb emitted from the second collimating lens 521 has a cross-sectional shape that is generally in the positive direction, with both the fast axis direction and the slow axis direction being parallel. The first optical block 51 and the second optical block 52 are collectively referred to as the collimating optical system 54K (see Figures 3 and 4).

The third optical block 53 has a mirror 531, which is a total reflection mirror, and a third optical pedestal 532 to which the mirror 531 is fixed. The slow deflection beam Lsb emitted from the second collimator lens 521 is reflected by the mirror 531, and is redirected by 90 degrees to be emitted as a parallel beam Lsc. In the odd-numbered first, third, fifth, ..., fifteenth light source blocks TB1, TB3, TB5, ..., TB15 fixed to the left-row pedestal group 62L shown in FIG. 6, the mirror 531 is arranged in a direction to deflect the laser beam Ls by 90 degrees to the right in the traveling direction, as shown in FIG. 8. On the other hand, the even-numbered second, fourth, sixth, ..., fourteenth light source blocks TB2, TB4, TB6, ..., TB14 fixed to the right-row pedestal group 62R are arranged in a direction to deflect the laser beam Ls by 90 degrees to the left in the traveling direction.

As a result, as shown in FIG. 6, the laser beams Ls emitted from the laser diodes 1 of the first to fifteenth light source blocks TB1 to TB15 are all deflected 90 degrees so that they are directed forward. In FIG. 6 and FIG. 7, the laser beams Ls of the fourteenth light source block TB14 and the fifteenth light source block TB15 are shown by dashed lines as representatives (only the optical axis is shown in FIG. 6).

The difference ΔP in height between adjacent pedestals between pedestal group 62L and pedestal group 62R on the unit base 6 is set to be approximately the same as the vertical width of the laser beam Ls emitted as a parallel beam Lsc from the light source block TB as shown in FIG. 8. As a result, the laser light source unit LU emits a line laser beam BmL in which the first laser beam Bm1 to the fifteenth laser beam Bm1, which are the fifteen laser beams Ls emitted from the first light source block TB1 to the fifteenth light source block TB15, are arranged in a vertical straight line as shown in FIG. 9 when viewed from the front.

Figure 10 is a schematic plan view showing a laser light source module 7 having multiple laser light source units LU.

As shown in FIG. 11, which is a cross-sectional view taken at the S11-S11 position in FIG. 10, the laser light source module 7 has a laminated structure in which a cooling plate 71 and a base plate 72 are fixed together. The base plate 72 has a refrigerant flow path 721 formed therein in a predetermined pattern (zigzag, lattice, etc.) for cooling. A hose 791 (see FIG. 10) is connected to the refrigerant flow path 721, and a fluid such as water that serves as a refrigerant flows in abundantly from the outside at a temperature below room temperature. The refrigerant flowing through the refrigerant flow path 721 exchanges heat with the base plate 72, raising its temperature, and is discharged to the outside through the hose 792 (see FIG. 10).

This allows the base plate 72 to be cooled effectively. In addition, the base plate 72 is tightly attached to the cooling plate 71 using a bonding method such as brazing, so the cooling plate 71 is also cooled effectively.

As shown in FIG. 10, a plurality of laser light source units LU are provided on the upper surface of the cooling plate 71. Each laser light source unit LU is placed on the flat upper surface of the cooling plate 71 with the flat bottom surface of the base portion 61 sandwiching the thermally conductive sheet 73 as shown in FIG. 11, and is fixed to the cooling plate 71 with screws using the mounting holes 611a (see FIG. 6).

A light source unit group is formed by grouping together multiple laser light source units LU. In this example, the laser light source module 7 has three light source unit groups, the first to third light source unit groups LUG1 to LUG3.

In FIG. 10, line laser beams LmG1 to LmG3 are output from the first to third light source unit groups LUG1 to LUG3, respectively. The laser light source module 7 is equipped with a coupling optical system CK having a condensing lens 772. The multiple line laser beams LmG1 to LmG3 are combined by the coupling optical system CK to form a combined laser beam BmS. The combined laser beam BmS is condensed by the condensing lens 772 and enters the fiber 78 via the light entrance portion 773 of the fiber 78.

As shown in FIG. 12, the combined laser beam BmS incident on the focusing lens 772 is a light beam with a rectangular cross section based on the line laser beams LmG1 to LmG3. For example, if the combined laser beam BmS is made up of 14 line laser beams BmL1 to BmL14, it corresponds to the output of 420 laser diodes 1.

The characteristics of a typical blue laser diode are, for example, an output of 5W for an input current of 4A and a voltage of 5V, and an electrical-to-optical conversion efficiency of 25%. The upper limit of the operating temperature is 60°C. Therefore, the output of the combined laser beam BmS of the laser light source module 7 is 5W x 420, or 2100W, and the heat generation per unit time is 2100W x (100-25)/25, or 6300W.

As described above, the laser light source module 7 can achieve high output, and the multiple laser diodes 1, which are heat sources, generate a corresponding amount of heat. However, in the laser light source module 7, the laser diodes 1 are joined to the fixed wall portion 22 of the light source base 2 by the first solder Sd1 that acts as a heat conductive sheet, the light source base 2 is joined to the pedestal 621 of the unit base 6 in the laser light source module 7 by the second solder Sd2 that acts as a heat conductive sheet, the unit base 6 is formed in a solid stepped shape, the bottom surface that is the largest area is in surface contact with the cooling plate 71 via the heat conductive sheet 73, and the base plate 72, which is integrated with the cooling plate so that there is substantially no thermal resistance, is cooled by a refrigerant, thereby effectively suppressing the temperature rise of each laser diode 1.

The temperature rise of the laser diode 1 during operation of the laser light source module 7 will be described with reference to Figures 13 and 14. Figure 13 is a graph for explaining the change over time in temperature of the laser diode 1 in the laser light source module 7. Figure 14 is a graph for explaining the temperature rise width ΔT of the laser diode 1 in the laser light source module 7.

Figure 13 shows the transition of temperature Tc from one minute after the start of aging for the laser diode 1 of the light source block TB1, the laser diode 1 of the light source block TB15, and the laser diode 1 of the light source block TB9 as representatives of the 15 light source blocks TB of the laser light source module 7, as LD1, LD15, and LD9, respectively. The laser diode 1 of the light source block TB1 is located at the farthest position (high position) from the cooling plate 71. The laser diode 1 of the light source block TB15 is located at the closest position (low position) to the cooling plate 71. The laser diode 1 of the light source block TB9 is located at an intermediate height position between these. Here, the start of aging is the point in time when one minute has passed since the current applied to the laser diode 1 was gradually increased from 0 A (amperes) to reach the rated current of 3.2 A. The ambient temperature was room temperature, 25°C. In addition, the laser light source module 7 was cooled by abundantly flowing 25°C water into the refrigerant flow path 721.

As a result, as shown in FIG. 13, in all the laser diodes 1, the temperature Tc rose from the start of the measurement and reached a substantially constant saturated temperature after about 20 minutes of aging time had elapsed.
The saturation temperature of the laser diode 1 in the first light source block TB1 located farthest from the cooling plate 71 was the lowest at approximately 33.9° C., followed by the saturation temperature of the laser diode 1 in the fifteenth light source block TB15 located closest to the cooling plate 71 at approximately 36.0° C. The saturation temperature of the laser diode 1 in the ninth light source block TB9 located at an intermediate height position was the highest at approximately 38.5° C. The saturation temperature of the laser diode 1 in this ninth light source block TB9 was the highest of the saturation temperatures of the fifteen laser diodes 1.

Figure 14 is a graph showing the temperature rise ΔT, which is the temperature rise from room temperature, of the saturation temperature of the laser diodes 1 in the first, third, fifth, seventh, ninth, eleventh, thirteenth, and fifteenth light source blocks TB1, TB3, TB5, TB7, TB9, TB11, TB13, and TB15.

As shown in FIG. 14, it is clear that the temperature rise ΔT of the laser diode 1 at the intermediate height is greater than the temperature rise ΔT of the laser diode 1 on the far side and the near side of the cooling plate 71. Even so, the temperature rise ΔT is kept below 14°C. Therefore, when the operating environment temperature is room temperature, or even if the operating environment temperature is as high as 40°C, the saturation temperature of the laser diode 1 is below the rated upper limit temperature of 60°C. In this way, the laser light source module 7 provides extremely good cooling of the laser diode 1.

The inventors evaluated the effect of temperature rise due to the shape of the light source base 2. Specifically, the saturation temperatures were measured and compared under the same operating and environmental conditions for a case in which the light source base 2 is I-shaped in side view, formed only of the fixed wall portion 22, and a case in which the light source base 2 has a base seat portion 21 and is T-shaped in side view, with the fixed wall portion 22 erected on the base seat portion 21. The measurements were performed at two locations: the flange portion 11 of the laser diode 1 in a TO-CAN type package joined to the fixed wall portion 22, and the vicinity of the laser beam emission port (LD end).

As a result, it was found that the saturation temperature of the T-shape was approximately 0.9°C lower than that of the I-shape for both the flange portion 11 and the LD end. This revealed that it is more preferable for the light source base 2 to have a base seat portion 21 and a T-shape in side view.

As described above in detail, the light source block TB of the laser light source unit LU, which is one aspect of the present invention, is fixed to the bottom surface 26 (see FIG. 3) of the light source base 2 and the upper surface of each pedestal by the second solder Sd2 that serves as a thermally conductive sheet. The melting temperature of the second solder is the second melting temperature T2 that is lower than the first melting temperature T1 of the first solder that serves as a thermally conductive sheet. Therefore, when a malfunction occurs in any of the light source blocks TB, the temperature of the light source block TB can be made to exceed the second melting temperature T2 and lower than the first melting temperature T1, so that the target light source block TB can be removed from the unit base 6 while leaving the laser diode 1 and the first to third optical blocks 51 to 53 of the light source block TB fixed by the first solder Sd1 intact. This allows the laser light source unit LU and the laser light source module 7 to be repaired and replaced on a light source block TB basis, improving the efficiency of maintenance work.

The optical characteristics of the light source block TB can be evaluated by itself. This improves the efficiency of maintenance work on the laser light source unit LU and the laser light source module 7. In addition, since the laser light source unit LU can be constructed by selecting light source blocks TB with uniform optical characteristics, high-performance light source blocks TB can be manufactured stably.

In this manner, the laser light source unit LU according to one aspect of the present invention has high maintainability because the light source block TB can be individually removed from the pedestal 621 (step pedestal portion 612).
On the other hand, in the laser light source unit LU, the first solder Sd1 that brings the laser diode 1, which is a heat source, into close contact with the light source base 2 also plays the role of a heat conductive sheet. Furthermore, the second solder Sd2 that separates the light source block TB from the pedestal 621 and brings the light source base 2 of the light source block TB into close contact with the pedestal 621 also plays the role of a heat conductive sheet. In detail, the first solder Sd1 joins the laser diode 1 to the light source base 2 over the entire surface of the contact target surface of the laser diode 1 with the light source base 2, and the second solder Sd2 joins the light source base 2 to the unit base 6 over the entire surface of the contact target surface of the light source base 2 with the unit base 6. Here, the contact target surface refers to a surface that can be joined when the first solder Sd1 or the second solder Sd2 is interposed by being adjacent to or in contact with a mating component when the first solder Sd1 and the second solder Sd2 are not interposed. For example, for the laser diode 1, the side surface 11c and the bottom surface 11d of the flange portion 11 are surfaces that can be joined by the first solder Sd1 by closely facing or contacting the inner side surface of the accommodation recess 22a of the fixed wall portion 22 and the accommodation bottom portion 22d of the fixed wall portion 22 when the first solder Sd1 is not interposed (see FIG. 1). Also, for the light source base 2, the side surface 11c and the bottom surface 11d are surfaces that can be joined by the second solder Sd2 by closely facing or contacting the pedestal 621 on the bottom surface 26 of the base seat portion 21 when the first solder Sd1 is not interposed (see FIG. 3). For example, if the bottom surface 26 of the light source base 2 is a flat plane, the entire surface of the bottom surface 26 becomes the contact target surface. As a result, even if the laser light source unit LU does not have a conventional structure in which the light source block TB and the pedestal 621 are integrally formed, the heat generated by the laser diode 1 is sufficiently transmitted to the pedestal 621 side via the light source block TB, so that the laser diode 1 and the light source block TB are well cooled. In other words, the configuration of the laser light source unit LU of one embodiment of the present invention can solve the secondary problem of reduced cooling efficiency due to a tiny air layer existing between the contact surfaces of the light source base 2 of the light source block TB and the base 621, which may occur when the light source block TB is configured to be individually removable from the base 621.

In addition, the laser light source unit and the laser light source module are required to arrange the multiple laser diodes mounted thereon at a high density in order to increase the laser output, to be able to sufficiently cool each laser diode even when multiple laser diodes are arranged at a high density, and to ensure that the cooling performance of each laser diode is not compromised even when the laser diodes are arranged at a high density while maintaining ease of maintenance. The laser light source unit LU and the laser light source module 7 of one embodiment of the present invention have a configuration that, as described above, achieves all of these requirements.

As described above, the laser light source module 7 can effectively cool the laser diode 1 with an extremely simple configuration including the unit base 6 on which multiple light source blocks TB each having a laser diode 1 are mounted in a stepped manner, a flat cooling plate to which the unit base 6 is tightly fixed, and a base plate 72 having a refrigerant flow path stacked on the cooling plate. The laser light source module 7 can effectively cool and stably operate the laser diode 1 with an inexpensive configuration, even if the laser diode 1 is a TO-CAN packaged laser diode that does not have a thermoelectric cooling element.

The light source block TB is fixed between the bottom surface 26 (see FIG. 3) of the light source base 2 and the top surface of each pedestal by the second solder Sd2, which acts as a thermally conductive sheet. The melting temperature of the second solder is a second melting temperature T2, which is lower than the first melting temperature T1 of the first solder, which acts as a thermally conductive sheet. Therefore, if a malfunction occurs in any of the light source blocks TB, the temperature of the light source block TB can be made higher than the second melting temperature T2 and lower than the first melting temperature T1, and the target light source block TB can be removed from the unit base 6 while leaving the laser diode 1 and the first to third optical blocks 51 to 53 of the light source block TB fixed by the first solder Sd1 intact. This allows the laser light source unit LU and the laser light source module 7 to be repaired and replaced on a light source block TB basis, improving the efficiency of maintenance work.

The optical characteristics of the light source block TB can be evaluated by itself. This improves the efficiency of maintenance work on the laser light source unit LU and the laser light source module 7. In addition, since the laser light source unit LU can be constructed by selecting light source blocks TB with uniform optical characteristics, high-performance light source blocks TB can be manufactured stably.

That is, one aspect of the laser light source unit of the present invention is a laser light source unit including a laser diode 1 in a TO-CAN type package, a light source base 2 to which the laser diode 1 is fixed with a first solder Sd1 that melts at a first melting temperature T1, a collimating optical system 54K that shapes the laser beam Ls emitted from the laser diode 1 into a parallel beam and emits it, and a plurality of light source blocks TB1 to TB15 each having a mirror 531 that reflects the shaped laser beam Ls and changes the traveling direction, and a plate-shaped base portion 61 and a plurality of pedestals 621 on which the light source blocks TB can be placed are arranged at a predetermined height pitch. The unit base 6 is integrated with a stepped pedestal portion 612 having pedestal groups 62L, 62R arranged in a stepped manner with a difference ΔP, and the multiple light source blocks TB1 to TB15 are fixed to the multiple pedestals 621 of the pedestal groups 62L, 62R of the unit base 6 with a second solder Sd2 that melts at a second melting temperature T2 lower than the first melting temperature T1, and the laser beam Ls reflected by the mirror 531 in each of the multiple light source blocks TB1 to TB15 is a laser light source unit LU that is aligned in a straight line in the height direction and radiates as a line laser beam BmL.

This laser light source unit has a stepped unit base 6, which has a large heat capacity, and the stepped bottom surface of the unit base 6 has a large area. Therefore, the bottom surface of the unit base 6 is in close contact with the cooling plate 71 via a thermally conductive sheet 73, and the cooling plate 71 is cooled by a well-known inexpensive cooling method such as water cooling, thereby allowing each laser diode 1 to be cooled well.

In addition, in the above laser light source unit, the light source block TB can be removed from the pedestal 621 of the pedestal groups 62L and 62R by heating it to a temperature that exceeds the second melting temperature T2 and is lower than the first melting temperature T1.

This allows the laser light source unit LU to be repaired and replaced on a light source block TB basis, improving the efficiency of maintenance work.

In addition, one aspect of the laser light source module of the present invention is a laser light source module 7 that includes a cooling plate 71, a base plate 72 having a cooling refrigerant flow path 721 inside and integrally attached to the cooling plate 71, a plurality of the above-mentioned laser light source units LU attached to the cooling plate 71 with a heat conductive sheet 73 sandwiched therebetween, and a coupling optical system CK that aligns and arranges a plurality of line laser beams BmL emitted from each of the plurality of laser light source units LU, and then couples and inputs them into a fiber 78.

As a result, by flowing a coolant such as water into the coolant flow path 721, the base plate 72, as well as the laser light source unit LU and the cooling plate 71, can be cooled well, and even if the laser diode 1 is a TO-CAN package laser diode that does not have a thermoelectric cooling element, it can be cooled well and operated stably with an inexpensive configuration.
In the laser light source module 7, the light source block TB can be removed from the pedestal 621 of the pedestal group 62L, 62R by heating the light source block TB to a temperature higher than the second melting temperature T2 and lower than the first melting temperature T1. This allows the laser light source module 7 to be repaired and replaced on a light source block TB basis, improving the efficiency of maintenance work.

The embodiment of the present invention is not limited to the above-mentioned configuration, and may be modified without departing from the spirit of the present invention.

The light source block TB has been described as capable of fixing the laser diode 1, the first optical block 51, the second optical block 52, and the third optical block 53, but is not limited to this. For example, the base seat portion 21 may be shaped to fix only the laser diode 1, and fixed to the base of the unit base 6 (such as the first base 621) with the second solder Sd2. In this case, the first to third optical blocks 51 to 53 are also fixed independently to the first base 621 by the first solder Sd1 after adjusting the beam path.

The laser diode 1 is not limited to a TO-CAN type package, but may be a surface-emitting laser diode. The joining between the laser diode 1 and the fixed wall portion 22 of the base seat portion 21 is not limited to soldering, so long as it is made of an alloy made of metal elements. In addition, the joining between the light source base 2 and the stepped base portion 612 of the unit base 6 is not limited to soldering, so long as it is made of an alloy made of metal elements.

As described above in detail, the laser light source unit LU of one embodiment of the present invention comprises a base seat 21, a fixed wall 22 erected on the base seat 21, a TO-CAN type package or surface-emitting laser diode 1 surrounded by the fixed wall 22 and fixed to the fixed wall 22 with a first alloy Sd1 made of metal elements, a plurality of light source bases 2, and a unit base 6 integrated with a plate-shaped base 61 and a stepped pedestal 612 in which pedestals on which the light source bases 2 can be placed are arranged in a stepped manner at predetermined height intervals, and the plurality of light source bases 2 are fixed to their respective pedestals on the unit base 6 with a second alloy Sd2 made of metal elements.

This prevents the temperature of the laser diode 1 from rising.

In this embodiment of the laser light source unit LU, a collimating optical system 54K that shapes the laser beam emitted from the laser diode 1 into a parallel beam and emits it may be fixed to the base seat 21.

This improves the accuracy of the optical axis of the lasers emitted from the multiple laser light source units LU.

In this embodiment of the laser light source unit LU, the base seat 21 extends in the opposite direction to the position where the collimating optical system 54K is fixed to the fixed wall 22.

This further improves the heat dissipation effect of the base seat portion 21.

In this embodiment of the laser light source unit LU, the first alloy Sd1 or the second alloy Sd2 may be solder.

As a result, the first and second alloys Sd1 and Sd2 are easy to obtain and handle, preventing increases in costs.

In this embodiment of the laser light source unit LU, the first alloy Sd1 may melt at a first melting temperature T1, and the second alloy Sd2 may melt at a second melting temperature T2 that is lower than the first melting temperature T1.

By this, by setting the laser light source unit LU to a temperature intermediate between the first melting temperature T1 and the second melting temperature T2, the light source base 2 can be removed from the step pedestal portion 612 while keeping the laser diode 1 fixed to the fixed wall portion 22.

In this embodiment of the laser light source unit LU, the laser diode 1 may remain attached to the light source base 2 even when the light source base 2 is heated to the second melting temperature T2 and removed from the unit base 6.

This improves maintainability.

In this embodiment of the laser light source unit LU, the first alloy Sd1 bonds the laser diode 1 to the light source base 2 over the entire surface of the contact surface of the laser diode 1 with the light source base 2, and the second alloy Sd2 bonds the light source base 2 to the unit base 6 over the entire surface of the contact surface of the light source base 2 with the unit base 6.

This effectively prevents the temperature rise of the laser diode 1.

In this embodiment of the laser light source unit LU, the light source block TB is configured to include a light source base 2 and a mirror 531 that reflects the laser beam emitted from the collimating optical system 54K and changes the direction of travel, and the laser beam reflected by the mirror 531 in each of the multiple light source blocks TB may be arranged in a straight line in the height direction and emitted as a line laser beam BmL.

This makes it easy to construct a highly accurate line laser beam BmL.

The laser light source module 7, which is a second embodiment of the present invention, comprises a cooling plate 71, a base plate 72 having a cooling refrigerant flow path 721 therein and integrally attached to the cooling plate 71, a plurality of laser light source units LU of the above embodiment attached to the cooling plate 71, and a coupling optical system CK that aligns and arranges a plurality of line laser beams BmL emitted from each of the plurality of laser light source units LU, and then couples and inputs them into a fiber.

This results in a laser light source module 7 that effectively suppresses temperature rise in the laser diode 1.

REFERENCE SIGNS LIST 1 laser diode 11 flange portion 11a first cutout portion 11b second cutout portion 11c side surface 11d bottom surface 12 base portion 12a radiation port 13 terminal 2 light source base 21 base seat portion 21a upper surface 213 step portion 22 fixed wall portion 22a accommodation recess 22b terminal clearance portion
22c: Notch 22d: Housing bottom 23: Extension 24: Round hole 25: Slot 26: Bottom surface 3: Insulating tube 3a: Terminal hole 51: First optical block 511: First collimating lens 512: First optical base
52 Second optical block 521 Second collimating lens 522 Second optical base 53 Third optical block 531 Mirror 532 Third optical base 54K Collimating optical system 6 Unit base 61 Base portion 611 Mounting seat portion 611a Mounting hole 612 Stepped base portion 62L, 62R Base group 621 to 6215 First to fifteenth bases 63L, 63R Connection wire 64L, 64R Connection terminal 65 Conductive bar 7 Laser light source module 71 Cooling plate 72 Base plate 721 Coolant flow path 73 Thermal conduction sheet 772 Condenser lens 773 Light entrance portion 78 Fiber 791, 792 Hose AF Fast axis, AS Slow axis A1 to A3 First region to third region BC Beam combiner Bm1 to Bm15 1st to 15th laser beam BmL Line laser beams BmL1 to BmL14 1st to 14th line laser beams BmS Combined laser beam CK Coupling optical system CL2 Axis LU Laser light source unit LUG1 to LUG3 1st to 3rd light source unit groups Ls Laser beam Lsa Fast deflection beam Lsb Slow deflection beam Lsc Parallel beam PL, PR Height pitch P24, P25 Positioning pin Sd1 First solder Sd2 Second solder SFa, SFb Virtual plane TB Light source block TB1 to TB15 1st light source block to 15th light source block Tc Temperature T1 First melting temperature T2 Second melting temperature ΔP Difference ΔT Temperature rise width

Claims (8)

a plurality of light source bases each having a base seat portion formed in a rectangular plate shape and having an extension portion extending from one end by less than half the width of the base seat portion, a fixed wall portion erected on the base seat portion, and a TO-CAN type package or a surface emitting laser diode that is surrounded by the fixed wall portion and is fixed to the fixed wall portion by a first alloy made of a metal element;
a unit base including a plate-like base portion and a stepped base portion having two rows of pedestals on which the light source base can be placed, the first row and the second row being arranged in a stepped shape with a constant height pitch, the two rows being arranged in a first direction such that the difference in height between the first row and the second row is half the height pitch;
A collimating optical system that shapes the laser beam emitted from the laser diode into a parallel beam and emits the parallel beam is fixed to the base seat, and a mirror that changes the traveling direction of the laser beam emitted as the parallel beam from the collimating optical system by reflection is fixed to the extension.
A laser light source unit in which the multiple light source bases are fixed with a second alloy made of metal elements so that the bottom surfaces of the base seats are attached to the pedestals of the first row and the second row of the unit base, the extension portions are oriented toward the center, and the laser beams reflected by the mirror are aligned in a straight line in the height direction and emitted as line laser beams . The laser light source unit according to claim 1, wherein the base seat also extends in a direction opposite to the position where the collimating optical system is fixed to the fixed wall. The laser light source unit of claim 1, wherein the first alloy is solder. The laser light source unit of claim 1, wherein the second alloy is solder. The laser light source unit of claim 1, wherein the first alloy melts at a first melting temperature, and the second alloy melts at a second melting temperature that is lower than the first melting temperature. The laser light source unit according to claim 5, wherein the laser diode remains attached to the light source base even when the light source base is heated to the second melting temperature and removed from the unit base. The first alloy bonds the laser diode to the light source base over the entire surface of the laser diode that is to be in contact with the light source base;
2. The laser light source unit according to claim 1, wherein the second alloy bonds the light source base to the unit base over the entire surface of the light source base that comes into contact with the unit base . A laser light source module comprising: a cooling plate; a base plate having a cooling refrigerant flow path therein and integrally attached to the cooling plate; a plurality of laser light source units according to any one of claims 1 to 7 attached to the cooling plate; and a coupling optical system which aligns and arranges a plurality of line laser beams emitted from each of the plurality of laser light source units, and then couples and inputs the line laser beams into a fiber.

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