JP6677073B2 - Laser sheet light source device - Google Patents

Description

  The present invention relates to a laser sheet light source device.

  Conventionally, a technique called PIV (Particle Image Velocimetry) has been known as a method of measuring the flow or velocity of a fluid. PIV is a technique in which the flow of a fluid is reduced by mixing fine particles called tracer particles into a fluid and photographing scattered light obtained by irradiating the tracer particles with a sheet-like laser beam (hereinafter, laser sheet). This is a technology that measures in two dimensions.

  In the above-described PIV, a solid-state laser or a gas laser capable of obtaining a high output has been used as a light source. For example, Patent Literature 1 discloses that an Nd: YAG laser is used as a light source of a PIV. Patent Literature 2 discloses that an argon laser is used as a light source of PIV.

JP 2007-085784 A JP 2010-117190 A

  In recent years, with the progress of solid-state light source technology, the use of semiconductor lasers instead of solid-state lasers and gas lasers as PIV light sources has been studied. In particular, from the viewpoint of realizing a high output, it has been studied to use a plurality of semiconductor laser elements (that is, CAN type semiconductor laser elements) mounted on a CAN package in a row.

  By the way, according to the earnest study of the present inventors, when a plurality of CAN type semiconductor laser elements are used side by side as a light source of PIV, the width of the laser sheet is not sufficiently widened, so that a large number of tracer particles cannot be irradiated. I understood that.

  Therefore, the present inventor has studied to increase the width of the laser sheet using a lens capable of expanding the laser light from each semiconductor laser element. Then, it turned out that the intensity | strength of a laser sheet did not become uniform and variation occurred.

  When the intensity of the laser sheet varies, each tracer particle may be irradiated with laser light of different intensity. That is, tracer particles irradiated by laser light of relatively high intensity and tracer particles irradiated by laser light of relatively low intensity are mixed. As a result, there is a problem that the intensity of the scattered light from the tracer particles fluctuates, and the accuracy of the measurement result decreases. Therefore, there is a need for a technique capable of increasing the width of the laser sheet without making the strength of the laser sheet non-uniform.

  The above demand is not limited to the PIV, but is common when a laser sheet is formed using a light source in which a plurality of CAN type semiconductor laser elements are arranged. For example, an illumination device that irradiates a laser sheet or a measurement device that measures the shape of an object using a laser sheet is similarly obtained.

  According to the present invention, when a laser sheet is formed using a light source in which a plurality of CAN type semiconductor laser elements are arranged, it is possible to increase the width of the laser sheet while suppressing the intensity of the laser sheet from becoming uneven. The purpose is to provide simple technology.

The laser sheet light source device of the present invention,
A plurality of CAN laser diodes;
A first optical system that converts each laser light emitted from the plurality of semiconductor laser elements into parallel light having a certain width in at least a first direction,
A second optical system that includes an incident surface on which the parallel light is incident, and expands the width of the parallel light in a second direction orthogonal to the first direction,
The parallel light travels from different positions with respect to the second direction toward the incident surface of the second optical system,
The parallel light beams adjacent in the second direction overlap with each other on the incident surface of the second optical system.

  According to the above configuration, the laser light emitted from each semiconductor laser element is converted into parallel light having a certain width at least in the first direction. Further, the width of the parallel light in the second direction orthogonal to the first direction is enlarged by the second optical system. Thereby, the width of the laser sheet in the second direction can be increased.

  Further, according to the above configuration, the parallel lights adjacent in the second direction overlap each other and enter the incident surface of the second optical system. Thus, the variation in the intensity of the light incident on the second optical system can be suppressed, so that the variation in the intensity of the light emitted from the second optical system can also be suppressed.

  As described above, according to the above configuration, the width of the laser sheet can be increased, and the strength of the laser sheet can be prevented from becoming uneven.

In the above configuration,
In the parallel light adjacent in the second direction, the principal ray of one of the parallel lights is closer to the incident surface of the second optical system so that the principal ray of one of the parallel lights is closer to the other of the parallel lights. The light may be inclined with respect to the principal ray of light.

  According to the above configuration, the principal rays of one of the parallel lights are inclined with respect to the principal ray of the other parallel light so that the principal rays of the parallel lights adjacent to each other in the second direction approach each other. Two parallel lights can be superimposed on the incident surface of the second optical system.

In the above configuration,
The principal ray of the parallel light of at least a part of the parallel light is inclined with respect to the optical axis so as to be closer to the optical axis of the second optical system toward the incident surface of the second optical system. ,
The angle at which the principal ray of the parallel light inclines with respect to the optical axis may increase as the parallel light moves away from the optical axis in the second direction.

  According to the above configuration, even parallel light separated from the optical axis of the second optical system can be superimposed on parallel light adjacent in the second direction on the incident surface of the second optical system.

In the above configuration,
The semiconductor laser device is arranged at different positions with respect to the second direction,
In the semiconductor laser devices adjacent in the second direction, the light emission surface of one semiconductor laser device may be inclined with respect to the light emission surface of the other semiconductor laser device.

  According to the above configuration, in the semiconductor laser devices adjacent in the second direction, the light emission surface of one semiconductor laser device is inclined with respect to the light emission surface of the other semiconductor laser device, so that two adjacent semiconductor laser devices can be formed. The parallel light can be superimposed on the incident surface of the second optical system.

In the above configuration,
The first optical system,
A first convex cylindrical lens that converts the laser light emitted from the semiconductor laser element to have a certain width in the first direction;
A second convex cylindrical lens that converts the laser light emitted from the convex cylindrical lens to have a certain width in the second direction,
The biconvex cylindrical lens receives the laser light from different positions with respect to the second direction, converts the incident laser light, and condenses the laser light toward the incident surface of the second optical system. It doesn't matter.

  According to the above configuration, by using the convex cylindrical lens and the convex lens without inclining the light emitting surface of the semiconductor laser element, two adjacent parallel lights can be overlapped on the incident surface of the second optical system. It becomes possible.

In the above configuration,
The first optical system,
A collimator lens that converts the laser light emitted from the semiconductor laser element into the parallel light,
A plurality of reflecting mirrors arranged corresponding to the plurality of semiconductor laser elements and reflecting the converted parallel light by the collimator lens to be incident on the incident surface of the second optical system,
The reflecting mirrors are arranged at positions different from each other with respect to the second direction,
In the reflection mirrors adjacent in the second direction, the reflection surface of one reflection mirror may be inclined with respect to the reflection surface of the other reflection mirror.

  According to the above configuration, in the reflection mirror adjacent in the second direction, the reflection surface of one reflection mirror is inclined with respect to the reflection surface of the other reflection mirror without tilting the light emission surface of the semiconductor laser element. By doing so, it becomes possible to overlap two adjacent parallel lights on the incident surface of the second optical system.

In the above configuration,
The second optical system may be a plano-concave cylindrical lens or a biconcave cylindrical lens.

In the above configuration,
The first direction is a direction optically equivalent to the fast axis direction of the laser light emitted from the semiconductor laser element,
The second direction may be a direction optically equivalent to a slow axis direction of the laser light emitted from the semiconductor laser element.

  According to the laser sheet light source device of the present invention, in the case where a laser sheet is formed using a light source in which a plurality of CAN type semiconductor laser elements are arranged, while suppressing the intensity of the laser sheet from becoming uneven, The width of the laser sheet can be increased.

It is a schematic diagram for explaining the outline of PIV. FIG. 2 is a schematic diagram illustrating a configuration of a laser sheet light source device according to the first embodiment. FIG. 3 is a schematic diagram showing laser light emitted from a semiconductor laser element. FIG. 3 is a schematic diagram when the semiconductor laser device, the plano-convex cylindrical lens, and the plano-concave cylindrical lens of the first embodiment are viewed in the −y direction. It is a schematic diagram for explaining the inclination of the light emitting surface of each semiconductor laser device of the first embodiment. It is a schematic diagram for explaining the laser sheet light source device of the reference example. It is a figure for explaining an operation effect of a laser sheet light source device of a first embodiment. It is a schematic diagram which shows the structure of the laser sheet light source device of 2nd embodiment. It is a schematic diagram for explaining the inclination of the light emission surface of each semiconductor laser device of the second embodiment. It is a schematic diagram showing a configuration of a laser sheet light source device of a third embodiment. It is a schematic diagram when the semiconductor laser device of the third embodiment, two plano-convex cylindrical lenses, and a plano-concave cylindrical lens are viewed in the −y direction. It is a mimetic diagram for explaining inclination of each parallel light of a third embodiment. It is a schematic diagram showing a configuration of a laser sheet light source device of a fourth embodiment. It is a schematic diagram for demonstrating the inclination of each parallel light of 4th Embodiment.

  A laser sheet light source device according to an embodiment will be described with reference to the drawings. In each of the drawings, the dimensional ratio in the drawings does not always match the actual dimensional ratio. Further, the numbers of semiconductor laser elements and optical systems shown in each embodiment are merely examples.

(First embodiment)
[Overview of PIV]
The laser sheet light source device 1 according to the first embodiment is used as a light source of PIV (Particle Image Velocimetry). First, an outline of PIV will be described with reference to FIG.

  As shown in FIG. 1, the laser sheet light source device 1 emits a sheet-like laser beam LS. Hereinafter, the sheet-shaped laser light LS is referred to as a “laser sheet LS”.

  In FIG. 1, the direction in which a plurality of semiconductor laser elements (details will be described later) included in the laser sheet light source device 1 are arranged is the y direction, and the optical axis of a plano-concave cylindrical lens (details will be described later) included in the laser sheet light source device 1 is shown. Is defined as a z direction, and a direction orthogonal to the y direction and the z direction is defined as an x direction. Note that the x direction corresponds to the “first direction” and the y direction corresponds to the “second direction”.

  The laser sheet LS is light that has a certain width in the x direction and travels while spreading in the y direction. In FIG. 1, illustration of the width of the laser sheet LS in the x direction is omitted. As an example, the width of the laser sheet LS in the x direction is 1 mm. The laser sheet LS has a width of about 0.5 m to 2 m in the y direction in a region at least 1 to 2 m away from the laser sheet light source device 1 in the z direction. That is, in this region, the width of the laser sheet LS in the y direction is much larger than the width in the x direction.

  Tracer particles 12 are mixed in the fluid to be measured. In FIG. 1, although the fluid itself is not shown, a large number of tracer particles 12 are mixed in a predetermined fluid, and when the fluid is irradiated with the laser sheet LS, the laser sheet LS Only a part of the tracer particles 12 located in the region irradiated with is shown. The tracer particles 12 are, for example, microparticles made of a resin such as polystyrene, microdroplets sprayed with water and oil, plastic microparticles, smoke, and the like. When the laser sheet LS emitted from the laser sheet light source device 1 irradiates the tracer particles 12 in the fluid, scattered light is generated.

  The imaging device 14 captures the scattered light from the tracer particles 12 and outputs the captured image to the image processing device 16. Note that, as an example, the image capturing device 14 captures an image of 1000 frames per second. The image processing device 16 calculates the velocity of the fluid based on the input image. Since the method of calculating the velocity of the fluid is a known technique (for example, see Patent Documents 1 and 2 described above), description thereof will be omitted in this specification.

[Constitution]
Subsequently, the configuration of the laser sheet light source device 1 will be described. FIG. 2 is a schematic diagram when the laser sheet light source device 1 of the first embodiment is viewed in the −x direction. FIG. 2 shows an internal configuration of the laser sheet light source device 1.

  The laser sheet light source device 1 includes a plurality of semiconductor laser elements 3, a plurality of plano-convex cylindrical lenses 5, and a plano-concave cylindrical lens 7.

  The semiconductor laser device 3 is a semiconductor laser device mounted on a CAN package (for example, a metal package). That is, the semiconductor laser element 3 is a CAN type semiconductor laser element. FIG. 3 is a schematic diagram showing a laser beam L emitted from one semiconductor laser element 3.

  As shown in FIG. 3, the semiconductor laser element 3 emits a laser beam L traveling while spreading in both the x direction and the y direction. That is, the laser light L diverges in both the x direction and the y direction. The laser light L diverges more in the x direction than in the y direction. That is, the divergence angle of the laser beam L in the x direction is larger than the divergence angle in the y direction. That is, the x direction corresponds to the “fast axis direction”, and the y direction corresponds to the “slow axis direction”. In FIG. 3, the divergence angle of the laser light L in the y direction is defined as an angle θ.

  Returning to FIG. 2, the description of the semiconductor laser device 3 will be continued. The semiconductor laser elements (31, 32, 33, 34) are arranged at different positions in the y direction. The semiconductor laser elements (31, 32, 33, 34) are arranged such that light emission surfaces (31A, 32A, 33A, 34A) are inclined with respect to an emission surface 7B of a later-described plano-concave cylindrical lens 7. More specifically, each semiconductor laser element 3 approaches the optical axis OA of the plano-concave cylindrical lens 7 as the principal rays (for example, L1 and L4) of the laser light L progress toward the plano-concave cylindrical lens 7 described later. Are arranged as follows. Hereinafter, the semiconductor laser elements (31, 32, 33, 34) may be collectively referred to as "semiconductor laser element 3".

  In this specification, the “principal ray” refers to a ray having the highest light intensity among the laser beams L. The “light emitting surface of the semiconductor laser device 3” is a surface from which the semiconductor laser device 3 emits the laser light L, and refers to a surface perpendicular to the principal ray.

  In FIG. 2, only the principal ray L1 of the laser light L emitted from the semiconductor laser element 31 and the principal ray L4 of the laser light L emitted from the semiconductor laser element 34 are indicated by dashed lines for convenience. The illustration of the principal ray of the laser beam L emitted from the element (32, 33) is omitted.

  Subsequently, the plano-convex cylindrical lens 5 and the plano-concave cylindrical lens 7 will be described with reference to FIGS. FIG. 4 is a schematic diagram when the semiconductor laser element 31, the plano-convex cylindrical lens 5 and the plano-concave cylindrical lens 7 corresponding to the semiconductor laser element 31 are viewed in the -y direction.

  The plano-convex cylindrical lens 5 is a lens having a shape obtained by cutting out a part of a side surface of a cylinder. As described above, the laser sheet light source device 1 has the plurality of plano-convex cylindrical lenses 5, and each plano-convex cylindrical lens 5 is arranged corresponding to each semiconductor laser element 3. Each plano-convex cylindrical lens 5 converts the laser light L emitted from the corresponding semiconductor laser element 3 into a parallel light LP. In this specification, “parallel light” is light that travels with a certain width in a specific direction (in the present embodiment, x direction). That is, “parallel light” is light that travels parallel to a specific plane (the yz plane in the present embodiment).

  As shown in FIG. 4, the plano-convex cylindrical lens 5 converts the laser light L so as to have a certain width (for example, 1 mm) in the x direction. Although not shown, the laser light L emitted from the other semiconductor laser elements (32, 33, 34) is also given a constant width (for example, 1 mm) in the x direction by the corresponding plano-convex cylindrical lens 5. Is converted to have

  On the other hand, as shown in FIG. 2, the plano-convex cylindrical lens 5 maintains the divergence of the laser light L in the y direction. That is, the plano-convex cylindrical lens 5 holds the divergence angle θ of the laser beam L in the y direction (see FIGS. 2 and 3).

  As described above, the plano-convex cylindrical lens 5 converts the laser light L emitted from each semiconductor laser element 3 into light having a fixed width (for example, 1 mm) in the x direction and traveling while spreading in the y direction. Convert. Note that the plano-convex cylindrical lens 5 corresponds to the “first optical system”.

  As shown in FIG. 2, the plano-concave cylindrical lens 7 increases the width of the parallel light LP emitted from the plano-convex cylindrical lens 5 in the y direction. That is, the plano-concave cylindrical lens 7 enlarges the divergence angle of the incident parallel light LP in the y direction. On the other hand, as shown in FIG. 4, the plano-concave cylindrical lens 7 holds the width (for example, 1 mm) of the parallel light LP in the x direction. That is, the plano-concave cylindrical lens 7 does not enlarge the divergence angle (0 degrees in the present embodiment) of the parallel light LP in the x direction.

  As described above, the plano-concave cylindrical lens 7 enlarges the width in the y direction of each of the incident parallel lights LP while maintaining the width in the x direction. Note that the plano-concave cylindrical lens 7 corresponds to the “second optical system”.

  The plano-concave cylindrical lens 7 includes an incident surface 7A on which the parallel light LP emitted from the plano-convex cylindrical lens 5 is incident, and an exit surface 7B for emitting the converted parallel light LP. As shown in FIG. 2, the parallel light LPs adjacent in the y direction overlap on the incident surface 7 </ b> A of the plano-concave cylindrical lens 7.

  The parallel light LP is emitted from the emission surface 7B of the plano-concave cylindrical lens 7, and then overlaps with the parallel light LP adjacent in the y direction to form the laser sheet LS. The laser sheet LS is emitted outside the laser sheet light source device 1.

[Inclination of semiconductor laser element]
Next, with reference to FIG. 5, the inclination of the light emitting surface (31A, 32A, 33A, 34A) of the semiconductor laser device (31, 32, 33, 34) will be described. For convenience of description, FIG. 5 shows a case where the parallel light LPs adjacent in the y direction overlap for the first time on the incident surface 7A of the plano-concave cylindrical lens 7. In FIG. 5, the principal ray of each laser beam L is indicated by a dashed line.

As shown in FIG. 5, the distance from the semiconductor laser element 3 to the plano-concave cylindrical lens 7 is D ₁ , and the interval between the semiconductor laser elements 3 is P ₁ . Note that the distance D ₁ represents a distance between the emission point Q at which the semiconductor laser element 3 emits the laser light L and the center O of the plano-concave cylindrical lens 7 in the z direction. At this time, the light emitting surfaces (31A, 32A) of the semiconductor laser elements (31, 32) are on the emitting surface 7B of the plano-concave cylindrical lens 7 (that is, a plane orthogonal to the optical axis OA of the plano-concave cylindrical lens 7). The angles (α ₁ , α ₂ ) inclined relative to each other satisfy the following expression (1).

D ₁ · tan {(θ / 2) + α ₁ } + D ₁ · tan {(θ / 2) −α ₂ }> P ₁ Equation (1)

In the left-hand side of equation (1), paragraph, when the laser beam L and the parallel light LP corresponding to the semiconductor laser element 31 has progressed in the z-direction by a distance D _1, most y direction of the parallel light LP (i.e. , The lower part of the paper) and the distance that the semiconductor laser element 31 is separated in the y direction. The second term, when the laser beam L and the parallel light LP corresponding to the semiconductor laser element 32 has progressed in the z-direction by a distance D _1, most -y direction side of the parallel light LP (i.e., upper side) of the The distance represents the distance between the traveling light and the semiconductor laser element 32 in the y direction.

If the angles (α ₁ , α ₂ ) do not satisfy Expression (1), the parallel light (LP) after the laser light L emitted from the semiconductor laser elements (31, 32) is converted by the plano-concave cylindrical lens 5 , LP) for the first time overlap at a distance from the semiconductor laser element 3 in the z direction by a distance D _1, do not overlap the incident surface 7A of the plano-concave cylindrical lens 7.

Similarly, the angles (α ₂ , α ₃ ) at which the light exit surfaces (32A, 33A) of the semiconductor laser elements (32, 33) are inclined with respect to the exit surface 7B of the plano-concave cylindrical lens 7 are expressed by the following equation (2). Meet).

D ₁ · tan {(θ / 2) + α ₂ } + D ₁ · tan {(θ / 2) + α ₃ }> P ₁ Equation (2)

Similarly, angles (α ₃ , α ₄ ) at which the light emission surfaces (33A, 34A) of the semiconductor laser elements (33, 34) are inclined with respect to the emission surface 7B of the plano-concave cylindrical lens 7 are expressed by the following formula (3). Meet).

D ₁ · tan {(θ / 2) −α ₃ } + D ₁ · tan {(θ / 2) + α ₄ }> P ₁ Equation (3)

  Although the expressions (1) to (3) have been described with reference to FIG. 5, in the case of FIG. 2 (that is, before the parallel light LP enters the plano-concave cylindrical lens 7, the parallel light adjacent to each other in the y direction). Equations (1) to (3) are satisfied also in the case of overlapping with LP).

As shown in FIG. 5, the angles (α ₁ , α ₂ ) at which the light emitting surfaces (31A, 32A) of the semiconductor laser elements (31, 32) are inclined with respect to the emitting surface 7B of the plano-concave cylindrical lens 7 are shown. By comparison, angle α ₁ is greater than angle α ₂ . Also, comparing the angles (α ₃ , α ₄ ) at which the light emitting surfaces (33A, 34A) of the semiconductor laser elements (33, 34) are inclined with respect to the emitting surface 7B of the plano-concave cylindrical lens 7, the angle α ₄ is greater than the angle α _3. That is, as the semiconductor laser element 3 is further away from the optical axis OA of the concave cylindrical lens 7 in the y direction or the −y direction, the light emission surface is more inclined with respect to the emission surface 7B of the plano-concave cylindrical lens 7.

[Effects]
Subsequently, with reference to FIGS. 6 and 7, the operation and effect of the laser sheet light source device 1 of the present embodiment will be described. For convenience of description, a laser sheet light source device of a reference example will be described first with reference to FIG.

  FIG. 6A is a schematic diagram illustrating a configuration of a laser sheet light source device of a reference example. The laser sheet light source device of the reference example includes a semiconductor laser element 3 and a plano-concave cylindrical lens 7. Although not shown in FIG. 6A, the laser sheet light source device of the reference example has a laser beam emitted from the semiconductor laser element 3 between the semiconductor laser element 3 and the plano-concave cylindrical lens 7. It has a plano-convex cylindrical lens (for example, plano-convex cylindrical lens 5 in FIG. 2) that converts L into parallel light LP.

  As shown in FIG. 6A, in the laser sheet light source device of the reference example, unlike the laser sheet light source device 1 of the present embodiment, each parallel light LP does not overlap each other and is incident on the incident surface 7A of the plano-concave cylindrical lens 7. Incident. That is, each parallel light LP enters the incident surface 7A of the plano-concave cylindrical lens 7 without being affected by other parallel lights LP. Therefore, the intensity of light incident on the incident surface 7A of the plano-concave cylindrical lens 7 fluctuates greatly according to the y coordinate.

  FIG. 6B shows the intensity of each parallel light LP when each parallel light LP is cut along the line AA in FIG. 6A. The AA line is a line that is parallel to the y direction and bisects the incident surface 7A of the plano-concave cylindrical lens 7. As shown in FIG. 6B, sharp peaks appear in intensity corresponding to the number of the semiconductor laser elements 3 (five in FIG. 6A). As a result, the intensity of the parallel light LP emitted from the plano-concave cylindrical lens 7 also fluctuates greatly according to the y coordinate.

  FIG. 6C shows the intensity of each parallel light LP when each parallel light LP is cut along the line BB in FIG. 6A. As shown in FIG. 6C, even after the parallel light LP is emitted from the plano-concave cylindrical lens 7, the fluctuation of the intensity is large.

  As described above, in the laser sheet light source device of the reference example, the parallel light LP whose intensity varies greatly according to the y coordinate is incident on the incident surface 7A of the plano-concave cylindrical lens 7. As a result, the intensity of the parallel light LP emitted from the plano-concave cylindrical lens 7 also fluctuates greatly according to the y coordinate. Therefore, a laser sheet LS in which the intensity varies according to the y coordinate is formed. As described in the section of the problem to be solved by the invention, when the strength of the laser sheet LS varies, there is a problem that the accuracy of the PIV measurement result is reduced.

  On the other hand, according to the laser sheet light source device 1 of the present embodiment, each parallel light LP is incident on the incident surface 7A of the plano-concave cylindrical lens 7 in a state of overlapping with the parallel light LP adjacent in the y direction (FIG. 2). Therefore, in the laser sheet light source device 1 of the present embodiment, the fluctuation of the intensity of light incident on the incident surface 7A of the plano-concave cylindrical lens 7 is smaller than that of the laser sheet light source device of the reference example.

  FIG. 7A shows the intensity of each parallel light LP when each parallel light LP is cut along the line CC in FIG. The CC line is a line that is parallel to the y direction and bisects the incident surface 7A of the plano-concave cylindrical lens 7. In FIG. 7A, the intensity of the state in which the parallel lights LP overlap each other is shown by a solid line, and the laser light L emitted from one semiconductor laser element 3 is converted by the plano-convex cylindrical lens 5 into a parallel light. The intensity of the light LP is indicated by a broken line.

  As shown in FIG. 7A, the fluctuation of the intensity is smaller than that of FIG. 6B of the reference example. That is, according to the laser sheet light source device 1 of the present embodiment, the parallel light LP is incident on the incident surface 7A of the plano-concave cylindrical lens 7 with a relatively small change in intensity. Therefore, even in the case of the parallel light LP emitted from the plano-concave cylindrical lens 7, the variation in the intensity is reduced, so that the variation in the intensity of the laser sheet LS can be suppressed.

  FIG. 7B shows the strength of the laser sheet LS when the laser sheet LS is cut along the line DD in FIG. In FIG. 7B, the intensity of the laser sheet LS is indicated by a solid line, and the laser light L emitted from one semiconductor laser element 3 is converted by the plano-convex cylindrical lens 5 and the plano-concave cylindrical lens 7 to be parallel. The intensity of the light LP is indicated by a broken line. As shown in FIG. 7B, the fluctuation of the intensity of the laser sheet LS is smaller than that of FIG. 6C of the reference example.

  As described above, according to the laser sheet light source device 1 of the present embodiment, it is possible to form the laser sheet LS having a uniform strength as compared with the reference example.

In addition, by reducing the arrangement interval of the semiconductor laser elements 3 (that is, P ₁ in FIG. 5), it is possible to overlap the laser beams LP adjacent in the y direction on the incident surface 7A of the plano-concave cylindrical lens 7. Seem. However, the laser sheet light source device 1 of the present embodiment has a plurality of CAN type semiconductor laser elements 3. Since the CAN type semiconductor laser device 3 is mounted on the CAN package as described above, it is physically difficult to arrange the semiconductor laser devices 3 at small intervals.

  As an example, the width of the semiconductor laser element 3 in the y direction is 9 mm, and in the case of FIG. 2, even if the semiconductor laser elements 3 are arranged without a gap, at least the laser light L emitted from the semiconductor laser element 3 An interval of 9 mm occurs. Therefore, even if the arrangement interval of the semiconductor laser elements 3 is made as small as possible, the interval of the laser light L is still large and the interval of the parallel light LP is also large. As a result, the incident surface 7A of the plano-concave cylindrical lens 7 has Cannot overlap laser beams LP adjacent to each other.

  On the other hand, according to the laser sheet light source device 1 of the present embodiment, each parallel light LP approaches the optical axis OA of the plano-concave cylindrical lens 7 as the principal ray advances toward the plano-concave cylindrical lens 7. Incline. Thereby, the interval between the parallel light LPs adjacent in the y direction can be narrowed, so that the adjacent parallel light LPs can be overlapped on the incident surface 7A of the plano-concave cylindrical lens 7. That is, according to the laser sheet light source device 1 of the present embodiment, when the width of the laser sheet LS is increased by using the plano-concave cylindrical lens 7, the intensity of the laser sheet LS can be prevented from becoming uneven.

(Second embodiment)
[Constitution]
Subsequently, a laser sheet light source device 20 according to the second embodiment will be described. The laser sheet light source device 20 of the second embodiment is different from the laser sheet light source device 1 of the first embodiment in that a convex lens is provided instead of the plano-convex cylindrical lens 5. Hereinafter, differences between the second embodiment and the first embodiment will be described with reference to FIG.

  FIG. 8 is a schematic diagram illustrating a configuration of the laser sheet light source device 20 according to the second embodiment. The laser sheet light source device 20 includes a semiconductor laser element 3, a convex lens 21, and a plano-concave cylindrical lens 7. As shown in FIG. 8, the laser sheet light source device 20 has the same number of convex lenses 21 as the semiconductor laser elements 3, and each convex lens 21 is arranged corresponding to each semiconductor laser element 3.

  As shown in FIG. 8, each convex lens 21 converts each laser beam L emitted from each semiconductor laser element 3 into light that travels with a certain width (for example, 3 mm) in the y direction. Although not shown, when the semiconductor laser elements (31, 32, 33, and 34), the convex lens 21, and the plano-concave cylindrical lens 7 are viewed in the −y direction, the state is the same as that in FIG. 4 of the first embodiment. Has become. That is, the convex lens 21 has a curved surface projecting in the z direction when viewed in the −y direction, similarly to the plano-convex cylindrical lens 5 of the first embodiment. The convex lens 21 converts the laser light L emitted from the semiconductor laser element 3 into light that travels with a certain width (for example, 1 mm) in the x direction (see FIG. 4 of the first embodiment). ).

  As described above, the convex lens 21 converts each laser beam L into parallel light LP that travels with a certain width in the x direction and the y direction. In the second embodiment, the convex lens 21 corresponds to the “first optical system”, and the plano-concave cylindrical lens 7 corresponds to the “second optical system”.

  As shown in FIG. 8, also in the second embodiment, similarly to the first embodiment, the semiconductor laser elements (31, 32, 33, 34) have light emitting surfaces (31A, 32A, 33A, 34A) which are flat. It is disposed so as to be inclined with respect to the exit surface 7B of the concave cylindrical lens 7. Further, the parallel light LPs adjacent in the y direction overlap on the incident surface 7A of the plano-concave cylindrical lens 7.

[Inclination of semiconductor laser element]
Next, with reference to FIG. 9, the inclination of the light emitting surface (31A, 32A, 33A, 34A) of the semiconductor laser device (31, 32, 33, 34) in the second embodiment will be described. For convenience of explanation, FIG. 9 shows a case where the parallel light LPs adjacent in the y direction overlap for the first time on the incident surface 7A of the plano-concave cylindrical lens 7.

As shown in FIG. 9, the distance from the convex lens 21 to the plano-concave cylindrical lens 7 is D ₂ , the interval between the convex lenses 21 is P ₂ , and the width of the parallel light LP emitted from the convex lens 21 in the y direction is S. At this time, the angles (α ₁ , α ₂ ) at which the light emission surfaces (31A, 32A) of the semiconductor laser elements (31, 32) are inclined with respect to the emission surface 7B of the plano-concave cylindrical lens 7 are expressed by the following formula (4). Meet).

D ₂ · tan α ₁ -D ₂ · tan α ₂ > P ₂ -S Equation (4)

In the left-hand side of equation (4), paragraph, when the laser beam LP corresponding to the semiconductor laser element 31 has progressed in the z-direction by a distance D _2, represents the distance of the parallel light LP has progressed in the y-direction . The second term, when the laser beam LP corresponding to the semiconductor laser element 32 has progressed in the z-direction by a distance D _2, represents the distance of the parallel light LP has progressed in the y-direction.

If the angles (α ₁ , α ₂ ) do not satisfy Expression (4), the parallel light (LP, LP) after the laser light L emitted from the semiconductor laser elements (31, 32) is converted by the convex lens 21 is the first overlap at a distance from the convex lens 21 in the z-direction by a distance D _2, do not overlap the incident surface 7A of the plano-concave cylindrical lens 7.

Similarly, the angles (α ₂ , α ₃ ) at which the light emission surfaces (32A, 33A) of the semiconductor laser elements (32, 33) are inclined with respect to the emission surface 7B of the plano-concave cylindrical lens 7 are expressed by the following equation (5). Meet).

D ₂ · tan α ₂ + D ₂ · tan α ₃ > P ₂ -S Equation (5)

Similarly, angles (α ₃ , α ₄ ) at which the light emission surfaces (33A, 34A) of the semiconductor laser elements (33, 34) are inclined with respect to the emission surface 7B of the plano-concave cylindrical lens 7 are expressed by the following formula (6). Meet).

D ₂ · tan α ₄ -D ₂ · tan α ₃ > P ₂ -S Equation (6)

  Although equations (4) to (6) have been described with reference to FIG. 9, in the case of FIG. 8 (that is, before the parallel light LP enters the plano-concave cylindrical lens 7, the parallel light adjacent to each other in the y direction). Equations (4) to (6) are satisfied also in the case of overlapping with LP). Therefore, the laser sheet light source device 20 of the second embodiment can also suppress the variation in the strength of the laser sheet LS, similarly to the laser sheet light source device 1 of the first embodiment.

Also in the second embodiment, like the first embodiment, the angle alpha ₁ is larger than the angle alpha _2, also the angle alpha ₄ is greater than the angle alpha _3. That is, as the semiconductor laser element 3 is further away from the optical axis OA of the plano-concave cylindrical lens 7 in the y direction or the −y direction, the light emission surface of the semiconductor laser element 3 is larger than the emission surface 7B of the plano-concave cylindrical lens 7. Incline.

(Third embodiment)
[Constitution]
Next, a laser sheet light source device 30 according to a third embodiment will be described. The laser sheet light source device 30 of the third embodiment is different from the laser sheet light source device 1 of the first embodiment in that it has two plano-convex cylindrical lenses instead of the plano-convex cylindrical lenses 5. Hereinafter, differences between the third embodiment and the first embodiment will be described with reference to FIG.

  FIG. 10 is a schematic diagram illustrating a configuration of the laser sheet light source device 30 according to the third embodiment. The laser sheet light source device 30 includes a semiconductor laser element 3, a plano-convex cylindrical lens 35, a plano-convex cylindrical lens 37, and a plano-concave cylindrical lens 7.

  As shown in FIG. 10, the light emitting surfaces (31A, 32A, 33A, 34A) of the semiconductor laser elements (31, 32, 33, 34) are parallel to the emitting surface 7B of the plano-concave cylindrical lens 7. That is, the light emission surfaces (31A, 32A, 33A, 34A) are not inclined with respect to the emission surface 7B.

  Like the plano-convex cylindrical lens 5 of the first embodiment, the plano-convex cylindrical lens 35 and the plano-convex cylindrical lens 37 have a shape obtained by cutting out a part of a side surface of a cylinder. The plano-convex cylindrical lens 35 and the plano-convex cylindrical lens 37 will be described with reference to FIGS. FIG. 11 is a schematic diagram when the semiconductor laser element 3, the plano-convex cylindrical lens 35, the plano-convex cylindrical lens 37, and the plano-concave cylindrical lens 7 are viewed in the -y direction.

  As shown in FIG. 10, the plano-convex cylindrical lens 35 holds the divergence of the laser light L emitted from each semiconductor laser element 3 in the y direction. Further, as shown in FIG. 11, the plano-convex cylindrical lens 35 converts the laser light L emitted from each semiconductor laser element 3 so as to have a constant width (for example, 1 mm) in the x direction. As described above, the plano-convex cylindrical lens 35 converts each laser light L into a parallel light LP that does not diverge in the x direction and diverges in the y direction.

  As shown in FIG. 10, the plano-convex cylindrical lens 37 converts each parallel light LP emitted from the plano-convex cylindrical lens 35 so as to have a certain width (for example, 3 mm) in the y direction. Further, the plano-convex cylindrical lens 37 condenses each of the converted parallel lights LP toward the focal point f of the plano-convex cylindrical lens 37.

  In FIG. 10, two broken lines are shown in order to explain the focal point f of the plano-convex cylindrical lens 37. If the plano-concave cylindrical lens 7 does not exist, the principal ray of the laser light L emitted from the semiconductor laser element (31, 32) travels on the optical path shown by the broken line.

  Further, as shown in FIG. 11, the plano-convex cylindrical lens 37 holds the width (for example, 1 mm) of the parallel light LP in the x direction. That is, the plano-convex cylindrical lens 37 does not enlarge the divergence angle (0 degrees in the present embodiment) of the parallel light LP in the x direction.

  As shown in FIG. 10, in the third embodiment, as in the first embodiment and the second embodiment, the parallel light LPs adjacent in the y direction overlap on the incident surface 7A of the plano-concave cylindrical lens 7. ing.

  In the third embodiment, the plano-convex cylindrical lens 35 corresponds to “first convex cylindrical lens”, and the plano-convex cylindrical lens 37 corresponds to “second convex cylindrical lens”. Further, both the plano-convex cylindrical lens 35 and the plano-convex cylindrical lens 37 correspond to the “first optical system”, and the plano-concave cylindrical lens 7 corresponds to the “second optical system”.

[Inclination of parallel light LP]
As shown in FIG. 10, the parallel light LP emitted from the plano-convex cylindrical lens 37 is inclined so as to approach the optical axis OA of the plano-concave cylindrical lens 7 as the principal ray proceeds toward the plano-concave cylindrical lens 7. doing. Hereinafter, the inclination of the parallel light LP will be described with reference to FIG. For convenience of description, FIG. 12 illustrates a case where the parallel light LPs adjacent in the y direction overlap for the first time on the incident surface 7A of the plano-concave cylindrical lens 7.

As shown in FIG. 12, the distance from the plano-convex cylindrical lens 37 to the plano-concave cylindrical lens 7 is D ₃ , the interval between the semiconductor laser elements 3 is P ₁ , and the parallel light LP emitted from the plano-convex cylindrical lens 37 is the y direction. Is S. The parallel light LP after the laser light L emitted from the semiconductor laser elements (31, 32, 33, 34) is converted by the plano-convex cylindrical lenses (35, 37) is referred to as a “semiconductor laser element (31, 32). , 33, 34). "

At this time, the angle (α ₁ , α ₂ ) at which the parallel light LP corresponding to the semiconductor laser element (31, 32) is inclined with respect to the optical axis OA of the plano-concave cylindrical lens 7 is given by the following equation (7). Fulfill.

D ₃ · tan α ₁ -D ₃ · tan α ₂ > P ₁ -S Equation (7)

Similarly, the angle (α ₂ , α ₃ ) at which the parallel light LP corresponding to the semiconductor laser element (32, 33) is inclined with respect to the optical axis OA of the plano-concave cylindrical lens 7 is obtained by the following equation (8). Fulfill.

D ₃ · tan α ₁ + D ₃ · tan α ₂ > P ₁ -S Equation (8)

Similarly, the angle (α ₃ , α ₄ ) at which the parallel light LP corresponding to the semiconductor laser element (33, 34) is inclined with respect to the optical axis OA of the plano-concave cylindrical lens 7 is obtained by the following equation (9). Fulfill.

D ₃ · tan α ₄ -D ₃ · tan α ₃ > P ₁ -S Equation (9)

  Equations (7), (8), and (9) are equivalent to equations (4), (5), and (6) of the second embodiment, respectively. Therefore, the laser sheet light source device 30 of the third embodiment can also suppress the variation in the strength of the laser sheet LS, similarly to the laser sheet light source device 1 of the first embodiment. Furthermore, according to the laser sheet light source device 30 of the third embodiment, it is not necessary to tilt the semiconductor laser elements (31, 32, 33, 34). Therefore, the semiconductor laser elements (31, 32, 33, 34) can be easily fixed, and the package of the laser sheet light source device 30 can be reduced. The expressions (7) to (9) have been described with reference to FIG. 12. However, in the case of FIG. 10 (that is, before the parallel light LP enters the plano-concave cylindrical lens 7, the parallel light adjacent to each other in the y direction). Expressions (7) to (9) are satisfied also in the case of overlapping with LP).

Also in the third embodiment, similarly to the first embodiment and the second embodiment, the angle alpha ₁ is larger than the angle alpha _2, also the angle alpha ₄ is greater than the angle alpha _3. That is, as the semiconductor laser element 3 moves away from the optical axis OA (not shown) of the plano-concave cylindrical lens 7 in the y direction or the −y direction, the parallel light LP corresponding to the semiconductor laser element 3 It is greatly inclined with respect to the optical axis OA.

(Fourth embodiment)
[Constitution]
Next, a laser sheet light source device 40 according to a fourth embodiment will be described. The laser sheet light source device 40 according to the fourth embodiment is different from the laser sheet light source device 1 according to the first embodiment in that a convex lens and a reflection mirror are provided instead of the plano-convex cylindrical lens 5. Hereinafter, differences between the fourth embodiment and the first embodiment will be described with reference to FIG. In FIG. 13 and the following FIG. 14, for the sake of illustration, the angle of the light beam incident on the reflecting mirror does not always coincide with the angle of the light beam emitted from the reflecting mirror, but these are only schematically illustrated. It is.

  FIG. 13 is a schematic diagram illustrating a configuration of a laser sheet light source device 40 according to the fourth embodiment. The laser sheet light source device 40 has a semiconductor laser element 3, a convex lens 41, a reflection mirror 9, and a plano-concave cylindrical lens 7. The laser sheet light source device 40 has the same number of convex lenses 41 and reflecting mirrors 9 as the semiconductor laser elements 3, and each convex lens 41 and each reflecting mirror 9 are arranged corresponding to each semiconductor laser element 3.

  As shown in FIG. 13, the convex lens 41 converts the laser beam L emitted from the semiconductor laser element 3 so as to have a constant width (for example, 3 mm) in the z direction. Although not shown, the convex lens 41 converts each laser beam L so as to have a certain width (for example, 1 mm) in the x direction. As described above, the convex lens 41 converts each laser light L into a parallel light LP that does not diverge in the x direction and the z direction.

  The reflecting mirror 9 reflects the parallel light LP emitted from the convex lens 41 and makes the parallel light LP enter the incident surface 7A of the plano-concave cylindrical lens 7. As shown in FIG. 13, the reflection mirrors (91, 92, 93, 94) are such that the reflection surfaces (91A, 92A, 93A, 94A) make different angles with respect to the optical axis OA of the plano-concave cylindrical lens 7. Are located in That is, the respective reflecting mirrors 9 are arranged such that the reflecting surfaces are not parallel to each other.

  Note that, as shown in FIG. 13, in the fourth embodiment, as in the first to third embodiments, the parallel light LPs adjacent in the y direction overlap on the incident surface 7A of the plano-concave cylindrical lens 7. ing.

  In the fourth embodiment, the convex lens 41 corresponds to a “collimator lens”, both the convex lens 41 and the reflection mirror 9 correspond to a “first optical system”, and the plano-concave cylindrical lens 7 corresponds to a “second optical system”. ". In the fourth embodiment, the x direction corresponds to the “first direction”, and the y direction corresponds to the “second direction”. The x direction is a direction optically equivalent to the fast axis direction of the laser light L emitted from the semiconductor laser element 3. The y direction is a direction optically equivalent to the slow axis direction of the laser light L emitted from the semiconductor laser element 3.

[Inclination of parallel light LP]
As shown in FIG. 13, each parallel light LP reflected by the reflection mirror 9 approaches the optical axis OA of the plano-concave cylindrical lens 7 as the principal ray (not shown) advances toward the plano-concave cylindrical lens 7. So inclined. Hereinafter, the inclination of the parallel light LP will be described with reference to FIG. For convenience of description, FIG. 14 illustrates a case where the parallel light LPs adjacent in the y direction overlap for the first time on the incident surface 7A of the plano-concave cylindrical lens 7.

As shown in FIG. 14, the distance from the reflecting mirror (91, 92, 93, 94) to the plano-concave cylindrical lens 7 is (D ₄ , D ₅ , D ₆ , D ₇ ), and the distance of the reflecting mirror 9 in the y direction. Is P ₃ , and the width of the parallel light LP in the z direction is S. The laser light L emitted from the semiconductor laser elements (31, 32, 33, and 34) is converted by the lens 41, and the parallel light LP reflected by the reflection mirror 9 is referred to as a “semiconductor laser element (31, 32). , 33, 34). "

At this time, the angle (α ₁ , α ₂ ) at which the parallel light LP corresponding to the semiconductor laser element (31, 32) is inclined with respect to the optical axis OA of the plano-concave cylindrical lens 7 is given by the following equation (10). Fulfill.

D ₄ · tan α ₁ -D ₅ · tan α ₂ > P ₃ -S Equation (10)

Similarly, the angle (α ₂ , α ₃ ) at which the parallel light LP corresponding to the semiconductor laser element (32, 33) is inclined with respect to the optical axis OA of the plano-concave cylindrical lens 7 is calculated by the following equation (11). Fulfill.

D ₅ · tan α ₂ + D ₆ · tan α ₃ > P ₃ -S Equation (11)

Similarly, the angles (α ₃ , α ₄ ) at which the parallel light LP corresponding to the semiconductor laser elements (33, 34) is inclined with respect to the optical axis OA of the plano-concave cylindrical lens 7 are given by the following equation (12). Fulfill.

D ₇ · tan α ₄ -D ₆ · tan α ₃ > P ₃ -S Equation (12)

  The above equations (10), (11) and (12) are respectively equivalent to the equations (4), (5) and (6) of the second embodiment. Therefore, the laser sheet light source device 40 of the fourth embodiment can also suppress the variation in the intensity of the laser sheet LS, similarly to the laser sheet light source device 1 of the first embodiment. Further, according to the laser sheet light source device 40 of the fourth embodiment, as in the third embodiment, it is not necessary to tilt the semiconductor laser element 3, so that the semiconductor laser element 3 can be easily fixed and the laser sheet light source can be easily fixed. The package of the device 40 can be made smaller. Although equations (10) to (12) have been described with reference to FIG. 14, in the case of FIG. 13 (that is, before the parallel light LP enters the plano-concave cylindrical lens 7, the parallel light adjacent to each other in the y direction). Expressions (10) to (12) are satisfied also in the case of overlapping with LP).

Also in the fourth embodiment, similarly to the third embodiment from the first embodiment及, the angle alpha ₁ is larger than the angle alpha _2, also the angle alpha ₄ is greater than the angle alpha _3. In other words, as the reflection mirror 9 is located farther away from the optical axis OA of the plano-concave cylindrical lens 7 in the y direction or the −y direction, the parallel light LP reflected by the reflection mirror 9 becomes more susceptible to the optical axis of the plano-concave cylindrical lens 7. It is greatly inclined with respect to OA.

According to the laser sheet light source device 40 of the fourth embodiment, by reducing the distance P ₃ of the reflecting mirror 9, the interval of the parallel light LP after reflection (i.e., the interval P ₃ of the reflecting mirror 9), before reflection (That is, the interval between the semiconductor laser elements 3). Thus, the angles (α ₁ , α ₂ , α ₃ , α) formed by the reflecting surfaces (91A, 92A, 93A, 94A) of the reflecting mirrors (91, 92, 93, 94) with the optical axis OA of the plano-concave cylindrical lens 7 are formed. ₄ ) can be made smaller than (α ₁ , α ₂ , α ₃ , α ₄ ) in the first to third embodiments.

[Another embodiment]
Hereinafter, another embodiment will be described.

  <1> In the laser sheet light source device (1, 20, 30, 40) of each of the above-described embodiments, the parallel light LP is such that as the principal ray travels toward the plano-concave cylindrical lens 7, the plano-concave cylindrical lens 7 (See FIGS. 2, 6, 8, and 11). However, this is an example, and in some parallel light LPs, the more the principal ray travels toward the plano-concave cylindrical lens 7, the more it may be inclined away from the optical axis OA of the plano-concave cylindrical lens 7. . More generally, the principal ray of one parallel light LP is inclined with respect to the principal ray of the other parallel light LP such that adjacent parallel lights LP overlap on the incident surface 7A of the plano-concave cylindrical lens 7. It does not matter.

  <2> In the laser sheet light source device (1, 20, 30, 40) of each embodiment, the parallel light (LP, LP) adjacent in the y direction overlaps on the incident surface 7A of the plano-concave cylindrical lens 7, but this is not the case. Not exclusively. In other words, some of the parallel lights (LP, LP) of the parallel lights (LP, LP) adjacent in the y direction do not have to overlap on the incident surface 7A of the plano-concave cylindrical lens 7. In other words, it is sufficient that at least a part of the parallel light (LP, LP) of the parallel light (LP, LP) adjacent in the y direction overlaps on the incident surface 7A of the plano-concave cylindrical lens 7.

  <3> In the laser sheet light source device (1, 20, 30, 40) of each embodiment, the plano-concave cylindrical lens 7 is used as a lens for expanding the divergence angle of the parallel light LP in the y direction. A lens may be used. Further, a plano-concave cylindrical lens array composed of a plurality of plano-concave cylindrical lenses may be used. Further, a plurality of plano-concave cylindrical lenses 7 may be arranged in the z direction. That is, any lens may be used as long as the lens can increase the divergence angle of the parallel light LP in the y direction.

  <4> In the first and third embodiments, a plano-convex cylindrical lens (5, 35) is used as a lens for converting the laser light L emitted from the semiconductor laser element 3 into a parallel light LP. Not exclusively. That is, any lens may be used as long as it can be converted into the parallel light LP.

  <5> The laser sheet light source device (1, 20, 30, 40) of each embodiment has been described as being used for the light source of the PIV. However, the present invention is not limited to this. The present invention can also be used for a measuring device that measures the shape and the like of an object using the laser sheet LS.

1: laser sheet light source device 3 (31, 32, 33, 34): semiconductor laser elements 31A, 32A, 33A, 34A: light emitting surface 5: plano-convex cylindrical lens 7: plano-concave cylindrical lens 21: convex lenses 35, 37: Plano-convex cylindrical lens 9 (91, 92, 93, 94): reflection mirrors 91A, 92A, 93A, 94A: reflection surface L: laser light L1, L4: principal ray LP: parallel light LS: laser sheet

Claims (8)

A plurality of CAN laser diodes;
A first optical system that converts each laser light emitted from the plurality of semiconductor laser elements into parallel light having a certain width in at least a first direction,
A second optical system that includes an incident surface on which the parallel light is incident, and expands the width of the parallel light in a second direction orthogonal to the first direction,
The parallel light travels from different positions with respect to the second direction toward the incident surface of the second optical system,
The parallel sheet light adjacent to the second direction is overlapped on the incident surface of the second optical system.   In the parallel light adjacent in the second direction, the principal ray of one of the parallel lights is closer to the incident surface of the second optical system so that the principal ray of one of the parallel lights is closer to the other of the parallel lights. The laser sheet light source device according to claim 1, wherein the laser sheet light source device is inclined with respect to a principal ray of light. The principal ray of the parallel light of at least a part of the parallel light is inclined with respect to the optical axis so as to be closer to the optical axis of the second optical system toward the incident surface of the second optical system. ,
3. The laser sheet light source device according to claim 2, wherein, as the parallel light is further away from the optical axis with respect to the second direction, an angle at which the principal ray of the parallel light is inclined with respect to the optical axis is larger. 4. . The semiconductor laser device is arranged at different positions with respect to the second direction,
2. The semiconductor laser device adjacent to the second direction, wherein a light emitting surface of one of the semiconductor laser devices is inclined with respect to a light emitting surface of the other semiconductor laser device. 4. The laser sheet light source device according to any one of items 1 to 3. The first optical system,
A first convex cylindrical lens that converts the laser light emitted from the semiconductor laser element to have a certain width in the first direction;
A second convex cylindrical lens that converts the laser light emitted from the convex cylindrical lens to have a certain width in the second direction,
The second convex cylindrical lens receives the laser light from different positions with respect to the second direction, converts the incident laser light, and condenses the laser light toward the incident surface of the second optical system. The laser sheet light source device according to claim 1, wherein: The first optical system,
A collimator lens that converts the laser light emitted from the semiconductor laser element into the parallel light,
A plurality of reflecting mirrors arranged corresponding to the plurality of semiconductor laser elements and reflecting the converted parallel light by the collimator lens to be incident on the incident surface of the second optical system,
The reflecting mirrors are arranged at positions different from each other with respect to the second direction,
The reflection mirror adjacent to the second direction, wherein the reflection surface of one reflection mirror is inclined with respect to the reflection surface of the other reflection mirror. 3. The laser sheet light source device according to claim 1.   The laser sheet light source device according to any one of claims 1 to 6, wherein the second optical system is a plano-concave cylindrical lens or a biconcave cylindrical lens. The first direction is a direction optically equivalent to the fast axis direction of the laser light emitted from the semiconductor laser element,
The laser sheet light source according to any one of claims 1 to 7, wherein the second direction is a direction optically equivalent to a slow axis direction of the laser light emitted from the semiconductor laser element. apparatus.

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