JP5742331B2 - Laser light scanner - Google Patents

Description

  The present invention relates to a laser light scanner.

  Laser light scanners that scan laser light are used in various fields such as laser printers, laser processing, displays, measurement, and optical communication. The laser light scanner is generally composed of a light source and an optical deflection element that scans the laser light emitted from the light source. Furthermore, if necessary, an optical coupling optical system that shapes the laser beam emitted from the light source into an emission beam profile corresponding to the optical polarization element, and an output that adjusts the shaping and deflection angle of the emission beam profile output from the optical deflection element A configuration including an optical system is also known.

  When an optical polarization element having an optical waveguide configured such that a core layer that propagates light is sandwiched between clad layers is used as the optical polarization element, the laser light incident on the optical polarization element propagates through the core layer. . The core layer is provided with a refractive index changing region in which the optical refractive index changes according to the applied voltage, and the laser light is deflected according to the voltage applied to the refractive index changing region. For this reason, in order to optically couple the laser light emitted from the light source to the optical deflection element, it is necessary to focus the laser light to a width corresponding to the thickness of the core layer. Further, it is necessary to adjust the width of the laser beam in the direction perpendicular to the light propagation direction and the thickness direction of the core layer according to the width of the refractive index changing region of the core layer in the direction. Furthermore, the light of the direction component in the laser light needs to be shaped into a light beam parallel to the light propagation direction in the core layer.

  That is, when the laser beam emitted from the light source is optically coupled to the optical deflection element, the component in the thickness direction of the core layer in the optical deflection element is a condensed light beam condensed in the thickness direction, and the light propagation direction The component in the direction perpendicular to the thickness direction of the core layer is required to be a parallel light flux parallel to the light propagation direction in the core layer.

  For example, Patent Document 1 discloses that a two-dimensional array of laser beams emitted from a laser diode is optically coupled to one optical fiber. Specifically, in Patent Document 1, after collimating the fast axis components of a laser beam group emitted from a laser diode, the laser beam group is rotated 90 ° by a beam converter, collimated, and then condensed. Is disclosed.

  According to Patent Document 1, it is considered that high light efficiency can be obtained because the fast axis direction component having better quality than the slow axis direction component is condensed. However, according to Patent Document 1, by passing through the beam converter, the slow axis direction component is included in the fast axis direction component included in the laser beam, and the number of resolution points of the laser beam emitted from the optical deflection element is increased. Is low.

  The present invention has been made in view of the above, and an object of the present invention is to provide a laser light scanner capable of achieving both high utilization efficiency and high resolution points.

To solve the above problems and achieve the object, the present invention includes a first collimator lens for converting the fast axis direction component contained in the laser beam emitted from the light source to a flat Yukimitsu bundle from said first collimating lens A second collimating lens that converts a slow axis direction component included in the emitted laser light into a parallel light beam, a core layer having the slow axis direction as a thickness direction and the fast axis direction as a light deflection direction, and a pair sandwiching the core layer A light deflecting element having a clad layer and a light condensing element that condenses a slow axis direction component included in the laser light emitted from the second collimating lens and optically couples the laser light to the light incident side end face of the core layer A refractive index changing region having a predetermined width in the fast axis direction of the laser beam, and the core layer of the light deflection element has a light refractive index that changes according to an applied voltage. a, wherein the Collimator lens has a hemispherical lens the light incident side is formed on the plane and the light emitting side is formed in a spherical, and a meniscus lens provided on the light emitting side of the hemispherical lens, the meniscus lens, the hemisphere adjust the fast axis direction of the beam width of the laser beam emitted from the lens to the beam width corresponding to the predetermined width of the fast axis direction of the refractive index change region and said Rukoto.

  According to the present invention, there is an effect that it is possible to achieve both high utilization efficiency and high resolution points.

1A and 1B are schematic views showing the configuration of the laser light scanner according to the first embodiment, FIG. 1A is an XZ plan view of the laser light scanner, and FIG. 1B is Y of the laser light scanner. It is -Z top view. FIG. 2 is a schematic diagram showing a laser beam profile of the laser beam emitted from the light source. 3A and 3B are schematic views showing the light deflection element, FIG. 3A is a perspective view showing the light deflection element, and FIG. 3B is a perspective view showing the core layer. 4A and 4B are schematic views showing the configuration of the laser beam scanner according to the second embodiment. FIG. 4A is an XZ plan view of the laser beam scanner, and FIG. 4B is Y of the laser beam scanner. It is -Z top view. FIG. 5 is a table showing an example of specific specifications of the hemispherical lens, the meniscus lens, and the collimating lens in the example. FIG. 6 is a table showing an example of specific specifications of the aspherical cylindrical lens and the semi-cylindrical lens in the example. FIG. 7 is a schematic diagram illustrating an example of the configuration of the laser beam scanner in the embodiment. FIG. 8 is a schematic diagram illustrating an example of the configuration of the collimating lens in the embodiment. FIG. 9 is a schematic diagram illustrating an example of the configuration of the collimating lens and the condensing lens in the embodiment. FIG. 10 is a schematic diagram showing a configuration of a conventional laser light scanner.

  Hereinafter, an embodiment of a laser light scanner according to the present invention will be described in detail with reference to the accompanying drawings.

(First embodiment)
FIG. 1 shows an example of the configuration of the laser light scanner 10 according to the present embodiment. FIG. 1A is an XZ plan view of the laser light scanner 10. FIG. 1B is a YZ plan view of the laser light scanner 10.

  As shown in FIG. 1, the laser light scanner 10 of the present embodiment includes a light source 12, an optical coupling optical unit 19, an optical deflection element 14, and an output optical unit 16.

  The light source 12 is a semiconductor laser that emits laser light. An example of the light source 12 is a laser diode. Specifically, as shown in FIG. 2, the light source 12 is formed in a substantially rectangular parallelepiped shape, and an active layer 12 </ b> A serving as a light emitting region is exposed on one side surface serving as a light emitting end surface. The exposed end surface of the active layer 12A has a rectangular shape that is long in a direction (see the Y-axis direction in FIG. 2) perpendicular to the thickness direction of the active layer 12A (see the X-axis direction in FIG. 2). That is, the exposed end surface of the active layer 12A has a thickness direction (X-axis direction) length perpendicular to the thickness direction of the exposed end surface (hereinafter sometimes simply referred to as “width direction”) (Y-axis). The shape is shorter than the length of (direction). The light source 12 will be described in detail later, but by increasing the length in the Y-axis direction, which is the long side direction, of the exposed end surface of the active layer 12A with respect to the length in the X-axis direction, which is the short side direction, The emission intensity can be adjusted to increase.

  In the present embodiment, the thickness direction of the active layer 12A is the X-axis direction. The width direction of the exposed end surface of the active layer 12A is the Y-axis direction. The direction orthogonal to the exposed end face of the active layer 12A is taken as the Z-axis direction.

  Laser light is emitted from the exposed end face of the active layer 12A with a spread angle. Here, as described above, the shape of the exposed end face of the active layer 12A is rectangular, and the aspect ratio thereof is different. Therefore, the laser light is emitted from the exposed end face of the active layer 12A in the Y-axis direction and the X-axis direction. Output with different divergence angles. For this reason, in the laser light emitted from the light source 12, the spread angle in the X-axis direction is larger than the spread angle in the Y-axis direction. That is, the laser beam profile of the laser beam emitted from the light source 12 is a profile as shown by the emission beam profile P in FIG.

  In the present embodiment, the X-axis direction, which is the thickness direction of the exposed end face (light emitting region) in the active layer 12A, that is, the short direction, is referred to as the “fast axis direction”. Further, the width direction of the exposed end face in the active layer 12A, that is, the Y-axis direction which is the longitudinal direction is referred to as “slow axis direction”.

  Returning to FIG. 1, the laser light emitted from the light source 12 passes through the optical coupling optical unit 19 and is optically coupled to the optical deflection element 14. Details of the optical coupling optical unit 19 will be described later.

  FIG. 3 shows an example of the light deflection element 14. As shown in FIG. 3A, the optical deflection element 14 includes an optical waveguide 31. The optical waveguide 31 is sandwiched between a pair of electrode layers (electrode layer 38 and electrode layer 36).

  The optical waveguide 31 is a so-called slab type optical waveguide having a configuration in which a core layer 30 having a high refractive index is sandwiched between a pair of clad layers (clad layer 34 and clad layer 32) having a refractive index lower than that of the core layer 30. .

The core layer 30 is made of a material having an electro-optic effect. Specifically, as the electro-optic material constituting the core layer 30, nonlinear optical crystals such as lithium niobate (LiNbO ₃ ), lithium tantalate (LiTaO ₃ ), KTP (KTiOPO ₄ ), SBN, and KTN are used. Can be mentioned. These nonlinear optical crystals can be formed into a thin film while maintaining the electro-optical performance of the crystal by forming a layer on the support substrate and then polishing.

  In addition, although the thickness of the core layer 30 is not limited, Specifically, it is preferable that the thickness of the core layer 30 is 10 micrometers or more and 50 micrometers or less. When the thickness of the core layer 30 is in the above range, a significant change in refractive index can be generated by applying a lower voltage while suppressing the influence of a voltage drop due to the cladding layer 32 and the cladding layer 34.

The clad layer 32 and the clad layer 34 are provided so as to sandwich the core layer 30, and are made of a material having a refractive index lower than that of the core layer 30. For this reason, the laser light incident on the core layer 30 propagates in the core layer 30. Specifically, the constituent material of the clad layer 32 and the clad layer 34 is silicon dioxide (SiO ₂ ), tantalum oxide (Ta ₂ O ₅ ), titanium oxide (TiO ₂ ), nitride, which is a general glass material. Examples thereof include dielectrics such as silicon (Si ₃ N ₄ ), aluminum oxide (Al ₂ O ₃ ), and hafnium oxide (HfO ₂ ), and mixed glass thereof. Further, as a constituent material of the clad layer 32 and the clad layer 34, PMMA (polymethyl methacrylate) can also be used.

  The electrode layer 38 and the electrode layer 36 are provided so as to face the outside of each of the clad layer 32 and the clad layer 34. In the optical deflection element 14, an electric field is formed in the thickness direction of the core layer 30 by applying a voltage to the electrode layer 38 and the electrode layer 36.

  Specific examples of the constituent material of the electrode layer 38 and the electrode layer 36 include metal electrodes such as Au, Pt, Ti, Al, Ni, and Cr, and transparent electrodes such as ITO.

In the present embodiment, as shown in FIG. 3B, the core layer 30 is provided with a domain-inverted region 30A. In the domain-inverted region 30A in the core layer 30 and the region other than the domain-inverted region 30A, the direction of the crystal axis (polarization axis) of the electro-optic material constituting the core layer 30 is inverted. In this embodiment, the polarization inversion region 30A illustrates a case where a plurality of prism portions 30A ₁ is a region arranged in the Z-axis direction. Each prism portion 30A ₁ is a region of the prism-shaped (triangular).

  The width of the domain-inverted region 30A (the width in the X-axis direction (fast axis direction) in the domain-inverted region 30A (see width D in FIG. 3B, hereinafter may be simply referred to as “width D”)) is not limited. However, 1 mm etc. are mentioned, for example.

  In detail, the electrode layer 38 and the electrode layer 36 are provided in a region covering the domain-inverted region 30 </ b> A in the optical waveguide 31. When a voltage is applied to the core layer 30 by applying a voltage to the electrode layer 38 and the electrode layer 36, the amount of change in refractive index is changed between the domain-inverted region 30A and the region other than the domain-inverted region 30A. The sign is reversed. For this reason, the light deflection element 14 has a structure capable of creating a plurality of prism structures inside the core layer 30.

Here, in general, light is refracted (deflected) at the interface between regions having different refractive indexes. For this reason, the laser light is refracted at the interface between the region where the voltage is applied and the region where the voltage is not applied. Therefore, the laser beam is refracted as it goes the interfaces between the prism portion 30A ₁ constituting the domain inversion regions 30A. Further, the refractive index change amount Δn of the domain-inverted region 30 </ b> A varies depending on the voltage applied to the electrode layer 36 and the electrode layer 38. Therefore, the refractive index at the interface also changes depending on the voltage applied to the electrode layer 36 and the electrode layer 38.

  Therefore, the light deflection element 14 in the present embodiment can adjust the deflection angle θ of the laser light propagating through the domain-inverted region 30A by adjusting the voltage applied to the electrode layer 36 and the electrode layer 38. .

  Specifically, when the width D of the domain-inverted region 30A (see width D in FIG. 3B) is constant, the deflection angle θ (emission angle) of the laser beam emitted from the optical deflection element 14 is expressed by the following equation: It can be indicated by (1).

In the above formula (1), Δn indicates the amount of change in the refractive index of the core layer 30, and D indicates the width in the X-axis direction (fast axis direction) in the domain-inverted region 30A. In the formula (1), L is shown a plurality of prism portions 30A ₁ total Z-axis direction length (i.e. the length in the Z-axis direction of the domain inversion regions 30A).

  Since the refractive index change amount (Δn) can be controlled by the voltage applied to the electrode layer 36 and the electrode layer 38, the optical deflection element 14 can adjust the deflection angle θ of the laser beam, It functions as an optical deflection element that deflects the incident laser beam.

  In general, the refractive index change amount of the electro-optic material constituting the core layer 30 of the optical deflection element 14 is very small, and it is necessary to form an electric field of 10 kV / mm or more when the optical deflection element 14 is operated. There is. However, by using a slab type optical waveguide as the optical waveguide 31, the distance between the electrodes of the electrode layer 36 and the electrode layer 38 can be made closer, and the operating voltage can be reduced.

For example, the thickness of the core layer 30 is 20 μm, the width D of the domain-inverted region 30A is 2.0 mm, and the length of the domain-inverted region 30A in the Z-axis direction (see length B in FIG. 3B) is 20 mm. In this case, by applying a voltage of ± 300 V between the electrodes of the electrode layer 36 and the electrode layer 38, a deflection angle of about 4 ° in all angles can be obtained. In order to increase the deflection angle (in a triangular prism shape, the maximum length in the Z-axis direction) prism width of each prism portion 30A ₁ in the domain-inverted region 30A it is effective to further narrow the. Examples of the prism width include a range of about 0.5 mm to 5 mm.

  Next, the optical coupling optical unit 19 will be described.

  The optical coupling optical unit 19 is an optical system that optically couples the laser light emitted from the light source 12 to the light incident side end face of the polarization inversion region 30 </ b> A in the core layer 30 of the light deflection element 14.

  In the present embodiment, the optical coupling optical unit 19 includes a collimating optical unit 18 and a condenser lens 20 in order from the light source 12 side.

  The collimating optical unit 18 has a configuration in which a collimating lens 26 and a collimating lens 28 are arranged in order from the light incident side.

  The collimating lens 26 collimates (in parallel) the fast axis direction (X-axis direction) component included in the laser light emitted from the light source 12 and converts the collimated lens into a parallel light flux having the first beam width. In addition, this 1st beam width has shown the width | variety of the fast-axis direction in a laser beam.

  The collimating lens 26 has a configuration in which a hemispherical lens 22 and a meniscus lens 24 are sequentially arranged from the light incident side.

  The hemispherical lens 22 is a lens that converts a fast axis direction component included in an incident laser beam into a parallel light beam. The hemispherical lens 22 is a hemispherical lens having a plane on the light incident side and a spherical surface on the light emitting side, and has curvature in the fast axis direction and the slow axis direction of the incident laser light. In the following description, the surface on the light incident side may be simply referred to as a light incident surface, and the surface on the light output side may be simply referred to as a light output surface.

  Specifically, the hemispherical lens 22 has S-TIH 53 as the material of the hemispherical lens 22, the radius of curvature of the exit surface is 3.0 mm, and the distance between the exposed end surface of the laser and the incident surface of the hemispherical lens 22 is 1.5 mm. With this configuration, the fast axis component contained in the laser light incident from the light incident surface is converted into a parallel light beam.

  The hemispherical lens 22 only needs to be a lens that converts a component in the fast axis direction included in the laser light into a parallel light beam. The specifications such as the radius and the material may be appropriately adjusted so as to satisfy the above characteristics according to the configuration of the laser light scanner 10.

  Specifically, the radius of curvature of the light emitting side surface (spherical surface) of the hemispherical lens 22 may be adjusted so that the component in the fast axis direction becomes a parallel light beam according to the refractive index of the lens material. For example, when the refractive index of the lens material is in the range of 1.70 to 1.90, the radius of curvature of the hemispherical lens 22 is in the range of 2.5 mm to 3.5 mm.

  The material of the hemispherical lens 22 is not particularly limited as long as it is transparent at the wavelength of the light source. For example, since it exhibits high transmittance with high refractive index and high dispersion, for example, S-TIH53 manufactured by OHARA CORPORATION, S -NPH53 etc. are mentioned.

  The meniscus lens 24 emits the beam width in the fast axis direction of the laser beam emitted from the hemispherical lens 22 and converted in the fast axis direction component into a parallel light flux, and the width in the X axis direction (fast axis direction) in the polarization inversion region 30A. The width (first beam width) is adjusted according to D (see FIG. 3B).

  The meniscus lens 24 may adjust the beam width in the fast axis direction of the laser light emitted from the hemispherical lens 22 to a width corresponding to the width D, but the meniscus lens 24 has the beam in the fast axis direction. It is preferable to adjust the width to a value smaller than the width D and closer to the width. Specifically, when the width D of the domain-inverted region 30A is 2.0 mm, it is preferable to adjust the beam width to a range of 0.4 mm or more and 2.0 mm or less, and 1.5 mm or more and 2.0 mm or less. It is more preferable to adjust to this range.

  Specifically, the meniscus lens 24 is a curved aspheric lens in which both the light incident surface and the light emitting surface protrude toward the light incident side. The light incident side end of the meniscus lens 24 and the light incident side end of the hemispherical lens 22 may be arranged in contact with each other, or may be arranged in a non-contact manner. What is necessary is just to adjust the distance between these lenses according to the assembly holder mechanism at the time of fixing a lens.

  By arranging a meniscus lens 24 which is an aspherical lens on the light emitting side of the hemispherical lens 22, the laser beam incident on the hemispherical lens 22 is collimated by the hemispherical lens 22 on the fast axis direction component, and then the meniscus lens 24. Is converted into a parallel light flux having a beam width corresponding to the width D.

  The fast axis direction component included in the laser light that has passed through the hemispherical lens 22 may not be a perfect parallel light beam due to the spherical aberration of the hemispherical lens 22. For this reason, the meniscus lens 24 is preferably designed so as to cancel the spherical aberration of the hemispherical lens 22.

  That is, the meniscus lens 24 is adjusted so that the focal length of the convex lens formed by the curved surface of the light entrance surface of the meniscus lens 24 is longer than the focal length of the concave lens formed by the curved surface of the light exit surface. The lens has a characteristic that the beam width in the fast axis direction of the laser light emitted from the lens 22 is adjusted to a width corresponding to the width D. Further, the meniscus lens 24 adjusts the curved shape of the light incident surface of the meniscus lens 24 so that the light beam after passing through the light incident surface converges to a single focal point, thereby reducing the spherical aberration of the hemispherical lens 22. Designed to offset.

  The meniscus lens 24 may be any lens that satisfies the above-described characteristics. The center thickness (the shortest length in the light passing direction of the meniscus lens 24), the radius of curvature of the light incident surface and the light exit surface, the light incident surface, and the light exit surface The specifications such as the effective diameter, the conic constant of the light incident surface and the light exit surface, the aspherical constant of the light incident surface and the light exit surface, and the material are appropriately set so as to satisfy the above characteristics according to the configuration of the laser light scanner 10. adjust.

  Further, the material of the meniscus lens 24 is not limited as long as it is transparent at the wavelength of the light source and can be processed into a non-linear curved surface. For example, it is easy to cut into an arbitrary shape. ZEONEX-480R manufactured by the company etc. are mentioned.

  Next, the collimating lens 28 will be described.

  The collimating lens 28 is a lens that collimates the slow axis direction component included in the incident laser light.

  The fast-axis direction component included in the laser light emitted from the light source 12 is collimated by the collimating lens 26 and converted into a parallel light flux having the first beam width, and the slow-axis direction included in the converted laser light. Ingredients are not collimated. For this reason, by arranging the collimating lens 28 on the light emitting side of the collimating lens 26, the slow axis component included in the laser light emitted from the collimating lens 26 can be converted into a parallel light beam.

  Specifically, the collimating lens 28 is an aspherical lens whose light incident surface is a flat surface and whose light exit surface is a curved surface protruding toward the light exit side. The collimating lens 28 has a characteristic of collimating the slow axis direction component by providing the convex lens function only to the slow axis direction component on the curved surface of the light exit side of the collimator lens 28.

  The collimating lens 28 may be any lens that satisfies the above-described characteristics. The center thickness (the shortest length in the light passing direction of the collimating lens 28), the radius of curvature of the light exit surface, the effective diameter of the light exit surface, and the conic of the light exit surface. The specifications such as the constant and the material are appropriately adjusted so as to satisfy the above characteristics according to the configuration of the laser light scanner 10.

  The material of the collimating lens 28 is not limited as long as it is transparent at the wavelength of the light source and can be processed into a non-linear curved surface. For example, since it can be easily cut into an arbitrary shape, ZEON CORPORATION ZEONEX-480R manufactured by the company etc. are mentioned.

  Next, the condenser lens 20 will be described.

  The condenser lens 20 is provided on the light exit side of the collimating optical unit 18. The condensing lens 20 condenses the slow axis direction component included in the laser light emitted from the collimating optical unit 18 and optically couples it to the light incident side end face of the core layer 30.

  In the present embodiment, a cylindrical lens is used as the condenser lens 20. The cylindrical lens is a curved surface whose light incident surface protrudes toward the light incident side, and whose light exit surface is a flat lens. In this embodiment, the lens has such a characteristic that the NA of the cylindrical lens is made larger than the NA of the collimating lens 26 so that the slow axis direction component included in the laser light is condensed.

  The condensing lens 20 may be any lens that satisfies the above characteristics, and has a central thickness (the shortest length in the light passing direction in the condensing lens 20), a radius of curvature of the light incident surface, an effective diameter of the light incident surface, and a light incident surface. The conic constant and the material specifications may be appropriately adjusted according to the configuration of the laser light scanner 10 so as to satisfy the above characteristics.

  The condensing lens 20 has a slow axis direction component included in the laser light at a beam width (width in the slow axis direction) corresponding to the thickness of the core layer 30 (length in the Y axis direction of the core layer 30). It is preferably optically coupled to the light incident side end face of the core layer 30.

  The beam width (width in the slow axis direction) according to the thickness of the core layer 30 is specifically preferably 1.5 times or less the thickness of the core layer 30 and less than the thickness of the core layer 30. More preferably. Furthermore, it is particularly preferable that the beam width corresponding to the thickness of the core layer 30 matches the thickness of the core layer 30.

  The width of the slow axis component included in the laser light (width in the slow axis direction) when optically coupled to the light incident side end face of the core layer 30 is adjusted by the numerical aperture (NA) of the condenser lens 20. Can be controlled by.

  Although details will be described later, the slow-axis direction component included in the laser light oscillates in multimode. However, by using a cylindrical lens having a specific numerical aperture (NA) as the condensing lens 20, the slow axis direction component can be condensed to a beam width corresponding to the thickness of the core layer 30.

  The numerical aperture (NA) required for the condensing lens 20 is such that the divergence angle in the slow axis direction (Y-axis direction) of the laser light emitted from the light source 12, the beam width of the laser light (width in the slow axis direction), and The following equation (2) can be used.

In the above formula (2), θ _b indicates the spread angle in the slow axis direction (Y-axis direction) of the laser light emitted from the light source 12, and W _b is the slow axis direction of the laser light emitted from the light source 12. The beam width in the (Y-axis direction) is shown. Further, θ _c represents the spread angle in the slow axis direction (Y-axis direction) of the laser light when optically coupled to the core layer 30 of the optical deflection element 14. Further, d indicates the width of the laser beam in the slow axis direction (Y-axis direction) when optically coupled to the core layer 30 of the optical deflection element 14.

For example, θ _b is 10 °, W _b is 200 μm, and d is 20 μm. In this case, from the above equation (2), θ _c is about 120 °.

  Since the condensing capability required for the condensing lens 20 is the same as the capability of converting the laser light having the divergence angle θc into a parallel light beam, the numerical aperture (NA) of the condensing lens 20 is expressed by the following equation (3). Any value that satisfies the above) is acceptable.

  As described above, for example, when θc is 120 °, the condensing lens 20 has a value exceeding 0.87 which is the numerical aperture (NA) of the condensing lens 20, so that the condensing lens 20 is incident on the incident laser beam. Can be focused to a beam width corresponding to the thickness of the core layer 30.

  Next, the output optical unit 16 will be described.

  The output optical unit 16 is provided on the light emission side of the light deflection element 14 and converts the slow axis direction component included in the laser light emitted from the light deflection element 14 into a parallel light beam. In the present embodiment, a cylindrical lens is used as the output optical unit 16. The cylindrical lens used in the output optical unit 16 is a curved lens whose light incident surface is planar and whose light exit surface protrudes toward the light exit side. In the present embodiment, the output optical unit 16 converts the slow axis component included in the incident laser light into a parallel light beam by making the curved surface shape of the light exit surface of the cylindrical lens an aspherical shape. The lens has the following characteristics.

  The output optical unit 16 may be any lens as long as it satisfies the above characteristics, and has a center thickness (the shortest length in the light passing direction in the output optical unit 16), the radius of curvature of the light exit surface, and the light exit. The specifications such as the effective diameter of the surface, the conic constant of the light emitting surface, and the material may be appropriately adjusted so as to satisfy the above characteristics according to the configuration of the laser light scanner 10.

  The output optical unit 16 is preferably the same lens as the condenser lens 20 described above. And what is necessary is just to arrange | position so that the light-incidence surface side in the said condensing lens 20 may be made into a light-projection surface.

  By using the same lens as the condensing lens 20 as the cylindrical lens of the output optical unit 16, the emission beam profile of the laser beam emitted from the output optical unit 16 is changed to the emission beam profile of the laser beam incident on the optical deflection element 14. Can be almost the same.

  Next, the operation of the laser light scanner 10 will be described.

  In the laser light scanner 10 configured as described above, the laser light emitted from the light source 12 passes through the collimating lens 26 and the collimating lens 28 to be converted into a parallel light flux having a laser width whose width direction component is width D. After that, the slow axis direction component is converted into a parallel light flux. That is, the laser light emitted from the light source 12 passes through the collimating optical unit 18 to be converted into a parallel light beam with respect to both the slow axis direction component and the fast axis direction component, and the width of the fast axis direction component is polarization-inverted. It is converted into a width corresponding to the width D of the region 30A.

  Then, the laser light that has passed through the collimating optical unit 18 passes through the condenser lens 20, whereby the slow axis direction component contained in the laser light is condensed and optically coupled to the light incident side end face of the core layer 30. .

  For this reason, the slow axis direction of the slow axis direction component coincides with the thickness direction of the core layer 30 (Y axis direction) on the light incident side end face of the core layer 30 of the light deflection element 14, and the fast axis direction component of the core layer 30 Laser light whose fast axis direction coincides with the width D direction (X-axis direction) of the domain-inverted region 30A of the core layer 30 is optically coupled. Further, on the light incident side end face of the core layer 30, the laser beam condensed in the thickness direction of the core layer 30 with respect to the slow axis direction component after the fast axis direction component and the slow axis direction component are both parallel light beams. , Photocouple.

  The laser beam optically coupled to the light incident side end surface of the core layer 30 of the light deflection element 14 is deflected by the light deflection element 14 and emitted through the output optical unit 16.

  Here, in the semiconductor laser as the light source 12, the exposed end face of the active layer 12A has a thickness direction (X-axis direction (fast axis direction)) length (width direction) perpendicular to the thickness direction of the exposed end face. It is a rectangular shape shorter than the length in the (Y-axis direction (slow axis direction)).

  For this reason, the beam width in the fast axis direction (X-axis direction) included in the laser light immediately after being emitted from the exposed end face of the active layer 12A is smaller than the beam width in the slow axis direction (Y-axis direction). Further, the spread angle in the fast axis direction (X-axis direction) included in the laser light immediately after being emitted from the exposed end face of the active layer 12A is larger than the spread angle in the slow axis direction (Y-axis direction) (see FIG. 2). ).

  Although depending on the configuration of the light source 12, for example, the beam width in the fast axis direction included in the laser light just emitted from the exposed end face of the active layer 12A is 1 μm, and the spread angle in the fast axis direction is about 30 °. Further, for example, in the laser light immediately after being emitted from the exposed end face of the active layer 12A, the beam width in the slow axis direction is 40 μm to 400 μm, and the spread angle in the slow axis direction is about 10 °.

  Thus, since the fast axis direction component contained in the laser light emitted from the exposed end face of the active layer 12A is emitted from a narrower area than the slow axis direction component, single mode oscillation is performed. On the other hand, since the slow axis direction component included in the laser light emitted from the exposed end surface of the active layer 12A is emitted from a wider area than the fast axis direction component, the beam width becomes larger than the wavelength of the laser light, Mode oscillation occurs. The light emission intensity of the light source 12 is increased by increasing the length in the slow axis direction (Y-axis direction), which is the long side of the exposed end face of the active layer 12A, and the light emission intensity is increased. The slower the component in the slow axis direction, the easier the multimode oscillation occurs. Specifically, from the viewpoint of increasing the light emission intensity, when the width in the slow axis direction (Y-axis direction) on the exposed end face of the active layer 12A is set to a length of 40 μm to 400 μm, the slow axis component is multimode oscillation. It becomes.

  Single mode oscillation refers to laser oscillation in a mode in which the intensity distribution in the cross section of the laser beam is large at the center and becomes probabilistic in the periphery. Multimode oscillation refers to oscillation in which the intensity distribution in the cross section of the laser beam is a mode other than the single mode. In this multimode oscillation laser beam, the coherence is lowered, so that the light condensing property is poor, and the beam quality is inferior to that in the single mode oscillation.

  Since the fast axis direction component included in the laser light emitted from the light source 12 oscillates in a single mode, the emission beam profile of the fast axis direction component is close to a Gaussian beam. On the other hand, since the slow axis direction component included in the laser light emitted from the light source 12 oscillates in multimode, the emission beam profile cannot be expressed by a specific function.

  For the reasons described above, conventionally, the slow axis direction component included in the laser light emitted from the light source 12 is matched with the direction perpendicular to the thickness direction of the light incident end face of the core layer 30, and the slow axis direction component is converted into a parallel light flux. Therefore, the slow axis direction component plays a role of the light deflection direction in the light deflection element 14, leading to a decrease in the number of resolution points of the deflected laser light emitted from the light deflection element 14.

  In contrast, conventionally, the slow axis direction component included in the laser light emitted from the light source 12 is made to coincide with the thickness direction of the light deflection element 14, and the slow axis direction component is condensed in the thickness direction of the core layer 30. In this case, it is necessary to focus the slow axis direction component which is inferior in beam quality compared to the fast axis direction component, resulting in a decrease in light utilization efficiency.

  On the other hand, in the present embodiment, as described above, in the laser light scanner 10, the laser light scanner 10 includes the collimating optical unit 19 including the collimating optical unit 18 and the condenser lens 20, and the collimating optical unit. 18, the collimating lens 26 and the collimating lens 28 are arranged in order from the light incident side.

  For this reason, the slow axis direction of the slow axis direction component coincides with the thickness direction of the core layer 30 (Y axis direction) on the light incident side end face of the core layer 30 of the light deflection element 14, and the fast axis direction component of the core layer 30 Laser light whose fast axis direction coincides with the width D direction (X-axis direction) of the domain-inverted region 30A of the core layer 30 is optically coupled.

  Further, in the present embodiment, the collimating lens 26 has a configuration in which the hemispherical lens 22 and the meniscus lens 24 are arranged in order from the light incident side.

  Here, if the fast axis direction component included in the laser light is to be converted into a parallel light flux having a beam width corresponding to the width D of the polarization inversion region 30A in the optical deflection element 14, the light source 12 of the light source 12 is changed according to the width D. It is necessary to arrange the light emitting side end face and the light incident side end face of the collimating lens 26 so as to be very close to each other. For this reason, it is practically difficult to form the collimating lens 26 with a single lens.

  However, in the laser light scanner 10 of the present embodiment, the collimating lens 26 includes the hemispherical lens 22 and the meniscus lens 24, and the hemispherical lens 22 converts the fast axis direction component included in the laser light into a parallel light beam. The width in the fast axis direction is adjusted by the meniscus lens 24. Further, the spherical aberration of the hemispherical lens 22 is canceled by the meniscus lens 24. Therefore, the fast axis direction component included in the laser light incident on the collimating lens 26 can be converted into a parallel light beam corresponding to the width D. Therefore, the number of resolution points of the light deflection element 14 can be increased.

  In the laser beam scanner 10 of the present embodiment, a collimator lens 28 is provided on the light emission side of the collimator lens 26. A condensing lens 20 is provided on the light exit side of the collimating optical unit 18 having the collimating lens 26 and the collimating lens 28.

  For this reason, in the laser light scanner 10 according to the present embodiment, the core layer 30 is converted into a parallel light flux on the light incident side end face of the core layer 30 and then the slow axis direction component is converted into the core layer. The laser beam condensed in the thickness direction 30 is optically coupled. For this reason, high light utilization efficiency is realizable.

  Therefore, in the laser light scanner 10 of the present embodiment, high light utilization efficiency and a high number of resolution points can be realized.

  Further, in the laser light scanner 10 of the present embodiment, by increasing the width of the active layer 12A in the light source 12 in the slow axis direction in order to increase the emission intensity, the degree of multimode oscillation of the slow axis direction component can be increased. Even when it becomes stronger, high light utilization efficiency and a high number of resolution points can be realized.

  Further, in the laser light scanner 10 of the present embodiment, the laser light scanner 10 can be downsized by adopting the configuration including the optical coupling optical unit 19 described above.

  Furthermore, since the laser beam that has passed through the collimating optical unit 18 is a parallel light beam in both the fast axis direction component and the slow axis direction component, the laser beam is transmitted between the collimating optical unit 18 and the condenser lens 20. The optical path may be folded by a mirror or the like, and the laser light emitted from the collimating optical unit 18 may be folded by the mirror and incident on the condenser lens 20.

  With such a configuration, the laser light scanner 10 can be further reduced in size.

  In the present embodiment, it has been described that the core layer 30 and the cladding layer 32 and the cladding layer 34 in the optical deflection element 14 have different refractive indexes. The refractive indexes of the layer 32 and the clad layer 34 are preferably adjusted so that the optical waveguide 31 has a numerical aperture (NA) equal to or higher than the numerical aperture (NA) of the condenser lens 20.

  The numerical aperture (NA) of the optical waveguide 31 can be expressed by the following formula (4).

In the above formula (4), n ₁ represents the refractive index of the core layer 30. N ₂ represents the refractive index of the cladding layer 32 and the cladding layer 34.

  For example, when the numerical aperture (NA) of the condensing lens 20 is a high NA lens close to 1.0, the core layer 30, so that the numerical aperture (NA) of the optical waveguide 31 is 1.0 or more. The refractive indexes of the cladding layer 32 and the cladding layer 34 may be adjusted. The refractive index may be adjusted by appropriately selecting the constituent materials for these layers. For example, when lithium niobate having a refractive index of 2.2 is used as the constituent material of the core layer 30, a material having a refractive index of 1.96 or less is selected as the constituent material of the cladding layer 32 and the cladding layer 34. That's fine.

  In this way, the refractive indexes of the core layer 30, the cladding layer 32, and the cladding layer 34 are adjusted so that the optical waveguide 31 has a numerical aperture (NA) that is equal to or higher than the numerical aperture (NA) of the condenser lens 20. Thus, the laser beam optically coupled to the light incident side end face of the core layer 30 via the condenser lens 20 is not reflected at the interface between the core layer 30, the clad layer 32, and the clad layer 34, and the outside of the optical waveguide 31. It is possible to suppress leakage into the water.

  That is, the laser light whose slow axis direction component is condensed by the condensing lens 20 is optically coupled to the light incident side end surface of the core layer 30 at a large incident angle. For this reason, the refractive index difference between the core layer 30 and the cladding layer 32 and the cladding layer 34 is small, and the numerical aperture (NA) of the optical waveguide 31 is smaller than the numerical aperture (NA) of the condenser lens 20. Laser light having a propagation angle larger than the angle capable of propagating is optically coupled to the light incident side end surface of the core layer 30. Such light does not satisfy the total reflection conditions of the core layer 30, the cladding layer 32, and the cladding layer 34, and therefore leaks to the outside of the optical waveguide 31.

  However, by adjusting the refractive indexes of the core layer 30, the cladding layer 32, and the cladding layer 34 so that the optical waveguide 31 has a numerical aperture (NA) equal to or higher than the numerical aperture (NA) of the condenser lens 20, It is possible to suppress leakage outside the optical waveguide 31 without being reflected at the interface between the core layer 30 and the cladding layer 32 and the cladding layer 34. For this reason, high light utilization efficiency can be realized.

(Second Embodiment)
In the first embodiment, the case where the condenser lens 20 is a single lens has been described. On the other hand, in the present embodiment, a case where the condenser lens 20 is configured by a plurality of lenses will be described.

  FIG. 4 schematically shows the configuration of the laser light scanner 10A of the present embodiment.

  As shown in FIG. 4, the laser light scanner 10 </ b> A of the present embodiment includes a light source 12, an optical coupling optical unit 19 </ b> A, an optical deflection element 14, and an output optical unit 16. The optical coupling optical unit 19A includes a collimating optical unit 18 and a condenser lens 20A.

  The laser light scanner 10A of the present embodiment is different from the laser light scanner 10 described in the first embodiment except that a condensing lens 20A is provided instead of the condensing lens 20 (see FIG. 1). The configuration is the same as that of the laser light scanner 10. For this reason, in the laser light scanner 10A, members having the same functions and configurations as those of the laser light scanner 10 are given the same reference numerals and detailed description thereof is omitted.

  The condenser lens 20 </ b> A is provided on the light exit side of the collimating optical unit 18 and has the same characteristics as the condenser lens 20. That is, the condensing lens 20 </ b> A uses the beam width (the width in the slow axis direction) corresponding to the thickness of the core layer 30 as the slow axis direction component included in the laser light emitted from the collimating optical unit 18, and the light of the core layer 30. The light is condensed on the incident side end face.

  In the present embodiment, the condensing lens 20A has a configuration in which an aspherical cylindrical lens 21 and a semi-cylindrical lens 23 are arranged in order from the light incident side.

  The semi-cylindrical lens 23 is provided between the aspherical cylindrical lens 21 and the light deflection element 14, and a slow axis direction component included in the laser light emitted from the collimating optical unit 18 is equal to or less than the thickness of the core layer 30. The light is condensed on the light incident side end face of the core layer 30 with the beam width.

  The semi-cylindrical lens 23 is a semi-cylindrical lens in which the light incident surface is a spherical surface having a curvature in the slow axis direction of incident laser light and the light emitting surface is a flat surface. The light incident surface of the semi-cylindrical lens 23 is a curved surface protruding toward the light incident side.

  The semi-cylindrical lens 23 has a configuration in which only the slow-axis direction component of the light incident surface of the semi-cylindrical lens 23 is a spherical surface, so that the slow-axis direction component included in the laser light incident from the light incident surface is the core layer. The lens has a characteristic of focusing on the light incident side end face of the core layer 30 with a beam width (width in the slow axis direction) corresponding to the thickness of 30.

  The semi-cylindrical lens 23 may be any lens satisfying the above characteristics, and specifications such as the center thickness (the shortest length in the light passing direction of the semi-cylindrical lens 23), the radius of curvature of the light incident surface, and the material are laser It adjusts suitably so that the said characteristic may be satisfy | filled according to the structure of 10 A of optical scanners.

  Specifically, the radius of curvature of the light incident surface of the semi-cylindrical lens 23 may be adjusted according to the refractive index of the lens material and the NA value of the condenser lens so that the luminous flux is within the effective diameter of the lens. . For example, when the NA of the condenser lens exceeds 0.9, the radius of curvature of the semi-cylindrical lens 23 may be in the range of 2.0 mm or less.

  The material of the semi-cylindrical lens 23 is not particularly limited as long as it is transparent at the light source wavelength and has a refractive index of about 1.60 or more. For example, the semi-cylindrical lens 23 has a particularly high refractive index and high dispersion and high transmittance. As shown, S-TIH53, S-NPH53, etc. manufactured by OHARA INC. Can be mentioned.

  The aspherical cylindrical lens 21 is provided on the light emitting side of the collimating optical unit 18 and on the light incident side of the semi-cylindrical lens 23. The aspheric cylindrical lens 21 has a function of removing (cancelling) the spherical aberration of the semi-cylindrical lens 23.

  Specifically, the aspherical cylindrical lens 21 is an aspherical cylindrical lens in which the light incident surface is a curved surface having a curvature in the slow axis direction and the light emitting surface is a flat surface.

  Then, the light beam incident from the light incident surface of the aspherical cylindrical lens 21 passes through the condenser lens 20A, and is then converged on a minute region on the incident end surface of the light deflection element 14, so that the curved surface of the aspherical cylindrical lens 21 is curved. The aspherical cylindrical lens 21 is designed to cancel the spherical aberration of the semi-cylindrical lens 23 by adjusting.

  The aspherical cylindrical lens 21 may be any lens that satisfies the above characteristics, and has a central thickness (the shortest length in the light passing direction in the aspherical cylindrical lens 21), the radius of curvature of the light incident surface, the effective diameter of the light incident surface, the light The specifications such as the conic constant of the incident surface, the aspherical coefficient of the light incident surface, and the material are appropriately adjusted so as to satisfy the above characteristics according to the configuration of the laser light scanner 10A.

  The material of the aspherical cylindrical lens 21 is not limited as long as it is transparent at the wavelength of the light source and can be processed into a non-linear curved surface. For example, it can be easily cut into an arbitrary shape. Examples thereof include ZEONEX-480R manufactured by Co., Ltd.

  As described above, in the laser light scanner 10 </ b> A of the present embodiment, the condensing lens 20 </ b> A includes the aspherical cylindrical lens 21 and the semicylindrical lens 23.

  Here, in order to condense the slow-axis direction component that oscillates in multimode onto a minute region such as the core layer 30 of the optical deflection element 14, a cylindrical lens having a very large numerical aperture (NA) is used as the condensing lens 20A. Employment is required. For this reason, when a lens with such a large numerical aperture is constituted by a single lens, the aspherical curved surface becomes steep, and the degree of difficulty may be high in terms of processing and surface accuracy.

  On the other hand, in the laser light scanner 10 </ b> A of the present embodiment, the condensing lens 20 </ b> A is composed of two lenses, an aspherical cylindrical lens 21 and a semicylindrical lens 23. Then, the slow axis direction component included in the laser light is condensed by the semi-cylindrical lens 23, and the curved aberration of the semi-cylindrical lens 23 is canceled by the aspherical cylindrical lens 21.

  Since the semi-cylindrical lens 23 is a lens having a curved light incident surface and a constant radius of curvature, it can be easily processed. Also. Since the aspherical cylindrical lens 21 placed on the light incident side of the semi-cylindrical lens 23 is a lens that cancels out the spherical aberration of the semi-cylindrical lens 23, the curved surface is a relatively gently inclined surface and is easy to process. is there.

  For this reason, in this Embodiment, the condensing lens 20A which has the said characteristic can be implement | achieved easily.

  In the present embodiment, the case where the condensing lens 20A is composed of two lenses, the aspherical cylindrical lens 21 and the semi-cylindrical lens 23, is shown, but the output optical unit 16 is also composed of two lenses. May be.

  In this case, the output optical unit 16 may have a configuration in which the semi-cylindrical lens 23 and the aspherical cylindrical lens 21 are arranged in order from the light incident side. Then, the plane side of the semi-cylindrical lens 23 may be disposed as a light incident surface, and the plane side of the aspherical cylindrical lens 21 may be disposed as a light incident surface.

  In this way, the output optical unit 16 can also be a lens having the above-described characteristics of the output optical unit 16 as in the case of the condensing lens 20A.

  Hereinafter, the laser light scanner 10A described in the above embodiment will be described with reference to examples. However, the laser light scanner 10A is not limited to these examples.

Example 1
FIG. 7 shows an example of a specific configuration of the laser light scanner 10A described in the above embodiment. FIG. 8 shows an enlarged view of the collimating lens 26 in FIG. FIG. 9 shows an enlarged view of the collimating lens 28 and the condenser lens 20A in FIG.

  As the light source 12, a multimode LD (laser diode) that emits laser light having a wavelength of 870 nm was used. The beam width in the fast axis direction included in the laser light immediately after being emitted from the exposed end face of the active layer 12A of the light source 12 was 1 μm, and the spread angle in the fast axis direction was about 30 °. Further, in the laser light immediately after being emitted from the exposed end face of the active layer 12A, the beam width in the slow axis direction was 200 μm, and the spread angle in the slow axis direction was 10 °.

In the optical waveguide 31 of the optical deflection element 14, lithium niobate was used as the constituent material of the core layer 30, and SiO ₂ was used as the constituent material of the cladding layer 32 and the cladding layer 34. The thickness of the core layer 30 was 20 μm.

  The width D (see FIG. 3B) of the domain-inverted region 30A in the core layer 30 was 2.0 mm.

  In addition, the hemispherical lens 22 and the meniscus lens 24 used the lens of the specification shown in FIG. 5 (refer to the rows of “hemispherical lens” and “meniscus lens” in FIG. 5). In addition, the collimating lens 28 is also a lens having the specifications shown in FIG. 5 (see the row of “slow axis direction collimating lens” in FIG. 5). The shape of the light incident surface of the meniscus lens 24 was designed to be completely condensed at a point 15 mm from the light source 12.

  Further, as the aspherical cylindrical lens 21 and the semi-cylindrical lens 23, lenses having the specifications shown in FIG. 6 were used (see the rows of “aspherical cylindrical lens” and “semi-cylindrical lens” in FIG. 6).

  And the distance between each lens was made into the distance shown in FIGS.

  Specifically, the distance between the light emitting side end face of the light source 12 and the hemispherical lens 22 was 1.6 mm. The distance between the light incident side end surface of the hemispherical lens 22 and the light exit side end surface of the meniscus lens 24 was set to 10.2 mm (11.8−1.6 = 10.2). The distance between the light exit side end face of the meniscus lens 24 and the collimating lens 28 was 18.2 mm (30.0-11.8 = 18.2). The distance between the light incident side end face of the collimating lens 28 and the light incident side end face of the aspherical cylindrical lens 21 was set to 5 mm. The distance between the light incident side end face of the aspherical cylindrical lens 21 and the light exit side end face of the semi-cylindrical lens 23 was set to 5.3 mm. The distance between the light emission side end face of the semi-cylindrical lens 23 and the light emission side end face of the output optical unit 16 was set to 25.3 mm. Similarly, the distance between each lens was determined in the relationship shown in FIGS.

  When the laser light is emitted from the light source 12 of the laser light scanner 10A having the configuration shown in FIGS. 5 to 9, the laser light passes through the hemispherical lens 22 as shown in FIGS. Was converted into a parallel light beam to become a parallel light beam with a beam width of 3.0 mm in the fast axis direction. Further, by passing through the meniscus lens 24, a parallel light flux having a beam width of 1.4 mm in the fast axis direction was obtained (see FIG. 8).

  On the other hand, the slow-axis direction component included in the laser light that has passed through the collimator lens 26 does not become a parallel light flux but has a spread angle, as shown in FIG.

  Then, the laser beam that has passed through the collimating lens 26 passes through a collimating lens 28 installed at a position 30 mm away from the light source 12, so that the slow axis direction component is also converted into a parallel beam (FIGS. 7 and 9). reference). Further, by passing through the condensing lens 20A, the slow axis direction component included in the laser light is condensed to a beam width of about 20 μm of the slow axis direction component, and is optically coupled to the core layer 30 of the light deflection element 14. (See FIGS. 7 and 9).

  The light utilization efficiency of the light deflection element 14 was calculated by ray tracing simulation to be 94%.

Further, when the number of resolution points of the optical deflection element 14 is calculated by dividing the deflection angle of the optical deflection given by the equation (1) by the beam divergence angle of the fast axis direction component, L = 20 mm, Δn = 3.7 × When 10 ⁻³ and the beam width of the fast axis direction component = 1.5 mm, the number of resolution points was 100.

  For this reason, the realization of high light utilization efficiency and high resolution points could be confirmed.

  In the first embodiment, as shown in FIGS. 7 to 9, the distance until the laser light emitted from the light source 12 is output from the output optical unit 16 is 65.6 mm. For this reason, it was confirmed that the module size of the laser light scanner 10A including this optical system was such a size that there was no practical problem.

(Comparative Example 1)
FIG. 10 shows a schematic diagram of a laser beam scanner having a general conventional configuration (see the laser beam scanner 100 in FIG. 10). As shown in FIG. 10, in Comparative Example 1, a collimating lens 102 was used instead of the hemispherical lens 22 and the meniscus lens 24 in Example 1. In addition, a condensing cylindrical lens 104 was used in place of the collimating lens 28 in Example 1. As the light changing element 14, the same element as in Example 1 was used. As the output optical unit 106, the same output optical unit 16 as that in Example 1 was used.

  Further, the same laser diode as that used in Example 1 was used as the laser diode.

  By configuring the laser light scanner 100 in the comparative example 1 in this way, in the comparative example 1, divergent light emitted from the laser diode is converted into a parallel light beam by the collimating lens 102, and the condensing cylindrical lens 104. Thus, it was confirmed that only the slow axis direction component was condensed and guided into the optical deflection element 14 having an optical waveguide structure. Further, although the light output from the light deflecting element 14 has a large divergence angle in the slow axis direction, it was confirmed that it was converted into a parallel light beam by the output optical system 106 and emitted as an output from the laser light scanner 100. .

  Here, assuming that the divergence angle of the fast axis direction component output from the laser diode in Comparative Example 1 is 30 °, when a lens having a focal length of 3.0 mm is adopted as the collimating lens 102, the beam in the fast axis direction is used. The width was about 1.6 mm, which was suitable for the width of the domain-inverted region (see width D in FIG. 3B). However, the slow axis direction component is not completely converted into a parallel light beam and has a certain spread angle. This slow-axis direction component is collected by the condensing cylindrical lens 104, and the condensing cylindrical lens 104 collects the slow-axis direction component that is not a parallel light flux, so that the light deflection element 14 is configured. It was confirmed that it was difficult to focus on a minute region corresponding to the core thickness of the optical waveguide.

  That is, in Comparative Example 1, the light utilization efficiency of the light deflector 14 was calculated by ray tracing simulation and found to be 20% or less.

  In the laser light scanner 100 having the configuration of the comparative example 1, it is possible to improve the light utilization efficiency by setting the fast axis direction component in the core thickness direction of the waveguide. The slow axis direction component with poor quality is the direction in which the beam is deflected. In general, it is known that the beam divergence angle of a multimode oscillation laser diode is as large as about 10 to 100 times the beam divergence angle of single mode oscillation. This is equivalent to reducing the number of resolution points of the laser light scanner to about 1/10 to 1/100. That is, it can be said that the number of resolution points of the laser light scanner in Example 1 is about 100, whereas the number of resolution points is reduced to about 1 to 10 in the configuration of Comparative Example 1.

  Therefore, it can be said that the laser light scanner having the configuration of Comparative Example 1 cannot achieve both high light utilization efficiency and a high resolution point as compared with the laser light scanner having the configuration of Example 1.

DESCRIPTION OF SYMBOLS 10, 10A Laser light scanner 12 Light source 14 Optical deflecting element 18 Collimating optical unit 19 Optical coupling optical unit 20, 20A Condensing lens 22 Hemispherical lens 24 Meniscus lens 26 Collimating lens 28 Collimating lens 30 Core layer 30A Polarization inversion area | region 31 Optical waveguide 32 34 Clad layer

Japanese Patent No. 4427280

Claims (5)

A first collimator lens for converting the fast axis direction component contained in the laser beam emitted from the light source to a flat Yukimitsu bundle,
A second collimating lens that converts a slow axis direction component included in the laser light emitted from the first collimating lens into a parallel light beam;
An optical deflection element having a core layer having the slow axis direction as a thickness direction and the fast axis direction as an optical deflection direction and a pair of cladding layers sandwiching the core layer;
A condensing lens that condenses a slow axis direction component included in the laser light emitted from the second collimating lens and optically couples the laser light to the light incident side end surface of the core layer;
With
The core layer of the light deflection element has a refractive index change region having a predetermined width in the fast axis direction of the laser beam, the light refractive index changing according to an applied voltage.
The first collimating lens, possess a hemispherical lens the light incident side is formed on the plane and the light emitting side is formed in a spherical, and a meniscus lens provided on the light emitting side of the hemispherical lens,
The meniscus lens is a laser light scanner that adjusts the beam width in the fast axis direction of the laser light emitted from the hemispherical lens to a beam width corresponding to the predetermined width in the fast axis direction of the refractive index change region . The said meniscus lens adjusts the beam width of the said fast axis direction of the laser beam radiate | emitted from the said hemispherical lens to the beam width below the said predetermined width of the said fast axis direction of the said refractive index change area | region. Laser light scanner. The condensing lens is disposed on the light incident side of the semi-cylindrical lens, and a spherical aberration of the semi-cylindrical lens. The semi-cylindrical lens condenses a slow axis component included in the laser light emitted from the second collimating lens. The laser beam scanner according to claim 1, further comprising: a hemispherical cylindrical lens that corrects the above. The optical deflection element has an optical waveguide having the core layer and the cladding layer,
Numerical aperture of the optical waveguide, the laser beam scanner according to any one of claims 1 to 3 is equal to or greater than the numerical aperture of the condenser lens.   The laser light scanner according to any one of claims 1 to 4, further comprising an output optical system that shapes laser light emitted from the light polarizing element.

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