Method for manufacturing optical module

Abstract

A laser device (3) emits laser light. A lens cap (4) covers the laser device (3). A lens (5) is built in the lens cap (4) and collects or collimates the laser light. A flat surface (7) perpendicular to an optical axis (6) of the laser light is provided in an upper surface of the lens (5).

Claims

1. A method for manufacturing an optical module which includes a laser device emitting laser light, a lens cap covering the laser device, and a lens built in the lens cap and collecting or collimating the laser light, wherein a flat surface perpendicular to an optical axis of the laser light is provided in an upper surface of the lens, comprising: radiating recognition light onto the upper surface of the lens; recognizing a center position of the lens from a shape of reflected light; and aligning a light emission point of the laser device with the center position of the lens.

2. The method for manufacturing the optical module according to claim 1, wherein the flat surface is provided at a center position of the upper surface of the lens.

3. The method for manufacturing the optical module according to claim 1, wherein the flat surface is provided in a region which the laser light substantially does not pass through.

4. The method for manufacturing the optical module according to claim 1, wherein the radiating the recognition light onto the upper surface of the lens causes the recognition light to be reflected from the upper surface of the lens.

5. The method for manufacturing the optical module according to claim 1, wherein the recognition light is radiated from an upper side of the lens onto the upper surface of the lens.

6. A method for manufacturing an optical module which includes a laser device emitting laser light, a lens cap covering the laser device, and a lens built in the lens cap and collecting or collimating the laser light, wherein a flat surface perpendicular to an optical axis of the laser light is provided in an upper surface of the lens, comprising: radiating recognition light onto the upper surface of the lens; recognizing a center position of the lens from a shape of reflected light; and aligning a light emission point of the laser device with the center position of the lens, wherein a shape of the flat surface has anisotropy in a rotational direction with a center of the upper surface of the lens being as a rotational center.

7. The method for manufacturing the optical module according to claim 6, wherein the flat surface is provided at a center position of the upper surface of the lens.

8. The method for manufacturing the optical module according to claim 6, wherein the flat surface is provided in a region which the laser light substantially does not pass through.

9. A method for manufacturing an optical module which includes a laser device emitting laser light, a lens cap covering the laser device, and a lens built in the lens cap and collecting or collimating the laser light, wherein a concave surface is provided at a center position of an upper surface of the lens, comprising: radiating recognition light onto the upper surface of the lens; recognizing a center position of the lens from a shape of reflected light; and aligning a light emission point of the laser device with the center position of the lens.

10. The method for manufacturing the optical module according to claim 9, wherein the radiating the recognition light onto the upper surface of the lens causes the recognition light to be reflected from the upper surface of the lens.

11. The method for manufacturing the optical module according to claim 9, wherein the recognition light is radiated from an upper side of the lens onto the upper surface of the lens.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a sectional view showing an optical module according to Embodiment 1.

(2) FIG. 2 is a sectional view showing a method for manufacturing of the optical module according to Embodiment 1.

(3) FIG. 3 is a sectional view showing a method for manufacturing of the optical module according to Embodiment 1.

(4) FIG. 4 is a diagram showing the shape of a collimation lens according to a comparative example and optical paths of laser light.

(5) FIG. 5 is a diagram showing the shape of the lens according to Embodiment 1 and optical paths of laser light.

(6) FIG. 6 is a top view showing a lens of an optical module according to Embodiment 2.

(7) FIG. 7 shows a top view and a lateral view showing a lens of an optical module according to Embodiment 3.

(8) FIG. 8 shows a top view and a lateral view showing Modification 1 of the lens of the optical module according to Embodiment 3.

(9) FIG. 9 shows a top view and a lateral view showing Modification 2 of the lens of the optical module according to Embodiment 3.

(10) FIG. 10 is a sectional view showing a cap with a built-in lens of an optical module according to Embodiment 4.

DESCRIPTION OF EMBODIMENTS

(11) An optical module and a method for manufacturing the same according to the embodiments of the present invention will be described with reference to the drawings. The same components will be denoted by the same symbols, and the repeated description thereof may be omitted.

Embodiment 1

(12) FIG. 1 is a sectional view showing an optical module according to Embodiment 1. A submount 2 is provided on a package 1, and a laser device 3 is provided on the submount 2. The laser device 3 emits laser light. The laser device 3 is covered with a lens cap 4. A lens 5 which collects or collimates the laser light is built in the lens cap 4. When this cap with the built-in lens is formed, a lens material is put in the lens cap 4 to be heated to a high temperature, and the softened lens material is pressed with molds from the upper side and the lower side to obtain the lens 5 in a desired shape. A flat surface 7 perpendicular to an optical axis 6 of the laser light is provided in the upper surface of the lens 5.

(13) FIG. 2 and FIG. 3 are sectional views showing a method for manufacturing of the optical module according to Embodiment 1. First, as shown in FIG. 2, the emission end face of the laser device 3 is irradiated perpendicularly with recognition light 8, and reflected light 9 thereof is captured by a camera 10. Then, since reflection of the reflected light occurs most strongly on the emission end face portion of the laser device 3, the camera 10 can recognize the end ace shape of the laser device 3. When the end face shape of the laser device 3 is found out, it can be found out where the light emission point position is.

(14) Next, as shown in FIG. 3, recognition light 11 is radiated toward the upper surface of the lens 5 built in the lens cap 4, and from the shape of its reflected light 12, the center position of the lens 5 is recognized. Since a vertex portion of the lens 5 is the flat surface 7 perpendicular to the recognition light 11, the reflected light 12 from this flat surface 7 enters the camera 10 at the center position thereof evenly with an identical strength. Meanwhile, the reflected light 12 from other than the flat surface 7 enters the camera 10 at positions off the center thereof. Thereby, the brightness of the circular bright spot recognized with the reflection from the flat surface 7 by the camera 10 and the brightness of its surrounding region are discontinuous therebetween. Accordingly, since the bright spot is clearly projected on the camera 10, the center of the lens 5 can be recognized as the center of the bright spot with excellent accuracy.

(15) Then, by moving the lens cap 4 rightward and leftward, the light emission point position of the laser device 3 and the center position of the lens 5 are made coincide with each other. The lens cap 4 is welded to the package 1 at the positions. Thereby displacement between the light emission point position of the laser device 3 and the center position of the lens 5 can be reduced. As a result, there can be obtained an optical module small in spreading of a beam and in deviation of the emission direction of the beam.

(16) FIG. 4 is a diagram showing the shape of a collimation lens according to a comparative example and optical paths of laser light. The upper surface of the lens 5 has a shape in which the laser light is parallelly emitted. Accordingly, when laser light emitted from the light emission point of the laser device 3 enters the lens 5 at any position thereon, the laser light is emitted from the upper surface of the lens 5 to be parallel to the optical axis.

(17) FIG. 5 is a diagram showing the shape of the lens according to Embodiment 1 and optical paths of laser light. As indicated by the solid lines, laser light that passes through the dead center position of the lens 5 and the region thereof beyond the flat surface 7 results in emitted light parallel to the optical axis. As indicated by the dotted lines, laser light that passes through the flat surface 7 except the dead center position of the lens 5 is however to be emitted with slight inclinations relative to the optical axis. Nevertheless, it is sufficient for the flat surface 7 of the lens 5 to have a dimension with which the resolution of the camera 10 is suitable for recognition thereof and an angular difference thereof from except the flat surface 7 can be sufficiently secured. This dimension is sufficiently about hundreds of micrometers. Meanwhile, spreading of the laser light on the upper surface of the lens 5 is not less than millimeters, and the influence of the flat surface 7 of the lens 5 is extremely small. Moreover, in the case of use for projectors, for example, since all the amount of light is taken into an integrator rod finally guiding the light when a parallelism relative to the optical axis is within plus or minus several degrees, slight angular deviation due to the flat surface 7 does not cause any problem.

(18) For example, it is supposed that the distance between the light emission point center of the laser device 3 and the upper surface of the lens 5 is 3 mm, the radius of the flat surface 7 of the lens 5 is 0.12 mm, and the refractive index of the lens 5 is 1.8. In this case, a deviation angle θ, from the optical axis, of laser light that passes through the lens 5 at the outermost peripheral portion of the flat surface 7 is sin.sup.−1(1/1.8×0.12/3)=1.06° from the Fresnel formulas.

(19) Moreover, even in the case of collecting light or in the case where a stricter parallelism is required, desired characteristics can be obtained by designing of enlarging a focal distance and more reducing the size of the flat surface 7, or the similar designing.

(20) Notably, while in the present embodiment, a case where the lens 5 is built in the lens cap 4 has been described, the same hold true for a separate, sole lens 5 which is not built in any lens cap 4. In this case, the lens 5 is to be solely moved to be fixed onto the package 1 with an adhesive agent or the like.

Embodiment 2

(21) FIG. 6 is a top view showing a lens of an optical module according to Embodiment 2. This view is a view of the lens 5 as seen from the laser emission side. A flat surface 7a perpendicular to the optical axis of laser light is provided at the center position of the upper surface of the lens 5. A flat surface 7b is provided so as to be in contact with only a part of the periphery of the flat surface 7a. Accordingly, a shape having the flat surfaces 7a and 7b combined has anisotropy in a rotational direction with the center of the upper surface of the lens 5 being as a rotational center.

(22) An assembly method of the lens cap is similar to that in Embodiment 1, and similarly to Embodiment 1, the center of the lens 5 can be recognized with excellent accuracy. Moreover, the rotational direction of the lens 5 can be easily specified by reflected light from the flat surfaces 7a and 7b. Notably, the flat surface may have any shape as long as, with it, the rotational direction of the lens 5 can be recognized. Even when the flat surface has an elliptic shape, for example, the rotational direction of the lens 5 can be specified.

(23) The present embodiment is particularly effective when an asymmetric lens the planar shapes of which in the top-bottom direction and the right-left direction are different is used as the lens 5 in order to shape laser light. In this case, by relatively positioning the rotational direction of the lens 5 and the rotational direction of the laser device 3, there can be obtained a semiconductor laser small in spreading of a beam, and particularly, in deviation of the emission direction of the beam.

Embodiment 3

(24) FIG. 7 shows a top view and a lateral view showing a lens of an optical module according to Embodiment 3. When spreading angles of laser light in the vertical direction and the horizontal direction are different, a spot 13 of laser light that passes through the lens 5 at its upper surface position is elliptic. Regions which laser light substantially does not pass through exist on both sides of the elliptic spot 13 in the upper surface of the lens 5. Each flat surface 7 perpendicular to the optical axis of laser light is provided in each of the regions. Notably, not limited to this, such a flat surface 7 may be provided in a region, except the lens vertex, that laser light substantially does not pass through. The flat surface 7 has a shape obtained by cutting off a curved surface of the periphery of the lens 5.

(25) An assembly method of the lens cap is similar to that in Embodiment 1. Recognition light radiated onto the lens 5 is intensely reflected on the flat surfaces 7, and the planar shapes of the flat surfaces 7 are recognized by the camera. The center position and the rotational direction of the lens 5 can be recognized from these shapes with excellent accuracy. These flat surfaces 7 being in the curved surface, on the lens 5, which has a lens effect, not beyond the lens 5, enables the center position and the rotational direction of the lens 5 to be recognized with further excellent accuracy.

(26) Moreover, the lens cap 4 supports the periphery of the lens 5, and the lens 5 is exposed in a circular shape from the lens cap 4. Accordingly, the flat surfaces 7 are preferably inside the circular shape of the lens 5 in order that the flat surfaces 7 can be observed with the recognition light as the lens cap 4 is seen from the upper surface.

(27) FIG. 8 shows a top view and a lateral view showing Modification 1 of the lens of the optical module according to Embodiment 3. In this modification, the flat surfaces 7 protrude from the curved surface of the periphery of the lens 5. The aforementioned effect can also be obtained in this case.

(28) FIG. 9 shows a top view and a lateral view showing Modification 2 of the lens of the optical module according to Embodiment 3. In this modification, the flat surfaces 7 are narrower than the spot 13 in the longitudinal direction of the elliptic spot 13. Therefore, the center and the rotational direction of the lens 5 can be further easily recognized.

(29) Notably, the flat surfaces 7 may have any shapes as long as the center and the rotational direction of the lens 5 can be recognized. For example, not limited to being rectangular, the flat surfaces 7 may have triangular shapes each of which is tapered toward the center of the lens 5. Thereby, the center and the rotational direction of the lens 5 can be further easily recognized.

Embodiment 4

(30) FIG. 10 is a sectional view showing a cap with a built-in lens of an optical module according to Embodiment 4. A concave surface 14 is provided at the center position of the upper surface of the lens 5. The other configurations are similar to those in Embodiment 1, and an assembly method of the lens cap 4 is also similar to that in Embodiment 1. Recognition light radiated onto the lens 5 at its center is reflected on the upper surface of the lens 5. Reflected light from the concave surface 14 is then collected at the position of the camera 10, and a bright spot of the reflected light is recognized as a brighter and smaller spot. Thereby, the center position of the lens 5 can be further easily recognized.

REFERENCE SIGNS LIST

(31) 3 laser device; 4 lens cap; 5 lens; 7,7a,7b flat surface; 11 recognition light; 12 reflected light; 14, concave surface