JPWO2019116469A1 - Optical element and parallel light generator - Google Patents

Abstract

The lens (2, 2A to 2C) is located outside the effective aperture (6) of the entrance surface (2a) or the exit surface (2b) having a surface shape that is not axially symmetric with respect to the optical axis (a). It has one or more deep recessed markings (7, 7A, ~ 7C).

Description

  The present invention relates to an optical element having a plane shape that is not axially symmetric with respect to an optical axis on an incident surface or an exit surface, and a parallel light generating device including the same.

In recent years, light sources for realizing highly efficient illumination have attracted attention, and solid-state illumination products using light-emitting diodes (hereinafter, referred to as LEDs) or laser elements have become widespread.
Since the light emitted from the light source spreads as it propagates, it is necessary to reduce the spread angle and propagate the light to the optical system or the irradiation surface as a light beam close to parallel light. For example, a light beam emitted from a light source is converted into a parallel light by a lens provided on an emission side of the light source.

  2. Description of the Related Art A semiconductor laser is known as a parallel light generator that outputs a light beam emitted from a light source as parallel light. A semiconductor laser generally has a collimating lens installed on the emission side of a laser element. The laser element is mounted on the stem, the collimating lens is mounted on the lens barrel, and the lens barrel is joined to the stem.

The laser element and the lens are assembled under conditions where the positional accuracy and the angular accuracy are strictly controlled so that the laser light emitted from the laser element is accurately applied to the lens.
In particular, a lens having a surface shape such as a cylindrical surface that is not axially symmetric with respect to the optical axis on the entrance surface or the exit surface has, in addition to positional accuracy with respect to the light source, the rotation angle around the optical axis with respect to the light source within the reference range. It is necessary to implement it with high accuracy.

  For example, Patent Document 1 describes a lens assembly in which an alignment mark called a D-cut is provided on a lens barrel. In this lens assembly, the rotation angle of the lens around the optical axis can be adjusted to be within the reference range by using a D-cut made on the lens barrel.

JP 2009-244787 A

  However, in the lens assembly described in Patent Literature 1, when the lens is installed in the lens barrel in a state where the rotation angle around the optical axis is shifted, the lens barrel can be used even if a D-cut made on the lens barrel is used. There is a problem that the rotation angle around the optical axis of the lens installed in the camera cannot be accurately adjusted.

  SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide an optical element and a parallel light generating device that can accurately adjust a rotation angle around an optical axis.

  An optical element according to the present invention includes an incident surface on which light is incident, and an emission surface from which light incident from the incident surface is emitted. In this configuration, the entrance surface or the exit surface has a surface shape that is not axially symmetric with respect to the optical axis, and the surface that has a surface shape that is not axially symmetric with respect to the optical axis is outside the effective aperture. It has one or more recesses deeper than the surface.

  According to the present invention, since one or more concave portions deeper than the surface are provided outside the effective aperture of the surface having a surface shape that is not axially symmetric with respect to the optical axis, the light of the optical element is determined based on the concave portion. The rotation angle about the axis can be accurately adjusted.

FIG. 1A is a front view showing a parallel light generator according to Embodiment 1 of the present invention. FIG. 1B is a side view showing the parallel light generator according to Embodiment 1. FIG. 1C is a diagram showing a configuration of the parallel light generating device according to the first embodiment. FIG. 2A is a side view showing the optical element according to the first embodiment. FIG. 2B is a rear view showing the optical element according to Embodiment 1. FIG. 2C is a cross-sectional view illustrating a shape of the optical element according to the first embodiment cut along line AA in FIG. 2B. FIG. 3A is a side view showing a positional relationship between the optical element according to Embodiment 1 and a light source. FIG. 3B is a side sectional view showing the positional relationship between the optical element and the light source, taken along line AA in FIG. 2B. FIG. 4A is a diagram illustrating a positional relationship between a lens barrel in which the optical element according to Embodiment 1 is installed and a camera that captures markings. FIG. 4B is a diagram illustrating a captured image of the incident surface of the optical element captured by the camera. FIG. 4C is a diagram showing a positional relationship between the lens barrel on which the optical element according to Embodiment 1 is installed and the laser element. FIG. 5 is a rear view showing a modification of the optical element according to the first embodiment. FIG. 5 is a rear view showing a modification of the optical element according to the first embodiment. FIG. 5 is a rear view showing a modification of the optical element according to the first embodiment.

Hereinafter, in order to describe the present invention in more detail, modes for carrying out the present invention will be described with reference to the accompanying drawings.
Embodiment 1 FIG.
FIG. 1A is a front view showing a parallel light generator according to Embodiment 1 of the present invention, and shows a semiconductor laser 1 which is a parallel light generator. FIG. 1B is a side view showing the parallel light generating device, and shows the shape of the semiconductor laser 1 as viewed from the side. The emission side of the laser beam in the semiconductor laser 1 is defined as the front side, and the direction orthogonal to the optical axis is defined as the side surface. FIG. 1C is a diagram showing a configuration of the parallel light generating device, and shows an internal configuration of the semiconductor laser 1 excluding the lens barrel 3.

  As shown in FIG. 1A, the semiconductor laser 1 includes a lens 2 that is an optical element according to Embodiment 1, and the lens 2 is provided in a lens barrel 3. As shown in FIGS. 1A and 1B, the lens barrel 3 is a cylindrical member having an entrance side and an exit side opened, and the lens 2 is held and fixed therein. The lens barrel 3 provided with the lens 2 is joined to the stem 4.

  As shown in FIG. 1C, the stem 4 is provided with a lead pin 4a, and a block 4b is provided on a surface opposite to the lead pin 4a. A submount 4c is joined to the block 4b. The submount 4c is a member serving as a pedestal of the laser element 5, and the laser element 5 is held and fixed to the stem 4 by the submount 4c.

  The laser element 5 is a light source of the parallel light generating device according to the first embodiment. For example, a semiconductor laser element having different spread angles of light emitted in the x direction (horizontal direction) and the y direction (vertical direction) is used. Is done. Note that the x direction is a direction orthogonal to the optical axis and along the horizontal direction of the laser element 5. The y direction is a direction perpendicular to the optical axis and along the vertical direction of the laser element 5. The z direction is a direction along the optical axis.

  The minimum spread half angle of the light beam emitted from the semiconductor laser element in the horizontal direction is a typical value of 2 ° to 15 ° (half angle 1 / e2), and the maximum spread half angle of the light beam in the vertical direction is a typical value. Typical value is 15 ° to 45 ° (half angle 1 / e2). The laser element 5 has a finite light emitting point width in the horizontal direction and the vertical direction. The light emitting point width in the horizontal direction of the semiconductor laser device is usually in the range of several micrometers to several hundred micrometers, and the light emitting point width in the vertical direction is usually in the range of one micrometer to several micrometers.

  The laser element 5 has a single light emitting point, but the light source in the first embodiment is not limited to this. For example, the light source in the first embodiment may be a laser element having an array structure in which a plurality of light emitting points are arranged in a horizontal direction. Further, the light source in the first embodiment may be a light source other than a laser element that emits a laser beam.

  FIG. 2A is a side view illustrating the optical element according to the first embodiment, and illustrates a lens 2 that is the optical element according to the first embodiment. FIG. 2B is a rear view showing the optical element according to Embodiment 1, with the incident surface side of the lens 2 as the rear surface. FIG. 2C is a cross-sectional view showing the shape of the lens 2 cut along the line AA in FIG. 2B.

  The lens 2 has an entrance surface 2a and an exit surface 2b, has a center thickness d, and is made of, for example, glass having a refractive index n. The material of the lens 2 may be a plastic or a crystalline material.

  An anti-reflection film (not shown) for the wavelength of light incident from the laser element 5 as a light source is provided on the entrance surface 2a and the exit surface 2b of the lens 2. In the example shown in FIG. 2A, the entrance surface 2a of the lens 2 has a cylindrical concave shape with respect to the light in the horizontal direction, and the exit surface 2b has a convex shape that is axially symmetric with respect to the optical axis. ing. The lens 2 is made by polishing and molding glass having a refractive index of n.

  The effective aperture 6 is an area on the incident surface 2a of the lens 2 through which the laser light emitted from the laser element 5 passes. In FIG. 2B, the effective aperture 6 is a rectangular area formed in a concave portion along the y direction on the incident surface 2a. Further, markings 7 which are concave portions deeper than the incident surface 2a are formed at both ends outside the effective opening 6, respectively. The marking 7 serves as a reference for adjusting the rotation angle around the optical axis when the lens barrel 3 provided with the lens 2 is joined to the stem 4 holding and fixing the laser element 5.

  It is desirable that the transmittance, which is the ratio between the input power of the laser light incident on the lens 2 and the output power of the laser light emitted from the lens 2, does not attenuate even if the marking 7 is provided on the incident surface 2a. When a part of the laser beam is applied to the marking 7, the transmittance is attenuated. Therefore, the marking 7 is installed outside the effective opening 6. If the attenuation of the transmittance of the laser beam is within the allowable range, the marking 7 may be formed to extend over the inside and outside of the effective opening 6. That is, it is sufficient that a part of the marking 7 is formed outside the effective opening 6.

  FIG. 3A is a side view showing a positional relationship between the optical element and the light source according to the first embodiment, and shows a horizontal positional relationship between the lens 2 and the laser element 5 in the semiconductor laser 1. FIG. 3B is a side sectional view showing a vertical positional relationship between the lens 2 and the laser element 5 taken along the line AA in FIG. 2B. The laser light incident on the incident surface 2a of the lens 2 from the laser element 5 is collimated by the lens 2 in each of the horizontal direction and the vertical direction based on the design of the lens 2, and is emitted from the emission surface 2b.

  In the design of the lens 2, the refractive index n of the lens material (for example, glass), the center thickness d, the vertical and horizontal radii of curvature of the entrance surface 2a, and the exit surface 2b The parameters such as the vertical and horizontal radii of curvature are selected appropriately. When the entrance surface 2a or the exit surface 2b of the lens 2 has an aspherical shape, a conic coefficient for defining the shape in more detail and a higher-order aspherical coefficient are selected. The positional relationship of the lens 2 with respect to the laser element 5 is defined based on such a design, and in the semiconductor laser 1, the lens 2 and the laser element 5 are installed so as to have this positional relationship.

  For example, the effective aperture 6 on the entrance surface 2a of the lens 2 is a rectangular area having a longitudinal direction as shown in FIG. 2B. The laser element 5 has different light emitting point widths in the x direction (horizontal direction) and the y direction (vertical direction), and the light emitted from the laser element 5 has a larger spread angle in the y direction than in the x direction. The lens 2 is aligned with the optical axis a with the laser element 5, and the shorter direction of the effective opening 6 is in the x direction and the longer direction of the effective opening 6 is in the y direction with respect to the laser element 5. Is installed as follows. Thereby, as shown in FIGS. 3A and 3B, the laser light incident on the lens 2 from the laser element 5 is collimated by the lens 2 to a beam width h in the horizontal direction and collimated to a beam width p in the vertical direction. Out of the light exit surface 2b.

The lens 2 may be manufactured by molding. In this case, the mold is provided with a shape for forming the marking 7. By using a mold having a shape for forming the marking 7, it is not necessary to separately perform marking after manufacturing the lens, an increase in the number of steps in lens manufacturing is suppressed, and the cost of lens manufacturing is reduced. be able to.
Furthermore, by using a mold having a shape for forming the marking 7, there was no individual difference compared to separately performing marking after manufacturing the lens, and the surface shape was not axially symmetric with respect to the optical axis a. It is possible to accurately mark the surface.
However, the production of the lens 2 is not limited to the die molding, and the marking 7 may be provided on the lens 2 in an additional step after the production of the lens 2.

Next, a procedure for assembling the semiconductor laser 1 will be described.
FIG. 4A is a diagram showing a positional relationship between a lens barrel 3 on which a lens 2 which is an optical element according to Embodiment 1 is installed and a camera 8 for photographing a marking 7, and the semiconductor laser 1 shown in FIG. 2 shows the positions of the lens barrel 3 and the camera 8 when assembling. FIG. 4B is a diagram illustrating a captured image of the incident surface 2 a of the lens 2 captured by the camera 8. FIG. 4C is a diagram showing the positional relationship between the lens barrel 3 on which the lens 2 is installed and the laser element 5, and shows the positional relationship between the lens barrel 3 and the laser element 5 when assembling the semiconductor laser 1 shown in FIG. Indicates the position.

  First, as shown in FIG. 4A, the camera 8 photographs the incident side of the lens barrel 3. At this time, as shown in FIG. 4B, the incident surface 2a of the lens 2 is photographed by the camera 8. The assembling operator or the mounting apparatus recognizes the two markings 7 on the incident surface 2a from the image captured by the camera 8, and sets a straight line b connecting the two markings 7.

  Subsequently, while maintaining the photographing state of the camera 8, the lens barrel 3 is attached to the stem 4 on which the laser element 5 is held and fixed, as shown in FIG. 4C. At this time, if the straight line b is inclined with respect to a reference line c (a straight line that is a reference in the y direction) shown in FIG. The lens barrel 3 is rotated around the optical axis by using a rotation mechanism (not shown) so that the two coincide.

The assembling operator or the mounting apparatus moves the lens barrel 3 closer to the stem 4 using the moving mechanism (not shown) in a state where the straight line b and the reference line c match, and assembles both.
As described above, the lens barrel 3 on which the lens 2 is installed can be assembled on the laser element 5 side with the rotation angle θz around the optical axis accurately adjusted with respect to the marking 7 provided on the lens 2. It is possible. The lens barrel 3 and the stem 4 are joined after the position of the laser element 5 and the rotation angle around the optical axis are adjusted based on the reference point on the stem 4 side photographed by the camera 8.

The above-described method of assembling the semiconductor laser 1 is an example, and the method of assembling the parallel light generating device according to the first embodiment is not limited to this method.
For example, even if the assembling operator or the mounting apparatus specifies the position of the marking 7 using an image captured from the emission direction of the lens 2, the rotation angle θz about the optical axis is accurately adjusted as described above. be able to.

Next, a modified example of the optical element according to the first embodiment will be described.
FIG. 5 is a rear view showing a modified example of the optical element according to Embodiment 1, and shows a lens 2A provided with a marking 7A. As shown in FIG. 5, the marking 7A is a concave portion that is deeper than the incident surface 2a, and is provided at both ends in the lateral direction outside the effective opening 6 on the incident surface 2a. In the lens 2A, a marking 7A is formed on a curved portion of the cylindrical incident surface 2a which falls toward the effective opening 6 side. Even with such a configuration, the lens barrel 3 provided with the lens 2A can be assembled to the laser element 5 side in a state where the rotation angle θz around the optical axis is accurately adjusted with respect to the marking 7A.

  FIG. 6 is a rear view showing a modification of the optical element according to Embodiment 1, and shows a lens 2B provided with a marking 7B. As shown by the broken line in FIG. 6, the marking 7B is a linear concave portion deeper than the incident surface 2a, and is installed in the lateral direction outside the effective opening 6 on the incident surface 2a. For example, the marking 7B is formed along the horizontal direction on the cylindrical incident surface 2a. Even with such a configuration, the lens barrel 3 on which the lens 2B is installed can be mounted on the laser element 5 side with the rotation angle θz around the optical axis accurately aligned with the marking 7B as a reference.

  FIG. 7 is a rear view showing a modified example of the optical element according to Embodiment 1, and shows a lens 2C provided with a marking 7C. As shown by the broken line in FIG. 7, the marking 7C is a linear recess deeper than the incident surface 2a, and is installed in the longitudinal direction outside the effective opening 6 on the incident surface 2a. For example, the marking 7C is formed along the vertical direction on the cylindrical incident surface 2a. Even with such a configuration, the lens barrel 3 provided with the lens 2C can be assembled on the laser element 5 side in a state where the rotation angle θz around the optical axis is accurately adjusted with respect to the marking 7C.

The optical element according to the first embodiment is not limited to the configuration described above. For example, the number of markings may be three or more as long as it can be a reference when adjusting the rotation angle around the optical axis. In a lens provided with three or more markings, the rotation angle around the optical axis is recognized by a polygon having the marking photographed from the incident side as a vertex.
The shape of each marking may be any shape as long as it can be recognized from the captured image, and may be a line shape, a round shape, a polygonal shape of a triangle or more, or an x-shape.

Furthermore, in the optical element according to Embodiment 1, the emission surface 2b may be a surface having a surface shape that is not axially symmetric with respect to the optical axis. For example, when the emission surface 2b has a cylindrical shape, the marking is provided on the emission surface 2b. In this case, the rotation angle around the optical axis of the lens is recognized by the marking photographed from the emission side.
Even with such a configuration, it is possible to assemble the lens barrel 3 on which the lens is installed on the laser element 5 side in a state where the rotation angle θz about the optical axis is accurately adjusted.

  The surface shape that is not axially symmetric with respect to the optical axis may be a toroidal shape, or may be a free-form surface lens formed of an aspheric surface having no symmetry axis. That is, the concave portion (marking) in Embodiment 1 can be applied to any surface having a surface shape that is not axially symmetric with respect to the optical axis, regardless of the type of lens shape.

  The lenses 2 and 2A to 2C have a concave shape on the incident side and a convex shape on the emission side, but the optical element according to the first embodiment is not limited to this shape. For example, the entrance side may have a convex shape, and the exit side may have a concave shape. Even with an optical element having such a structure, the above-described effects can be obtained.

  As described above, the lenses 2 and 2A to 2C according to Embodiment 1 are located outside the effective aperture 6 of the entrance surface 2a or the exit surface 2b having a surface shape that is not axially symmetric with respect to the optical axis a. And one or more deep recesses 7, 7A, 7C. With this structure, the rotation angles θz of the lenses 2, 2A to 2C around the optical axis a can be accurately adjusted with reference to the markings 7, 7A, to 7C. In molding the lenses 2, 2A to 2C, a mold having a shape for forming the markings 7, 7A, to 7C may be used. Accordingly, it is not necessary to separately perform marking after manufacturing the lens, and an increase in the number of processes can be suppressed, and the cost of manufacturing the lens can be reduced.

  Note that the present invention is not limited to the above-described embodiment, and within the scope of the present invention, any constituent element of the embodiment can be modified or any constituent element of the embodiment can be omitted.

  INDUSTRIAL APPLICABILITY The optical element according to the present invention can accurately adjust the rotation angle around the optical axis, and can be used for various optical devices such as a lens for illumination, a lens for optical communication, and a lens for an optical pickup.

  Reference Signs List 1 semiconductor laser, 2, 2A to 2C lens, 2a entrance surface, 2b exit surface, 3 lens barrel, 4 stem, 4a lead pin, 4b block, 4c submount, 5 laser element, 6 effective aperture, 7, 7A to 7C marking , 8 cameras.

An optical element according to the present invention, an incident surface to which light is incident, a lens where light is incident Ru and a emitting surface is emitted from the incident surface, an incident surface or exit surface with respect to the optical axis Has a surface shape that is not axially symmetric, and a surface that has a surface shape that is not axially symmetric with respect to the optical axis is outside the effective aperture as a marking for recognizing the rotation angle of the surface around the optical axis. has have a deep one or more recesses than the surface, the recesses provided in the lens itself.

An optical element according to the present invention is a lens including an incident surface on which light is incident, and an exit surface from which light incident from the incident surface is emitted, wherein the incident surface or the exit surface has a cylindrical shape . The surface having the cylindrical shape has one or more concave portions deeper than the surface as markings for recognizing a rotation angle around the optical axis of the surface outside the effective aperture. The concave portion is provided in a cylindrical portion on the surface.

Claims (8)

An incident surface on which light is incident,
An emission surface from which light incident from the incident surface is emitted,
The entrance surface or the exit surface has a surface shape that is not axially symmetric with respect to an optical axis,
An optical element characterized in that a surface having a surface shape that is not axially symmetric with respect to the optical axis has one or more concave portions deeper than the surface outside the effective aperture. The optical element according to claim 1, wherein the concave portions are provided at both ends outside the effective opening. The optical element according to claim 1, wherein the concave portion is a linear concave portion provided outside the effective opening. The optical element according to any one of claims 1 to 3, wherein the surface shape that is not axially symmetric with respect to the optical axis is a cylindrical shape. The optical element according to any one of claims 1 to 3, wherein the surface shape which is not axially symmetric with respect to the optical axis is a toroidal shape. The surface having a surface shape which is not axially symmetric with respect to the optical axis is a free-form surface lens formed of an aspherical surface having no symmetry axis. Item 6. The optical element according to item 1. The incident surface has a cylindrical shape,
The optical element according to any one of claims 1 to 3, wherein the exit surface is a lens having a convex shape that is axially symmetric with respect to an optical axis. An optical element according to any one of claims 1 to 3,
And a light source for incident light on the incident surface.

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