Laser device and method for manufacturing a laser device

Abstract

To realize a laser device which can be easily adjusted.SOLUTION: A laser device comprises: a substrate (2); a laser package having a laser diode (3) that discharges an outgoing beam and a cap (4) having a surface that transfers the outgoing beam; a flat convex lens (5) that collimates the outgoing beam; and a support plate (6) that is arranged between the laser package and the flat convex lens. In the flat convex lens, an outer peripheral part of a lens surface on a flat surface of the flat convex lens is fixed in a state so as to be contacted to a first flat surface (61) as a surface on the flat convex lens of a board.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to a laser device. [Background technology]

[0002] Laser devices equipped with laser diodes are widely used. In recent years, the development of wearable devices has progressed, and glasses for VR (Virtual Reality), AR (Augmented Reality), and MR (Mixed Reality) have been developed. Glasses for these applications often use laser scanning (hereinafter abbreviated as LBS method) optical systems.

[0003] In the LBS method, a beam emitted from a laser device is scanned using a MEMS (Micro Electro Mechanical Systems) mirror, such as a piezoelectric type, to form an image. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] U.S. Patent No. 10656426 [Overview of the project] [Problems that the invention aims to solve]

[0005] For VR glasses and similar devices to become widespread among consumers, it is necessary to miniaturize and lighten the optical system and make it inexpensive through mass production. Furthermore, to stabilize the characteristics of the laser diode and extend its lifespan, it is necessary to use a package that encapsulates the laser diode in the laser device. However, it is not easy to realize a laser device that incorporates such a package, reduces the burden on consumers when wearing VR glasses and similar devices, while also allowing for adjustment of the optical system during assembly.

[0006] One aspect of the present invention aims to realize a laser device that can be easily adjusted. [Means for solving the problem]

[0007] To solve the above problems, a laser device according to one aspect of the present invention comprises a laser package having a substrate, a laser diode mounted on the substrate and emitting light in a direction parallel to the main surface of the substrate, and a cap for sealing the laser diode, the cap having a side surface that transmits the emitted light; a plano-convex lens for collimating the emitted light; and a support plate disposed between the laser package and the plano-convex lens, the support plate having an opening through which the emitted light passes, wherein the plano-convex lens is fixed such that the outer periphery of the lens surface on the planar side of the plano-convex lens is in contact with a first plane which is the surface of the support plate on the plano-convex lens side. [Effects of the Invention]

[0008] According to one aspect of the present invention, a laser device that can be easily adjusted can be realized. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram showing the configuration of the main parts of the laser device 1 according to Embodiment 1. [Figure 2] This is a perspective view showing the configuration of the laser package according to Embodiment 1. [Figure 3] This is a schematic diagram illustrating the optical geometric relationships of a typical convex lens 5d. [Figure 4] This graph shows the correlation between working distance and radius of curvature. [Figure 5] This graph shows the correlation between the working distance WD and the beam radius y2. [Figure 6] This is a schematic diagram showing the configuration of the main parts of the laser device 1a according to Embodiment 2. [Figure 7] This is a schematic diagram showing the configuration of the main parts of the laser device 1b according to Embodiment 3. [Figure 8]It is a perspective view showing the configuration of the laser package according to Embodiment 3. [Figure 9] It is a schematic diagram showing the configuration of the main part of the laser device 1c according to Embodiment 4. [Figure 10] It is a perspective view showing the configuration of the laser package according to Embodiment 4.

Mode for Carrying Out the Invention

[0010] 〔Embodiment 1〕 Hereinafter, an embodiment of the present invention will be described in detail. FIG. 1 is a schematic diagram showing the configuration of the main part of the laser device 1 according to Embodiment 1.

[0011] (Configuration of Laser Device 1) As shown in FIG. 1, the laser device 1 includes a substrate 2, a laser diode 3, a cap 4, a plano-convex lens 5, and a support plate 6. The substrate 2, the laser diode 3, and the cap 4 also constitute a laser package. FIG. 2 is a perspective view showing the configuration of the laser package according to Embodiment 1.

[0012] The substrate 2 is a member that serves as the base of the laser package. The substrate 2 is preferably made of a metal plate. A pattern is formed on the substrate 2 so that the position of the laser diode 3 can be arranged at a position determined based on the design conditions described later.

[0013] The laser diode 3 is a light source that emits laser light. The main direction of the emitted light emitted by the laser diode 3 is parallel to the main surface of the substrate 2. The wavelength of the light emitted by the laser diode 3 is not limited, but it is preferably the light emission color that constitutes an image. The position of the laser diode 3 in the Z direction (the traveling direction of the laser light emitted by the laser diode 3) is defined by the pattern formed on the substrate 2. The emission surface of the laser emission light of the laser diode 3 is referred to as the emission surface 31.

[0014] Cap 4 is a glass cap that seals the space on which the laser diode 3 is mounted. Cap 4 has a side surface (transmitting portion 41) that transmits the emitted light. The material of cap 4 is not limited to glass; any material with high transmittance at the desired wavelength is acceptable. Cap 4 does not need to be entirely made of glass; only the transmitting portion 41 that transmits the laser light emitted by the laser diode 3 needs to be made of glass (a material with high transmittance). Furthermore, the transmitting portion 41 has a plane perpendicular to the laser light emitted by the laser diode 3. Note that the transmitting portion 41 is the side surface of cap 4, but it may also be a part of the side surface.

[0015] The plano-convex lens 5 is a convex lens in which one of its two surfaces is flat and the other is convex. The plano-convex lens 5 collimates the incident laser light. The flat lens surface of the plano-convex lens 5 is called the lens surface 51. The lens surface 51 faces the penetrating portion 41 of the cap 4.

[0016] The support plate 6 is a support member for the plano-convex lens 5, positioned between the laser package and the plano-convex lens 5. Its main surface is positioned parallel to the XY plane (the plane perpendicular to the laser light emitted by the laser diode 3). The support plate 6 has an opening in the area through which the laser light passes. This opening is slightly smaller than the diameter of the plano-convex lens 5, and the support plate 6 supports the plano-convex lens 5 in the area where it overlaps with the support plate 6. The plano-convex lens 5 may be fixed to the support plate 6 using adhesive.

[0017] The surface (XY plane) on the support plate 6 that faces the lens surface 51 of the plano-convex lens 5 is called the first plane 61. The first plane 61 is a plane perpendicular to the laser light emitted by the laser diode 3. The plano-convex lens 5 can slide while its lens surface 51 is in contact with the first plane 61.

[0018] (Application conditions for the LBS method for glass applications) In LBS (Laser Beam Scanning) systems for glass applications, the beam conditions are limited by the size of the mirror that scans the beam. The mirror (not shown) is formed using MEMS (Micro-Electro-Mechanical Systems) technology, and its fabrication size is limited. Therefore, it is necessary to fabricate a laser device 1 that is specifically designed for that mirror.

[0019] Here, in order to reduce the burden on the user when wearing the glasses, it is preferable that the size of the glasses be small, and in order to reduce the size of the glasses, the optical system including the laser device 1 needs to be ultra-compact. In order to realize an ultra-compact optical system, it is preferable to make the beam size (spot size) about 1.5 mm due to the design conditions limited by the mirror. This is because the size of the mirror is limited by the resonant frequency, etc.

[0020] (A typical 5D convex lens) Here, we will explain the optical geometric relationships of a typical convex lens. Figure 3 is a schematic diagram showing the optical geometric relationships of a typical convex lens 5d.

[0021] The laser light emitted from the laser diode 3 spreads out radially as it propagates. This radial spread has a radiation angle θ. ⊥ This is the maximum angle of incidence α of the light rays incident on the convex lens 5d. i1 It is good to consider it as approximately equal to α i1 =θ ⊥ There is a relationship between the laser light emitted from laser diode 3 and the refractive index n. i1 It moves through air where = 1.

[0022] The distance from the emission surface 31 of the laser diode 3 to the convex lens 5d is called the working distance WD. Furthermore, the beam size becomes size y1 when the laser light enters the convex lens 5d. Therefore, the following relationship holds for y1.

[0023]

number

[0024] In FIG. 3, h1 and h2 represent the distance between the incident side - front principal plane of the lens and the distance between the exit side - rear principal plane of the lens, respectively.

[0025] (Application in plano-convex lens 5) From Equation 2, in order to reduce the beam size, it is necessary to reduce the working distance WD, reduce the emission angle θ ⊥ , increase the radius of curvature R1, increase the refractive index n t1 , or reduce the thickness d.

[0026] Here, the emission angle θ ⊥ is a value inherent to the laser diode 3, and is approximately 25° (half angle at peak intensity × 1 / e 2 defines the emission angle θ ⊥ ). Also, the refractive index n t1 of the lens is a fixed value when using inexpensive general optical glass (n d = 1.5).

[0027] If the thickness d is made too thin, the effective diameter of the lens becomes small, and as a result, it becomes inevitable to reduce the beam size. Therefore, d = 0.8 mm was set.

[0028] Therefore, among the conditions for reducing the beam size as described above, the only variables are the working distance WD and the radius of curvature R1, and these two are correlated. Figure 4 shows this correlation. Since it is a plano-convex lens 5, the radius of curvature R1 on the planar side is at infinity. Therefore, as described above, if the beam size is reduced to about 1.5 mm, the beam radius becomes about 0.75 mm, and as a result, Figure 4 shows that an upper limit of about 1.2 mm is appropriate for the working distance WD.

[0029] Next, the lower limit of the working distance WD is derived from the design conditions. Since the mounting error of the laser diode 3 to the substrate 2 is 0.2 mm, the minimum thickness of the transparent portion 41 of the cap 4 is 0.3 mm, and 0.3 mm is required as adjustment for the plano-convex lens 5, the lower limit of the working distance WD is 0.8 mm. Figure 5 is a graph showing the correlation between the working distance WD and the beam radius y2. Thus, it is understood that in optical systems for realizing VR glasses with superior comfort, the working distance WD is limited to an extremely narrow range of 0.8 to 1.2 mm.

[0030] The overall configuration of the laser device 1, which transmits laser light from the side (transmissive portion 41) of the cap 4, and the use of an extremely thin cap 4 with a thickness of 0.3 mm for the transparent portion 41, make it possible to keep the working distance WD within the extremely small value mentioned above.

[0031] In this case, since the beam needs to be collimated, the working distance WD and the focal length f are related by the following equation.

number

[0032] Therefore, there is a predetermined relationship between the focal length f and the radius of curvature R2. The focal length f is set within the range that satisfies this relationship. Then, the radius of curvature R2 is calculated using the set focal length f.

[0033] The plano-convex lens 5 is designed through the above process. The beam size y2 at this time can be expressed by the following equation.

[0034]

number

[0035] (Conditions for the plano-convex lens 5) The thickness of the plano-convex lens 5 along its optical axis is preferably between 0.4 mm and 1 mm. This value is determined by the relationship between the durability of the plano-convex lens 5 and the installation space required.

[0036] The effective diameter of the plano-convex lens 5 is preferably 1.2 mm or more and 1.6 mm or less. This value is derived as a result of adjusting various parameters so that the size of the laser device 1 and the lower limit of the beam size do not fall below 1 mm.

[0037] Here, the diameter of the plano-convex lens 5 may be larger than the effective diameter of the plano-convex lens 5. In other words, the actual diameter of the plano-convex lens 5 may be greater than or equal to the upper limit of the effective diameter as a lens, which is 1.6 mm, and there may be a frame portion outside the effective diameter.

[0038] (Adjustment and assembly of laser device 1) The laser device 1 is assembled while being adjusted according to the following procedure: The laser diode 3 is die-bonded to the predetermined position on the substrate 2 and fixed in place. Then, the cap 4 is placed over the laser diode 3, and the cap 4 is bonded to the substrate 2 to seal the laser diode 3. The support plate 6 and the substrate 2 are then fixed to the housing (not shown).

[0039] The plano-convex lens 5 is slid along the first plane 61 on the support plate 6 in the XY direction (a direction perpendicular to the laser beam emitted by the laser diode 3) to adjust it so that the optical axis of the plano-convex lens 5 and the optical axis of the laser diode 3 coincide. After that, the plano-convex lens 5 is bonded to the support plate 6.

[0040] (summary) The basic collimation of the emitted laser beam is performed by the position of the laser diode 3 in the Z direction, and fine adjustment of the collimation can be adjusted by the clearance between the support plate 6 and the plano-convex lens 5. Furthermore, by sliding the plano-convex lens 5 in the XY direction on the first plane 61 of the support plate 6, the optical axis of the plano-convex lens 5 can be aligned with the optical axis of the already fixed laser diode 3. In this way, the laser device 1 can easily achieve both collimation adjustment and optical axis adjustment.

[0041] [Embodiment 2] Other embodiments of the present invention are described below. For the sake of clarity, components having the same function as those described in the above embodiments will be denoted by the same reference numerals, and their descriptions will not be repeated.

[0042] Figure 6 is a schematic diagram showing the configuration of the main parts of the laser device 1a according to Embodiment 2. Unlike the laser device 1, the laser device 1a has a configuration in which the support plate 6 is in contact with and slides against the transparent portion 41 of the cap.

[0043] In this embodiment, the plano-convex lens 5 may be fixed to the support plate 6. In this case, the optical axis of the plano-convex lens 5 is adjusted by adjusting the position of the support plate 6 in the XY direction relative to the cap 4.

[0044] In this configuration, the plano-convex lens 5 is already fixed to the support plate 6, so the support plate is glued to the cap 4. This makes it easy to increase the bonding area. Another advantage is that the lower limit of the working distance WD can be further reduced.

[0045] Alternatively, instead of bonding the support plate 6 to the plano-convex lens 5, the cap 4 may be bonded to the support plate 6. In this case, the plano-convex lens 5 slides in contact with the support plate 6, and the optical axis of the plano-convex lens 5 is adjusted by adjusting its position in the XY direction. This configuration also has the advantage of further reducing the lower limit of the working distance WD.

[0046] [Embodiment 3] Other embodiments of the present invention are described below. For the sake of clarity, components having the same function as those described in the above embodiments will be denoted by the same reference numerals, and their descriptions will not be repeated.

[0047] Figure 7 is a schematic diagram showing the main components of the laser device 1b according to Embodiment 3. Unlike the laser device 1, the laser device 1b is equipped with three laser diodes 3a to c and three plano-convex lenses 5a to c. Figure 8 is a perspective view showing the configuration of the laser package according to Embodiment 3.

[0048] Laser diode 3a emits a red wavelength beam, which is collimated by the plano-convex lens 5a. Laser diode 3b emits a green wavelength beam, which is collimated by the plano-convex lens 5b. Laser diode 3c emits a blue wavelength beam, which is collimated by the plano-convex lens 5c.

[0049] The laser device 1b is further equipped with a prism 7, which combines collimated red, green, and blue wavelength beams. As a result, the laser device 1b emits a full-color beam.

[0050] Since the laser diodes 3a to c have different wavelengths, their working distances are different (WD_R ≠ WD_G, WD_G ≠ WD_B, WD_B ≠ WD_R). Therefore, these differences for each wavelength are compensated for by adjusting the mounting positions of the laser diodes 3a to c in the Z direction relative to the substrate 2.

[0051] Furthermore, since the size of each collimated color beam needs to be the same, fine adjustments in the Z direction are required when mounting (adhering) the plano-convex lenses 5a to c.

[0052] In this case, the support plate 6 that fixes the plano-convex lenses 5a to c may be common to all colors, or different support plates 6a to c may be used for each color (Figure 7 shows the case where the support plate 6 is common).

[0053] [Embodiment 4] Embodiments 1 to 3 describe a case where the beam is emitted from the laser diode 3, travels in a straight line, and exits from the side of the cap 4, but are not limited to this. Embodiment 4 describes a case where the beam is emitted from the top surface of the cap 4.

[0054] Figure 9 is a schematic diagram showing the configuration of the main parts of the laser device 1c according to Embodiment 4. Unlike the laser device 1, the surface through which the beam is transmitted in the laser device 1c is the top surface, the transmission part 41a, rather than the side surface, the transmission part 41. Figure 10 is a perspective view showing the configuration of the laser package according to Embodiment 4. Note that the transmission part 41a is the top surface of the cap 4, but it may be a part of the top surface.

[0055] The laser device 1c is equipped with a mirror 8, which bends the beam emitted from the laser diode 3 by 90°, causing the beam to be emitted from the transparent portion 41a on the upper surface of the cap 4. At this time, the working distance WD is the sum of the distance WDa from the emission surface 31 to the mirror 8 and the distance WDb from the mirror 8 to the plano-convex lens 5. The plano-convex lens 5 and the support plate 6 are arranged parallel to the upper surface of the cap 4.

[0056] The laser device 1c according to Embodiment 4 has the advantage of being able to reduce the thickness in the direction of beam emission. The laser device 1c can be installed in environments where the laser devices 1, 1a, and 1b according to Embodiments 1 to 3 are unsuitable.

[0057] 〔summary〕 Laser devices 1, 1a, 1b, and 1c according to embodiment 1 of the present invention include a laser package having a substrate 2, a laser diode 3 mounted on the substrate 2 and emitting light in a direction parallel to the main surface of the substrate 2, and a cap 4 that seals the laser diode 3 and has a surface that transmits the emitted light, a plano-convex lens 5 that collimates the emitted light, and a support plate 6 disposed between the laser package and the plano-convex lens 5 and having an opening through which the emitted light passes, wherein the plano-convex lens 5 is fixed in such a state that the outer periphery of the lens surface on the planar side of the plano-convex lens 5 is in contact with a first plane 61 which is the surface of the support plate 6 on the plano-convex lens 5 side.

[0058] With the above configuration, the collimation of the emitted light can be adjusted by changing the position of the laser diode 3, and the optical axis of the emitted light can be adjusted by changing the position of the plano-convex lens 5. Therefore, laser devices 1, 1a, 1b, and 1c that can be easily adjusted can be realized.

[0059] In the laser devices 1, 1a, 1b, and 1c according to embodiment 2 of the present invention, in embodiment 1, the optical distance between the light emission surface of the laser diode 3 and the planar lens surface of the plano-convex lens 5 may be 0.8 mm or more and 1.2 mm or less.

[0060] With the above configuration, the emitted light can be collimated and then sized to the desired dimensions.

[0061] In the laser devices 1, 1a, 1b, and 1c according to embodiment 3 of the present invention, in embodiment 1 or 2, the thickness of the plano-convex lens 5 on the optical axis may be 0.4 mm or more and 1.0 mm or less.

[0062] According to the above configuration, a durable plano-convex lens 5 can be obtained.

[0063] In the laser devices 1, 1a, 1b, and 1c according to embodiment 4 of the present invention, the effective diameter of the plano-convex lens 5 may be 1.2 mm or more and 1.6 mm or less in any of embodiments 1 to 3 above.

[0064] With the above configuration, an appropriate beam size can be achieved for the mirror.

[0065] In the laser device 1c according to embodiment 5 of the present invention, the emitted light may be bent by a mirror in any of embodiments 1 to 4 above.

[0066] With the above configuration, the emitted light can be bent by a mirror, and the beam can be emitted from the top surface of the cap.

[0067] In the laser apparatus 1b and 1c according to embodiment 6 of the present invention, in any of embodiments 1 to 5 above, the laser package may have a plurality of laser diodes 3a to c, and may also include a plurality of plano-convex lenses 5a to c that collimate the light emitted from each of the laser diodes 3a to c.

[0068] According to the above configuration, laser devices 1b and 1c capable of producing full-color emitted light can be realized.

[0069] A method for manufacturing laser devices 1, 1a, 1b, and 1c according to aspect 7 of the present invention includes the steps of adjusting the position of the plano-convex lens in the first plane perpendicular to the optical axis of the laser diode by sliding the outer periphery of the planar lens surface of the planar lens against the first plane of the support plate, and then bonding the plano-convex lens to the support plate.

[0070] Based on the above characteristics, it is possible to manufacture a laser device that allows for easy collimation adjustment and optical axis adjustment.

[0071] [Additional Notes] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment. [Explanation of Symbols]

[0072] 1, 1a, 1b, 1c Laser device 2 circuit boards 3, 3a, 3b, 3c Laser diodes 4 caps 5, 5a, 5b, 5c plano-convex lens 5D convex lens 6 Support plate 7 Prisms 8 Mirrors 31 Emission surface 41, 41a Transparent part 51 Lens surface 61 1st plane

Claims

1. A laser package comprising a substrate, a laser diode mounted on the substrate and emitting light in a direction parallel to the main surface of the substrate, and a cap for sealing the laser diode, the cap having a surface that transmits the emitted light, A plano-convex lens that collimates the emitted light, A support plate disposed between the laser package and the plano-convex lens, the support plate having an aperture through which the emitted light passes, The plano-convex lens is fixed such that the outer periphery of the planar side of the lens surface of the plano-convex lens is in contact with the first plane, which is the surface of the support plate on the plano-convex lens side. The optical axis of the plano-convex lens is parallel to the main surface of the substrate, The first plane of the support plate is perpendicular to the main surface of the substrate, The support plate has a uniform thickness and is bonded to the surface of the cap through which the emitted light passes. The plano-convex lens is directly fixed to the first plane of the support plate in the laser device.

2. The laser apparatus according to claim 1, wherein the optical distance between the light-emitting surface of the laser diode and the planar lens surface of the plano-convex lens is 0.8 mm or more and 1.2 mm or less.

3. The laser apparatus according to claim 2, wherein the thickness of the plano-convex lens on the optical axis is 0.4 mm or more and 1.0 mm or less.

4. The laser apparatus according to claim 3, wherein the effective diameter of the plano-convex lens is 1.2 mm or more and 1.6 mm or less.

5. The laser package has a plurality of laser diodes, The laser apparatus according to any one of claims 1 to 4, further comprising a plurality of plano-convex lenses for collimating the light emitted from each of the laser diodes.

6. A method for manufacturing a laser apparatus according to Claims 1 to 4, A step of adjusting the position of the plano-convex lens in the first plane perpendicular to the optical axis of the laser diode by sliding the support plate and the surface of the cap through which the emitted light is transmitted, A method for manufacturing a laser apparatus, comprising the step of subsequently bonding the support plate to the surface of the cap through which the emitted light is transmitted.

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