JP2023178741A - Laser device and manufacturing method of the laser device - Google Patents

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

The present invention relates to a laser device.

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 uses often use a laser scanning type (hereinafter abbreviated as LBS type) optical system.

In the LBS method, a beam emitted from a laser device is scanned using a piezo-driven MEMS (Micro Electro Mechanical Systems) mirror to form an image.

US Patent No. 1,065,426

In order for VR glasses etc. to become popular among consumers, it is necessary to make the optical system ultra-small and lightweight, and to make it cheaper through mass production. Further, in order to stabilize the characteristics of the laser diode and extend its lifespan, it is necessary to use a package for sealing the laser diode in the laser device. However, it is necessary to create a laser device that has an ultra-compact optical system that can reduce the burden on consumers when wearing VR glasses, etc., has such a package, and has a configuration that allows adjustment of the optical system during assembly. It is not easy to achieve this.

One aspect of the present invention aims to realize a laser device that can be easily adjusted.

In order to solve the above problems, a laser device according to one aspect of the present invention includes a substrate, a laser diode placed on the substrate and emitting light in a direction parallel to the main surface of the substrate, and a laser package including a cap for sealing the laser diode and having a side surface that transmits the emitted light; a plano-convex lens for collimating the emitted light; and a space between the laser package and the plano-convex lens. a support plate disposed, the support plate having an aperture through which the emitted light passes; and the plano-convex lens has an outer circumferential portion of a lens surface on a plane side of the plano-convex lens aligned with the flat surface of the support plate. It is fixed in contact with the first plane, which is the surface on the convex lens side.

According to one aspect of the present invention, a laser device that can be easily adjusted can be realized.

1 is a schematic diagram showing the configuration of main parts of a laser device 1 according to Embodiment 1. FIG. 1 is a perspective view showing the configuration of a laser package according to Embodiment 1. FIG. It is a schematic diagram which shows the optical geometrical relationship in 5d of general convex lenses. It is a graph showing the correlation between working distance and radius of curvature. It is a graph showing the correlation between the working distance WD and the beam radius _y2 . 2 is a schematic diagram showing the configuration of main parts of a laser device 1a according to Embodiment 2. FIG. 3 is a schematic diagram showing the configuration of main parts of a laser device 1b according to Embodiment 3. FIG. FIG. 7 is a perspective view showing the configuration of a laser package according to Embodiment 3. FIG. 7 is a schematic diagram showing the configuration of main parts of a laser device 1c according to a fourth embodiment. FIG. 7 is a perspective view showing the configuration of a laser package according to Embodiment 4.

[Embodiment 1]
Hereinafter, one embodiment of the present invention will be described in detail. FIG. 1 is a schematic diagram showing the configuration of main parts of a laser device 1 according to the first embodiment.

(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, laser diode 3, and cap 4 are also referred to as a laser package. FIG. 2 is a perspective view showing the configuration of the laser package according to the first embodiment.

The substrate 2 is a member that becomes the base of the laser package. Preferably, the substrate 2 is made of a metal plate. A pattern is formed on the substrate 2 so that the laser diode 3 can be placed at a position determined based on design conditions described later.

The laser diode 3 is a light source that emits laser light. The main direction of the light emitted by the laser diode 3 is parallel to the main surface of the substrate 2 . Although the wavelength of the light emitted by the laser diode 3 is not limited, it is preferable that the light emitted has a 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 a pattern formed on the substrate 2. The emission surface of the laser diode 3 from which the laser beam is emitted is referred to as an emission surface 31.

The cap 4 is a glass cap that seals a space in which the laser diode 3 is placed. The cap 4 has a side surface (transmissive portion 41) that transmits the emitted light. The material of the cap 4 is not limited to glass, but may be any material that has high transmittance at a desired wavelength. The entire cap 4 does not need to be made of glass; only the transmitting portion 41 that transmits the laser light emitted by the laser diode 3 may be made of glass (a material with high transmittance). Furthermore, the transmitting section 41 has a plane perpendicular to the laser light emitted by the laser diode 3. Note that although the transparent portion 41 is a side surface of the cap 4, it may be a part of the side surface.

The plano-convex lens 5 is a convex lens in which one of the two surfaces of the lens is a flat surface and the other surface is a convex surface. The plano-convex lens 5 collimates the incident laser light. The plane-side lens surface of the plano-convex lens 5 is referred to as a lens surface 51. Lens surface 51 faces transparent portion 41 of cap 4 .

The support plate 6 is a support member for the plano-convex lens 5 disposed between the laser package and the plano-convex lens 5, and has a main surface parallel to the XY plane (a plane perpendicular to the laser beam emitted by the laser diode 3). It is arranged so that The support plate 6 has an opening at a portion through which the laser beam passes. Further, the opening is slightly smaller than the diameter of the plano-convex lens 5, and supports the plano-convex lens 5 at a portion where the support plate 6 and the plano-convex lens 5 overlap. The plano-convex lens 5 may be fixed to the support plate 6 using an adhesive.

The surface (XY plane) of the support plate 6 that faces the lens surface 51 of the plano-convex lens 5 is called a 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 the lens surface 51 of the plano-convex lens 5 is in contact with the first plane 61.

(Applicable conditions for LBS method for glass applications)
In the LBS method for glass applications, beam conditions are limited depending on the size of the mirror that scans the beam. The mirror (not shown) is formed using MEMS technology, and the size that can be manufactured is limited. Therefore, it is necessary to manufacture a laser device 1 suited to the mirror.

Here, in order to reduce the burden on the user when wearing the glasses, it is preferable that the glasses be small in size, and in order to reduce the size of the glasses, the optical system including the laser device 1 should be ultra-small. There is a need. In order to realize an ultra-compact optical system, it is preferable to set the beam size (spot size) to about 1.5 mm due to design conditions limited by the mirror. This is because the size of the mirror is limited by the resonance frequency and the like.

(General convex lens 5d)
Here, the optical geometric relationship of a general convex lens will be explained. FIG. 3 is a schematic diagram showing the optical geometric relationship in a general convex lens 5d.

The laser light emitted from the laser diode 3 spreads radially and travels. This radially expanding radiation angle θ _⊥ is preferably approximately equal to the maximum incident angle α _i1 of the light beam incident on the convex lens 5d, and there is a relationship of α _i1 =θ _⊥ . The laser light emitted from the laser diode 3 travels through air with a refractive index n _i1 =1.

The distance from the emission surface 31 of the laser diode 3 to the convex lens 5d is referred to as a working distance WD. Furthermore, the beam size becomes size _y1 at the time when the laser beam is incident on the convex lens 5d. Therefore, _y1 has the following relationship.

レーザ光が凸レンズ５ｄに入射すると、レンズ自体の媒質（屈折率ｎ_ｔ１）が入射側（空気）と異なるため、屈折する。そのため、屈折角α_ｔ１で進行する。凸レンズ５ｄの厚みだけ、屈折角α_ｔ１で進行するため、凸レンズ５ｄを通過したビームサイズのサイズｙ_２は、幾何光学から、次式で表せる。

ここで、Ｒ_１は、凸レンズ５ｄの入射側の曲率半径であり、ｄは凸レンズ５ｄの光軸上の厚みである。また、凸レンズ５ｄによって屈折されることによって、ビームはコリメートされる。

When the laser beam is incident on the convex lens 5d, the medium (refractive index n _t1 ) of the lens itself is different from that on the incident side (air), so that it is refracted. Therefore, it advances at a refraction angle α _t1 . Since the beam travels at a refraction angle α _t1 by the thickness of the convex lens 5d, the beam size _y2 that has passed through the convex lens 5d can be expressed by the following equation from geometric optics.

Here, _R1 is the radius of curvature on the incident side of the convex lens 5d, and d is the thickness of the convex lens 5d on the optical axis. Furthermore, the beam is refracted by the convex lens 5d, thereby collimating the beam.

h ₁ and h ₂ in FIG. 3 represent the distance between the lens entrance side and the front principal plane, and the distance between the lens exit side and the rear principal plane, respectively.

(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, the radiation angle _θ⊥ , the radius of curvature _R1 , the refractive index _nt1 , or the thickness d. needs to be made smaller.

Here, the radiation angle θ _⊥ is a value specific to the laser diode 3, and is about 25° (the radiation angle θ _⊥ is defined as a half angle at peak intensity×1/e ² ). Further, the refractive index n _t1 of the lens is a fixed value when using an inexpensive general optical glass (n _d =1.5).

The thickness d was set to 0.8 mm because if the lens is made too thin, the effective diameter of the lens becomes small, and as a result, the beam size must be made small.

Therefore, among the conditions for reducing the beam size described above, the only variables are the working distance WD and the radius of curvature _R1 , and there is a correlation between these two. FIG. 4 is a diagram showing the correlation between these two. Since it is a plano-convex lens 5, the radius of curvature _R1 on the plane side is infinite. Therefore, as mentioned above, if the beam size is set to about 1.5 mm, the beam radius will be about 0.75 mm, and as a result, from FIG. Recognize.

Next, the lower limit value of the working distance WD is derived based on design conditions. The attachment error of the laser diode 3 to the substrate 2 is 0.2 mm, the minimum thickness of the transparent part 41 of the cap 4 is 0.3 mm, and 0.3 mm is required as an adjustment allowance for the plano-convex lens 5, so the working distance WD is The lower limit is 0.8 mm. FIG. 5 is a graph showing the correlation between the working distance WD and the beam radius _y2 . As described above, it is understood that in an optical system for realizing VR glasses etc. that are comfortable to wear, the working distance WD is limited to an extremely narrow range of 0.8 to 1.2 mm.

The working distance WD is as described above due to the overall configuration of the laser device 1 that transmits the laser beam through the side surface (transmission part 41) of the cap 4, and the use of the very thin cap 4 with the thickness of the transmission part 41 of 0.3 mm. This allows it to be kept to an extremely small value.

ここで、Ｒ_２は、平凸レンズ５の出射側の曲率半径である。 In this case, since the beam needs to be collimated, the working distance WD and the focal length f have the following relationship.

Here, _R2 is the radius of curvature on the exit side of the plano-convex lens 5.

Therefore, there is a predetermined relationship between the focal length f and the radius of curvature _R2 . The focal length f is set within a range that satisfies this relationship. Thereafter, the radius of curvature _R2 is calculated using the set focal length f.

Through the above steps, the plano-convex lens 5 is designed. Note that the beam size _y2 at this time can be expressed by the following equation.

ｙ_２の上限値は、ミラーの半径によって定まり、本実施形態では０．８ｍｍである。対して、ｙ_２の下限値は０．５５ｍｍとなる。これは、米国のＭＩＬ－ＰＲＦ－１３８３０Ｂ規格に従う光学部品のキズ‐ブツ要求精度がレーザアプリケーションでは、２０－１０である。このため、ビームサイズが１．５ｍｍなことから、平凸レンズ５の有効径を１．６ｍｍとすると、この１０％までのブツの総直径を許容する。下限値０．５５に対して、
０．１６／２／０．５５＝１４．５％
となり、キズ‐ブツ要求精度を満たす値となる。

The upper limit value of _y2 is determined by the radius of the mirror, and is 0.8 mm in this embodiment. On the other hand, the lower limit value of _y2 is 0.55 mm. This means that the required flaw-to-bump accuracy for optical components according to the US MIL-PRF-13830B standard is 20-10 for laser applications. Therefore, since the beam size is 1.5 mm, if the effective diameter of the plano-convex lens 5 is 1.6 mm, a total diameter of up to 10% of this is allowed. For the lower limit value 0.55,
0.16/2/0.55=14.5%
This is a value that satisfies the flaw-to-bump accuracy requirement.

(Conditions of plano-convex lens 5)
The thickness of the plano-convex lens 5 on the optical axis is preferably 0.4 mm or more and 1 mm or less. This is a value determined from the relationship between the durability of the plano-convex lens 5 and the installation space.

The effective diameter of the plano-convex lens 5 is preferably 1.2 mm or more and 1.6 mm or less. This is a value derived as a result of adjusting various parameters such that the size of the laser device 1 and the lower limit of the beam size are not less than 1 mm.

Here, the diameter of the plano-convex lens 5 may be larger than the effective diameter of the plano-convex lens 5. That is, the actual diameter of the plano-convex lens 5 may be 1.6 mm or more, which is the upper limit of the effective diameter of the lens, and a frame portion may be provided outside the effective diameter.

(Adjustment and assembly of laser device 1)
The laser device 1 is assembled while being adjusted according to the following procedure. A laser diode 3 is die-bonded and fixed at a predetermined position on the substrate 2. Thereafter, a cap 4 is placed so as to cover the laser diode 3, and the cap 4 is adhered to the substrate 2, thereby sealing the laser diode 3. Further, the support plate 6 and the substrate 2 are fixed to a housing (not shown).

The plano-convex lens 5 is slid on the first plane 61 of the support plate 6 in the XY direction (direction perpendicular to the laser beam emitted by the laser diode 3), and the optical axis of the plano-convex lens 5 and the laser diode 3 are aligned. Adjust to match the optical axis. Thereafter, the plano-convex lens 5 is adhered to the support plate 6.

(Brief Summary)
Basic collimation of the emitted laser light is performed depending on the position of the laser diode 3 in the Z direction, and fine adjustment of the collimation can be made by adjusting the clearance between the support plate 6 and the plano-convex lens 5. Furthermore, by sliding the plano-convex lens 5 in the XY directions on the first plane 61 of the support plate 6, the optical axis of the plano-convex lens 5 can be made to coincide with the optical axis of the laser diode 3 which is already fixed. can. In this way, the laser device 1 can easily realize collimation adjustment and optical axis adjustment.

[Embodiment 2]
Other embodiments of the invention will be described below. For convenience of explanation, members having the same functions as the members described in the above embodiment are given the same reference numerals, and the description thereof will not be repeated.

FIG. 6 is a schematic diagram showing the configuration of main parts of a laser device 1a according to the second embodiment. The laser device 1a is different from the laser device 1 in that the support plate 6 contacts and slides on the transparent portion 41 of the cap.

In this embodiment, the plano-convex lens 5 may be fixed to the support plate 6, and in this case, the optical axis of the plano-convex lens 5 can be adjusted by adjusting the position of the support plate 6 in the XY direction with respect to the cap 4. I do.

In this configuration, since the plano-convex lens 5 is fixed to the support plate 6 in advance, the support plate is bonded to the cap 4. Therefore, the bonding area can be easily increased. There is also the advantage that the lower limit value of the working distance WD can be further reduced.

Furthermore, instead of bonding the support plate 6 and the plano-convex lens 5, the cap 4 and the support plate 6 may be bonded together. In this case, the plano-convex lens 5 slides in contact with the support plate 6 and adjusts the position in the XY directions, thereby adjusting the optical axis of the plano-convex lens 5. This configuration also has the advantage that the lower limit value of the working distance WD can be further reduced.

[Embodiment 3]
Other embodiments of the invention will be described below. For convenience of explanation, members having the same functions as the members described in the above embodiment are given the same reference numerals, and the description thereof will not be repeated.

FIG. 7 is a schematic diagram showing the configuration of main parts of a laser device 1b according to the third embodiment. The laser device 1b differs from the laser device 1 in that it includes three laser diodes 3a to 3c and three plano-convex lenses 5a to c, respectively. FIG. 8 is a perspective view showing the configuration of a laser package according to the third embodiment.

The laser diode 3a emits a beam of red wavelength, which is collimated by a plano-convex lens 5a. The laser diode 3b emits a beam of green wavelength, which is collimated by a plano-convex lens 5b. The laser diode 3c emits a blue wavelength beam, which is collimated by a plano-convex lens 5c.

The laser device 1b further includes a prism 7, which combines collimated beams of red, green, and blue wavelengths. As a result, the laser device 1b emits a full color beam.

Since the laser diodes 3a to 3c have different wavelengths, they have different working distances (WD_R≠WD_G, WD_G≠WD_B, WD_B≠WD_R). Therefore, these differences between wavelengths are absorbed by adjusting the mounting positions of the laser diodes 3a to 3c in the Z direction with respect to the substrate 2.

Further, since it is necessary to make the collimated beams of each color the same size, fine adjustment in the Z direction is also required when attaching (adhering) the plano-convex lenses 5a to 5c.

At this time, the support plate 6 for fixing the plano-convex lenses 5a to 5c may be common to each color, or different support plates 6a to c may be used for each color (FIG. 7 shows the case where the support plate 6 is common).

[Embodiment 4]
In Embodiments 1 to 3, the beam is emitted from the laser diode 3, travels straight, and is emitted from the side surface of the cap 4. However, the present invention is not limited to this. In the fourth embodiment, a case where the beam is emitted from the upper surface of the cap 4 will be described.

FIG. 9 is a schematic diagram showing the configuration of main parts of a laser device 1c according to the fourth embodiment. The laser device 1c differs from the laser device 1 in that the surface through which the beam passes is not the transmissive portion 41 on the side surface but the transmissive portion 41a on the top surface. FIG. 10 is a perspective view showing the configuration of a laser package according to the fourth embodiment. Note that although the transparent portion 41a is the upper surface of the cap 4, it may be a part of the upper surface.

The laser device 1c includes a mirror 8, which bends the beam emitted from the laser diode 3 by 90 degrees, and emits the beam from the transmission 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. Further, the plano-convex lens 5 and the support plate 6 are arranged parallel to the upper surface of the cap 4.

The laser device 1c according to the fourth embodiment has the advantage that the thickness of the beam in the direction of the emitted light can be reduced. The laser device 1c can be installed in an installation environment that is not suitable for the laser devices 1, 1a, and 1b according to the first to third embodiments.

〔summary〕
Laser devices 1, 1a, 1b, and 1c according to aspect 1 of the present invention include a substrate 2, a laser diode 3 placed on the substrate 2, and a laser diode 3 that emits emitted light in a direction parallel to the main surface of the substrate 2. , a laser package having a cap 4 for sealing the laser diode 3 and having a surface that transmits the emitted light; a plano-convex lens 5 for collimating the emitted light; a support plate 6 disposed between the plano-convex lens 5 and the support plate 6 having an aperture through which the emitted light passes; The outer peripheral portion is fixed in a state in which it is in contact with a first plane 61 that is a surface of the support plate 6 on the plano-convex lens 5 side.

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

Laser apparatuses 1, 1a, 1b, and 1c according to aspect 2 of the present invention, in aspect 1 above, are optically connected between the emission surface of the emitted light of the laser diode 3 and the plane-side lens surface of the plano-convex lens 5. The distance may be 0.8 mm or more and 1.2 mm or less.

According to the above configuration, the emitted light can be collimated and then made into a desired size.

In the laser devices 1, 1a, 1b, and 1c according to aspect 3 of the present invention, in aspect 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. good.

According to the above configuration, the plano-convex lens 5 can be made durable.

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

According to the above configuration, the beam size can be set to be appropriate for the mirror.

In the laser device 1c according to Aspect 5 of the present invention, in any of Aspects 1 to 4 above, the emitted light may be bent by a mirror.

According to the above configuration, the emitted light can be bent by the mirror and the beam can be emitted from the upper surface of the cap.

Laser devices 1b and 1c according to aspect 6 of the present invention are the laser devices 1b and 1c according to any one of aspects 1 to 5 above, wherein the laser package has a plurality of the laser diodes 3a to 3c, and each of the laser diodes 3a A plurality of plano-convex lenses 5a to 5c may be provided to collimate the emitted light of 5a to 5c.

According to the above configuration, it is possible to realize laser devices 1b and 1c that can produce full-color emitted light.

A method of manufacturing laser devices 1, 1a, 1b, and 1c according to aspect 7 of the present invention includes sliding an outer peripheral portion of a lens surface on the plane side of the plano-convex lens and the first plane of the support plate. The method may include adjusting the position of the plano-convex lens in the first plane perpendicular to the optical axis of the laser diode, and then bonding the plano-convex lens to the support plate.

According to the above features, it is possible to manufacture a laser device in which collimation adjustment and optical axis adjustment are easy.

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

1, 1a, 1b, 1c laser device 2 substrate 3, 3a, 3b, 3c laser diode 4 cap 5, 5a, 5b, 5c plano-convex lens 5d convex lens 6 support plate 7 prism 8 mirror 31 emission surface 41, 41a transmission part 51 lens Surface 61 1st plane

Claims (7)

A substrate, a laser diode placed on the substrate and emitting emitted 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 cap having a laser package;
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 opening through which the emitted light passes;
The plano-convex lens is a laser device in which the outer periphery of the plane-side lens surface of the plano-convex lens is fixed in a state in which it is in contact with a first plane, which is a surface of the support plate on the plano-convex lens side. 2. The laser device according to claim 1, wherein the optical distance between the emission surface of the emitted light of the laser diode and the plane-side lens surface of the plano-convex lens is 0.8 mm or more and 1.2 mm or less. The laser device 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 device according to claim 3, wherein the plano-convex lens has an effective diameter of 1.2 mm or more and 1.6 mm or less. The laser device according to claim 1, wherein the emitted light is bent by a mirror. The laser package has a plurality of the laser diodes,
The laser device according to any one of claims 1 to 5, comprising a plurality of said plano-convex lenses that collimate the emitted light of each of said laser diodes. A method for manufacturing a laser device according to claims 1 to 5, comprising:
By sliding the outer periphery of the lens surface on the plane side of the plano-convex lens and the first plane of the support plate, the plano-convex lens is moved in the first plane perpendicular to the optical axis of the laser diode. a process of adjusting the position;
Thereafter, a method for manufacturing a laser device, including the step of bonding the plano-convex lens to the support plate.

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