JP2024098555A - Lens, light source device, mold, and mold manufacturing method - Google Patents

Abstract

To facilitate manufacture of a mold for molding a lens having a fine structure.SOLUTION: A lens 20 has a fine structure 40. The fine structure 40 has an antireflection function. The fine structure 40 has grooves 50 with a cross-sectional V-shape. The grooves 50 are arranged side by side on an optical surface (first optical surface 21) of the lens 20. The grooves 50 each have a first surface 51 and a second surface 52. The first surface 51 forms a first angle with respect to an optical axis X1 of the lens 20. The second surface 52 is inclined with respect to the optical axis X1 at a second angle larger than the first angle.SELECTED DRAWING: Figure 4

Description

The present invention relates to a lens, a light source device, a mold, and a method for manufacturing the mold.

Conventionally, lenses are known that have a microstructure with an anti-reflection function on their optical surfaces (see Patent Document 1). The anti-reflection function suppresses reflection on the lens surface and improves transmittance. The microstructure has grooves with a U-shaped cross section and columnar protrusions.

JP 2006-201371 A

However, the molds used to form the microstructures in the shapes used in the conventional technology must be processed using special methods, such as the anodized alumina method, which makes the manufacturing of the molds complicated.

Therefore, the present invention aims to facilitate the manufacture of molds for molding lenses having microstructures.

In order to achieve the above object, the lens according to the present invention has a microstructure.
The microstructure has an anti-reflection function. The microstructure has a groove having a V-shaped cross section.
The groove is aligned with an optical surface of the lens. The groove has a first surface and a second surface. The first surface is at a first angle with respect to an optical axis of the lens. The second surface is inclined with respect to the optical axis at a second angle greater than the first angle.

By configuring the microstructure grooves to have a V-shaped cross section, the mold for molding the lenses can be easily manufactured by cutting using a cutting tool such as a diamond tip.

The optical surface may also be a convex surface. In this case, the first surface may face away from the optical axis.

In a configuration in which the optical surface is convex, by having the first surface face away from the optical axis, the height of the convex portion corresponding to the groove in the lens can be increased during machining of the mold. This allows the depth of the groove in the lens to be increased, thereby increasing the transmittance of the lens.

The optical surface may also be concave. In this case, the first surface may face the optical axis.

In a configuration in which the optical surface is concave, by having the first surface face the optical axis, the height of the convex portion corresponding to the groove in the lens can be increased during machining of the mold. This allows the depth of the groove in the lens to be increased, thereby increasing the transmittance of the lens.

The groove may also be formed in a spiral shape centered on the optical axis.

By forming the grooves in a spiral shape centered on the optical axis, the shape of the microstructure becomes approximately symmetrical about the optical axis, making it possible to obtain approximately the same anti-reflection effect at any point on the lens.

The lens may also have a refractive power in a first direction perpendicular to the optical axis that is different from a refractive power in a second direction perpendicular to both the optical axis and the first direction.

The optical surface may also have second grooves that form a diffraction grating. In this case, the depth of the second grooves may be greater than the depth of the grooves.

By having an optical surface with grooves that form a microstructure and second grooves that form a diffraction grating, the lens that functions as a diffraction grating can be endowed with anti-reflection properties.

The second groove may also be a groove that constitutes a blazed diffraction grating. In this case, the angle between the first surface and the second surface may be smaller than 90° minus the blaze angle.

The first surface may also be parallel to the optical axis.

A light source device according to the present invention includes the lens and a semiconductor laser.
The semiconductor laser emits light toward the lens.
The lens converts the light from the semiconductor laser into a beam.

In addition, in the lens constituting the light source device, the dimension D of the first surface in the direction along the optical axis may satisfy λ/20<D<λ/4, where λ is the wavelength of the semiconductor laser.

In addition, in the lenses constituting the light source device, the pitch P of adjacent first surfaces in a direction perpendicular to the optical axis may satisfy P<λ, where λ is the wavelength of the semiconductor laser.

The mold according to the present invention is a mold for molding a lens provided with a microstructure having an anti-reflection function.
The microstructure has grooves with a V-shaped cross section aligned with the optical surface of the lens.
The mold has a first molding surface and a second molding surface.
The first molding surface forms a first side of the groove.
The second molding surface forms a second side of the groove.
The angle of the second molding surface relative to a reference axis corresponding to the optical axis of the lens is greater than the angle of the first molding surface relative to the reference axis.

The mold has a first molding surface and a second molding surface with a V-shaped cross section that correspond to the V-shaped cross-section of the lens, so that the mold can be easily manufactured by cutting using a machining tool with a tip.

The optical surface may also be a convex surface. In this case, the first molding surface may face the reference axis side.

In a mold for molding a lens with a convex optical surface, the first molding surface faces the reference axis, so that the height of the convex portion corresponding to the groove in the lens can be increased when machining the mold. This makes it possible to increase the depth of the groove in the lens and increase the transmittance of the lens.

The optical surface may also be concave. In this case, the first molding surface may face away from the reference axis.

In a mold for molding a lens with a concave optical surface, the first molding surface faces away from the reference axis, so that the height of the convex portion corresponding to the groove in the lens can be increased when machining the mold. This makes it possible to increase the depth of the groove in the lens and increase the transmittance of the lens.

The first molding surface may also be parallel to the reference axis.

A method for producing a mold according to the present invention is a method for producing the mold.
In the method of manufacturing a mold, the base material of the mold is cut with a cutting edge whose tip angle is the angle between the first molding surface and the second molding surface, thereby forming the first molding surface and the second molding surface.

The present invention makes it easier to manufacture molds for molding lenses with microstructures.

1 is a perspective view showing a light source device according to a first embodiment. FIG. 2 is a cross-sectional view showing a light source device. FIG. 4(a) is a cross-sectional view taken along line IV-IV in FIG. 3, and FIG. 4(b) is an enlarged view of a portion enclosed by a dashed line in FIG. FIG. 6A is a cross-sectional view taken along the line VI-VI in FIG. 5, and FIG. 6B is an enlarged view of a portion enclosed by a dashed line in FIG. 7A is a cross-sectional view showing a lens and a first die according to a second embodiment, and FIG. 7B is an enlarged view of a portion surrounded by a dashed line in FIG. 7A . FIG. 13 is a plan view showing a lens according to a third embodiment. IX-IX cross-sectional view of FIG. 8 (a), an enlarged view of the part surrounded by the dashed line in FIG. 9 (a) (b), and an enlarged view of the part surrounded by the dashed line in FIG. 9 (b) (c). 10A is a cross-sectional view showing a first mold of the third embodiment, FIG. 10B is an enlarged view of the part surrounded by the dashed line in FIG. 10A, and FIG. 10C is an enlarged view of the part surrounded by the dashed line in FIG. 10B.

Next, a first embodiment of the present invention will be described in detail with reference to the drawings as appropriate.
1, the light source device 1 is a device that constitutes a scanning optical device of a printer. The light source device 1 includes a semiconductor laser 10, a lens 20, and a holder 30.

In the following description, the direction along the optical axis X1 of the lens 20 is also referred to as the "optical axis direction." The direction perpendicular to the optical axis X1 is also referred to as the "first direction." The direction perpendicular to both the optical axis X1 and the first direction is also referred to as the "second direction." The arrows indicating each direction in the drawings will point to one side in that direction.

The semiconductor laser 10 emits light toward the lens 20 .
The lens 20 converts the light from the semiconductor laser 10 into a beam. The lens 20 is disposed on one side of the semiconductor laser 10 in the optical axis direction.
The holder 30 holds the semiconductor laser 10 and the lens 20 .

As shown in FIG. 2 , the lens 20 has a first optical surface 21 and a second optical surface 22 .
The first optical surface 21 is located at one end of the lens 20 in the optical axis direction. The second optical surface 22 is located at the other end of the lens 20 in the optical axis direction.

The first optical surface 21 is a convex surface that is convex toward one side in the optical axis direction. The second optical surface 22 is a flat surface that is perpendicular to the optical axis X1.

As shown in FIG. 3, the lens 20 has a microstructure 40 on the first optical surface 21. The microstructure 40 has an anti-reflection function. The microstructure 40 has grooves 50 arranged in a direction perpendicular to the optical axis X1 on the first optical surface 21. The grooves 50 are formed in a concentric or spiral shape centered on the optical axis X1.

The lens 20 may or may not have a microstructure 40 on the second optical surface 22.

As shown in Figures 4(a) and (b), the groove 50 is a V-shaped groove in cross section. The groove 50 has a first surface 51 and a second surface 52. There are multiple first surfaces 51 and multiple second surfaces 52 in the cross section along the optical axis X1. The multiple first surfaces 51 and the multiple second surfaces 52 are arranged alternately in order from the optical axis X1 side in the cross section along the optical axis X1.

More specifically, in a cross section taken along the optical axis X1, the first surface 51 is located between two second surfaces 52. In a cross section taken along the optical axis X1, the first surface 51 is connected to two second surfaces 52.

In a cross section taken along the optical axis X1, the second surface 52 is located between the two first surfaces 51. In a cross section taken along the optical axis X1, the second surface 52 is connected to the two first surfaces 51.

The first surface 51 has a first angle with respect to the optical axis X1 of the lens 20. In this embodiment, the first angle is 0°. That is, in this embodiment, the first surface 51 is parallel to the optical axis X1. The first surface 51 faces the opposite side to the optical axis X1.

The second surface 52 is inclined at a second angle greater than the first angle with respect to the optical axis X1. The second surface 52 extends obliquely from the other end of the first surface 51 in the optical axis direction toward one side in the optical axis direction and toward a direction away from the optical axis X1 in the first direction.

The depth and width of the groove 50 are on the order of nanometers. More specifically, the dimension D of the first surface 51 in the optical axis direction satisfies λ/20<D<λ/4, where λ is the wavelength of the semiconductor laser 10. Here, the dimension D is the depth of the groove 50.

The pitch P of two first faces 51 adjacent in the first direction satisfies P<λ, where λ is the wavelength of the semiconductor laser 10. Here, the pitch P is the width of the groove 50. The two first faces 51 adjacent in the first direction are the first face 51 located at one end of the second face 52 in the first direction, and the first face 51 located at the other end of the second face 52 in the first direction.

The mold 60 shown in FIG. 5 is a mold for molding the lens 20. The mold 60 has a first mold 61 and a second mold. The lens 20 is manufactured by injecting a material into the space formed by mating the first mold 61 and the second mold and then solidifying the material. Note that the second mold is not shown or described.

The first mold 61 is a mold for mainly forming the first optical surface 21 of the lens 20. The first mold 61 has a convex portion 70 corresponding to the groove 50. The convex portion 70 is formed in a shape corresponding to the groove 50, specifically, in a concentric or spiral shape centered on the reference axis X2 of the mold 60.

Here, the reference axis X2 of the mold 60 is located at a position corresponding to the optical axis X1 of the lens 20. More specifically, the reference axis X2 coincides with the optical axis X1 of the lens 20 after molding in the mold 60.

As shown in Figures 6(a) and (b), the convex portion 70 has a first molding surface 71 and a second molding surface 72. The first molding surface 71 is a surface for forming the first surface 51 of the groove 50. The second molding surface 72 is a surface for forming the second surface 52 of the groove 50.

There are multiple first molding surfaces 71 and multiple second molding surfaces 72 in the cross section along the reference axis X2. The multiple first molding surfaces 71 and multiple second molding surfaces 72 are arranged alternately in order from the reference axis X2 in the cross section along the reference axis X2.

More specifically, in a cross section taken along the reference axis X2, the first molding surface 71 is located between two second molding surfaces 72. In a cross section taken along the reference axis X2, the first molding surface 71 is connected to two second molding surfaces 72.

In a cross section taken along the reference axis X2, the second molding surface 72 is located between the two first molding surfaces 71. In a cross section taken along the reference axis X2, the second molding surface 72 is connected to the two first molding surfaces 71.

The first molding surface 71 is parallel to the reference axis X2. The first molding surface 71 faces the reference axis X2.
The angle of second molding surface 72 with respect to reference axis X2 is greater than the angle of first molding surface 71 with respect to reference axis X2. The angle between first molding surface 71 and second molding surface 72 is equal to the angle between first surface 51 and second surface 52 of lens 20.

Next, a method for manufacturing the first mold 61 will be described.
The machining tool used in the manufacturing method of the first mold 61 has a tip 80 for cutting the first mold 61. The cutting edge 81 at the tip of the tip 80 is made of, for example, single crystal diamond. The angle θ1 of the cutting edge 81 is the angle θ2 between the first molding surface 71 and the second molding surface 72. The base material of the first mold 61 is cut by this cutting edge 81 to form the first molding surface 71 and the second molding surface 72.

In more detail, first, the first mold 61 is rotated around the reference axis X2. Next, the tip 80 is placed on the reference axis X2 of the first mold 61. Thereafter, the tip 80 is gradually moved in a direction away from the reference axis X2 to form a concentric or spiral convex portion 70 on the first mold 61. Note that the concentric or spiral convex portion 70 may also be formed on the first mold 61 by moving the tip 80 closer to the reference axis X2.

As described above, according to this embodiment, the following effects can be obtained.
Since the grooves 50 of the microstructure 40 have a V-shaped cross section, the mold 60 for molding the lens 20 can be easily manufactured by cutting using a cutting tool such as a diamond tip.

By having the first surface 51 formed on the convex first optical surface 21 face away from the optical axis X1, the height of the convex portion 70 corresponding to the groove 50 of the lens 20 can be increased when machining the first mold 61, compared to a configuration in which the first surface 51 formed on the convex first optical surface 21 faces the optical axis X1. This allows the depth of the groove 50 of the lens 20 to be increased, thereby increasing the transmittance of the lens 20.

By forming the grooves 50 in a concentric or spiral shape centered on the optical axis X1, the shape of the microstructure 40 becomes approximately symmetrical with respect to the optical axis, so that an approximately equal anti-reflection effect can be obtained at any point on the lens 20.

In the first mold 61 for molding the lens 20 in which the first optical surface 21 is a convex surface, the first molding surface 71 faces the reference axis X2, so that the height of the convex portion 70 corresponding to the groove 50 of the lens 20 can be increased when the first mold 61 is processed. This makes it possible to increase the depth of the groove 50 of the lens 20 and increase the transmittance of the lens 20.

Next, a second embodiment of the present invention will be described in detail with reference to the drawings as appropriate.
As shown in Fig. 7(a), the lens 220 of the second embodiment has a concave first optical surface 221 and a planar second optical surface 222. As shown in Fig. 7(b), the lens 220 has a microstructure 240 on the first optical surface 221. Note that the lens 220 may or may not have the microstructure 240 on the second optical surface 222.

The microstructure 240 has an anti-reflection function. The microstructure 240 has grooves 250 arranged in a direction perpendicular to the optical axis X21 on the first optical surface 221. The grooves 250 are formed in a concentric or spiral shape centered on the optical axis X21.

Groove 250 is a groove with a V-shaped cross section. Groove 250 has a first surface 251 and a second surface 252. There are multiple first surfaces 251 and multiple second surfaces 252 in the cross section along the optical axis X21. The multiple first surfaces 251 and the multiple second surfaces 252 are arranged alternately in order from the optical axis X21 side in the cross section along the optical axis X21.

The first surface 251 has a first angle with respect to the optical axis X21 of the lens 20. In this embodiment, the first angle is 0°. That is, in this embodiment, the first surface 251 is parallel to the optical axis X21. The first surface 251 faces the optical axis X21.

The second surface 252 is inclined at a second angle greater than the first angle with respect to the optical axis X21. The second surface 252 extends obliquely from the other end of the first surface 251 in the optical axis direction toward one side in the optical axis direction and toward the optical axis X21 in the first direction.

The depth and width of the groove 250 are the same as in the first embodiment, so a detailed description is omitted.

As shown in FIG. 7(a), the first mold 261 is a mold for mainly forming the first optical surface 221 of the lens 220. The first mold 261 has a convex portion 270 corresponding to the groove 250. The convex portion 270 is formed in a shape corresponding to the groove 250, specifically, in a concentric or spiral shape centered on the reference axis X22 of the first mold 281.

Here, the reference axis X22 of the first mold 261 is located at a position corresponding to the optical axis X21 of the lens 220. In more detail, the reference axis X22 coincides with the optical axis X21 of the lens 220 after molding in the first mold 261.

As shown in FIG. 7(b), the protrusion 270 has a first molding surface 271 and a second molding surface 272. The first molding surface 271 is a surface for forming the first surface 251 of the groove 250. The second molding surface 272 is a surface for forming the second surface 252 of the groove 250.

There are multiple first molding surfaces 271 and multiple second molding surfaces 272 in the cross section taken along the reference axis X22. The multiple first molding surfaces 271 and multiple second molding surfaces 272 are arranged alternately in order from the reference axis X22 side in the cross section taken along the reference axis X22. The first molding surface 271 faces the side opposite the reference axis X22.

As described above, according to the second embodiment, the following effects can be obtained.
By having the first surface 251 formed on the concave first optical surface 221 face the optical axis X21, the height of the convex portion 270 corresponding to the groove 250 of the lens 220 can be made larger during machining of the first mold 261, as compared to, for example, a configuration in which the first surface 251 formed on the concave first optical surface 221 faces the opposite side to the optical axis X21. This makes it possible to increase the depth of the groove 250 of the lens 220 and increase the transmittance of the lens 220.

In the first mold 261 for molding the lens 220 in which the first optical surface 221 is a concave surface, the first molding surface 271 faces away from the reference axis X22, so that the height of the convex portion 270 corresponding to the groove 250 of the lens 220 can be increased when the first mold 261 is processed. This makes it possible to increase the depth of the groove 250 of the lens 220 and increase the transmittance of the lens 220.

Next, a third embodiment of the present invention will be described in detail with reference to the drawings as appropriate.
8, the lens 320 according to the third embodiment is a lens whose refractive power in a first direction is different from that in a second direction. The lens 320 has a substantially elliptical shape when viewed from the optical axis direction.

As shown in FIG. 9(a), the lens 320 has a first optical surface 321 and a second optical surface 322.

The first optical surface 321 has a plurality of second grooves 90 that constitute a blazed diffraction grating. As shown in FIG. 8, each second groove 90 extends in a generally elliptical shape when viewed from the optical axis direction. The size of the plurality of second grooves 90 increases in order from the optical axis X31 side. Of two adjacent second grooves 90, the second groove 90 farther from the optical axis X31 is arranged so as to surround the second groove 90 closer to the optical axis X31.

As shown in FIG. 9(a), the second grooves 90 are located at the same position in the optical axis direction. The second grooves 90 are grooves with a V-shaped cross section. The second grooves 90 have a third surface 93 and a fourth surface 94.

There are multiple third surfaces 93 and multiple fourth surfaces 94 in the cross section along the optical axis X31. The multiple third surfaces 93 and multiple fourth surfaces 94 are arranged alternately in order from the optical axis X31 side in the cross section along the optical axis X31.

The third surface 93 has a third angle with respect to the optical axis X31 of the lens 320. In this embodiment, the third angle is 0°. The third surface 93 faces the optical axis X31.

The fourth surface 94 is inclined at a fourth angle, which is greater than the third angle, with respect to the optical axis X31. The fourth surface 94 extends obliquely from the other end of the third surface 93 in the optical axis direction toward one side in the optical axis direction and toward the optical axis X31 in the first direction. The angle between the fourth surface 94 and a plane perpendicular to the optical axis X31 is the blaze angle θb of the blazed diffraction grating.

The depth and width of the second groove 90 are on the order of micrometers. The fourth surface 94 of the second groove 90 has a groove 350 on the order of nanometers, as shown in FIG. 9(b).

Groove 350 is a V-shaped cross-sectional groove that constitutes microstructure 340 having an anti-reflection function. The depth of groove 350 is smaller than the depth of second groove 90. As shown in FIG. 9(c), groove 350 has first surface 351 and second surface 352. Note that lens 320 may or may not have a microstructure on second optical surface 322.

There are multiple first surfaces 351 and multiple second surfaces 352 in the cross section along the optical axis X31. The multiple first surfaces 351 and the multiple second surfaces 352 are arranged alternately in order from the optical axis X31 side in the cross section along the optical axis X31.

The first surface 351 has a first angle with respect to the optical axis X31 of the lens 320. In this embodiment, the first angle is 0°. The first surface 351 faces the optical axis X31. In other words, the first surface 351 and the third surface 93 face in the same direction.

The second surface 352 is inclined at a second angle greater than the first angle with respect to the optical axis X31. The second surface 352 extends obliquely from the other end of the first surface 351 in the optical axis direction toward one side in the optical axis direction and toward the optical axis X31 in the first direction. The angle θ3 between the first surface 351 and the second surface 352 is smaller than the value obtained by subtracting the blaze angle θb from 90°.

As shown in Figures 10(a) and (b), the first mold 361 is a mold for forming the first optical surface 321 of the lens 320. The first mold 361 has a reference axis X32 corresponding to the optical axis X31 of the lens 320. The first mold 361 has a second convex portion 390 corresponding to the second groove 90, and a convex portion 370 corresponding to the groove 350.

The second convex portion 390 has a third molding surface 393 and a fourth molding surface 394. The third molding surface 393 is a surface for forming the third surface 93 of the second groove 90. The fourth molding surface 394 is a surface for forming the fourth surface 94 of the second groove 90. The angle between the plane perpendicular to the reference axis X32 and the fourth molding surface 394 is the blaze angle θb of the blazed diffraction grating.

The convex portion 370 has a first molding surface 371 and a second molding surface 372. The first molding surface 371 is a surface for forming the first surface 351 of the groove 350. The second molding surface 372 is a surface for forming the second surface 352 of the groove 350. The angle θ4 between the first molding surface 371 and the second molding surface 372 is equal to the angle θ3 between the first surface 351 and the second surface 352.

The convex portion 370 is formed by a tip 380 whose tip angle θ5 is θ4. More specifically, the tip 380 has a first tip surface 381 and a second tip surface 382 which form the cutting edge of the tip 380. The first tip surface 381 is a surface for forming the first molding surface 371. The second tip surface 382 is a surface for forming the second molding surface 372. The angle between the first tip surface 381 and the second tip surface 382 is θ5.

When the first molding surface 371 and the second molding surface 372 are formed by the tip 380, the first tip surface 381 is parallel to the reference axis X32. This allows the tip 380 to satisfactorily form the first molding surface 371 and the third molding surface 393 that are aligned with the reference axis X32.

Here, if the first surface 351 of the microstructure groove 350 is significantly inclined with respect to the optical axis X31, the first chip surface 381 of the chip 380 is also significantly inclined with respect to the reference axis X32, and the third molding surface 393 is also significantly inclined with respect to the reference axis X32.

Here, an example of a case where the first surface 351 is greatly inclined with respect to the optical axis X31 is when the first surface and the second surface form two equal sides of an isosceles triangle, specifically, when the angle of the first surface relative to the optical axis is the same as the angle of the second surface relative to the optical axis. More specifically, this is the case where the angle of the first surface relative to a line that passes through the bottom of the groove and is parallel to the optical axis is the same as the angle of the second surface relative to this line.

In contrast, in this embodiment, the angle of the first surface 351 relative to the optical axis X31 is smaller than the angle of the second surface 352 relative to the optical axis X31, so that the angle of the first chip surface 381 relative to the reference axis X32 can be reduced, and the third molding surface 393 can be prevented from being significantly inclined relative to the reference axis X32.

In particular, by making the first surface 351 parallel to the optical axis X31, the first chip surface 381 becomes parallel to the reference axis X32, so that the first molded surface 371 and the third molded surface 393 can be formed parallel to the reference axis X32 as in this embodiment. In addition, by making the first chip surface 381 parallel to the reference axis X32, at least one of the first molded surface 371 and the third molded surface 393 can also be formed at an angle to the reference axis X32.

As described above, according to the third embodiment, the following effects can be obtained.
Since the first optical surface 321 has grooves 350 that form the microstructure 340 and second grooves 90 that form a blazed diffraction grating, the lens 320 that functions as a blazed diffraction grating can be provided with an anti-reflection function.
In the third embodiment, the lens has a refractive power different from that in the second direction, but the lens having the grooves 350 constituting the microstructure 340 and the second grooves 90 constituting the blazed diffraction grating may be a lens having the same refractive power in the first direction and the second direction. Also, the first optical surface 321 may be formed as a convex or concave surface having a refractive power.

The present invention is not limited to the above embodiment, but can be used in various forms, as exemplified below.

The first surface of the groove formed on the convex optical surface may face the optical axis. Also, the first surface of the groove formed on the concave optical surface may face the opposite side to the optical axis.

The first molding surface of the mold for forming the convex optical surface may face away from the reference axis. The first molding surface of the mold for forming the concave optical surface may face toward the reference axis.

The elements described in the above embodiments and variations may be implemented in any combination.

20 Lens 21 First optical surface 40 Microstructure 50 Groove 51 First surface 52 Second surface X1 Optical axis

Claims (16)

A lens provided with a microstructure having an anti-reflection function,
The microstructure has a V-shaped groove aligned on the optical surface of the lens,
The groove is
a first surface that forms a first angle with respect to an optical axis of the lens;
a second surface inclined at a second angle relative to the optical axis that is greater than the first angle. the optical surface is a convex surface;
The lens of claim 1 , wherein the first surface faces away from the optical axis. the optical surface is concave;
The lens according to claim 1 , wherein the first surface faces toward the optical axis. The lens according to claim 1, characterized in that the groove is formed in a spiral shape centered on the optical axis. The lens of claim 1, characterized in that the refractive power in a first direction perpendicular to the optical axis is different from the refractive power in a second direction perpendicular to both the optical axis and the first direction. the optical surface has second grooves that form a diffraction grating;
The lens of claim 1 , wherein the second groove has a depth greater than the depth of the groove. the second grooves are grooves that constitute a blazed diffraction grating,
7. The lens according to claim 6, wherein an angle between the first surface and the second surface is smaller than a value obtained by subtracting a blaze angle from 90 degrees. The lens of claim 1, wherein the first surface is parallel to the optical axis. A lens according to any one of claims 1 to 8;
a semiconductor laser that emits light toward the lens,
The light source device is characterized in that the lens converts the light from the semiconductor laser into a beam. The dimension D of the first surface in the direction along the optical axis is expressed as follows, where λ is the wavelength of the semiconductor laser:
λ/20<D<λ/4
10. The light source device according to claim 9, wherein the following is satisfied. The pitch P of the first surfaces adjacent in a direction perpendicular to the optical axis is expressed as follows, where λ is the wavelength of the semiconductor laser:
P < λ
11. The light source device according to claim 10, wherein the following is satisfied. A mold for molding a lens having a microstructure with an anti-reflection function, the microstructure having a V-shaped cross-sectional groove aligned on an optical surface of the lens, comprising:
a first molding surface for forming a first surface of the groove;
a second molding surface for forming a second surface of the groove;
A mold, characterized in that an angle of the second molding surface with respect to a reference axis corresponding to an optical axis of the lens is larger than an angle of the first molding surface with respect to the reference axis. the optical surface is a convex surface;
The mold according to claim 12 , wherein the first molding surface faces the reference axis side. the optical surface is concave;
The mold according to claim 12 , wherein the first molding surface faces away from the reference axis. The mold according to claim 12, characterized in that the first molding surface is parallel to the reference axis. A method for manufacturing a mold according to any one of claims 12 to 15, comprising the steps of:
A method for manufacturing a mold, characterized in that the first molding surface and the second molding surface are formed by cutting the base material of the mold with a cutting edge whose tip angle is the angle between the first molding surface and the second molding surface.

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