Optical element, optical device, and manufacturing method

Abstract

To provide an optical element capable of suppressing a ghost due to a light beam passing between adjacent lenses with a simple configuration.SOLUTION: An optical element includes: a first lens array having a plurality of first lenses joined to each other along a first direction; a second lens array having a plurality of second lenses joined to each other along the first direction; and a light shielding part. At least one of surfaces parallel to the first direction in the first and second lenses is a metasurface. The light shielding part is arranged between facing surfaces of adjacent first lenses of the plurality of first lenses and between facing surfaces of adjacent second lenses of the plurality of second lenses.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an optical element, an optical device, and a manufacturing method.

Background Art

[0002] Conventionally, a lens array capable of forming an erect and same-magnification image has been used in an image reading device such as a scanner. In recent years, a configuration including a lens array formed by arranging a plurality of small-diameter lenses has been proposed (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When using a lens array, in order to suppress noise (ghost noise) generated by obliquely incident light entering adjacent lenses, it is necessary to provide a light-shielding member for isolating light between adjacent lenses. However, since the shape of the light-shielding member becomes complicated and high-precision alignment between the light-shielding plate material and the lens is required, it is difficult to install the light-shielding member.

[0005] An object of the present invention is to provide an optical element capable of suppressing ghosts caused by light rays passing between adjacent lenses with a simple configuration.

Means for Solving the Problems

[0006] The optical element as one aspect of the present invention includes a first lens array including a plurality of first lenses respectively joined along a first direction, a second lens array including a plurality of second lenses respectively joined along the first direction, and a light-shielding portion. At least one of the surfaces of the first lens and the second lens parallel to the first direction is a metasurface, and the light-shielding portion is provided between the opposing surfaces of adjacent first lenses among the plurality of first lenses and between the opposing surfaces of adjacent second lenses among the plurality of second lenses.

Effects of the Invention

[0007] According to the present invention, it is possible to provide an optical element capable of suppressing ghosts caused by light rays passing between adjacent lenses with a simple configuration.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each figure, the same members are denoted by the same reference numerals, and redundant descriptions are omitted.

[0010] As an image reading device (image forming device), those that perform printing of an image by attaching toner to an electrostatic latent image formed on the surface of a photoreceptor drum by light from an exposure device are widely spread. As the exposure device, for example, an LED head that uses light emitted from an LED (Light Emitting Diode) is used. The LED head has a substrate on which an LED array in which a plurality of LEDs are arranged linearly is mounted, and a lens unit (optical device) in which a plurality of lenses that respectively collect light emitted from each LED are aligned. The light emitted from the LED array passes through the lens unit and is converged, and an electrostatic latent image is formed by exposing the surface of the photoreceptor drum disposed at the imaging position of the lens unit.

[0011] In each embodiment, the configuration of the lens unit will be described.

Example

[0012] FIG. 1 is a schematic diagram of a lens array unit (optical device) of this embodiment. The lens array unit has a light source 1 and an erect imaging lens array element (optical element).

[0013] The light source 1 is composed of LEDs. In this embodiment, the light beam 1a near the center of the light beam emitted from the light source 1 and the peripheral light beam 1b pass through a plurality of lenses and are condensed on the image plane (the surface of the photoreceptor drum) 2.

[0014] The erect image-forming lens array element has a first lens array 3 and a second lens array 4 arranged in order from the object side (the side of the light source 1) to the image side (the side of the image plane 2). The first lens array 3 includes a plurality of first lenses 101 joined along a first direction (bonding direction, arrangement direction, array direction). The first lens 101 includes a first substrate portion 30. The first substrate portion 30 includes a first optical surface (first surface) 31 parallel to the first direction, four side surfaces 32, and a surface (second surface) 33 facing the first optical surface 31. The second lens array 4 includes a plurality of second lenses 102 joined along a first direction (bonding direction, arrangement direction, array direction). The second lens 102 includes a second substrate portion 40. The second substrate portion 40 includes a second optical surface (third surface) 41 parallel to the first direction, four side surfaces 42, and a surface (fourth surface) 43 facing the second optical surface 41. Note that being parallel to the first direction means that the base portions are parallel, including not only the case of being strictly parallel but also the case of being substantially parallel (roughly parallel).

[0015] In this embodiment, the first optical surface 31 is an incident surface on which light from the light source 1 is incident, and the second optical surface 41 is an emission surface from which light from the light source 1 is emitted. The surfaces 33 and 43 face each other and are bonded by an adhesive. Thereby, the first lens array 3 and the second lens array 4 are integrated. A light-shielding paint is applied to the bonding surface (opposing surface) with the adjacent first lens 101 among the four side surfaces 32. Thereby, the incidence of the light beam incident on a predetermined first lens 101 to the adjacent first lens 101 can be suppressed. Also, a light-shielding paint is applied to the bonding surface (opposing surface) with the adjacent second lens 102 among the four side surfaces 42. Thereby, the incidence of the light beam incident on a predetermined second lens 102 to the adjacent second lens 102 can be suppressed. Note that the light-shielding paint is preferably applied not only to the bonding surface but also to other side surfaces.

[0016] Figure 2 is an enlarged schematic diagram of the main part of the upright imaging lens array element of this embodiment. In this embodiment, the first substrate portion 30 is a substantially rectangular parallelepiped member made of glass with a thickness of 1.3 mm. The first optical surface 31 is a metasurface. That is, the first lens 101 is a metasurface lens. In this embodiment, the first optical surface 31 includes fine cylindrical pillars with a height of 1000 nm and a diameter of 70 to 300 nm formed by an etching process. Therefore, the first optical surface 31 can add a continuous phase to the wavefront of the incident light beam and bend the traveling direction of the light. The light-shielding paint 6 is provided between one joint surface and the other joint surface of the adjacent first lenses 101. In this embodiment, the light-shielding paint 6 is applied to the four side surfaces 32.

[0017] In this embodiment, the second substrate portion 40 is a substantially rectangular parallelepiped member made of glass with a thickness of 1.3 mm. The second optical surface 41 is a metasurface. That is, the second lens 102 is a metasurface lens. In this embodiment, the second optical surface 41 includes fine cylindrical pillars with a height of 1000 nm and a diameter of 70 to 300 nm formed by an etching process. Therefore, the second optical surface 41 can add a continuous phase to the wavefront of the incident light beam and bend the traveling direction of the light. The light-shielding paint 6 is provided between one joint surface and the other joint surface of the adjacent second lenses 102. In this embodiment, the light-shielding paint 6 is applied to the four side surfaces 42.

[0018] Note that the metasurface of this embodiment is a diffractive metasurface, but it may also use a diffraction grating.

[0019] Also, in this embodiment, the first optical surface 31 and the second optical surface 41 are metasurfaces, but any one of the first optical surface 31, surfaces 33, 43, and the second optical surface 41 may be a metasurface.

[0020] Figure 3 is a cross-sectional view of the first lens 101 and the second lens 102 of this embodiment. Table 1 shows the optical parameters of this embodiment. The ※ in Table 1 represents the surface whose structure is determined by the phase function. In this embodiment, the first optical surface 31 and the second optical surface 41 are diffractive metasurfaces whose structures are determined by the phase function expressed by Equation (1). In this embodiment, the phase function is determined by an eighth-order function in the radial direction from the center of the optical axis. Table 2 shows the phase coefficients of the phase function.

[0021]

Table 1

[0022]

Number

[0023] (1)

[0024]

Table 2

[0025] The light beam from the light source 1 is incident on the first optical surface 31 and is focused at the surface 33. The light beam focused near the surface 33 of the first lens 101 is incident on the surface 43, passes through the second optical surface 41, and is focused again at the image plane 2. As a result, an image of the object point is formed as an erect image on the image plane 2.

[0026] Figure 4 is a diagram showing a wafer (substrate) 200 for lens fabrication. The wafer 200 is composed of a glass substrate. The lens 201 is a metasurface lens that constitutes a lens array. In Figure 4, 208 lenses 201 can be fabricated on a single wafer 200. Cylindrical pillars on the order of nanometers (not shown) are formed on the surface of the lens 201.

[0027] Figure 5 is a flowchart showing the manufacturing method of the erect imaging lens array element of this embodiment. Figure 6 is a schematic diagram showing a processing example of this embodiment.

[0028] In step S11, the wafer is diced to create a plurality of one-dimensional elements (first elements) extending in a predetermined direction. The plurality of elements 301 to 312 in Fig. 6(a) are a part of the wafer 200 diced at the cutting plane 205 in Fig. 4. The cut surface after dicing is configured to be flat.

[0029] In step S12, as shown in Fig. 6(b), a light-shielding paint 6 is applied to one side surface in the longitudinal direction of the element created in step S11. In the process of this step, since the light-shielding paint 6 can be applied to the entire area of one side surface in the longitudinal direction of each of the plurality of elements at once, it is more efficient than applying it for each lens. In this embodiment, the light-shielding paint is applied to one side surface in the longitudinal direction, but it may be applied to two side surfaces in the longitudinal direction.

[0030] In step S13, as shown in Fig. 6(c), the element to which the light-shielding paint is applied in step S12 is adhered. By adhering the light-shielded surface, an element (second element) with one direction (first direction) light-shielded can be created.

[0031] In step S14, as shown in Fig. 6(d), the element obtained in step S13 is cut so as to be orthogonal to the surface adhered in step S13, and one-dimensional array elements (third elements) 330 to 333 light-shielded in the first direction are created.

[0032] In step S15, the array elements 330 to 333 created in step S14 are adhered in the first direction to create a one-dimensional array element. In this embodiment, a one-dimensional array element with a length of 320 mm is created. In this embodiment, the one-dimensional array element is used as the first lens array 3 and the second lens array 4.

[0033] In step S16, an erect imaging lens array element is created by bonding two one-dimensional array elements.

[0034] As described above, a lens can be fabricated using a high-precision semiconductor manufacturing process. That is, a fine shape on the order of nanometers can be formed on a wafer, and a high-precision erect imaging lens array element can be fabricated by utilizing high-precision cutting and bonding processes.

[0035] In this embodiment, the side surfaces of the rectangular parallelepiped-shaped first substrate portion 30 and second substrate portion 40 are planes perpendicular to the arrangement direction of the respective lenses. Thereby, a light-shielding paint can be applied in a single step to the side surfaces of the one-dimensional elements cut from the wafer.

[0036] In this embodiment, as shown in FIG. 2, the application height (length in the second direction orthogonal to the first direction) d of the light-shielding paint 6 is configured to be smaller than the sum D of the heights (lengths in the second direction orthogonal to the first direction) of the side surface 32 of the first substrate portion 30 and the side surface 42 of the second substrate portion 40. Specifically, it is configured to satisfy the conditional expression 0.5 < d / D < 1.0. By satisfying the above conditional expression, it is possible to suppress the occurrence of defective products due to the light-shielding paint 6 overflowing onto the first optical surface 31 or the second optical surface 41. If the lower limit value of the above conditional expression is exceeded, light beams leak from the non-light-shielding portions where the light-shielding paint 6 is not applied to each side surface, generating ghost light, which is not preferable. If the upper limit value of the above conditional expression is exceeded, since each lens is bonded with an adhesive layer interposed therebetween, the adhesive strength becomes weak, which is not preferable. In FIG. 2, the application height d and the sum D of the side surface heights are 2.3 mm and 2.6 mm, respectively, satisfying the above conditional expression. Note that the value d / D preferably satisfies 0.6 < d / D < 0.9, and more preferably satisfies 0.65 < d / D < 0.90.

[0037] Also, in this embodiment, light shielding is achieved by applying the light-shielding paint 6, but the same effect can be obtained by attaching a thin light-shielding member (for example, a film). Whether the light-shielding paint 6 or the film is used as the light-shielding portion, the thickness is preferably 0.5 mm or less.

[0038] As described above, by providing a light-shielding member on the side surface of the meta-surface lens to which the adhesive is applied, it is possible to realize an erect imaging lens array element that can suppress ghosting caused by light rays passing between adjacent lenses with a simple configuration.

Example

[0039] This example is different from Example 1 in that the erect imaging lens array element is two-dimensionalized. Other configurations are the same as those in Example 1. In this example, only the configuration different from that in Example 1 will be described, and the description of the common configuration will be omitted.

[0040] FIG. 7 is an enlarged schematic diagram of the main part of the erect imaging lens array element of this example. The erect imaging lens array element has a first lens array 8 and a second lens array 9 arranged in order from the object side to the image side. The first lens array 8 includes a plurality of first lenses 101 each joined along a first direction (joining direction, arrangement direction, array direction). The first lens 101 includes a first substrate portion 80. The first substrate portion 80 includes a first optical surface (first surface) 81 parallel to the first direction, four side surfaces 82, and a surface (second surface) 83 facing the first optical surface 81. The second lens array 9 includes a plurality of second lenses 102 each joined along a predetermined direction (joining direction, arrangement direction, array direction). The second lens 102 includes a second substrate portion 90. The second substrate portion 90 includes a second optical surface (third surface) 91 parallel to the first direction, four side surfaces 92, and a surface (fourth surface) 93 facing the second optical surface 91. Note that being parallel to the first direction means that the base portions are parallel, including not only the case of being strictly parallel but also the case of being substantially parallel (roughly parallel).

[0041] In this embodiment, the first optical surface 81 is an incident surface on which light from the light source 1 is incident, and the second optical surface 91 is an exit surface from which light from the light source 1 exits. The surfaces 83 and 93 face each other and are adhered by an adhesive. As a result, the first lens array 8 and the second lens array 9 are integrated. A light-shielding paint 6 is applied to the joint surface (opposing surface) with the adjacent first lens 101 among the four side surfaces 82. Thereby, the incidence of the light beam incident on a predetermined first lens 101 to the adjacent first lens 101 can be suppressed. Also, a light-shielding paint 6 is applied to the joint surface (opposing surface) with the adjacent second lens 102 among the four side surfaces 92. Thereby, the incidence of the light beam incident on a predetermined second lens 102 to the adjacent second lens 102 can be suppressed. Note that the light-shielding paint 6 is preferably applied not only to the joint surface but also to other side surfaces.

[0042] The first substrate portion 80 is, in this embodiment, a substantially rectangular parallelepiped member made of synthetic quartz with a thickness of 1.3 mm. The first optical surface 31 is a metasurface. That is, the first lens 101 is a metasurface lens. In this embodiment, the first optical surface 81 includes fine cylindrical pillars with a height of 1000 nm and a diameter of 70 to 300 nm formed by an etching process. Therefore, the first optical surface 81 can add a continuous phase to the wavefront of the incident light beam and bend the traveling direction of the light. The light-shielding paint 6 is provided between one joint surface and the other joint surface of the adjacent first lens 101. In this embodiment, the light-shielding portion 6 is applied to the four side surfaces 32.

[0043] In this embodiment, the second substrate portion 90 is a substantially rectangular parallelepiped member made of glass with a thickness of 1.3 mm. The second optical surface 91 is a metasurface. That is, the second lens 102 is a metasurface lens. In this embodiment, the second optical surface 91 includes fine cylindrical pillars with a height of 1000 nm and a diameter of 70 to 300 nm formed by an etching process. Therefore, the second optical surface 41 can add a continuous phase to the wavefront of the incident light beam and bend the traveling direction of the light. The light-shielding paint 6 is provided between one joint surface and the other joint surface of two adjacent second lenses 102. In this embodiment, the light-shielding portion 6 is applied to the four side surfaces 92.

[0044] Also, in this embodiment, although the first optical surface 81 and the second optical surface 91 are metasurfaces, any one of the first optical surface 81, surfaces 83, 93, and the second optical surface 91 may be a metasurface.

[0045] FIG. 8 is a flowchart showing a method for manufacturing the erect imaging lens array element of this embodiment. FIG. 9 is a schematic diagram showing a processing example of this embodiment.

[0046] Since the processes of steps S21 to S24 are the same as the processes of steps S11 to S14 in FIG. 5 respectively, the description is omitted.

[0047] In step S25, as shown in FIG. 9(a), the light-shielding paint 6 is applied to one side surface in the longitudinal direction of the array elements 330 to 333 created in step S24.

[0048] In step S26, as shown in FIG. 9(b), the array elements 330 to 333 are adhered in the short-side direction (adhering the surface coated with the light-shielding paint 320) to create a two-dimensional array element. The created two-dimensional array has its joint surface shielded from light. In this embodiment, the two-dimensional array element is used as the first lens array 8 and the second lens array 9.

[0049] In step S27, an erect imaging lens array element is created by bonding two two-dimensional array elements together.

[0050] As described above, in this embodiment, a lens can be created using a high-precision semiconductor manufacturing process. That is, a fine shape on the order of nanometers can be created on the wafer, and a high-precision erect imaging lens array element can be created by utilizing high-precision cutting and bonding processes.

[0051] In this embodiment, the side surfaces of the rectangular parallelepiped-shaped first substrate portion 80 and second substrate portion 90 are planes perpendicular to the arrangement direction of each lens. Thereby, a light-shielding paint can be applied to the side surface of the one-dimensional element cut from the wafer in a single process.

[0052] In FIG. 7, the sum D of the coating height d and the height of the side surface is 1.8 mm and 2.6 mm, respectively, satisfying the conditional expression 0.6 < d / D < 1.0 described in Example 1. Therefore, it is possible to suppress the occurrence of defective products due to the light-shielding paint 6 overflowing onto the first optical surface 81 and the second optical surface 91.

[0053] Also, in this embodiment, light shielding is achieved by applying the light-shielding paint 6, but the same effect can be obtained by stretching a thin light-shielding member. Whether the light-shielding paint 6 or a film is used as the light-shielding portion, the thickness is preferably 0.5 mm or less.

[0054] As described above, by providing a light-shielding member on the side surface of the metasurface lens to be adhered, it is possible to realize an erect imaging lens array element capable of suppressing ghosts caused by light rays passing between adjacent lenses with a simple configuration.

Example

[0055] This embodiment is different from Example 1 in that an intermediate member is disposed between the first lens array 3 and the second lens array 4. Other configurations are the same as those in Example 1. In this embodiment, only the configuration different from Example 1 will be described, and the description of the common configurations will be omitted.

[0056] FIG. 10 is an enlarged schematic view of a main part of the erect image-forming lens array element of this embodiment. The erect image-forming lens array element of this embodiment has an intermediate member 55 disposed between surfaces 33 and 43. In this embodiment, the surface 33 is adhered to the object-side surface of the intermediate member 55, and the surface 43 is adhered to the image-side surface of the intermediate member 55.

[0057] In this embodiment, the first substrate portion 30 and the second substrate portion 40 are substantially rectangular parallelepiped members made of glass with a thickness of 0.5 mm. The intermediate member 55 is a parallel plate (parallel member) made of glass with a thickness of 1.6 mm. In this embodiment, the light beam from the light source 1 is condensed into the intermediate member 55 by the first lens 101 of the first lens array 3. Since the light beam spreads at the joint between the surface 33 and the intermediate member 55 and at the joint between the surface 43 and the intermediate member 55, a part of the light beam is blocked due to the influence of dust or the like during bonding, and it is possible to suppress a decrease in the light amount. That is, in this embodiment, compared with Embodiment 1, the influence of dust during manufacturing can be suppressed.

[0058] Table 3 shows the optical parameters of this embodiment. The ※ in Table 3 is the surface whose structure is determined by the phase function.

[0059]

Table 3

[0060] The light beam that has passed through the first lens 101 is condensed inside the intermediate member 55 and enters the second lens 102. Then, it passes through the second optical surface 41 and is condensed again at the image plane 2. Thereby, an image of the object point is formed as an erect image on the image plane 2.

[0061] In this embodiment, as in Embodiment 1, lenses can be fabricated using a high-precision semiconductor fabrication process. That is, a fine shape on the order of nanometers can be created on the wafer, and a high-precision erect image-forming lens array element can be created by utilizing high-precision cutting and bonding processes.

[0062] In this embodiment, the side surfaces of the rectangular parallelepiped-shaped first substrate portion 30 and second substrate portion 40 are planes perpendicular to the arrangement direction of each lens. As a result, the light-shielding paint can be applied to the side surfaces of the one-dimensional elements cut from the wafer in a single process.

[0063] In FIG. 7, the sum D of the coating height d and the height of the side surface is 2.2 mm and 2.6 mm, respectively, satisfying the conditional expression 0.6 < d / D < 1.0 described in Example 1. Therefore, it is possible to suppress the occurrence of defective products due to the light-shielding paint 6 overflowing onto the first optical surface 31 and the second optical surface 41.

[0064] Also, in this embodiment, light shielding is achieved by applying the light-shielding paint 6, but the same effect can be obtained by stretching a thin light-shielding member. Whether the light-shielding paint 6 or a film is used as the light-shielding portion, the thickness is preferably 0.5 mm or less.

[0065] Also, the thickness of the adhesive layer between the surface 83 of this embodiment and the object-side surface of the intermediate member 55, and the thickness of the adhesive layer between the surface 93 and the image-side surface of the intermediate member 55 are 0.005 mm.

[0066] As described above, by providing a light-shielding member on the side surface of the meta-surface lens to be adhered, it is possible to realize an erect imaging lens array element capable of suppressing ghosts caused by light rays passing between adjacent lenses with a simple configuration. Also, by providing an intermediate member between the two lens arrays, it is possible to suppress the influence of dust or the like during assembly.

Example

[0067] This embodiment differs from Example 3 in that the first optical surface 31 is a surface having curvature. Other configurations are the same as those in Example 3. In this embodiment, only the configuration different from Example 3 will be described, and the description of the common configuration will be omitted.

[0068] FIG. 11 is an enlarged schematic view of the main part of the erect imaging lens array element of this embodiment. The first substrate portion 30 is, in this embodiment, a substantially rectangular parallelepiped member made of glass with a thickness of 1.3 mm. In this embodiment, the first optical surface 31 is a surface having a curvature. That is, in this embodiment, the first lens is a refractive lens. By using the first optical surface 31 as a refractive surface, dirt on the lens surface can be easily wiped off. The second substrate portion 40 is, in this embodiment, a substantially rectangular parallelepiped member made of glass with a thickness of 1.3 mm. The second optical surface 41 is a metasurface. That is, the second lens 102 is a metasurface lens. In this embodiment, the second optical surface 41 includes fine cylindrical pillars with a height of 1000 nm and a diameter of 70 to 300 nm formed by an etching process.

[0069] FIG. 12 is a cross-sectional view of the first lens 101 and the second lens 102 of this embodiment. Table 4 shows the optical parameters of this embodiment. In Table 4, # is a refractive surface whose shape is determined using the following formulas (2) and (3), and ※ is a surface whose structure is determined by a phase function. In formula (2), x is the displacement amount from the vertex of the surface in the optical axis direction, R is the radius of the base quadratic surface, k is the conic constant, and c2 to c8 are aspherical coefficients. Table 5 shows the aspherical coefficients and phase coefficients.

[0070] [Table 4]

[0071] [Table 5]

[0072] [Equation]

[0073] (2)

[0074] [Equation]

[0075] (3) In this embodiment, the shape of the first optical surface 31 is determined such that the light beam from the light source 1 is focused on the surface 33 which is the light emitting surface of the first lens 101. In this embodiment, the first optical surface 31 is an eighth-order aspherical surface, which corrects spherical aberration and field curvature. The light beam focused near the surface 33 of the first lens 101 enters the second lens 102, passes through the second optical surface 41, and is focused again at the image plane 2. As a result, an image of the object point is formed as an erect image on the image plane 2.

[0076] In this embodiment, similar to Embodiment 1, a lens can be fabricated using a high-precision semiconductor fabrication process. That is, a fine shape on the order of nanometers can be formed on the wafer, and a high-precision erect imaging lens array element can be fabricated by utilizing high-precision cutting and bonding processes. Further, by using the first optical surface 31 as a refractive surface, maintenance can be easily performed.

[0077] In this embodiment, the side surfaces of the rectangular parallelepiped-shaped first substrate portion 30 and the second substrate portion 40 are planes perpendicular to the arrangement direction of the respective lenses. Thereby, a light-shielding paint can be applied to the side surfaces of the one-dimensional elements cut from the wafer in a single step.

[0078] In FIG. 11, the coating height d and the sum D of the side surface heights are 2.2 mm and 2.6 mm, respectively, satisfying the conditional expression 0.6 < d / D < 1.0 described in Embodiment 1. Therefore, it is possible to suppress the occurrence of defective products due to the light-shielding paint 6 overflowing onto the first optical surface 31 and the second optical surface 41.

[0079] Also, in this embodiment, light shielding is achieved by applying the light-shielding paint 6, but the same effect can be obtained by attaching a thin light-shielding member. Whether the light-shielding paint 6 or the film is used as the light-shielding portion, the thickness is preferably 0.5 mm or less.

[0080] In addition, in this embodiment, the refractive lens is formed by glass molding, but the same effect can be obtained by using a method of molding a resin lens with a mold on a glass substrate. Also, although the incident surface is set as the refractive surface, the refractive surface may be used for the emission surface that is close to the surface of the photosensitive drum and is likely to get dirty.

[0081] As described above, according to the configuration of this embodiment, an erect imaging lens array element capable of suppressing ghosts caused by light rays passing between adjacent lenses with a simple configuration can be realized. Also, by setting at least one of the incident surface and the emission surface as the refractive surface, the maintainability can be improved.

[0082] The disclosure of this embodiment includes the following configurations and methods. (Configuration 1) A first lens array including a plurality of first lenses joined together along a first direction, A second lens array including a plurality of second lenses joined together along the first direction, A light-shielding portion, and having At least one of the surfaces of the first lens and the second lens parallel to the first direction is a metasurface, The light-shielding portion is provided between the opposing surfaces of adjacent first lenses among the plurality of first lenses and between the opposing surfaces of adjacent second lenses among the plurality of second lenses. An optical element characterized by this. (Configuration 2) In a second direction orthogonal to the first direction, the first lens array and the second lens array are bonded. The optical element according to Configuration 1, characterized by this. (Configuration 3) The opposing surface is a flat surface. The optical element according to Configuration 1 or 2, characterized by this. (Configuration 4) The light-shielding portion is either paint or a film, The length of the light-shielding portion in the first direction is 0.5 mm or less. The optical element according to any one of Configurations 1 to 3, characterized by this. (Configuration 5) When the length in the second direction orthogonal to the first direction of the first lens array and the second lens array is D, and the length in the second direction of the light shielding portion is d, 0.5 < d / D < 1.0 The optical element according to any one of Configurations 1 to 4, characterized by satisfying the conditional expression. (Configuration 6) The optical element according to any one of Configurations 1 to 5, characterized in that the first lens array and the second lens array are two-dimensional arrays. (Configuration 7) The optical element according to any one of Configurations 1 to 6, characterized in that the first lens and the second lens are each made of either synthetic quartz or glass. (Configuration 8) The optical element according to any one of Configurations 1 to 7, further comprising an intermediate member disposed between the first lens array and the second lens array in the second direction orthogonal to the first direction. (Configuration 9) The optical element according to any one of Configurations 1 to 8, characterized in that the light shielding portion is provided on at least one of the surfaces of the other first lens that are different from the surface parallel to the first direction of one of the adjacent first lenses and do not face the other first lens, and at least one of the surfaces of the other second lens that are different from the surface parallel to the first direction of one of the adjacent second lenses and do not face the other second lens. (Configuration 10) The surface of the first lens parallel to the first direction consists of a first surface and a second surface, The surface of the second lens parallel to the first direction consists of a third surface and a fourth surface, The first surface is an incident surface on which a light beam from a light source is incident, The second surface and the third surface face each other, The optical element according to any one of Configurations 1 to 9, characterized in that the fourth surface is an emission surface from which the light beam is emitted. (Configuration 11) The optical element according to any one of Configurations 1 to 10, and An optical device characterized by having a light source. (Method 1) A method for manufacturing an optical element, comprising: a first lens array including a plurality of first lenses respectively joined along a first direction; a second lens array including a plurality of second lenses respectively joined along the first direction; and a light-shielding portion. The step of creating a plurality of first elements extending in a predetermined direction from the substrate. The step of providing the light-shielding portion on at least one of the side surfaces extending in the predetermined direction of each of the plurality of first elements. The step of joining the plurality of first elements provided with the light-shielding portion through the light-shielding portion to create a second element. The step of creating a plurality of third elements extending in the first direction from the second element. The step of creating at least one of the first lens array and the second lens array using the third element. A method for manufacturing an optical element, characterized by comprising the above steps.

[0083] The preferred embodiments of the present invention have been described above. However, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist thereof.

Explanation of Reference Numerals

[0084] 3,8 First lens array 4,9 Second lens array 101 First lens 102 Second lens

Claims

1. A first lens array including a plurality of first lenses each joined along a first direction, a second lens array including a plurality of second lenses each joined along the first direction, and a light-shielding portion, wherein at least one of the planes parallel to the first direction of the first lens and the second lens is a metasurface, and the light-shielding portion is provided between opposing surfaces of adjacent first lenses among the plurality of first lenses and between opposing surfaces of adjacent second lenses among the plurality of second lenses. An optical element characterized by this.

2. The optical element according to claim 1, wherein the first lens array and the second lens array are adhered in a second direction orthogonal to the first direction.

3. The optical element according to claim 1 or 2, wherein the opposing surface is a flat surface.

4. The light-shielding portion is either paint or a film, and the length of the light-shielding portion in the first direction is 0.5 mm or less. The optical element according to claim 1 or 2, characterized by this.

5. When the length in a second direction orthogonal to the first direction of the first lens array and the second lens array is D and the length in the second direction of the light-shielding portion is d, 0.5 < d / D < 1.0 The optical element according to claim 1 or 2, characterized by satisfying the conditional expression.

6. The optical element according to claim 1 or 2, wherein the first lens array and the second lens array are two-dimensional arrays.

7. The first lens and the second lens are each either synthetic quartz or glass. The optical element according to claim 1 or 2, characterized by this.

8. The optical element according to claim 1 or 2, further comprising an intermediate member disposed between the first lens array and the second lens array in a second direction orthogonal to the first direction.

9. The light-shielding portion is provided on at least one of the surfaces of the other first lens that do not face the other first lens among the surfaces different from the plane parallel to the first direction of one of the adjacent first lenses, and at least one of the surfaces of the other second lens that do not face the other second lens among the surfaces different from the plane parallel to the first direction of one of the adjacent second lenses. The optical element according to claim 1 or 2, characterized by this.

10. The plane parallel to the first direction of the first lens consists of a first surface and a second surface, The plane of the second lens parallel to the first direction consists of a third surface and a fourth surface. The first surface is an incident surface on which a light beam from a light source is incident. The second surface and the third surface face each other. The optical element according to claim 1 or 2, wherein the fourth surface is an exit surface from which the light beam is emitted.

11. An optical device comprising the optical element according to claim 1 or 2 and a light source.

12. A method for manufacturing an optical element, comprising: a first lens array including a plurality of first lenses each joined along a first direction; a second lens array including a plurality of second lenses each joined along the first direction; and a light-shielding portion, the method comprising: creating a plurality of first elements extending from a substrate in a predetermined direction; providing the light-shielding portion on at least one of side surfaces of the plurality of first elements extending in the predetermined direction; joining the plurality of first elements provided with the light-shielding portion through the light-shielding portion to create a second element; creating a plurality of third elements extending from the second element in the first direction; and creating at least one of the first lens array and the second lens array using the third elements.

13.

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