JP3698133B2 - Micro lens array - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a two-dimensional microlens array suitable for use in combination with a plurality of optical fibers.
[0002]
[Prior art]
Conventionally, as a two-dimensional microlens array, those shown in FIGS. 7 to 9 have been proposed.
[0003]
As an example, 16 convex lenses 2a, 2b... 2e, 2f... Are two-dimensionally arranged on one main surface of the quartz substrate 1 along X and Y directions orthogonal to each other. On the other main surface of the substrate 1, inclined surface forming portions 3A, 3B, 3C, and 3D are provided corresponding to the four convex lens rows in the X direction, respectively.
[0004]
Each inclined surface forming portion typically forms an inclined surface having an inclination of θ = 5 to 15 degrees with respect to the other main surface of the substrate 1 as shown in FIG. The direction of the inclined surface is set so as to face the direction (minus Y direction) orthogonal to the X direction.
[0005]
When the microlens array is used, the optical fiber 4a is incident on the other principal surface side of the substrate 1 so that light enters the convex lenses 2a to 2d via the inclined surface forming portion 3A as shown in FIGS. ~ 4d are arranged. As an example, as shown in FIGS. 8 and 9, light 5 enters the convex lens 2a via the inclined surface forming portion 3A, and the light 5 is converted into parallel light by the convex lens 2a. At this time, the light 5r reflected by the inclined surface of the inclined surface forming portion 3A deviates from the optical fiber 4a as shown in FIG. 9, and does not enter the optical fiber 4a. That is, by providing the inclined surface forming portion 3A, it is possible to reduce reflected light returning to the optical fiber 4a and reflected light entering the optical fiber 4b.
[0006]
[Problems to be solved by the invention]
According to the above-described prior art, for example, some of the reflected light that enters the convex lens 2a from the optical fiber 4a is less likely to enter the optical fibers 4a and 4b, but the inclined surface forming portion 3A is in the minus Y direction. Since it faces, it becomes easy to inject into the optical fiber corresponding to the convex lens 2e. The same applies to some of the reflected light that enters the other convex lens from another optical fiber. For example, some of the reflected light that enters the convex lens 2b from the optical fiber 4b is Although it becomes difficult to enter the optical fibers 4a, 4b, and 4c, it becomes easy to enter the optical fiber corresponding to the convex lens 2f.
[0007]
An object of the present invention is to provide a novel micro that can reduce the light incident on the optical fiber in the vicinity of each optical fiber by reflection when light is incident on the plurality of lenses of the micro lens array from the plurality of optical fibers. It is to provide a lens array.
[0008]
[Means for Solving the Problems]
A microlens array according to the present invention is a microlens array in which a plurality of lenses are two-dimensionally arranged along two different directions on one main surface of a light-transmitting substrate,
The other principal surface of the translucent substrate is provided with a plurality of inclined surface forming portions opposed to the plurality of lenses, and each inclined surface forming portion has an angle of 5 to 15 degrees with respect to the other main surface. An inclined surface having an inclination is formed, and the direction of each inclined surface is set to be different from any of the two directions.
[0009]
According to the microlens array of the present invention, since the direction of each inclined surface is set to be different from any of the two directions which are the lens arrangement directions, a part of the incident light from the optical fiber is caused by the inclined surface for each lens. For example, the light that is reflected and deviated from the vertical and horizontal lens arrangement directions can reduce the light incident on the optical fiber in the vicinity thereof for each optical fiber.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a two-dimensional microlens array according to an embodiment of the present invention. FIG. 2 shows a cross section taken along line SS ′ of FIG.
[0011]
For example, circular convex lenses L ₁₁ , L ₁₂ ... L ₂₁ , L ₂₂ ... Are arranged two-dimensionally along the X and Y directions orthogonal to each other on one main surface of the light transmitting substrate 10 made of quartz. Yes. Convex lens _L 11 on the other main surface of the substrate _{10, L 12 ... L 21,} L 22 ... to oppositely square incline forming unit _K 11 _{in, K 12 ... K 21, K} 22 ... are respectively provided Yes.
[0012]
In the microlens array shown in FIG. 1, as an example, 4 × 4 convex lenses are provided on one main surface of the substrate 10, and 4 × 4 inclined surface forming portions are on the other main surface of the substrate 10. It is provided on the surface. A pitch P between adjacent convex lenses (a distance between lens centers) P can be set to 1 mm.
[0013]
Figure 2 shows a cross-sectional configuration of the lens unit for one piece Typically respect convex lens _{L 11,} the diameter R of the convex lens _{L 11} is a 0.5 mm, the length of one side of the inclined surface forming portion _{K 11} is , 0.5 mm. The thickness T of the substrate 10, and 1.2 mm, the height H of the convex lens _{L 11} may be a 0.06 mm. The inclined surface forming portion K ₁₁ forms an inclined surface having an inclination of θ = 5 to 15 degrees (preferably 8 degrees) with respect to the other main surface of the substrate 10. The other lens portions have the same configuration as described above with reference to FIG.
[0014]
In each inclined surface forming portion, as shown in FIG. 1, the direction of the inclined surface is set to be different from both the X and Y directions. This will be described for the inclined surface forming portion K ₄₂ corresponding to the convex lens L ₄₂ . In the inclined surface forming portion K _42, and a straight line Kx extending in the X direction through the center of the inclined surface, and the straight line Ky extending in the Y direction through the center of the inclined surface, the straight line Kx, Ky and in a common plane Assuming a straight line Kc extending in the direction of the inclined surface through the center of the inclined surface, the direction of the inclined surface is set so that the straight line Kc is sandwiched between the straight lines Kx and Ky. Assuming that the angle at which the straight lines Ky and Kc intersect is k, for example, the direction of the inclined surface can be set so that k = 30 degrees.
[0015]
According to the microlens array described above, the light emitted from the optical fiber is incident on the corresponding convex lens from the other main surface side of the substrate 10 via each inclined surface forming portion in the same manner as described above with reference to FIGS. When, a part of the incident light is reflected by the inclined surface of the inclined surface forming portion such as K ₄₂ X, deviate in a direction different from any of the direction of the Y. For this reason, the reflected light returning to the optical fiber is reduced for each optical fiber, and the reflected light incident on the optical fiber in the vicinity thereof is reduced for each optical fiber.
[0016]
As an example, when attention is focused on the optical fiber corresponding to the convex lens L _12, one of the inclined surface forming portion K _13, K ₂₂ part of the exit light from the optical fiber is reflected by the inclined surface of the inclined surface forming portion K ₁₂ Is directed in a direction that does not overlap. Therefore, the reflected light is reduced back to the optical fiber corresponding to the convex lens L _12, a convex lens L _{11, L 13,} reflected light incident on the corresponding optical fiber L ₂₂ is the reduced.
[0017]
The shape of the inclined surface is not limited to a square shape, and may be a polygonal shape such as a hexagonal shape or a circular shape. Moreover, the magnitude | size of an inclined surface should just be a magnitude | size which can inject | emit the emitted light from an optical fiber to a lens, and may be larger or smaller than the magnitude | size of a lens. Furthermore, the direction of each inclined surface is the same for all lenses, but may be different for each lens or lens array.
[0018]
3-6 shows an example of the manufacturing method of the microlens array of FIG. In the process of FIG. 3, resist layers R _{1 to} R ₄ are formed on the upper surface of the transparent substrate 10 made of quartz according to a desired lens pattern by photolithography and heat treatment. Each resist layer is formed so as to form a spherical convex portion.
[0019]
In the process of FIG. 4, the resist layers R _{1 to} R ₄ and the substrate 10 are etched by the RIE (reactive ion etching) method to thereby form the convex lenses L _{11 to} L ₁₄ corresponding to the resist layers R _{1 to} R ₄ , respectively. Form.
[0020]
In the process of FIG. 5, the substrate 10 is turned over, and a positive resist is applied to the upper surface (original lower surface) of the substrate 10. Then, a photomask 12 is prepared in which the optical density changes in an inclined manner from one side to the opposite side for each square region of the _four square regions M _{1 to} M ₄ respectively corresponding to the convex lenses L _{11 to} L _14. To do. Direction optical density in each square area of the photomask 12 varies gradiently also set differently with any of X, the Y-direction a lens array direction in the same manner as previously described with respect to the inclined surface forming portion K ₄₂ of FIG. 1 It is. Next, after exposing the positive resist layer on the substrate 10 through the photomask 12 and developing the positive resist layer, resist layers R _{11 to} R ₁₄ made of the remaining positive resist are obtained.
[0021]
In the exposure process, in the square resist region corresponding to each square region of the photomask 12, the exposure dose increases as it proceeds from one side to the opposite side, so that the resist thickness gradually decreases, and each resist layer As shown in FIG. 5, a resist layer having a blade-like cross section (having an inclined surface) is obtained. In addition, since the direction in which the optical density changes in an inclined manner in each square region of the photomask 12 is set to be different from both the X and Y directions, the direction of the inclined surface of each resist layer is set in the X and Y directions. It becomes different from any of.
[0022]
In the step of FIG. 6, the inclined surface forming portions K _{11 to} K ₁₄ corresponding to the resist layers R _{11 to} R ₁₄ are obtained by etching the resist layers R _{11 to} R ₁₄ and the substrate 10 by the RIE method. As each inclined surface forming portion, an inclined surface with respect to the substrate surface having an inclination of 5 to 15 degrees and a direction of the inclined surface different from both the X and Y directions can be obtained.
[0023]
【The invention's effect】
As described above, according to the present invention, a plurality of lenses are arranged two-dimensionally along two different directions on one main surface of the substrate and correspond to each lens on the other main surface of the substrate. In the microlens array in which the inclined surface having an inclination of 5 to 15 degrees is formed, the direction of each inclined surface is set to be different from any of the two lens arrangement directions. When light is incident on the lens, the effect of reducing the light incident on the optical fiber in the vicinity of each optical fiber by reflection can be obtained.
[Brief description of the drawings]
FIG. 1 is a plan view showing a microlens array according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along the line SS ′ of FIG.
3 is a cross-sectional view showing a resist layer forming step in the manufacturing method of the microlens array of FIG. 1. FIG.
4 is a cross-sectional view showing a lens formation step subsequent to the step of FIG. 3. FIG.
5 is a cross-sectional view showing a resist layer forming step that follows the step of FIG. 4. FIG.
6 is a cross-sectional view showing a step of forming an inclined surface forming portion subsequent to the step of FIG.
FIG. 7 is a plan view showing a conventional microlens array.
8 is a cross-sectional view taken along line AA ′ of FIG.
FIG. 9 is a cross-sectional view taken along line BB ′ of FIG.
[Explanation of symbols]
10: light transmitting substrate 12: _{photomask, L 11 ~L 22, L 42} : convex _{lens, K 11 ~K 22, K 42} : inclined surface forming _{portion, R 1 ~R 4, R 11} ~R 14: resist layer.

Claims (1)

A microlens array in which a plurality of lenses are two-dimensionally arranged along two different directions on one main surface of a light-transmitting substrate,
The other principal surface of the translucent substrate is provided with a plurality of inclined surface forming portions opposed to the plurality of lenses, and each inclined surface forming portion has an angle of 5 to 15 degrees with respect to the other main surface. A microlens array, wherein an inclined surface having an inclination is formed and the direction of each inclined surface is set to be different from any of the two directions.

Images