Beam intensity homogenization element

Abstract

This disclosure provides a beam intensity homogenizing element comprising an optical substrate, a first lens array disposed on the surface of the optical substrate, and a second lens array disposed on the back surface of the optical substrate. The first lens array has a plurality of first molded lens units arranged in multiple different directions along the surface of the optical substrate. Each of the plurality of first molded lens units has a surface formed with a plurality of first linear traces extending along a first direction and constituting the surface of the optical substrate. The second lens array has a plurality of second molded lens units arranged in multiple different directions along the back surface of the optical substrate. Each second molded lens unit has a surface formed with a plurality of second linear traces extending along a second direction different from the first direction and constituting the back surface of the optical substrate. This beam intensity homogenizing element can suppress the generation of interference fringes and can reduce costs.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a beam intensity homogenizing element for homogenizing a light intensity distribution of light rays. BACKGROUND

[0002] The beam intensity homogenizing element includes a lens array. The lens array has a structure in which a plurality of lens units are arranged in two dimensions. The lens array is manufactured by so-called mold forming in which a glass material is pressed to be shaped with a mold. In the mold in the mold forming, a shaped surface that transfers a lens surface is manufactured by cutting processing or the like, and thus a linear processing trace along a processing direction is formed on the shaped surface. The processing trace is transferred to a surface of a molded lens unit as a linear trace. Since the linear trace regularly exists on the surface of the molded lens unit, an interference fringe is generated in light rays that pass through the molded lens unit.

[0003] In order to suppress the interference fringe, a configuration is proposed in which a pitch of the linear trace of the plurality of molded lens units formed in the lens array is made different for each of the adjacent molded lens units.

[0004] A conventional beam intensity homogenizing element is disclosed in, for example, Patent Literature 1.

[0005] PRIOR ART DOCUMENT

[0006] PATENT LITERATURE

[0007] Patent Literature 1: Japanese Patent Application Publication No. 2016-1225 SUMMARY

[0008] In the conventional beam intensity homogenizing element described above in which the pitch of the linear trace is made different for each of the lens units, the processing condition of each of the lens units in the shaped surface of the mold must be changed. That is, the mold processing for mold forming of the lens array becomes very complicated. Therefore, the manufacturing cost of the mold becomes high, and as a result, the cost of the lens array rises.

[0009] The beam intensity homogenizing element includes an optical base, a first lens array arranged on a surface of the optical base, and a second lens array arranged on a back surface of the optical base. The first lens array has a plurality of first molded lens units arranged in a plurality of different directions along the surface of the optical base. The plurality of first molded lens units have surfaces on which a plurality of first linear traces extending in a first direction are formed and which constitute the surface of the optical base. The second lens array has a plurality of second molded lens units arranged in a plurality of different directions along the back surface of the optical base. The second molded lens units have surfaces on which a plurality of second linear traces extending in a second direction different from the first direction are formed and which constitute the back surface of the optical base.

[0010] The light beam intensity uniformization element can suppress the generation of interference fringes and can reduce costs. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 is a three-view diagram schematically showing a light beam intensity uniformization element in an embodiment of the present disclosure.

[0012] Figure 2 is a schematic diagram showing a manufacturing method of the light beam intensity uniformization element in an embodiment.

[0013] Figure 3 is a schematic diagram showing a manufacturing method of a mold forming surface in a forming device of the manufacturing method in an embodiment.

[0014] Figure 4 is a diagram showing interference fringes of the light beam intensity uniformization element in an embodiment.

[0015] Figure 5 is a diagram showing interference fringes of the light beam intensity uniformization element of a comparative example in which the directions of linear traces are uniform. DETAILED DESCRIPTION

[0016] Hereinafter, a light beam intensity uniformization element related to an embodiment of the present disclosure will be described using the drawings. In addition, each of the embodiments described below shows a preferred specific example of the present disclosure. Therefore, the shape, the constituent element, the arrangement of the constituent element, and the connection method, and the like shown in the following embodiments are one example, and the gist thereof is not intended to limit the present disclosure. Therefore, for the constituent element among the constituent elements in the following embodiments which is not described in the constituent element of the most general concept indicating the present invention, the independent technical solution, the constituent element is described as an arbitrary constituent element.

[0017] Further, each of the drawings is a schematic diagram, and the illustration is not necessarily strict. In each of the drawings, the same symbol is attached to the substantially same configuration, and the repeated description is omitted or simplified.

[0018] Figure 1 is a three-view diagram of a light beam intensity uniformization element 100 in an embodiment of the present disclosure.

[0019] The light beam intensity uniformization element 100 is an optical element which transforms the light intensity distribution of the incident light and outputs it. For example, the light having a Gaussian-type light beam intensity distribution outputted from a laser diode is transformed into light having a top-flat-type light beam intensity distribution and outputted. The basic configuration of the light beam intensity uniformization element 100 has an optical base 10 having a surface 10a and a back surface 10b which are opposite to each other, a lens array 11 arranged on the surface 10a of the optical base 10, and a lens array 12 arranged on the back surface 10b of the optical base 10.

[0020] The lens array 11 disposed on the surface 10a of the optical substrate 10 includes a plurality of molded lens units 11a arranged in two dimensions. The plurality of molded lens units 11a are arranged along the surface 10a of the optical substrate 10 in multiple different directions D100. In one embodiment, in the lens array 11, 16 molded lens units 11a are arranged in four columns longitudinally and four columns laterally. The plurality of molded lens units 11a have surfaces 11c formed with multiple linear traces 11b extending along the direction D11 and constituting the surface 10a of the optical substrate 10. Figure 1 The multiple solid vertical lines marked in the second column from the left of the molded lens unit 11a represent linear traces 11b formed on the surface 10a of the optical substrate 10. For ease of illustration, the linear traces 11b are only marked in the second column from the left of the molded lens unit 11a, but in reality, linear traces 11b are formed in all columns. Details regarding the linear traces 11b will be described later.

[0021] The lens array 12 disposed on the back surface 10b of the optical substrate 10 includes a plurality of molded lens units 12a arranged in a two-dimensional configuration. That is, the plurality of molded lens units 12a are arranged along the back surface 10b of the optical substrate 10 in multiple different directions D100. In one embodiment, in the lens array 12, 16 molded lens units 12a are arranged in four columns longitudinally and four columns laterally. The plurality of molded lens units 12a have surfaces 12c formed with multiple linear traces 12b extending along the direction D12 and constituting the back surface 10b of the optical substrate 10. Figure 1 The multiple horizontal dashed lines marked in the second column from the top of the molded lens unit 12a represent linear traces 12b formed on the back side of the optical substrate. For ease of illustration, the linear traces 12b are only marked in the second column from the top of the molded lens unit 12a, but in reality, linear traces 12b are formed in all columns. Details regarding the linear traces 12b will be described later.

[0022] Each molded lens unit 11a disposed on the surface 10a of the optical substrate 10 is configured to be opposite to a corresponding molded lens unit 12a disposed on the back surface 10b of the optical substrate 10.

[0023] Next, the manufacturing method of the beam intensity homogenization element 100 will be described. Figure 2 The manufacturing process of the beam intensity homogenizing element 100 is schematically shown. The forming apparatus 20 for manufacturing the beam intensity homogenizing element 100 includes a lower mold 21 and an upper mold 22.

[0024] The upper surface of the lower mold 21 is a molding surface 21b that molds the lens array 12. The molding surface 21b has a shape that transfers the shape of the surfaces 12c of the plurality of molded lens units 12a to the back surface 10b of the optical substrate 10.

[0025] The lower surface of the upper mold 22 is a molding surface 22b that molds the lens array 11. The molding surface 22b has a shape that transfers the shape of the surfaces of the plurality of molded lens units 11a to the surface 10a of the optical substrate 10.

[0026] The beam intensity uniformization element 100 is molded by the glass material 13 composed of optical glass. As shown in the figure, first, the glass material 13 is disposed on the molding surface 21b of the lower mold 21. Next, the glass material 13 is heated. The glass material 13 is warmed to a temperature at which it can be press-molded, and then the glass material 13 is press-molded by the lower mold 21 and the upper mold 22. After that, the glass material 13 that has been press-molded is cooled, and the glass material 13 that has been press-molded, that is, the beam intensity uniformization element 100 is taken out from between the lower mold 21 and the upper mold 22.

[0027] On the surfaces of the molded lens units 11a, 12a of the beam intensity uniformization element 100 thus produced, a plurality of linear marks 11b, 12b are formed. The linear marks 11b, 12b are formed as a result of the molding surface 21b, 22b of the lower mold 21 and the upper mold 22 being produced. The molding surface 21b, 22b of the lower mold 21 and the upper mold 22 is produced by cutting processing. In Figure 3 A working diagram of the cutting processing is shown in FIG. 12. The cutting tool 31 cuts the processing surface 30a of the mold member 30. At this time, the cutting tool 31 moves linearly in the direction D5 that is at right angles to the upward direction D3 and the downward direction D4 while adjusting the amount of sinking into the processing surface 30a by moving in the upward direction D3 and the downward direction D4. The cutting tool 31 cuts the processing surface 30a linearly, and thus forms one row of molded lenses. After the cutting is completed, the cutting tool 31 is moved relatively to the glass material 13 to perform cutting for forming an adjacent row of molded lenses. The molding surface is produced by repeating this process. Therefore, on the processing surface 30a after the cutting processing, linear processing marks corresponding to the cutting pitch at which the cutting tool 31 is moved are regularly formed. In addition, the plurality of processing marks that are formed with respect to one processing surface 30a are parallel to each other. Furthermore, in the case where the lens array 11, 12 is manufactured with the processing surface 30a having such processing marks, the processing marks are transferred to the surface of the lens array 11, 12, that is, the surfaces 11c, 12c of the molded lens units 11a, 12a. The processing marks that are transferred to the surfaces 11c, 12c of the molded lens units 11a, 12a become the linear marks 11b, 12b shown in FIGS. 1 and 2. Figure 1 ​

[0028] As Figure 1 shown, the light beam intensity homogenizing element 100 has a unitary configuration in which the two lens arrays 11, 12 are arranged on the surface 10a and the back surface 10b of the optical base 10. The direction D11 in which the linear traces 11b of the lens array 11 of the surface 10a extend is different from the direction D12 in which the linear traces 12b of the lens array 12 of the back surface 10b extend. The linear traces 11b, 12b in the lens arrays 11, 12 can become the cause of the generation of interference fringes as described above. However, by making the directions D11, D12 in which the linear traces 11b, 12b of the two lens arrays 11, 12 of the light beam intensity homogenizing element 100 extend different, the direction of the interference fringes in the lens array 11 and the direction of the interference fringes in the lens array 12 are made different, as a result of which the interference fringes of both interfere with each other, and the generation of interference fringes in the light beam intensity homogenizing element 100 can be suppressed.

[0029] For more effectively suppressing the generation of interference fringes in the light beam intensity homogenizing element 100, it is preferable to arrange the lens arrays 11, 12 in a manner in which the direction D11 in which the linear traces 11b of the lens array 11 extend and the direction D12 in which the linear traces 12b of the lens array 12 extend are orthogonal. Figure 4 The interference fringes of the light beam intensity homogenizing element 100 in which the directions D11, D12 are orthogonal to each other are shown. In Figure 4 , no clear interference fringes are confirmed. Figure 5 The interference fringes of the light beam intensity homogenizing element of the comparative example in which the directions D11, D12 are identical to each other are shown. In Figure 5 , clear interference fringes are confirmed. As Figure 4 and Figure 5 shown, by the direction D11 in which the linear traces 11b of the lens array 11 extend and the direction D12 in which the linear traces 12b of the lens array 12 extend being orthogonal, the interference fringes of the light beam intensity homogenizing element 100 are suppressed.

[0030] That is, the method of suppressing interference fringes achieved by the light beam intensity homogenizing element 100 in the present disclosure makes the directions of the linear traces 11b of the lens array 11 and the linear traces 12b of the lens array 12 different from each other. Therefore, it is not necessary to make the pitch of the linear traces different in units of molded lens units as in the past. That is, it is possible to set the pitch of the linear traces 11b, 12b to be equally spaced in the light beam intensity homogenizing element 100. In this case, there is no need to change the cutting pitch in the cutting processing explained in Figure 3 . As a result, it is possible to shorten the processing time of the cutting processing, and it is possible to reduce the cost of the light beam intensity homogenizing element 100.

[0031] Further, since the cutting pitch becomes uniform, it is possible to optimize the cutting pitch. For example, it is possible to set the cutting pitch to the minimum pitch in the cutting device. By setting the cutting pitch to the minimum, it is possible to further improve the machining precision of the shaped surface, and thus it is possible to reduce the transmission loss of the light in the light beam intensity uniformization element 100.

[0032] In order to uniformize the intensity distribution of light, it is common to arrange 2 or more lens arrays on the optical axis. By being configured to integrate the 2 lens arrays with the surface 10a and the back surface 10b of the optical base 10 as in the light beam intensity uniformization element 100, it is possible to ensure the relative positions of the 2 lens arrays 11, 12 at the level of the precision of the mold, and thus it is possible to easily assemble the light beam intensity uniformization element 100 to the light source device.

[0033] Industrial applicability

[0034] The present disclosure has the effect of suppressing the cost of the light beam intensity uniformization element that suppresses the interference fringes, and is particularly effective in a small laser source device.

[0035] Symbol explanation

[0036] 10 Optical base;

[0037] 11, 12 Lens array;

[0038] 11a, 12a Molded lens unit;

[0039] 11b, 12b Linear trace;

[0040] 100 Light beam intensity uniformization element.

Claims

1. A light beam intensity homogenizing element, comprising: an optical substrate having a surface and a back surface opposite to each other; a first lens array disposed on the surface of the optical substrate; and a second lens array disposed on the back surface of the optical substrate, the first lens array having a plurality of first molded lens units arranged in different directions along the surface of the optical substrate, the plurality of first molded lens units having a surface formed with a plurality of first linear traces extending along a first direction and constituting the surface of the optical substrate, the second lens array having a plurality of second molded lens units arranged in different directions along the back surface of the optical substrate, the plurality of second molded lens units having a surface formed with a plurality of second linear traces extending along a second direction different from the first direction and constituting the back surface of the optical substrate.

2. The light beam intensity homogenizing element according to claim 1, wherein the first direction is orthogonal to the second direction. ​ ​ ​ ​ ​ ​ ​ ​

Images