JP6917810B2 - Diffusion unit - Google Patents

Description

The present invention relates to a diffusion unit.

A diffusing plate or a diffusing unit provided with a diffusing plate that diffuses light incident from one side and emits it as diffused light from the other side is used in various optical devices such as a single-lens reflex camera.

As one of such diffusers, one using a microlens array in which a large number of microlenses are arranged in a plane is known.
In the diffuser plate using the microlens as described above, it is relatively easy to control the divergence angle by changing the optical characteristics of the microlens.

However, due to the characteristics of a microlens, diffraction and interference of emitted light are more likely to occur than a diffuser plate having a random surface such as frosted glass, and the light intensity diffused within the diffusion range is made uniform and the divergence angle is increased. It was difficult to meet control at the same time.

An object of the present invention is to realize a novel diffusion unit that achieves both uniform light intensity and control of divergence angle in order to solve such a problem.

The diffusion unit of the present invention has at least two diffusion surfaces in which a plurality of minute lens surfaces are arranged along the incident direction of the light beam, and the diffusion surfaces are the minute lens surfaces of each other when viewed from the incident direction side. Are arranged so that one side constituting the lens does not overlap and is non-parallel to each other, and the center positions of the minute lens surfaces are arranged so as to be offset from each other. The aperture shape that constitutes the lens surface is an equilateral triangle .

According to the present invention, it is possible to realize a novel diffusion unit that achieves both uniform light intensity and control of divergence angle.

It is a figure for demonstrating an example of embodiment of a diffusion unit. It is a figure which shows an example of the structure of the diffusion plate which constitutes a diffusion unit. It is a figure which shows an example of the cross-sectional shape of the diffusion plate shown in FIG. It is a figure which shows the deformation example which the lens shape of the diffuser plate shown in FIG. 2 is different. It is a figure which shows the deformation example which the lens shape of the diffuser plate shown in FIG. 2 is different. It is a figure which shows the conventional example of the image projected on the image plane when a diffuser plate is used. It is a figure which shows the example of the image projected on the image plane when the diffusion unit of this invention is used. It is a figure which shows the other embodiment of this invention. It is a figure which shows an example of the structure of the diffusion plate in the embodiment shown in FIG. It is a figure which shows the other structural example of the diffusion plate in the embodiment shown in FIG. It is a figure which shows the other structural example of the diffusion plate in this invention. It is a figure which shows the other structural example of the diffusion plate in this invention. It is a figure which shows the variation example of a different lens shape of a diffuser plate in this invention. It is a figure which shows the deformation example of a different lens shape shown in FIG.

FIG. 1 describes an optical device 100 using a diffusion unit 10 as a light diffusion means including a diffusion surface as an example of an embodiment of the present invention.
The optical device 100 diffuses the light source 20, the collimating lens 5 for converting the projected light L emitted from the light source 20 into a parallel luminous flux, and the projected light L that has become parallel light at a predetermined diffusion angle 2θ. It has a diffusion unit 10 for the purpose.

The light source 20 is a semiconductor laser light source in this embodiment.
The light source 20 is not limited to such a configuration, and may be another laser light source, a white light source, or the like.
However, since the diffusion unit 10 is intended to reduce interference fringes and speckles generated at the time of imaging when a light source having high coherence such as a laser light source is used, it is desirable that the diffusion unit 10 is a light source having high coherence.

As shown in FIG. 2, the diffusion unit 10 has diffusion plates 12a and 12b, which are MLAs (microlens arrays) in which a plurality of microlenses 11 are arranged in a plane.
In the present embodiment, as shown in FIG. 1, a set of two MLAs is arranged along the A direction, which is the incident direction of the projected light L.
In FIG. 2, a schematic view of the diffusion unit 10 when viewed from the A direction side is shown in a solid line with the MLA on the light source 20 side as the first diffusion plate 12a and the MLA on the emission side as the second diffusion plate in particular. It will be described and described as a one-dot chain line as 12b.

The first diffusion plate 12a and the second diffusion plate 12b are both plate-shaped members having the same shape, and the microlenses 11 having a regular hexagonal opening shape on the surface form an array pattern having a hexagonal close-packed structure. They are lined up.
As shown in FIG. 3, each microlens 11 forms a microlens surface 14 which is a diffusion surface having a convex shape whose cross section protrudes to one side.
With this configuration, the first diffusion plate 12a and the second diffusion plate 12b each have a function as a diffusion plate that diverges the incident projected light L at a divergence angle of 2θ, as shown in FIG. ..
In the present embodiment, the shape of the microlens 11 when viewed from the incident direction side of the projected light L, that is, the shape of the region surrounded by the side formed by the curve forming the microlens surface 14 and the bottom surface is expressed as an aperture shape. is doing.

In the present embodiment, the microlens 11 has a regular hexagonal shape when viewed from the incident direction of the projected light L, but is not limited to such a configuration, and is shown as a modified example in FIG. , It may be a square, or it may be a regular polygon.
Further, in the present embodiment, the first diffusion plate 12a and the second diffusion plate 12b are provided with the same microlens 11, and the arrangement pattern is also the same, but the configuration is not limited to this.
Specifically, as shown as a modification in FIG. 5, the opening shape of the microlens 11a arranged on the first diffusion plate 12a is square, and the opening shape of the microlens 11b arranged on the second diffusion plate 12b is regular six. It may have a square shape or the like.

The microlens 11 is arranged so that one side (for example, the sides 13a and 13b in FIG. 2) forming a regular hexagon is not parallel to each other, that is, not parallel to each other.
At this time, "non-parallel" means that one side of the two-sided pattern is not parallel. Further, "shifted" indicates a mode formed so as not to overlap when viewed from the incident direction of the projected light L. Most preferably, the sides 13a and 13b are arranged so as to be inclined by half an angle of the rotation angle β that becomes parallel to the next parallel state.
In other words, when the line drawn at the most reference position of the arrangement pattern formed by the minute lens surface 14 is used as the reference line, the reference line Ba of the first diffusion plate 12a and the reference of the second diffusion plate 12b are used. The line Bb is arranged so as to be rotated by a predetermined angle α.

For example, in the case of a regular hexagon as in the present embodiment, since the central angle of one side is 60 degrees, it is in a state of being inclined to each other by 30 degrees (or 90 degrees, 150 degrees, 210 degrees, 270 degrees, and 330 degrees). Is the most desirable.
Further, in the case of a square as shown in FIG. 4, since the central angle is 90 degrees, it is most desirable that the square is inclined to each other by 45 degrees.
With such a configuration, the projected light L transmitted through the first diffusion plate 12a and the second diffusion plate 12b can reduce the diffracted light.

As already described, the rotation angle β and the angle α formed by the reference lines are most preferably α = β / 2, but they may be within the range of the mathematical formula (1).
With such a configuration, the projected light L transmitted through the first diffusion plate 12a and the second diffusion plate 12b is diffused differently on each diffusion surface, and the light intensity can be made uniform.

Further, the minute lens 11 formed on the first diffusion plate 12a and the minute lens 11 formed on the second diffusion plate 12b are arranged so that their center positions are displaced from each other by a predetermined distance z.
With such a configuration, the diffracted light of the projected light L transmitted through the first diffusion plate 12a and the second diffusion plate 12b can be thinned, and the brightness unevenness can be reduced.
Here, the predetermined distance z may be appropriately set according to the shape of the minute lens 11, but it is desirable that the predetermined distance z is a value smaller than the diagonal line or the diameter.

As shown in FIG. 11 as a modified example, the angle α ≠ 0 formed by the reference lines in a state where the center positions of the first diffusion plate 12a and the second diffusion plate 12b are aligned with the predetermined distance z = 0. The arrangement pattern may be rotated so as to be.

In the present embodiment, the projected light L is diffused by using the diffusion unit 10.
When the projected light L is transmitted through the diffusion unit 10, it is diffused by the minute lens 11 at a predetermined diffusion angle, and as shown in FIG. 7, the light intensity in the irradiated surface is simply a diffusion plate using the minute lens. It is more uniform than FIG. 6, which is a conventional example using a single lens.
With such a configuration, both uniform light intensity and control of divergence angle are achieved.

Further, in the present embodiment, the diffusion unit 10 has a first diffusion plate 12a in which a plurality of minute lens surfaces 14 are arranged, and a second diffusion plate 12b.
When the first diffuser plate 12a and the second diffuser plate 12b are viewed from the incident direction A side of the projected light L, the sides 13a and 13b, which are one side constituting the minute lens surface, do not overlap each other and are not mutually exclusive. Arranged so that they are parallel.
With such a configuration, both uniform light intensity and control of divergence angle are achieved.

Further, in the present embodiment, the center positions of the minute lens surfaces 14 are arranged so as to be offset from each other.
With such a configuration, as shown in FIG. 8, uniform light intensity and control of divergence angle are compatible.

In the present embodiment, the following calculation formula (1) β / Satisfy 4 ≦ α ≦ 3β / 4. With such a configuration, uniform light intensity and control of divergence angle are compatible.

In the present embodiment, the angle α formed by the sides 13a and 13b constituting the minute lens surface is half of the rotation angle β from the position parallel to each other to the next parallel.
With such a configuration, uniform light intensity and control of the divergence angle are more compatible than simply satisfying the mathematical formula (1).

As another embodiment of the present invention, the diffusion unit 30 as shown in FIG. 8 will be described. For the sake of simplicity, the same configurations as those in the above-described embodiment will be designated by the same reference numerals and description thereof will be omitted.

The diffusion unit 30 has a first diffusion plate 12a and a second diffusion plate 12b, and has a drive unit 31 for relatively moving the first diffusion plate 12a and the second diffusion plate 12b. ..
As shown in FIG. 9, the drive unit 31 swings the second diffusion plate 12b when viewed from the incident direction of the projected light L, and in the present embodiment, particularly rotates in the direction indicated by C. Drive.

With this configuration, the relative positions of the arrangement patterns formed on the first diffuser plate 12a and the second diffuser plate 12b change with time, so that the diffusion degree of the projected light L fluctuates, and thus the coherence is high. Even with light, uniform light intensity and control of divergence angle are compatible.

In the present embodiment, the drive unit 31 is oscillated so as to rotate, but the present invention is not limited to this configuration. For example, the drive unit 31 may be reciprocated, and as shown in FIG. The two first diffusion plates 12a and the second diffusion plate 12b may be moved independently.
In FIG. 10, the moving distance is exaggerated in order to display the moving state in an easy-to-understand manner, but if the moving distance is about the size of the minute lens 11, for example, a distance of several μm is used. Sufficient and not limited to such configurations.

With this configuration, the relative positions of the arrangement patterns formed on the first diffusion plate 12a and the second diffusion plate 12b change with time, so that the uniform light intensity and the control of the divergence angle are further compatible.

Further, in the above-described embodiment, only the case where one diffusion plate has a minute lens surface which is one diffusion surface has been described, but as shown in FIGS. 12A and 12B, for example. , A configuration in which a single lens diffuser 12'provides a plurality of diffusion surfaces may be used.
As is clear from FIGS. 12A and 12B, the lens diffuser 12'has a first diffusion surface 14a and a second diffusion surface 14b as a plurality of diffusion surfaces having different arrangement patterns from each other.

The plurality of diffusion surfaces 14a and 14b are arranged so that one side constituting the minute lens surface does not overlap each other and is non-parallel to each other when viewed from the incident direction side.

At this time, as shown in FIG. 12A, the first diffusion surface 14a and the second diffusion surface 14b may be formed as convex shapes in the same direction as each other.
Further, as shown in FIG. 12B, the first diffusion surface 14a and the second diffusion surface 14b may be formed in a convex shape in opposite directions to each other.

With this configuration, the projected light L is diffused on the first diffusion surface 14a and the second diffusion surface 14b, so that uniform light intensity and control of the divergence angle are compatible.

Further, as another embodiment, as shown in FIG. 13, the aperture shape of the microlenses 11a arranged on the first diffusion plate 12a and the second diffusion plate 12b may be an equilateral triangle.
In this case, the reference line Ba of the first diffusion plate 12a and the reference line Bb of the second diffusion plate 12b are arranged in such a manner that they are rotated by a predetermined angle α, and the angle α is 0 ° ≦ α ≦ 30 °. It is desirable to satisfy, and in FIG. 13, α = 30 ° in particular.
By making the shapes of the first diffusion plate 12a and the second diffusion plate 12b an equilateral triangle in this way, the number of minute lenses that contribute to diffusion per unit area is maximized, and the diffusion effect is increased.

Further, as shown in FIG. 14, the aperture shape of the microlenses 11a arranged on the first diffusion plate 12a and the second diffusion plate 12b may be a triangle having an arbitrary angle. When the microlenses 11a having a triangular aperture shape are densely arranged, a quadrilateral such as a parallelogram may be formed. In such a case, the first diffusion surface 14a and the second diffusion surface 14b are arranged so that one side constituting the minute lens 11a does not overlap with each other when viewed from the incident direction side and is non-parallel to each other. Is desirable.

According to the present invention, a novel diffusion unit and an optical device using the new diffusion unit can be realized.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the above-described configuration, and various configurations may be adopted within the scope of the invention described in the claims. It is possible.

The effects described in the embodiments of the present invention merely list suitable effects arising from the invention, and the effects according to the invention are not limited to those described in the embodiments.

10 Diffusion unit 11 Micro lens 12a Diffusion plate (first diffusion plate)
12b Diffusion plate (second diffusion plate)
13a side (one side that constitutes the opening shape)
13b side (one side that constitutes the opening shape)
14 Micro lens surface (diffusion surface)
14a, 14b Diffusion surface 20 Light source 30 Diffusion unit 31 Drive unit

Japanese Unexamined Patent Publication No. 2016-045415

Claims (3)

It has at least two diffusion surfaces in which a plurality of minute lens surfaces are arranged along the incident direction of the luminous flux.
The diffusion surfaces are arranged so that when viewed from the incident direction side, one side forming the aperture shape of the minute lens surface does not overlap with each other and is non-parallel to each other .
The center positions of the microlens surfaces are offset from each other,
A diffusion unit characterized in that the aperture shape constituting the microlens surface is an equilateral triangle when the microlens surface is viewed from the incident direction side. The diffusion unit according to claim 1.
When the angle α formed by one side forming the aperture shape of the minute lens surface is the rotation angle β from the position parallel to each other to the next parallel, the following calculation formula is used.
(1) β / 4 ≤ α ≤ 3 β / 4
A diffusion unit characterized by satisfying. The diffusion unit according to claim 1 or 2.
A diffusion unit characterized by having a driving unit that relatively moves the diffusion surface.

Images