JP2011191404A - Two-face corner reflector array optical element and display device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a two-face corner reflector array optical element with cylindrical bodies projecting from the surface of a base which can be easily taken out from a stamper after molding. <P>SOLUTION: In the two-face corner reflector array optical element including a base integrally molded by a transparent material and the plurality of cylindrical bodies projecting from the joining flat face in the surface thereof, and in which two orthogonal side faces are formed as two-face corner reflectors in each of the cylindrical bodies, and the real image of the object to be observed on either main face side of the base is imaged on the space at the other side, the tapered structure of the cylindrical bodies is defined in such a manner that, regarding the side faces other than the two-face corner reflectors of the cylindrical bodies, the area of the edge face on the side opposite to the base side in each cylindrical body is made smaller than the area of the joining flat face with the base on the base face side in each cylindrical body. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a reflective real mirror image forming optical element that forms a real image (real mirror image) of an object to be observed in a space on the viewer side, and a display device using the same.

  A display device has been proposed in which a real image (real mirror image) of an object to be observed is formed in the air using a reflective real mirror image imaging optical element so that the observer can see it. (See Patent Document 1).

  Specifically, the display device includes a reflective real mirror image forming optical element that forms a real image (real mirror image) of an object to be observed in a space on the viewer side, and the reflective real mirror image forming optical. And an observation object for forming the real mirror image disposed in a space opposite to the observer side of the element.

  Patent Document 1 discloses a reflective real mirror image in which a plurality of unit optical elements (referred to as two-sided corner reflectors) composed of two mirror surfaces orthogonal to each other are arranged in an array, that is, aligned on an element surface constituting one plane. An imaging optical element (referred to as a dihedral corner reflector array optical element) is disclosed. As a specific example of the two-sided corner reflector array optical element, in Patent Document 1, the inner wall of a square hole drilled in a direction penetrating the element surface is used as a two-sided corner reflector, or a base is provided. A two-sided corner reflector array optical element is shown in which the inner wall of a transparent cubic-shaped cylindrical body protruding from the surface of the cylindrical body is used as a two-sided corner reflector, and a plurality of the cylindrical bodies are formed in a grid pattern. ing.

  In the two-surface corner reflector array optical element, each mirror surface of the plurality of aligned two-surface corner reflectors is arranged upright substantially perpendicular to the element surface, and therefore, from a projection object arranged on one side of the element surface. When light passes through the element surface, the light is reflected twice by the two-surface corner reflector, and forms a real image in the space on the other side of the element surface where there is no projection object. That is, the two-surface corner reflector array optical element can form a real image so that the object to be observed exists at a symmetrical position with respect to the element surface (also referred to as a symmetry plane) of the two-surface corner reflector array optical element. it can.

WO2007-116639

  In Patent Document 1, the inner wall surface other than the two mirror surfaces of the two-surface corner reflector of the two-surface corner reflector array optical element is provided at an angle so as not to be perpendicular to the element surface, thereby reducing multiple reflected light. Only that it can be removed is suggested. However, there is no suggestion for effective use of the inner wall surfaces other than the two surfaces that form the other two-surface corner reflectors, and no problems with the two-surface corner reflectors and other inner wall surfaces are pointed out.

  As a result of intensive research, the inventor has found that the conventional two-surface corner reflector array optical element using the side wall (inner wall surface) of the cubic cylindrical body protruding from the substrate surface as a two-surface corner reflector is transparent such as acrylic. In the production method by resin injection molding or hot press molding, when the four side surfaces of a cubic shaped cylindrical body are perpendicular to the base, it is very possible to remove the two-sided corner reflector array optical element from the stamper after molding. I found a difficult problem. As a method for producing such a two-sided corner reflector array optical element, a method by injection molding or heat press molding of a transparent resin such as acrylic can be considered. By such a molding method, a two-sided corner reflector array optical device having a cubic cylindrical body is conceivable. When the element is molded, it is very difficult to remove the two-sided corner reflector array optical element from the stamper after release.

  Accordingly, the present invention relates to a two-surface corner reflector array optical element having a cylindrical body protruding from the surface of the substrate, which can be easily taken out from a stamper after molding, and a display device using the same. The purpose is to provide.

The two-surface corner reflector array optical element of the present invention comprises a base and a plurality of cylindrical bodies protruding from a joining plane in the surface, which are integrally molded with a transparent material. A two-surface corner reflector array optical element, in which two orthogonal side surfaces are formed as a surface corner reflector, and forms a real image of an object to be observed on one main surface side of the base in a space on the other side,
The side surface of the cylindrical body other than the two-surface corner reflector is such that the area of the end surface opposite to the base side of the cylindrical body is smaller than the area of the joining plane with the base on the base surface side of the cylindrical body. And defining a tapered structure of the cylindrical body.

  In the above-described two-surface corner reflector array optical element, the cylindrical body includes a cube-shaped portion including a side surface as a two-surface corner reflector and a tapered portion including a side surface other than the two-surface corner reflector integrated with the cube-shaped portion as a plane. It can be said that it is a truncated pyramid consisting of.

  In the above-described two-surface corner reflector array optical element, the base and the cylindrical body can be manufactured by a resin molding method.

  In the above-described two-surface corner reflector array optical element, a metal reflection film may be further provided on the side surface of the cylindrical body that functions as the two-surface corner reflector.

  In the above-described two-surface corner reflector array optical element, the inclination angle of the side surface other than the two-surface corner reflector from the normal line of the substrate can be 5 degrees or more and 25 degrees or less.

  The display device of the present invention includes the above-described dihedral corner reflector array optical element and an object to be observed on one main surface side of the substrate, and forms a real image of the object to be observed in a space on the other side of the substrate. It is characterized by.

  The present invention makes it easy to remove the two-surface corner reflector array optical element from the stamper by attaching an inclination (so-called “drawer taper”) to a surface other than the two surfaces forming the two-surface corner reflector. Is a solution. The inclination direction at this time is an inclination direction in which a plane (upper surface, that is, an end surface) opposite to the substrate side is smaller than a bonding plane (bottom surface) on the substrate surface side of the cube-shaped cylindrical body.

  The inclination angle (angle from the plane perpendicular to the base) is preferably large when considering the removal of the two-surface corner reflector array optical element from the stamper, but if it is too large, it is the light exit surface reflected by the two-surface corner reflector. The real image (real mirror image) of the object to be observed becomes dark as the area of the upper surface of the cubic cylindrical body becomes small. In addition, when the upper surface area is secured, the area of the bottom surface of the cube-shaped cylindrical body is increased and the number of two-surface corner reflectors per unit area is reduced. (Image) becomes dark.

  As a result of molding experiments using stampers with various inclination angles for these contradictory phenomena, the inclination angle (angle from a plane perpendicular to the base) is preferably 5 degrees or more and 25 degrees or less. It turns out that.

  In the case of a cube-shaped cylindrical body, there are two side surfaces (excluding the top surface and the bottom surface) other than the two surfaces forming the two-surface corner reflector, and the both surfaces are inclined as described above. The inclination angles may or may not be equal. However, in the case of producing a mold by a reversal method such as electroforming, it is convenient that the angles of both surfaces are equal because only one type of cutting tool (bite) needs to be produced.

  According to the present invention, since the side surfaces other than the two surfaces forming the two-surface corner reflector are inclined, it is taken out while forming a space between the stamper and the two-surface corner reflector array optical element after molding. The frictional force generated between the contact surface of the stamper and the two-surface corner reflector array optical element is reduced. Thereby, the two-surface corner reflector array optical element can be easily taken out from the stamper. Further, as a secondary effect, it is possible to reduce the multiple reflected transmitted light toward the viewer.

It is a schematic partial notch perspective view which shows typically the example of a specific structure of the 2 surface corner reflector array optical element of embodiment by this invention. 2 is a cross-sectional view taken along lines AA and BB in FIG. It is a perspective view which shows typically the cylindrical body of the 2 surface corner reflector array optical element of embodiment by this invention. It is a schematic sectional drawing for demonstrating the procedure in the case of producing the 2 surface corner reflector array optical element of embodiment by this invention by the injection molding method. It is a schematic sectional drawing for demonstrating the shape of the diamond tool used at the time of the stamper production for producing the 2 surface corner reflector array optical element of embodiment by this invention. It is a schematic plan view of the copper master board used at the time of stamper production for producing the 2 surface corner reflector array optical element of embodiment by this invention. It is a partial expanded sectional view in the AA cross section of FIG. It is a partial expanded sectional view of the stamper used by the embodiment by the present invention obtained by electroforming reversal processing. It is a schematic sectional drawing for demonstrating the procedure in the case of producing the 2 surface corner reflector array optical element of embodiment by this invention by the hot press molding method. It is a schematic partial notch perspective view which shows typically the example of a specific structure of the 2 surface corner reflector array optical element which has the conventional cube-shaped cylindrical body. It is a schematic sectional drawing for demonstrating the shape of the diamond tool used at the time of the stamper production for producing the dihedral corner reflector array optical element which has the conventional cube-shaped cylindrical body. It is a general | schematic partial expanded cross section of the copper master board used at the time of stamper production for producing the dihedral corner reflector array optical element which has the conventional cube-shaped cylindrical body. It is a partial expanded sectional view of the stamper for producing the dihedral corner reflector array optical element which has the conventional cube-shaped cylindrical body. It is the schematic plan view and partial notch perspective view which show typically the example of a concrete structure of the 2 surface corner reflector array optical element applied to the display apparatus of the embodiment. The schematic perspective view which shows typically the image formation mode of the 2 surface corner reflector array optical element applied to the display apparatus of embodiment by this invention. It is a schematic plan view which shows typically the image formation mode by the 2 surface corner reflector array optical element applied to the display apparatus of embodiment by this invention. It is a schematic side view which shows typically the image formation mode by the 2 surface corner reflector array optical element applied to the display apparatus of embodiment by this invention.

  Hereinafter, a dihedral corner reflector array optical element and a display device according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 shows an enlarged partial perspective view of an embodiment of a dihedral corner reflector array optical element 6 having a cubic protruding cylindrical body 51 to which the present invention is applied. FIG. 2 is an enlarged partial sectional view taken along the lines AA and BB in FIG.

  The two-surface corner reflector array optical element 6 of the present embodiment is composed of a flat base 60 integrally molded with a transparent material and a plurality of cylindrical bodies 51 protruding from the joining plane in the surface. In each of the cylindrical bodies, two orthogonal side surfaces (mirror surfaces 61a and 61b) are formed as a two-surface corner reflector 61, and a side surface 62a other than the two mirror surfaces excluding the top surface and the bottom surface forming the two-surface corner reflector (cube in FIG. 1). The surface 62b has a certain angle (inclination) from the normal of the principal surface of the base 60. FIG. 2 shows the cylindrical body dimensions H, L, D and the angle θ. These values are as follows: height H = 170 μm, square side L = 150 μm, interval D = 10 μm, taper angle θ = 108. However, these are representative values, and the present invention is not limited to these values.

  As shown in FIG. 3, the side surfaces 62 a and 62 b other than the two-surface corner reflector of the cylindrical body 51 are opposite to the base side of the cylindrical body from the area of the joining plane 52 with the base on the base surface side of the cylindrical body. The tapered structure of the cylindrical body 51 is defined so that the area of the side end face 53 is smaller. Side surfaces 62a and 62b other than the two-surface corner reflector are tapered surfaces.

  Specifically, as shown in FIG. 3, the cylindrical body 51 is a truncated pyramid and is integrated with the cube-shaped portion C and the cube-shaped portion C including the side surfaces 61 a and 61 b that are two-sided corner reflectors. The taper portion T includes side surfaces 62a and 62b other than the surface corner reflectors as planes.

  An example of the double-sided corner reflector array optical element will be described because the base and the cylindrical body can be produced by a resin molding method. It is produced by the following procedure.

  First, as shown in FIG. 4A, in a state where a predetermined stamper 101 and a flat mold 102 are brought into close contact with each other, the resin is heated to a temperature higher than the softening temperature of the resin (for example, 200 ° C. when an acrylic resin is used). deep.

  Next, as shown in FIG. 4B, the resin 104 melted from the mold gate portion 103 is filled into the mold 102 at a high pressure.

  Next, as shown in FIG. 4C, after filling the resin 104, the stamper 101 and the mold 102 are kept in close contact with each other and cooled to a temperature equal to or lower than the softening temperature of the resin 104 (for example, 80 ° C. when an acrylic resin is used). .

  Next, as shown in FIG. 4D, the mold 102 is separated from the stamper 101. At this time, it is preferable that the molded two-surface corner reflector array optical element can be separated from the stamper 101 together with the mold 102.

  Next, as shown in FIG. 4 (e), the molded two-sided corner reflector array optical element 6 is removed from the mold 102. Since the mold side surface of the two-surface corner reflector array optical element is a flat surface, it can be removed relatively easily. If the resin portion formed by the gate portion is cut off, a two-surface corner reflector array optical element is completed.

  The predetermined stamper 101 can be manufactured by cutting with a diamond tool and electroforming reversal. The procedure is shown below.

  First, as shown in FIG. 5, a diamond tool (blade for cutting) having an angle corresponding to a vertical surface on one side and an angle corresponding to an inclined surface, which is a feature of the present invention, is prepared on the other side.

  Next, as shown in FIG. 6, the copper master plate 150 is cut by the diamond tool shown in FIG. 5 so as to form a reversal pattern of the two-sided corner reflector array optical element. Specifically, as shown in FIG. 6, a plurality of parallel horizontal grooves are sequentially cut at a predetermined pitch, and then a plurality of vertical grooves are formed at a predetermined pitch in a direction perpendicular to the previously cut grooves. Cut the grooves in order. In order to produce the cross-sectional shape shown in FIG. 2, after cutting until a depth of 170 μm is reached by repeating cutting of 5 μm per time for one groove, a diamond is formed at a predetermined pitch to the position of the next groove. The operation to move the byte was repeated. FIG. 7 is a partially enlarged cross-sectional view taken along the line AA of FIG. 6 after the cutting process.

  Next, a stamper for molding having a reversal pattern of the copper master plate 150 having the same cylindrical shape as the two-sided corner reflector array optical element by nickel electroforming reversal processing using the copper master plate 150 after cutting. 101 can be manufactured. FIG. 8 shows a partially enlarged sectional view of the stamper 101 obtained by electroforming reversal processing.

  If the predetermined stamper 101 is used, a two-sided corner reflector array optical element can be manufactured by hot press molding.

  The procedure for producing a two-surface corner reflector array optical element by hot press molding will be described below.

  First, as shown in FIG. 9A, the stamper 101 and the mold 202 are heated to a temperature equal to or higher than the softening temperature of the resin 104 that uses the stamper 101 and the mold 202 (for example, 200 ° C. when using an acrylic resin).

  Next, as shown in FIG. 9B, a sheet made of the resin 104 used is placed on the mold 202.

  Next, as shown in FIG. 9C, the sheet is pressed (pressed) with the stamper 101 and the mold 202. As it is, while the sheet is pressed with the stamper 101 and the mold 202, the sheet is cooled to a temperature equal to or lower than the softening temperature of the resin 104 (for example, 80 ° C. when acrylic resin is used).

  Next, as shown in FIG. 9 (d), the stamper 101 is separated from the mold 202. At this time, the molded two-surface corner reflector array optical element 6 and the mold 202 are adsorbed by using a vacuum or the like, and the molded two-surface corner reflector array optical element and the mold 202 together with the stamper 101. It is preferable that it can be separated from.

  Next, as shown in FIG. 9 (e), the molded two-sided corner reflector array optical element 6 is removed from the mold 202. Since the mold side surface of the two-surface corner reflector array optical element is a flat surface, it can be removed relatively easily.

  In the above example, a resin sheet is used. However, the resin 104 may be placed on a heated mold 202 and melted to form a sheet and then pressed.

  As described above, the two-surface corner reflector array optical element 6 having an array of cylindrical bodies 51 having a tapered structure can be molded with resin relatively easily.

  On the other hand, a two-sided corner reflector array optical element having a conventional structure having a cubic cylindrical body will be manufactured for comparison.

  FIG. 10 shows a partial perspective view of an example of a conventional two-sided corner reflector array optical element that uses the side wall of a cubic cylindrical body protruding from the surface of the manufactured base as a two-sided corner reflector. When such a conventional two-sided corner reflector array optical element is resin-molded, it is manufactured using a diamond tool (blade for cutting) whose both surfaces have an angle (right angle) corresponding to a vertical surface as shown in FIG. In the same manner as the procedure shown in FIG. 6 of the above-described embodiment, cutting is performed on the copper master plate with such a diamond tool so as to be a reversal pattern of the two-sided corner reflector array optical element. The partially enlarged cross-sectional view of the copper master plate 250 on which the cylindrical body 51 (height H = 170 μm, square side L = 150 μm, interval D = 65.2 μm (≈170 · tan 18 ° + 10)) formed after cutting is shown. As shown in FIG. From this copper master plate, a molding stamper having a reversal pattern of the copper master plate 250 can be produced by electroforming reversal of nickel as in the above embodiment. FIG. 13 is a partially enlarged cross-sectional view of a stamper 201 for a conventional two-sided corner reflector array optical element obtained by electroforming reversal processing.

  A conventional two-surface corner reflector array optical element was manufactured using the manufactured conventional stamper in the same manner as the procedure shown in FIG. 4 of the above embodiment. The stamper is preheated for the resin in a state where the flat mold is in close contact, and the molten resin is high-pressure filled into the mold from the mold gate portion. After the filling, the stamper and the mold are cooled to a predetermined temperature. The mold is separated from the stamper. At this time, as shown in FIG. 4 (f), the molded two-sided corner reflector array optical element 66 is stuck to the stamper side and is peeled off forcibly. Since the reflector array optical element is distorted, a real image (real mirror image) of the object to be observed cannot be formed in the air even if the display device is configured using the two-sided corner reflector array optical element. .

  On the other hand, according to the present invention, as shown in FIG. 14 (a), a thin flat plate-like base 60 is substantially a truncated pyramid (for example, a square bottom surface) in plan view, and its joining plane (bottom surface) to top surface, that is, A large number of transparent tubular bodies 51 (one side is, for example, 50 to 200 μm) through which light rays bend and pass between the end faces are formed, and two inner wall surfaces 61a and 61b that are adjacent and orthogonal to each other among the tubular bodies 51 are formed. The two-surface corner reflector array optical element 6 that is the two-surface corner reflector 61 can be obtained. The tapered portion that does not constitute the two-surface corner reflector 61 can be a non-reflective surface such as matte. In addition, each of the two-surface corner reflectors 61 is preferably formed on a regular lattice point so that the inner angles formed by the mirror surfaces 61a and 61b are all in the same direction on the base 60. Therefore, as shown in FIG. 14B, in each of the two-surface corner reflectors, it is preferable that the intersection line CL of two orthogonal mirror surfaces is orthogonal to the element surface 6S. The direction of the inner angle of the mirror surfaces 61a and 61b is referred to as the direction (direction) of the two-surface corner reflector 61.

  As schematically shown in FIG. 15, the display device of the present invention includes a dihedral corner reflector array optical element and an object to be observed 4 on one main surface side of a base, and a real image 5 (real image of the object to be observed). Mirror image) is formed in the space on the other side of the base. The two-surface corner reflector array optical element 6 is a set of a large number of two-surface corner reflectors 61 composed of two mutually orthogonal mirror surfaces 61 a and 61 b, and each of the two mirror surfaces 61 a constituting the entire two-surface corner reflector 61. , 61b is a plane substantially perpendicular to the element surface 6S, and the real mirror image 3 of the object to be observed 2 can be imaged at a plane symmetric position with the element plane 6S as a symmetry plane. In this embodiment, the dihedral corner reflector 61 is very small (μm order) compared to the overall size (cm order) of the dihedral corner reflector array optical element 6, and therefore the dihedral corner reflector in FIG. The whole set of 61 is represented by gray, and the direction of the inner corner is represented by a V shape.

  In the present invention, the dihedral corner reflector array optical element 6 is provided as a surface perpendicular to the substrate other than the inclined surface which is a feature of the present invention among the side surfaces of the protruding cylindrical body (61a and 61b in FIG. 15). ).

  In the two-surface corner reflector array optical element 6, each two-surface corner reflector 61 transmits light that has entered the protruding cylindrical body from one side of the two-surface corner reflector array optical element (observed object 4). The mirror surface 61a (or 61b) reflects the light, and the reflected light is reflected by the other mirror surface 61b (or 61a) to pass to the surface side. It will be plane symmetrical across 6S. That is, the element surface 6S of the two-surface corner reflector array optical element 6 (assuming a surface passing through the center in the height direction of each mirror surface and orthogonal to each mirror surface) is a real image (real mirror image) of the object 4 to be observed. A plane of symmetry is formed as an aerial image (real mirror image) 5 at a plane symmetrical position.

  Here, an image formation mode by the two-surface corner reflector array optical element 6 will be briefly described along with a path of light emitted from the point light source o as an object to be observed. FIG. 16 is a schematic plan view, and FIG. 17 is a schematic side view. As shown in FIG. 16, light emitted from a point light source o (indicated by an alternate long and short dash line arrow. When traveling through the two-surface corner reflector array optical element 6, it is reflected by one mirror surface 61a (or 61b) constituting the two-surface corner reflector 61 and further reflected by the other mirror surface 61b (or The light passes through the element surface 6S after being reflected at 61a), and passes through the element surface 6S of the two-surface corner reflector array optical element 6 while spreading the plane symmetry position of the point light source o. In FIG. 16, the incident light and the reflected light are shown to be parallel, but this is because the dihedral corner reflector 61 is greatly exaggerated with respect to the point light source o in FIG. Actually, each of the two-sided corner reflectors 61 is extremely small, so that when the two-sided corner reflector array optical element 6 is viewed from above as shown in FIG. It can be seen (in FIG. 16, the path of light that first strikes each of the two mirror surfaces (61a, 61b) of the two-surface corner reflector 61, ie, two paths, is described, but in FIG. 17, in order to avoid complications Only the first light that hits one of the mirrors is drawn). That is, in the end, the transmitted light gathers at a plane-symmetrical position with respect to the element surface 6S of the point light source o, and forms an image as a real mirror image at the position p in FIGS.

  Thus, since the two-surface corner reflector functions as a reflecting mirror, a surface perpendicular to the base that functions as the two-surface corner reflector among the side surfaces of the protruding cylindrical body of the resin molded product is provided with a reflecting surface such as a metal film, for example. It is preferable to attach it, but the inventor only uses a resin molded product, that is, a mirror with brightness that is practically satisfactory because sufficient reflection can be obtained by the difference in refractive index between the resin and the air interface without additional processing of the reflecting surface. I discovered that images can be imaged in the air.

  A low-cost display device that can display a real image (real mirror image) of an object to be observed in the air using a two-surface corner reflector array optical element that is only a resin molded product without providing a reflective surface. Can be produced.

4 Observation object 5 Aerial video (real mirror video)
6 Dihedral corner reflector array optical element 6S Element surface (symmetric plane)
51 Cylindrical body 52 Joining plane 53 End face 60 Base 61 Two-sided corner reflector 61a, 61b Mirror surface (side face)
62a, 62b Side surfaces other than the two-sided corner reflector (tapered surface)
66 Dihedral corner reflector array optical element 101, 201 Stamper 102, 202 Die 103 Die gate part 104 Resin 150, 250 Copper master plate CL Mirror crossing line C Cube-shaped part T Taper part

Claims (6)

It consists of a base and a plurality of cylindrical bodies protruding from the joining plane in the surface, which are integrally molded with a transparent material. Each of the cylindrical bodies is formed with two orthogonal side surfaces as a two-sided corner reflector. A two-surface corner reflector array optical element that forms a real image of an object to be observed on one main surface side of the base in a space on the other side,
Side surfaces of the cylindrical body other than the two-surface corner reflector are formed on an end surface opposite to the base side of the cylindrical body from an area of the joining plane with the base on the base surface side of the cylindrical body. 2. A dihedral corner reflector array optical element, wherein a tapered structure of the cylindrical body is defined so that an area is smaller.   The cylindrical body is a truncated pyramid comprising a cube-shaped portion including the side surface as the two-surface corner reflector and a tapered portion including a side surface other than the two-surface corner reflector integrated with the cube-shaped portion as a plane. The dihedral corner reflector array optical element according to claim 1, wherein the optical element is a dihedral corner reflector array optical element.   The two-surface corner reflector array optical element according to claim 1 or 2, wherein the base and the cylindrical body are produced by a resin molding method.   4. The two-surface corner reflector array optical element according to claim 1, further comprising a metal reflective film on a side surface of the cylindrical body that functions as the two-surface corner reflector. 5.   5. The two-surface corner reflector according to claim 1, wherein an inclination angle of a side surface other than the two-surface corner reflector from the normal line of the base is 5 degrees or more and 25 degrees or less. Array optical element.   A dihedral corner reflector array optical element according to any one of claims 1 to 5, and an object to be observed on one main surface side of the base, wherein a real image of the target is displayed on the base A display device characterized by forming an image in a space on the other side.

Images