JP2015146009A - imaging optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflection type imaging optical element that can be easily manufactured and displays a real image of an observation target in the air.SOLUTION: An imaging optical element includes: an optical element S1 that has a function to arrange V-groove shapes having a substantially right angle in one direction at constant intervals and use the surfaces of the V-grooves as a reflection surface, so as to collect incident light on a straight line through the reflection twice on the V-grooves mentioned above; and an optical element S2 that has a refractive power only in one direction and has a function to collect incident light on a straight line. The optical element S1 and optical element S2 has a transparent medium filling the space therebetween, and are arranged to have the light collection direction of a surface 1 and the light collection direction of a surface 2 to be substantially orthogonal to each other.

Description

  The present invention relates to an optical element that forms an aerial image of an observation object that can be realized with a simple configuration.

  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 and Non-Patent Document 1).

  The above-described aerial image forming optical element reflects the light emitted from the observation object arranged on one side of the element surface, once by each mirror surface constituting each two-surface corner reflector, twice in total. Allows the real image of the object to be observed to be formed at the same magnification and without distortion in the space on the other side of the element surface.

International Publication No. 2007-116639

S. Maekawa, K .; Nitta, and O.I. Matoba, ｀ ｀ Transmissive Optical Imaging Device with Micromirror Array, “SPIE 6392, 63920E (2006).

  In order to manufacture the above-described aerial image forming optical element, it is necessary that the two mirror surfaces constituting each two-surface corner reflector have extremely small one side of, for example, 1 mm or less, preferably 50 to 200 μm. In addition, the two mirror surfaces had to be kept facing each other at an angle of approximately 90 degrees.

  In order to produce such a two-sided corner reflector array, for example, it is conceivable to use a mold having a large number of convex or concave shapes corresponding to each two-sided corner reflector. In order to remove the product from the mold, the minute two-sided corner reflector and the minute convex or concave shape of the mold are firmly meshed with each other, so the mold must be melted each time. High costs are expected.

  Further, when the aerial image of the observation object is displayed using the aerial image imaging optical element described above, the aerial image imaging optical element described above is disposed between the observation object and the display image. The space between the image space and the object space could not be made hollow.

  Therefore, the present invention combines an image formed by a dihedral corner reflector and an image formed by refraction to provide an element configuration that has a relatively simple structure, reducing manufacturing costs, and reflecting aerial image forming elements. The object is to make the space between the image space and the object space to be hollow by using the structure that works as a child.

  The present invention arranges substantially right-angled V-shaped groove shapes in one direction at regular intervals, and uses the V-shaped groove surface as a reflecting surface, so that the reflection from the point light source to the V-shaped groove is performed twice in the aforementioned V-shaped groove. A surface 1 having a function of condensing light rays incident on the surface of a straight line, and a surface 2 having a refractive power only in one direction and condensing incident parallel light onto a focal line unique to the element. The back surface of the surface 1 is the surface 2, the space between them is filled with a transparent medium, and the light collecting direction of the surface 1 and the light collecting direction of the surface 2 are arranged substantially orthogonal to each other. And

Here, the “substantially right-angled V-shaped groove” means that an angle range of several degrees before and after the groove angle of the V-shaped groove can be regarded as approximately 90 degrees, for example, a V-shaped groove of 90 degrees ± 3 minutes is included. The crossing portion of the V-shaped groove may be rounded.

  Further, “substantially orthogonal” means not only 90 degrees but also an angular range of several degrees before and after that can be regarded as approximately 90 degrees.

  That is, the surface 1 functions as a one-dimensional array of two-surface corner reflectors to collect incident light on a straight line, and the surface 2 operates in the same manner as a convex lens having refractive power in only one direction. Focus on a straight line.

  The light of the observation object incident from the side of the surface 2 is refracted by the surface 2, reflected twice by the right-angle V-shaped groove of the surface 1, and then refracted by the surface 2 again.

  As a result, the direction in which the V-shaped grooves of the surface 1 are arranged in the incident light is condensed by reflection twice in the substantially right-angled V-shaped grooves, and the direction perpendicular to this direction is condensed by refraction by the surface 2. The

  In this condensing, the condensing by the surface 1 is due to retroreflection, and the image of the object to be observed is formed without distortion in the direction in which the V-shaped grooves of the surface 1 are arranged.

  By matching the condensing position by the surface 1 and the condensing position by the surface 2, a real image of the object to be observed is formed at the condensing positions of the surface 1 and the surface 2.

  As described above, the optical element of the present invention can form a real image of a non-observed object in the space on the viewer side without distortion in the direction in which the V-shaped grooves on the surface 1 are arranged.

  In addition, since the configuration of the optical element of the present invention is relatively simple, it is easy to manufacture a large element while reducing the manufacturing cost. In particular, by increasing the number of V-shaped grooves arranged, the direction in which the V-shaped grooves on the surface 1 are arranged can be easily extended, and a large aerial image can be displayed relatively easily in the direction in which the V-shaped grooves on the surface 1 are arranged.

  Furthermore, since the optical element of the present invention functions as a reflective aerial image forming element, the space between the image space and the object space can be made hollow.

It is a perspective view showing typically aerial imaging of an observation object by an embodiment of the present invention. It is sectional drawing when optical element S1 is cut in the cross section of the one-dimensional array of V-shaped groove 20 in optical element S1. FIG. 6 is a cross-sectional view of the optical element S1 when the optical element S1 is cut in a plane that is horizontal to the direction of the V-shaped groove 20 and perpendicular to the surface 10 in the optical element S1. This is a state in which the light beam is reflected twice by the V-shaped groove 20 in the optical element S1. This is a state of light rays incident from the surface 11 side of the optical element S1 when the optical element S1 is observed from a direction perpendicular to the surface 10. This is a state of light rays incident from the surface 10 side of the optical element S1 when the optical element S1 is observed from a direction horizontal to the surface 10 and perpendicular to the array direction of the V-shaped grooves 20. The light beam incident from the surface 10 side of the optical element S1 is collected on the straight line 30. This is a state of light beam bending by the optical element S2 having refractive power only in one direction. The light radiated from the light source 200 disposed at the focal line position of the optical element S2 is reflected and reflected by a mirror surface directly below the optical element S2. It is a mode that the real image of the to-be-observed object by embodiment of this invention is displayed as an aerial image. It is a mode at the time of making hollow space between the to-be-observed object and aerial image by embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows an optical element S1 in which a plurality of substantially right-angled V-shaped grooves are arranged in one direction at regular intervals, and each V-shaped groove surface is a reflecting surface. It is a perspective view which represents typically the aerial image formation of the to-be-observed object by embodiment of this invention provided with optical element S2 which has the function to condense on.

  First, the configuration and function of the optical element S1 will be described.

  FIG. 2 is a cross-sectional view when the optical element S1 is cut in a cross section of a one-dimensional array of V-shaped grooves 20 in the optical element S1. A smooth mirror surface treatment is applied to the surface of each V-shaped groove 20 to form a reflecting surface. The pitch of the plurality of V-shaped grooves 20 is, for example, 100 to 500 μm, and in the present embodiment, 100 μm. In this embodiment, the longitudinal dimension is 20 cm, but the pitch of the V-shaped grooves 20 and the longitudinal direction are applied. These dimensions can be appropriately set without being limited thereto. In particular, considering that the shape of the optical element S1 is a one-dimensional array of V-grooves 20, there is no limit to the extension in the array direction in principle.

  In the present embodiment, the optical element S1 made of an acrylic resin is used in this embodiment, and total reflection in the V-shaped groove 20 is used. However, the material is not limited to this as long as it is a material for optical use with sufficiently high transparency. can do. It is also possible to make the V-shaped groove 20 with a metal that has been subjected to a smooth mirror surface treatment and to utilize surface reflection. Hereinafter, it is assumed that the total reflection in the V-shaped groove 20 is used according to the present embodiment.

  FIG. 3 is a cross-sectional view of the optical element S1 when the optical element S1 is cut in a plane parallel to the direction of the V-shaped groove 20 and perpendicular to the surface 10 in the optical element S1. When the optical element S1 is observed from this direction, the V-shaped groove shape is not observed, and the optical element S1 is apparently observed as a flat plate.

  In the optical element S1, each V-shaped groove 20 functions as a micro optical element (unit optical element). As shown in FIG. 4, from the object to be observed placed in the space on the surface 11 side of the optical element S1. Part of the emitted light passes through the surface 10, is reflected twice by the V-shaped groove 20, and passes through the surface 10 again.

  As shown in FIG. 5, when observed from the same direction as in FIG. 2, the two-time reflection in the plurality of V-shaped grooves 20 functions as a retroreflection, and the direction of the light beam after the second reflection is from the light source 100. The direction of radiation is reversed. As a result of the above-mentioned reflection occurring in each V-shaped groove, the light beam after being reflected twice is twice from the light source 100 in the direction opposite to the direction when it is emitted from the light source 100 from the place where the reflection is twice. It appears to converge near a point that has traveled a distance equal to the optical path length traveled before reflection. The light collection width at this time is proportional to the pitch of the one-dimensional array of the V-shaped grooves 20, and the light is collected with a width of about twice the pitch in terms of geometric optics. However, as the pitch decreases, the influence of diffraction in the V-shaped groove 20 increases, and the light collection width increases.

  On the other hand, as shown in FIG. 6, when observed from the same direction as in FIG. 3, the light emitted from the light source 100 is reflected twice by the V-shaped groove 20, but the light after being reflected twice is reflected by a plane. Looks like. At this time, the light beam is condensed and cannot be seen.

  Condensation resulting from the two-time reflection in the V-shaped groove 20 described above is a result of the rays emitted from the light source 100 arranged on the straight line 30 having the same height from the surface 10 as shown in FIG. It can be viewed as slit-shaped light collection on the straight line 30. (Hereinafter, the above-described light collection may be referred to as lateral light collection). The following describes how an image looks when such a light beam is observed.

  When observing in a state where the line connecting the eyes of the observer is horizontal with the array direction of the V-shaped groove 20, the image of the light source 100 appears to be present where the observer's line of sight and the straight line 30 intersect. When no object exists on the straight line 30, the image of the light source 100 is observed as an aerial image. However, since a light beam spreading from a certain light condensing point and a light beam spreading from a light condensing point at a slightly different position on the straight line 30 enter the observer's pupil at the same time, the image is observed blurred. As the line connecting the eyes of the observer becomes non-horizontal with respect to the array direction of the V-shaped grooves 20, the above-described difference in position increases and the blur of the image increases. When the blur of the image increases, the image looks double and is not observed as an aerial image.

  Further, when the observation position is moved in parallel with the straight line 30 while maintaining a state in which the line connecting the eyes of the observer is horizontal with the array direction of the V-shaped groove 20, light rays spread from the condensing points at different positions. The image appears to move. That is, the observed image does not have a sense of localization in the direction parallel to the straight line 30. For example, as shown in FIG. 7, when the observation position is moved from V1 to V2, an image observed to exist at the light collection position 101 in V1 appears to move to the light collection position 102.

  Accordingly, the optical element S2 has a function of condensing light in the direction of the straight line 30, that is, having refractive power only in one direction, in order to reduce blurring and double images of the image and prevent movement of the image accompanying movement of the observation position. Is provided directly above the surface 10. Hereinafter, the configuration and function of the optical element S2 will be described.

  The optical element S2 condenses parallel light incident from a direction perpendicular to the element surface in a slit shape. That is, collimated light is condensed at the focal line position, and conversely, divergent light from a point light source placed on the focal line remains divergent in a direction having no refractive power and parallel to a direction having refractive power. It is an optical element having a function of light. Examples of the optical element S2 include a cylindrical lens and a linear Fresnel lens. In this embodiment, a linear Fresnel lens is used to reduce the thickness of the entire device. In this embodiment, an object having a focal length of 150 mm, a pitch of 0.3 mm, and a size of 100 mm × 300 mm is applied. However, the focal length, pitch, and size of the optical element S2 are not limited to these and are set as appropriate. can do.

  In this embodiment, the optical element S2 made of an acrylic resin is used. However, the optical element S2 can be appropriately set without being limited to this as long as the material has a sufficiently high transparency.

  Hereinafter, light collection by the optical element S2 will be described using the optical element S2 as a linear Fresnel lens.

  FIG. 8 is a cross-sectional view of the optical element S2 cut in a cross section of a plane parallel to the direction having the refractive power of the optical element S2, that is, the surface 40 provided with the Fresnel pattern. The light beam emitted from the light source 200 placed on the focal line of the optical element S2 passes through the surface 40 having refractive power, so that parallel light is diverged in the direction having refractive power and divergent in the direction having no refractive power. Light is emitted. On the contrary, the parallel light perpendicular to the surface 40 passes through the optical element S2, and is condensed in a slit shape at the focal line position of the optical element S2.

  FIG. 9 shows the state of light beam bending and reflection when the light source 200 is disposed on the focal line of the optical element and the mirror surface 50 that is a plane exists directly below the optical element S2. When the light beam emitted from the light source 200 passes through the surface 40, the light beam that has become parallel light with respect to the direction having the refractive power of the surface 40 is reflected by the mirror surface 50, passes through the surface 40 again, and the optical element S2. Condensed in a slit shape at the focal line position. (Hereafter, it may be referred to as vertical light collection)

  When the light source exists at a position deviating from the focal line position, the condensing position deviates from the focal line position, and the above-described vertical direction condensing is possible although affected by the aberration.

  When the optical element S1 is arranged so that the surface 10 is on the side of the surface 40 instead of the mirror surface 50, the light incident on the optical element S2 from the side of the surface 40 is bent by the optical element S2 and 2 of the optical element S1. Condensed by the reflection of light.

  By arranging the condensing direction of the optical element S1 and the condensing direction of the optical element S2 to be orthogonal to each other, it is possible to simultaneously condense the light emitted from the light source in the horizontal direction and the vertical direction. . When the horizontal light collecting position and the vertical light collecting position are substantially the same position, the light is collected at substantially the same position in the air.

  Here, “substantially the same position” includes not only the completely same position but also a position range of several millimeters to several centimeters before and after being regarded as substantially the same position. There is no practical problem as long as the observer feels that the light is concentrated at one point.

  That is, in FIG. 1, when the optical element S1 is disposed on the back surface of the optical element S2, the space between the optical elements S1 is filled with a transparent medium, and the light condensing direction thereof is arranged almost perpendicularly. Light rays emitted from a light source arranged near the focal line of the optical element S2 are condensed and imaged at substantially the same position. However, when the light source is disposed on the focal line, the formed aerial image is blocked by the light source and cannot be observed. Therefore, in order to observe an aerial image, it is necessary to arrange the light source at a position off the focal line of the optical element S2.

  As shown in FIG. 10, when the object to be observed O is arranged in a space near the focal line of the optical element S2 and not on the focal line in the space on the optical element S2 side, the object O is emitted from the object O2. Light or diffusely reflected light of the object to be observed O enters the optical element S2 and is bent, then enters the optical element S1, is reflected twice by the V-shaped groove 20, and is incident again on the optical element S2 and bent. Then, the aerial image I is observed by condensing the light in the horizontal direction and the light in the vertical direction at substantially the same position. The condensing position at this time is near the focal line of the optical element S2, and is a position where the distance between the object to be observed O and the optical element S1 is equal to the distance between the optical element S1 and the aerial image I. The observation direction is the direction of the arrow of the observer V in FIG.

  Further, in this case, the aerial image I becomes a vertically inverted image of the observation object O due to the condensing of the optical element S2. Therefore, in order to display a desired image, the object to be observed O needs to be arranged upside down in advance.

  As an advantage of the embodiment according to the present invention, since the optical element S1 has a one-dimensional array shape of the V-shaped grooves 20, it can be easily extended in the array direction and the display range in the horizontal direction can be easily expanded. It is done. This cannot be realized by an aerial image display element using only a lens.

  Further, as described above, the embodiment according to the present invention has a function of functioning as a reflective aerial image forming element. Accordingly, as shown in FIG. 11, a hollow space 300 can be formed between the aerial image I and the observation object O. This cannot be realized by the transmission type imaging optical element described in Patent Document 1 and Non-Patent Document 1, but is a function unique to the embodiment of the present invention.

  As described so far, the surface 10 of the optical element S1 is disposed on the surface 50 of the optical element S2, the space between them is filled with a transparent medium, and the light condensing direction thereof is substantially perpendicular. The present invention functions as an aerial image display element. Therefore, it is possible to realize the aerial image display element in the present invention without making the optical element S1 and the optical element S2 bonded to form an integral type.

  However, considering practical use, it is desirable that the optical element S1 and the optical element S2 are integrated so that the arrangement of the optical element S1 and the optical element S2 is not shifted. Then, next, an example of the manufacturing method of the aerial image display element in this invention provided with the said optical element S1 and the said optical element S2 is described.

  In this embodiment, a transparent adhesive is applied to the surface 10 of the optical element S1, and the surface 50 of the optical element S2 is disposed thereon so that the light collecting directions of the optical element S1 and the optical element S2 are orthogonal to each other. The adhesive was cured after removing bubbles between the optical element S1 and the optical element S2 by applying a vacuum. Further, as a manufacturing method suitable for mass production, one surface of one transparent flat plate is formed into a one-dimensional array shape of the V-shaped groove 20 and the opposite surface is formed into a Fresnel pattern surface 40 of a linear Fresnel lens. An aerial image display element can be realized. In this case, V-groove and Fresnel pattern processing methods include cutting with accuracy that the processed surface becomes a mirror surface, press molding with a mold, and injection molding. In addition, if the optical element S1 is arranged on the back surface of the optical element S2, the space between the optical elements S1 is filled with a transparent medium, and the condensing direction thereof can be arranged almost perpendicular, It can set suitably, without being restricted to the above-mentioned manufacturing method.

  In the display system for displaying an aerial image of an object to be observed, the present invention has no distortion with respect to light collection in the lateral direction, and facilitates extension of the V-shaped grooves 20 in the array direction. Therefore, it can be used for the purpose of presenting information having a long display range in the horizontal direction such as an electronic bulletin board in the air. In this case, the effect of attracting the viewer's attention is expected compared to a non-aerial image display device such as a conventional monitor, and when applied to the presentation or advertisement of text information in public or commercial facilities, It is expected to improve the degree of attention.

  Further, the present invention has a function of functioning as a reflective aerial image forming element, and makes it possible to make the space between the image space and the object space to be hollow. Therefore, it is possible to display an image in the air above the slot by installing the present invention and a display device such as a monitor inside the container used when throwing or throwing things such as trash cans and posts. It is. Thereby, it can utilize for the display which shows the target at the time of throwing in the guide which points the place of an insertion slot.

  In addition, since it is relatively simple and can be manufactured at low cost, it is possible to provide the aerial image display element according to the present invention not only for business use as described above but also in the price range for general consumers. is there. As an application example at this time, there is a use of adding an art effect by displaying a photograph, a painting, a digital photo frame or the like in the air.

S1, S2 Optical element 10 Smooth surface 20 V-shaped groove 30 Straight line 40 Fresnel pattern 50 Smooth mirror surface V, V1, V2 Observer 100, 200 Light source 101, 102, 201 Condensing position 100A, 200A Diffused light 100B, 200B Converged light 300 Hollow space O Object I Aerial image

Claims (7)

  Light beams incident on the V-shaped groove from the point light source by two reflections in the above-mentioned V-shaped groove by arranging substantially right-angled V-shaped grooves in one direction at regular intervals and using the V-shaped groove surface as a reflecting surface. A surface 1 having a function of condensing light on a straight line, and a surface 2 having a refractive power only in one direction and having a function of condensing incident parallel light on a focal line unique to the element. The optical element is characterized in that the back surface of the surface 2 is the surface 2, the space between them is filled with a transparent medium, and the light collecting direction of the surface 1 and the light collecting direction of the surface 2 are substantially orthogonal to each other. .   The optical element according to claim 1, wherein the reflection surface of the surface 1 utilizes reflection on a smooth surface formed of a glossy substance.   The optical element according to claim 1, wherein the reflection surface of the surface 1 uses reflection or total reflection at a flat boundary between transparent media having different refractive indexes.   The diffused light incident from the surface 2 side is refracted by the surface 2, then reflected twice by the surface 1, and then refracted again by the surface 2, and then emitted. The optical element according to claim 1, wherein the optical element has a function of forming an image in a space.   5. The imaging principle according to claim 4, wherein a real image of an object to be observed arranged near the focal distance of the surface 2 is imaged near the focal distance in the space on the surface 2 side. Item 5. The optical element according to Item 4.   6. The imaging principle according to claim 4 and claim 5, wherein a real image of an object to be observed is imaged without distortion in the direction in which the V-shaped grooves of the surface 1 are arranged. Item 6. The optical element according to Item 5.   According to the imaging principle according to claim 4 and claim 5, the surface 1 and the surface to be observed are not arranged between the surface 1 and the surface 2 between the object to be observed and the real image of the object to be observed. The optical element according to claim 1, wherein the real image can be made hollow.

Images