WO2012043471A1 - フレネルレンズ - Google Patents
フレネルレンズ Download PDFInfo
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- WO2012043471A1 WO2012043471A1 PCT/JP2011/071879 JP2011071879W WO2012043471A1 WO 2012043471 A1 WO2012043471 A1 WO 2012043471A1 JP 2011071879 W JP2011071879 W JP 2011071879W WO 2012043471 A1 WO2012043471 A1 WO 2012043471A1
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- lens
- fresnel lens
- axis
- elliptical cone
- fresnel
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B3/00—Simple or compound lenses
- G02B3/02—Simple or compound lenses with non-spherical faces
- G02B3/08—Simple or compound lenses with non-spherical faces with discontinuous faces, e.g. Fresnel lens
Definitions
- the present invention relates to a Fresnel lens.
- an aberration-free lens is known as an aberration-free lens (for example, Hiroshi Kubota, “Optics”, 12th edition, Iwanami Shoten Co., Ltd., April 9, 1986, p. 282-283). reference).
- RF HF
- R is the refraction point of the lens surface 71
- H is the intersection when the perpendicular is dropped from the refraction point R onto the optical axis Opa (the leg of the perpendicular dropped from the refraction point R to the optical axis Opa)
- RF is The optical path length between the refraction point R and the focal point F, HF, is the optical path length between the intersection point H and the focal point F.
- the lens surface 71 needs to be a hyperboloid or an ellipsoid.
- the lens surface 71 is given by equation (1), where n is the refractive index of the lens material and f is the back focus of the lens.
- the expression (1) defines orthogonal coordinates having the focal point F of the lens as the origin, the z-axis on the optical axis Opa, and the x-axis and y-axis orthogonal to each other in a plane orthogonal to the optical axis Opa. This is an equation obtained when the coordinates of an arbitrary point on the lens surface 71 are (x, y, z). Further, a, b, and c in the expression (1) are given by the expressions (2), (3), and (4), respectively.
- the rotation axis C of the hyperboloid 120 that is the exit surface (second surface) forms an angle ⁇ with the normal N of the plane 110 that is the entrance surface (first surface).
- a condensing lens 101 is known (Japanese Patent Publication No. 7-36041).
- a light ray incident at an angle ⁇ with respect to the rotation axis C and parallel to the rotation axis C of the hyperboloid 120 in the condensing lens 101 is at the focal point F. Condensed without aberration.
- the equation of the hyperboloid 120 has the focal point F as the origin, the z axis on the rotation axis C of the hyperboloid 120, and the x axis and the y axis that are orthogonal to each other in a plane orthogonal to the rotation axis C.
- the orthogonal coordinates it is expressed by the above-described equation (1).
- the document of the above-mentioned Japanese Patent Publication includes a condenser lens 101 as a Fresnel lens, and each hyperboloid 121 on the second surface in order to suppress the occurrence of off-axis aberrations.
- 122 and 123 are proposed in which the rotation axis C is obliquely intersected with the plane 110 which is the first surface.
- each hyperboloid 121, 122, 123 constitutes a lens surface.
- each hyperboloid 121, 122, 123 constituting the exit surface is oblique to the normal line N of the plane 110 that is the entrance surface
- each hyperboloid 121, 122, 123 is , Not rotationally symmetric with respect to the normal N of the plane 110. For this reason, it is difficult to manufacture the Fresnel lens 101 and the mold for the Fresnel lens 101 by rotational processing using a lathe or the like.
- a sharp tool having a nose radius (also referred to as a corner radius) of several ⁇ m is used as shown in FIG. It is necessary to form each hyperboloid 121, 122, 123 or each curved surface by making only 130 cutting edges point-contact with the workpiece 140 and performing cutting with a fine pitch.
- the workpiece 140 is a base material for directly forming the Fresnel lens 101 or a base material for forming a mold. For this reason, the processing time in manufacturing the above-mentioned Fresnel lens 101 and the mold for the Fresnel lens 101 becomes long, which causes an increase in the cost of the Fresnel lens 101.
- each lens surface is a straight line in the cross-sectional shape including the normal line of the plane that is the entrance surface of the Fresnel lens
- the cutting tool 130 is inclined with respect to the workpiece 140 as shown in FIG.
- the Fresnel lens 101 disclosed in the above-mentioned Japanese Patent Publication and the Fresnel lens disclosed in the above-mentioned U.S. Patent Literature are directed to infrared rays, and both documents include polyethylene as a lens material. Is disclosed.
- an object of the present invention is to provide a Fresnel lens capable of suppressing the occurrence of off-axis aberrations and reducing the cost when using incident light that is obliquely incident on the first surface from the outside. There is to do.
- the Fresnel lens of the present invention is a Fresnel lens in which the second surface opposite to the first surface has a plurality of lens surfaces, and at least one of the lens surfaces comprises a part of a side surface of an elliptical cone, Of the normals of each point on the first surface, an arbitrary normal that intersects the lens surface that is a part of the side surface of the elliptical cone, and the ellipse corresponding to the lens surface that intersects the arbitrary normal
- the central axis of the cone is non-parallel.
- At least two of the plurality of lens surfaces are each formed of the part of the side surface of the elliptical cone having a different central axis, and correspond to the lens surface located outside. It is preferable that the angle between the central axis and the normal line is larger as the elliptical cone is.
- the central lens surface of the plurality of lens surfaces is made up of a part of an aspherical surface with a continuously changing curvature, and the non-normality among the normals of the points on the first surface.
- An arbitrary normal that intersects the central lens surface that is a part of a spherical surface and an axis of symmetry of the aspheric surface that corresponds to the central lens surface that intersects the arbitrary normal are non-parallel. Is preferred.
- the aspheric surface is preferably a hyperboloid.
- the lens material is preferably polyethylene
- the first surface is preferably a curved surface that is convex on the side opposite to the second surface side.
- FIG. 4B It is a principal part schematic bottom view which shows the application example of the Fresnel lens of Embodiment 1 of this invention. It is an enlarged view of FIG. 4B. It is sectional drawing of the Fresnel lens of Embodiment 2 of this invention. It is explanatory drawing of the advancing path
- the first surface 10 is a flat surface
- the second surface 20 opposite to the first surface 10 has a plurality of (three in the illustrated example) lens surfaces 21.
- the Fresnel lens 1 includes a center lens portion 1a and a plurality (two in the illustrated example) of an annular lens portion 1b surrounding the center lens portion 1a.
- the number of the annular lens portions 1b is not particularly limited, and may be three or more.
- the Fresnel lens 1 is a condenser lens in which the second surface 20 opposite to the first surface 10 has a plurality of lens surfaces 21, and the lens surface 21 of the central lens portion 1a is a convex surface.
- the Fresnel lens 1 is a condensing lens that can be made thinner than a convex lens.
- Each ring-shaped lens portion 1b has a mountain portion 11b on the second surface 20 side.
- the mountain portion 11b has a rising surface (non-lens surface) 22 formed from a side surface on the central lens portion 1a side, and a lens surface 21 formed from a side surface opposite to the central lens portion 1a side. Therefore, the second surface 20 of the Fresnel lens 1 has a lens surface 21 in each of the annular lens portions 1b.
- the second surface 20 of the Fresnel lens 1 also has a lens surface 21 in the central lens portion 1a.
- FIG. 1B in the case where the first surface 10 is the entrance surface and the second surface 20 is the exit surface, the traveling path of the light beam is indicated by a thin solid line and an arrow is attached.
- the light rays incident on the first surface 10 from the direction oblique to the normal line of the first surface 10 of the Fresnel lens 1 are the second of the Fresnel lens 1. It can be seen that the light is focused on the focal point F on the surface 20 side.
- each lens surface 21 is composed of a part of the side surface of the elliptical cone 30, and the lens is composed of a part of the side surface of the elliptical cone 30 among the normal lines of the respective points on the first surface 10.
- An arbitrary normal intersecting the surface 21 and the central axis of the elliptical cone 30 corresponding to the lens surface 21 intersected by the arbitrary normal are non-parallel (that is, inclined).
- each elliptical cone 30 has a vertex P located on the second surface 20 side and a bottom surface (not shown) located on the first surface 10 side.
- the central axis of the elliptical cone 30 is oblique to the normal line at each point on the first surface 10. If the direction connecting the point on the first surface 10 and the intersection where the normal at that point intersects the lens surface 21 is defined as the lens thickness direction, if the first surface 10 is a plane, The direction along the normal at each point on the surface 10 is the lens thickness direction. Accordingly, in each of FIGS. 1A and 1B, the vertical direction is the lens thickness direction.
- each lens surface 21 has the apex P located on the second surface 20 side, the bottom surface located on the first surface 10 side, and the central axis obliquely intersecting the lens thickness direction. It is configured by a part of the side surface of the elliptical cone 30.
- a surface parallel to the first surface 10 and each lens surface 21 The angle formed is an obtuse angle, and the angle formed between the surface parallel to the first surface 10 and each rising surface 22 is substantially a right angle.
- the inventors of the present application solve the problem that it is possible to suppress the occurrence of off-axis aberrations and to reduce the cost when using incident light that is obliquely incident on the first surface 10 from the outside.
- the second surface 20 is configured by a part of each of a plurality of hyperboloids (one hyperboloid of a two-leaf hyperboloid) 25 whose principal axis is oblique to the normal of the first surface 10.
- hyperboloids one hyperboloid of a two-leaf hyperboloid
- a set of tangents at each point on the cross section orthogonal to the rotation axis of the hyperboloid 25 is a cone. Therefore, in a Fresnel lens in which the shape of each lens surface on the exit surface is rotationally symmetric with the normal of the entrance surface as the rotation axis, each lens surface can be approximated by a part of the side surface of the cone.
- an arbitrary cone is defined in the orthogonal coordinate system that defines the z-axis that is orthogonal to the arbitrary plane.
- the coordinate of the point is (x, y, z), b and c are coefficients, and the cone equation is expressed in the following standard form.
- the coefficient c is a constant unrelated to z.
- each hyperboloid 25 in the above-mentioned reference structure cannot be approximated by a truncated cone obtained by cutting this cone with two planes parallel to the xy plane.
- each lens surface 21 has a vertex P located on the second surface 20 side, a bottom surface (not shown) on the first surface 10 side, and a central axis (not shown). Is configured by a part of the side surface of the elliptical cone 30 that is oblique to the lens thickness direction.
- the elliptical cone 30 has a hyperboloid 25 inscribed in the elliptical cone 30, and the elliptical cone 30.
- the slopes of the tangent lines of the two coincide with each other, so that rays passing through the points on the intersection line between the elliptical cone 30 and the hyperboloid surface 25 are on the rotation axis of the hyperboloid 25. Focused on one point.
- At least one lens surface 21 of the plurality of lens surfaces 21 has a shape obtained by cutting a part of the elliptical cone 30 so as to include the intersection line of the elliptical cone 30 and the hyperboloid 25.
- the lower the height of the peak portion 11b the easier it is for the Fresnel lens 1 to collect light rays passing through the peak portion 11b at one point, so that the elliptical cone 30 and the hyperboloid 25 inscribed in the elliptical cone 30 intersect each other. It is desirable that the line intersects the mountain portion 11b.
- each mountain portion 11b and the interval between the vertices of adjacent mountain portions 11b must be set to a value equal to or greater than the wavelength of the electromagnetic wave to be condensed in the Fresnel lens 1.
- the Fresnel lens 1 when infrared rays having a wavelength of 10 ⁇ m are to be collected, it is necessary to set the height of each peak portion 11b and the interval between adjacent peak portions 11b to 10 ⁇ m or more.
- the Fresnel lens 1 when the height of each peak portion 11b and the interval between the vertices of adjacent peak portions 11b are increased, the off-axis aberration is increased, and the lens pattern is visible from the first surface 10 side. It is possible that the problem of becoming will arise.
- the Fresnel lens 1 has a peak portion 11b.
- the maximum height is preferably 150 ⁇ m or less.
- the distance between 11b is 0.3 mm or less.
- the interval between the adjacent peak portions 11b can be set within a range of 0.1 to 0.3 mm, for example. preferable.
- the height from the valley of the peak portion 11b in the annular lens portion 1b is perpendicular to the lens thickness direction (that is, parallel to the flat first surface 10) and the peak portion 11b.
- An intersection line between the elliptical cone 30 and the hyperboloid 25 inscribed in the elliptical cone 30 exists on the plane 15 that is 1 ⁇ 2 of the maximum height of. Therefore, in the Fresnel lens 1 of the present embodiment, the light beam passing on the intersection of the lens surface 21 and the plane 15 is condensed at the focal point F as shown in FIG.
- a general elliptic cone equation is defined as an orthogonal coordinate system in which an x-axis and a y-axis are defined to be orthogonal to each other in the arbitrary plane, and a z-axis is defined to be orthogonal to the arbitrary plane.
- the coordinates of an arbitrary point of the elliptical cone are (x, y, z), and a, b, c are coefficients, and are expressed in the standard form of the following equation (6).
- the coefficient c is a constant unrelated to z.
- the three elliptical cones 30 will be described with different symbols.
- the elliptical cone 30 0 corresponds to the central lens surface 21
- the elliptical cone 30 1 corresponds to the lens surface 21 that becomes the first annular zone closest to the central lens surface 21, and the central lens surface 21.
- the one corresponding to the lens surface 21 that is the second annular zone that is the second closest to is an elliptical cone 30 2 .
- the one corresponding to 21 is defined as an elliptical cone 30 n .
- the vertices P, P, P of the elliptical cones 30 0 , 30 1 , 30 2 are vertices P 0 , P 1 , P 2, and the respective centers of the elliptical cones 30 0 , 30 1 , 30 2 are used.
- the axes are CA 0 , CA 1 , CA 2 .
- the vertex of the elliptical cone 30 n corresponding to the lens surface 21 serving as the n-th annular zone is P n
- the central axis of the elliptical cone 30 n is CA n
- the vertex of the elliptical cone 30 n corresponding to the lens surface 21 serving as the n-th annular zone is P n
- the central axis of the elliptical cone 30 n is CA n .
- the equations of the elliptical cones 30 0 , 30 1 , 30 2 can be expressed by the above-described equation (6) in each orthogonal coordinate system.
- the hyperboloids 25, 25, 25 inscribed in the elliptical cones 30 0 , 30 1 , 30 2 are represented as hyperboloids 25 0 , 25 1 , 25 2 , respectively.
- a lens having six lens surfaces 21 each consisting of a part of a side surface of an elliptical cone 30 is illustrated.
- the one corresponding to the central lens surface 21 among the six elliptical cones 30 corresponds to the elliptical cone 30 0 , and the lens surfaces 21 that are the first to fifth annular zones.
- the objects are assumed to be elliptical cones 30 1 to 30 5 .
- the thickness t of the base portion other than each peak portion 11b is 0.5 mm, and the height of the peak portion 11b at the point closest to the focal point F in each annular zone lens portion 1b.
- the coefficients a, b, and c in equation (6) are the values shown in Table 1.
- the coefficients a, b and c shown in Table 1 are incident when the distance from the image plane I parallel to the first surface 10 of the Fresnel lens 1 to the first surface 10 is 5.5 mm and the incident angle is 45 °. It is the value calculated
- the central axis of the lens surface 21 of the second surface 20 where the normal intersects with respect to the normal at each point on the first surface 10 is inclined.
- the intersections of the normal line and the second surface 20 at points A1, A2, B1, B2, C1, and C2 on the first surface 10 are A11 and A22.
- B11, B22, C11, C22, and normal lines at points A1, A2, B1, B2, C1, C2 on the first surface 10 are respectively A1-A11, A2-A22, B1-B11, B2-B22, C1- These are referred to as C11 and C2-C22.
- the angle between the normal lines A1-A11, A2-A22 intersecting the central lens surface 21 and the central axis CA 0 of the elliptical cone 30 0 is ⁇ 0
- the first annular zone closest to the central lens surface 21 The angle formed by the normals B1-B11, B2-B22 intersecting the lens surface 21 and the central axis CA 1 of the elliptical cone 30 1 is ⁇ 1
- An angle between normal lines C1-C11, C2-C22 intersecting the lens surface 21 and the central axis CA 2 of the elliptical cone 30 2 is ⁇ 2 .
- the angle formed between the normal line intersecting the lens surface 21 serving as the third annular zone and the central axis CA 3 of the elliptical cone 30 3 is ⁇ 3
- the normal line intersecting the lens surface 21 serving as the fourth annular zone an angle between the center axis CA 4 of the elliptical cone 30 4 theta 4
- ⁇ 0 to ⁇ 5 are values shown in Table 2 below.
- the Fresnel lens 1 has an outer ring-shaped lens whose angle formed by the normal line at each point on the first surface 10 and the central axis of each lens surface 21 of the second surface 20 where the normal line intersects. It can be seen that the portion 1b becomes larger.
- FIG. 3 shows a spot diagram at the focal point F of the Fresnel lens 1.
- FIG. 3 shows a spot diagram in the range of 2 ⁇ 2 mm with the focal point F as the center.
- the size of the condensing spot may be less than or equal to the size of the photoelectric conversion element arranged in accordance with the focal point F of the Fresnel lens 1 (here, 0.6 ⁇ 0.6 mm or less).
- each lens surface 21 is a straight line in a cross-sectional shape including one virtual straight line along the lens thickness direction (a cross-sectional shape including the normal line of the first surface 10).
- the cutting tool 130 is attached to a workpiece (a base material for directly forming the Fresnel lens 1 or a base material for forming a mold) 140.
- the lens surface 21 or a curved surface corresponding to the lens surface 21 can be formed by inclining and bringing the side surface of the blade into line contact for cutting.
- the lens material that is the material of the Fresnel lens 1 may be appropriately selected according to the wavelength of the light beam, and may be appropriately selected from, for example, plastic (polyethylene, acrylic resin, etc.), glass, silicon, germanium, and the like.
- plastic polyethylene, acrylic resin, etc.
- glass silicon, germanium, and the like.
- polyethylene, silicon, germanium, etc. may be selected.
- the wavelength of light is in the wavelength range of visible light, acrylic resin, glass, etc. are selected. do it.
- die is not specifically limited, For example, phosphor bronze etc. are employable.
- mold is just to shape
- the first surface 10 is a flat surface
- the second surface 20 has a plurality of lens surfaces 21, and each lens surface 21 is on the second surface 20 side.
- the apex P is located
- the bottom surface is located on the first surface 10 side
- the central axis is constituted by a part of the side surface of the elliptical cone 30 that is oblique to the lens thickness direction.
- the Fresnel lens 1 of the present embodiment includes an arbitrary normal line that intersects the lens surface 21 formed of a part of the side surface of the elliptical cone 30 among the normal lines of the respective points on the first surface 10, and the arbitrary The central axis of the elliptical cone 30 corresponding to the lens surface 21 where the normal intersects is non-parallel. Therefore, in the Fresnel lens 1 of the present embodiment, it is possible to suppress the occurrence of off-axis aberration when using incident light that is obliquely incident on the first surface 10 from the outside, and it is possible to reduce the cost. It becomes.
- the Fresnel lens 1 uses at least one of the lens surfaces 21 by a part of the side surface of the elliptical cone 30 to use incident light obliquely incident on the first surface 10 from the outside.
- the occurrence of off-axis aberration can be suppressed and the cost can be reduced.
- a sensor device configured as shown in FIGS.
- a package 4 is mounted on a circuit board 8 made of a printed wiring board.
- the package 4 is arranged so as to close a disk-shaped stem 5, a bottomed cylindrical cap 6 joined to the stem 5, and an opening 6 a formed at the bottom of the cap 6.
- a light transmitting member 7 having a function of transmitting light.
- an element holding member for example, an MID substrate 3 that holds the photoelectric conversion element 2 is accommodated.
- a cover member 9 having a multi-lens composed of three Fresnel lenses 1, 1 ⁇ / b> A, 1 is disposed on one surface side of the circuit board 8 so as to cover the package 4.
- the photoelectric conversion element 2 for example, an infrared sensor element such as a pyroelectric element or a light receiving element such as a photodiode can be used.
- an infrared sensor element as the photoelectric conversion element 2
- each lens surface 21A on the second surface 20A has a vertex (not shown) on the second surface 20A side and a bottom surface (not shown) on the first surface 10A side. Is located and the central axis is constituted by a part of the side surface of the cone that coincides with the normal line of the center of the first surface 10A. Therefore, it becomes possible to provide a multi lens at low cost. Further, when, for example, an infrared sensor element is used as the photoelectric conversion element 2, an infrared sensor having a wide angle of view can be realized as a sensor device.
- Fresnel lenses 1 and 1A in the multi-lens is not particularly limited.
- the basic configuration of the Fresnel lens 1 of the present embodiment is substantially the same as that of the first embodiment, and the central lens surface 21 of the plurality of lens surfaces 21 is inclined with respect to the lens thickness direction and has a curvature. The difference is that it is part of a hyperboloid 25 that is a continuously changing aspheric surface.
- symbol is attached
- all of the plurality of lens surfaces 21 can be configured by a part of the elliptical cone 30.
- the lens surface 21 of the central lens portion 1 a includes the vertex P of the elliptical cone 30, and the curved surface is not formed at the vertex P. Since it is continuous, the light beam passing through the apex P is not easily collected at the focal point F.
- the central lens surface 21 of the plurality of lens surfaces 21, in other words, the lens surface 21 of the central lens portion 1a is part of the hyperboloid 25 described above. .
- the Fresnel lens 1 of the present embodiment can reduce aberrations compared to the Fresnel lens 1 of Embodiment 1, and can improve the light collecting performance. Therefore, if the Fresnel lens 1 of the present embodiment is applied to the sensor device described in the first embodiment, the sensitivity can be improved.
- the lens surface 21 of the central lens portion 1a is configured by a part of the hyperboloid 25, so that aberration is reduced as compared with a case where the lens surface 21 is configured by a part of an aspheric surface other than the hyperboloid 25. It becomes possible to make it smaller.
- the lens surface 21 of the central lens portion 1a is a part of the hyperboloid 25, when the mold for the Fresnel lens 1 is manufactured, the rake surface 131 of the cutting tool 130 is used as the lens surface 21 as shown in FIGS. 6A and 6B. It can be processed by moving while tilting so that it is perpendicular to the corresponding curved surface.
- the processing can be shortened even if the lens surface 21 of the central lens portion 1a is part of the hyperboloid 25. Is possible.
- the lens surface 21 of the central lens portion 1a is not limited to the hyperboloid 25, and the symmetry axis is oblique to the lens thickness direction and the curvature continuously changes. If it is a spherical surface, the light condensing performance can be improved as compared with the Fresnel lens 1 of the first embodiment.
- the central lens surface 21 of the plurality of lens surfaces 21 is a part of an aspherical surface whose curvature changes continuously, and an aspherical surface among the normals of each point on the first surface 10.
- the rotation axis OP1) of the hyperboloid 25 is preferably non-parallel (that is, tilted), so that the light condensing performance can be improved.
- the Fresnel lens 1 has each axis in the projection area on the first surface 10 when the axis of symmetry for the aspherical surface and the central lens surface 21 are projected in a direction parallel to the central axis of the first surface 10. As long as the normal line is non-parallel.
- the intersection line between the elliptical cone 30 and the hyperboloid 25 inscribed in the elliptical cone 30 intersects the peak portion 11b, as in the Fresnel lens 1 of the first embodiment.
- the height from the valley of the peak portion 11b in the annular lens portion 1b is perpendicular to the lens thickness direction (that is, parallel to the flat first surface 10).
- An intersecting line of the elliptical cone 30 and the hyperboloid 25 inscribed in the elliptical cone 30 exists on the plane 15 which is 1 ⁇ 2 of the maximum height of 11b. Therefore, in the Fresnel lens 1 of the present embodiment, the light beam passing on the intersection of the lens surface 21 and the plane 15 is condensed at the focal point F as shown in FIG. 5B.
- the hyperboloid 25 serving as the lens surface 21 of the central lens portion 1a has the focal point F as the origin, the rotation axis OP1 of the hyperboloid 25 as the z axis, and the x axis orthogonal to the z axis.
- the orthogonal coordinate system having the y axis is defined by the above equation (1).
- Each of the elliptic cones 30 1 and 30 2 has apexes P 1 and P 2 as the origin, the central axes CA 1 and CA 2 as the z axis, and along the major axis direction of the ellipse in the cross section orthogonal to the z axis. If an orthogonal coordinate system that defines the y-axis along the x-axis and minor axis directions is defined, it can be expressed by the above-described equation (6).
- the Fresnel lens 1 a lens having a central lens surface 21 formed of a part of a hyperboloid 25 and five lens surfaces 21 formed of a part of a side surface of an elliptical cone 30 is illustrated.
- the elliptical cones 30 1 to 30 5 are the ones corresponding to the lens surfaces 21 that are the first to fifth annular zones among the five elliptical cones 30.
- the thickness t of the base portion other than each peak portion 11b is 0.5 mm, and the height of the peak portion 11b at the point closest to the focal point F in each annular zone lens portion 1b.
- the angle formed between the rotation axis OP1 of the hyperboloid 25 of the central lens portion 1a and the normal line of the first surface 10 According to Snell's law, it may be set to 27.5 °. That is, the rotation axis OP ⁇ b> 1 may be inclined by 27.5 ° with respect to the normal line of the first surface 10. Further, the central axis of the lens surface 21 of the second surface 20 where the normal intersects with respect to the normal at each point on the first surface 10 is inclined.
- the angle formed by the normals B1-B11, B2-B22 intersecting the lens surface 21 which is the first annular zone closest to the central lens surface 21 and the central axis CA 1 of the elliptical cone 30 1 is ⁇ 1
- the central lens The angle formed between the normal lines C1-C11, C2-C22 intersecting the lens surface 21 that is the second annular zone closest to the surface 21 and the central axis CA 2 of the elliptical cone 30 2 is defined as ⁇ 2 .
- the angle formed between the normal line intersecting the lens surface 21 serving as the third annular zone and the central axis CA 3 of the elliptical cone 30 3 is ⁇ 3
- the normal line intersecting the lens surface 21 serving as the fourth annular zone an angle between the center axis CA 4 of the elliptical cone 30 4 theta 4
- ⁇ 0 to ⁇ 5 are values shown in Table 4 below.
- FIG. 7 shows a spot diagram at the focal point F of the Fresnel lens 1.
- FIG. 7 shows a spot diagram in the range of 2 ⁇ 2 mm with the focal point F as the center.
- the size of the condensing spot may be less than or equal to the size of the photoelectric conversion element arranged in accordance with the focal point F of the Fresnel lens 1 (here, 0.6 ⁇ 0.6 mm or less). Comparing FIG. 3 with FIG. 7, it can be seen that the Fresnel lens 1 of the present embodiment can reduce aberration compared to the Fresnel lens 1 of the first embodiment.
- the Fresnel lens 1 includes a lens surface 21 of at least one of the annular lens portions 1b of the plurality of annular lens portions 1b that is configured by a part of the side surface of the elliptic cone 30 so that the first surface can be seen from the outside.
- the Fresnel lens 1 of the present embodiment will be described with reference to FIGS. 8A and 8B.
- the basic configuration of the Fresnel lens 1 of the present embodiment is substantially the same as that of the second embodiment, except that the first surface 10 is a curved surface that is convex on the side opposite to the second surface 20 side.
- the first surface 10 is composed of a part of a spherical surface having a large curvature radius, but is not limited to a part of the spherical surface.
- the Fresnel lens 1 when polyethylene is used as the lens material, the first surface 10 is a flat surface. Therefore, due to cooling of the injection molding, uneven shrinkage caused by the solidification process, and so on, There is a concern that undulation will occur and the appearance will be damaged.
- the sensor device having the configuration shown in FIGS. 4A to 4C is mounted on a device such as a television or an air conditioner, the Fresnel lens 1 forms part of the appearance of the device, so that the design of the device is not impaired.
- the first surface 10 is preferably in a shape that is substantially flush with the periphery of the first surface 10 on the surface of the device.
- the Fresnel lens 1 is preferably a curved surface having a large radius of curvature (a curved surface having a small curvature) as shown in FIGS. 8A and 8B.
- the lens thickness direction is a normal direction at each point on the first surface 10.
- the Fresnel lens 1 of the present embodiment by making the first surface 10 a curved surface that is convex on the side opposite to the second surface 20 side, the direction of undulation can be suppressed in one direction, and the appearance is improved. It is possible to prevent damage.
- the first surface 10 has a gentler curvature radius than the central lens surface 21, which is a part of the aspherical hyperboloid 25, and is convex on the opposite side of the hyperboloid 25.
- a curved surface is preferred.
- the curvature of the first surface 10 is designed in a range where the off-axis aberration does not exceed the allowable value (below the size of the photoelectric conversion element), polyethylene is adopted as the lens material, It is possible to suppress the occurrence of sink marks and undulations while suppressing the occurrence of off-axis aberrations. Furthermore, if the first surface 10 that is the appearance surface of the Fresnel lens 1 has the same curvature as the peripheral portion of the first surface 10 on the surface of the device, the design of the device can be improved.
- the lens surface 21 of the central lens portion 1a is configured by a part of a hyperboloid 25 as in the second embodiment, but the hyperboloid is similar to one example of the second embodiment.
- the 25 rotation axes OP1 are tilted by 27.5 °, off-axis aberrations increase with respect to light rays incident at an incident angle of 45 °. Therefore, when the first surface 10 is a part of a spherical surface as in the Fresnel lens 1 of the present embodiment, the rotation axis OP1 of the hyperboloid 25 is further defined in the first embodiment with respect to the hyperboloid 25.
- the intersection of the elliptical cone 30 and the hyperboloid 25 inscribed in the elliptical cone 30 is It is desirable to cross.
- the elliptical cone 30 and the elliptical cone are formed on the plane 15 where the height from the valley of the peak portion 11b in the annular lens portion 1b is 1 ⁇ 2 of the maximum height of the peak portion 11b.
- the hyperboloid 25 of the central lens portion 1a is orthogonal with the focal point of the hyperboloid 25 as the origin, the rotation axis OP1 as the z axis, and the x axis and the y axis perpendicular to the z axis, respectively.
- the coordinate system right is defined, it is expressed by equation (1).
- Each of the elliptic cones 30 1 and 30 2 has apexes P 1 and P 2 as the origin, the central axes CA 1 and CA 2 as the z axis, and along the major axis direction of the ellipse in the cross section orthogonal to the z axis. If an orthogonal coordinate system that defines the y-axis along the x-axis and minor axis directions is defined, it can be expressed by the above-described equation (6).
- the Fresnel lens 1 a lens having a central lens surface 21 formed of a part of a hyperboloid 25 and five lens surfaces 21 formed of a part of a side surface of an elliptical cone 30 is illustrated.
- the elliptical cones 30 1 to 30 5 are the ones corresponding to the lens surfaces 21 that are the first to fifth annular zones among the five elliptical cones 30.
- the first surface 10 is a part of a spherical surface with a radius of curvature of 100 mm, the minimum height t of the base portion other than the peak portion 11b is 0.5 mm, and each annular lens.
- the coefficients a, b, and c shown in Table 5 are such that the distance from the image plane I of the Fresnel lens 1 to the plane parallel to the image plane I and in contact with the first surface 10 is 5.5 mm, and the incident angle is 45. It is a value obtained on the precondition that light rays incident at 0 ° are focused on the focal point F.
- the Fresnel lens 1 has a hyperboloid with respect to the hyperboloid 25 corresponding to the lens surface 21 of the center lens portion 1a with the rotation axis OP1 of the hyperboloid 25 of the center lens portion 1a of the second embodiment within the above-described xz plane.
- the off-axis aberration can be reduced by rotating and tilting around 25 vertices Px by 2.5 °.
- the normal line at each point on the first surface 10 is directed toward the center of curvature of the first surface 10, and the central axes CA 1 and CA 2 of the lens surfaces 21 of the second surface 20 where the normal lines intersect with each other. Is tilted.
- the angle formed between the normal of the image plane I and the central axis CA 1 of the elliptical cone 30 1 corresponding to the lens surface 21 that is the first annular zone is ⁇ 1
- the lens surface 21 that is the second annular zone is the image plane I.
- the angle between the corresponding elliptic cone 30 2 and the central axis CA 2 is ⁇ 2 .
- the angle formed between the normal of the image plane I and the central axis CA 3 of the elliptical cone 30 3 corresponding to the lens surface 21 which is the third annular zone is ⁇ 3
- the normal of the image plane I and the fourth annular zone are an angle between the center axis CA 4 of the elliptical cone 30 4 corresponding to the lens surface 21 to become theta 4
- FIG. 9 shows a spot diagram at the focal point F of the Fresnel lens 1.
- FIG. 9 shows a spot diagram in the range of 2 ⁇ 2 mm with the focal point F as the center.
- the size of the condensing spot may be less than or equal to the size of the photoelectric conversion element arranged in accordance with the focal point F of the Fresnel lens 1 (here, 0.6 ⁇ 0.6 mm or less). Comparing FIG. 7 and FIG. 9, it can be seen that the Fresnel lens 1 of the present embodiment has the same aberration as that of the Fresnel lens 1 of the second embodiment.
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Lenses (AREA)
- Optical Elements Other Than Lenses (AREA)
Abstract
Description
以下では、本実施形態のフレネルレンズについて図1A,1Bおよび図2を参照しながら説明する。
以下では、本実施形態のフレネルレンズについて図5A,5Bを参照しながら説明する。
以下では、本実施形態のフレネルレンズ1について図8A,8Bを参照しながら説明する。本実施形態のフレネルレンズ1の基本構成は実施形態2と略同じであり、第一面10が第二面20側とは反対側に凸となる曲面である点が相違する。なお、本実施形態のフレネルレンズ1では、第一面10が曲率半径の大きな球面の一部からなるが、球面の一部に限定するものではない。
Claims (5)
- 第一面とは反対側の第二面が複数のレンズ面を有するフレネルレンズであって、少なくとも1つの前記レンズ面が、楕円錐の側面の一部からなり、前記第一面上の各点の法線のうち前記楕円錐の側面の一部からなる前記レンズ面に交差する任意の法線と、当該任意の法線が交差する前記レンズ面に対応する前記楕円錐の中心軸とが、非平行であることを特徴とするフレネルレンズ。
- 前記複数の前記レンズ面のうち少なくとも2つの前記レンズ面が、それぞれ前記中心軸の異なる前記楕円錐の前記側面の前記一部からなり、外側に位置する前記レンズ面に対応する前記楕円錐ほど、前記中心軸と前記法線とのなす角度が大きいことを特徴とする請求項1記載のフレネルレンズ。
- 前記複数の前記レンズ面のうち中央の前記レンズ面は、曲率が連続的に変化する非球面の一部からなり、前記第一面上の各点の法線のうち前記非球面の一部からなる中央の前記レンズ面に交差する任意の法線と、当該任意の法線が交差する中央の前記レンズ面に対応する前記非球面の対称軸とが、非平行であることを特徴とする請求項1または請求項2記載のフレネルレンズ。
- 前記非球面は、双曲面であることを特徴とする請求項3記載のフレネルレンズ。
- レンズ材料がポリエチレンであり、前記第一面が前記第二面側とは反対側に凸となる曲面であることを特徴とする請求項1ないし請求項3のいずれか1項に記載のフレネルレンズ。
Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CN201180036576.8A CN103026269B (zh) | 2010-09-27 | 2011-09-26 | 菲涅耳透镜 |
KR1020137000804A KR101534119B1 (ko) | 2010-09-27 | 2011-09-26 | 프레넬 렌즈 |
EP11829025.3A EP2624021A4 (en) | 2010-09-27 | 2011-09-26 | LENS OF FRESNEL |
SG2013001813A SG187004A1 (en) | 2010-09-27 | 2011-09-26 | Fresnel lens |
US13/749,767 US8922912B2 (en) | 2010-09-27 | 2013-01-25 | Fresnel lens |
Applications Claiming Priority (6)
Application Number | Priority Date | Filing Date | Title |
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JP2010216197 | 2010-09-27 | ||
JP2010-216197 | 2010-09-27 | ||
JP2011031199 | 2011-02-16 | ||
JP2011-031199 | 2011-02-16 | ||
JP2011200320A JP6020979B2 (ja) | 2010-09-27 | 2011-09-14 | フレネルレンズ |
JP2011-200320 | 2011-09-14 |
Related Child Applications (1)
Application Number | Title | Priority Date | Filing Date |
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US13/749,767 Continuation US8922912B2 (en) | 2010-09-27 | 2013-01-25 | Fresnel lens |
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WO2012043471A1 true WO2012043471A1 (ja) | 2012-04-05 |
Family
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PCT/JP2011/071879 WO2012043471A1 (ja) | 2010-09-27 | 2011-09-26 | フレネルレンズ |
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US (1) | US8922912B2 (ja) |
EP (1) | EP2624021A4 (ja) |
JP (1) | JP6020979B2 (ja) |
KR (1) | KR101534119B1 (ja) |
CN (1) | CN103026269B (ja) |
SG (1) | SG187004A1 (ja) |
TW (1) | TWI432789B (ja) |
WO (1) | WO2012043471A1 (ja) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
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US9000378B2 (en) | 2010-12-21 | 2015-04-07 | Panasonic Intellectual Property Management Co., Ltd. | Optical detection device, and apparatus using same |
JP7095043B2 (ja) | 2016-11-11 | 2022-07-04 | グーグル エルエルシー | 多様なファセット角を有するフレネルレンズアセンブリ |
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US10120108B2 (en) * | 2015-02-13 | 2018-11-06 | Htc Corporation | Panel assembly and electronic device |
TWI551892B (zh) * | 2015-09-02 | 2016-10-01 | 原相科技股份有限公司 | 能有效提高訊號信噪比的多截面式光學元件及其光學偵測裝置 |
DE102016217749B4 (de) * | 2016-09-16 | 2023-07-06 | Sicoya Gmbh | Photonisches Bauelement |
TWI737720B (zh) * | 2017-04-28 | 2021-09-01 | 揚明光學股份有限公司 | 透鏡 |
US11054646B1 (en) * | 2017-05-11 | 2021-07-06 | Apple Inc. | Head-mounted display device with Fresnel lenses |
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US4787722A (en) | 1986-04-10 | 1988-11-29 | Fresnel Technologies, Inc. | Fresnel lens with aspiteric grooves |
JPH03186803A (ja) * | 1989-12-15 | 1991-08-14 | Matsushita Electric Works Ltd | 赤外線式検知装置用集光レンズ |
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US5054905A (en) * | 1987-11-12 | 1991-10-08 | Cohen Allen L | Progressive intensity phase bifocal |
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JP3308353B2 (ja) | 1993-07-23 | 2002-07-29 | 旭硝子株式会社 | 液晶光学素子 |
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JP4293857B2 (ja) * | 2003-07-29 | 2009-07-08 | シチズン電子株式会社 | フレネルレンズを用いた照明装置 |
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- 2011-09-14 JP JP2011200320A patent/JP6020979B2/ja not_active Expired - Fee Related
- 2011-09-26 KR KR1020137000804A patent/KR101534119B1/ko not_active IP Right Cessation
- 2011-09-26 EP EP11829025.3A patent/EP2624021A4/en not_active Withdrawn
- 2011-09-26 WO PCT/JP2011/071879 patent/WO2012043471A1/ja active Application Filing
- 2011-09-26 SG SG2013001813A patent/SG187004A1/en unknown
- 2011-09-26 TW TW100134527A patent/TWI432789B/zh not_active IP Right Cessation
- 2011-09-26 CN CN201180036576.8A patent/CN103026269B/zh not_active Expired - Fee Related
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2013
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Publication number | Priority date | Publication date | Assignee | Title |
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US9000378B2 (en) | 2010-12-21 | 2015-04-07 | Panasonic Intellectual Property Management Co., Ltd. | Optical detection device, and apparatus using same |
JP7095043B2 (ja) | 2016-11-11 | 2022-07-04 | グーグル エルエルシー | 多様なファセット角を有するフレネルレンズアセンブリ |
Also Published As
Publication number | Publication date |
---|---|
US20130141800A1 (en) | 2013-06-06 |
TWI432789B (zh) | 2014-04-01 |
US8922912B2 (en) | 2014-12-30 |
EP2624021A1 (en) | 2013-08-07 |
TW201224524A (en) | 2012-06-16 |
JP2012185470A (ja) | 2012-09-27 |
SG187004A1 (en) | 2013-02-28 |
KR101534119B1 (ko) | 2015-07-06 |
EP2624021A4 (en) | 2013-08-28 |
CN103026269A (zh) | 2013-04-03 |
CN103026269B (zh) | 2015-03-11 |
KR20130028959A (ko) | 2013-03-20 |
JP6020979B2 (ja) | 2016-11-02 |
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