JP2017067970A - Optical unit and converging lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical unit and a converging lens that enable achievement of miniaturization in an optical axis direction and a proper directional characteristic.SOLUTION: An optical unit 1 comprises: a converging lens 2; and an optical element 9 such as a light reception element 91 that is provided on an optical axis L on one side L1 of an optical axis L direction of the converging lens 2. The converging lens 2 includes: a lens part 3; and a translucent cylindrical barrel part 4 that protrudes onto the one side L1 of the optical axis L direction on an outer peripheral side of the lens part 3. A surface on the other side L2 of the optical axis direction of the lens part 3 is a converging Fresnel lens part 31, and a surface on the one side L1 is a convex lens surface 32. On an outer peripheral surface 4b of the barrel part 4, a reflection surface 41 is provided that has an outer diameter consecutively contracted toward the one side L1 from the other side L2. The reflection surface 41 does not have a reflection layer such as a metal layer, and reflection at an interface where the barrel part 4 is in contact with an air layer is utilized.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an optical unit and a condenser lens for improving the directivity of a light receiving element and a light emitting element.

  In light-emitting elements such as light-emitting diodes, a bullet-shaped lens is often provided so as to emit sufficient light over the entire predetermined angle range (see Patent Document 1). For example, since the light emitting diode emits light in an angle direction of ± 50 °, when sufficient light is emitted over an angle range of ± 30 °, the positive power of the bullet-shaped lens is used to make ± 30 °. The amount of emitted light in the entire angle range is increased.

JP 2003-69081 A

  However, the bullet-shaped lens has a problem that the dimension in the optical axis direction is long. Therefore, it is conceivable to reduce the size in the optical axis direction by using a Fresnel lens portion having positive power on the front surface of the lens. However, in such a configuration, there is a problem in that the amount of emitted light in the front direction decreases. Such a problem is not limited to the light emitting element, but also exists in the case where a lens is provided in the light receiving element so as to have sufficient sensitivity over a predetermined angle range.

  In view of the above problems, an object of the present invention is to provide an optical unit and a condensing lens capable of achieving downsizing in the optical axis direction and realizing appropriate directivity characteristics.

  In order to solve the above-described problems, an optical unit according to the present invention includes a lens portion and a light-collecting cylindrical body portion that protrudes to one side in the optical axis direction on the outer peripheral side of the lens portion. A lens and a light receiving element or a light emitting element, and an optical element provided on the optical axis of the lens unit on the one side with respect to the lens unit, and on the other side of the lens unit in the optical axis direction The surface is a condensing Fresnel lens part, the one side surface of the lens part is a convex lens surface, and the outer peripheral surface of the body part is from the other side to the one side. A reflection surface whose outer diameter is continuously reduced toward the surface is provided.

  In addition, a condensing lens according to the present invention includes a lens portion, and a translucent cylindrical body portion protruding to one side in the optical axis direction on the outer peripheral side of the lens portion, and the lens portion The surface on the other side in the optical axis direction is a light-collecting Fresnel lens portion, the surface on the one side of the lens portion is a convex lens surface, A reflection surface having an outer diameter continuously reduced from the other side toward the one side is provided.

In the present invention, since the lens part of the condenser lens has a convex lens surface on one side in the optical axis direction and a condensing Fresnel lens part on the other side in the optical axis direction, the lens part has positive power. Have. For this reason, in the light emitting element provided on the optical axis of the lens unit on one side with respect to the lens unit, sufficient light can be emitted over a predetermined angular range. Further, when a light receiving element is provided on the optical axis of the lens unit on one side with respect to the lens unit, sufficient sensitivity is provided over a predetermined angular range. In addition, the condenser lens includes a translucent cylindrical barrel protruding to one side in the optical axis direction on the outer peripheral side of the lens portion, and the outer peripheral surface of the barrel is directed from the other side to the one side. A reflective surface whose outer diameter is continuously reduced is provided. For this reason, even when a Fresnel lens portion is provided in the lens portion to reduce the size in the optical axis direction, the amount of emitted light and sensitivity in the front direction are excellent. Therefore, both downsizing in the optical axis direction and realization of appropriate directivity can be achieved.

  In the present invention, the optical element may employ an aspect including a light receiving element.

  In the present invention, it is preferable that the reflection surface uses reflection at an interface where the body portion and the air layer are in contact with each other. According to such a configuration, the reflective surface can be configured without providing a reflective layer such as a metal layer on the outer peripheral surface of the body portion, so that the cost of the condenser lens can be reduced.

  In the present invention, it is possible to adopt a mode in which the other side surface of the body portion is a flat surface or a convex curved surface. According to such a configuration, when the light emitting element is provided as the optical element, the light incident on the reflecting surface of the body portion can be appropriately emitted in the front direction, and when the light receiving element is provided as the optical element. The light incident on the reflecting surface of the body portion can be appropriately guided to the light receiving element.

  In the present invention, it is possible to adopt a mode in which the other side surface of the body portion is a flat surface. That is, if the configuration such as the inclination of the reflecting surface is made appropriate, the surface on the other side of the body portion can be made flat.

  In this invention, it is preferable that the internal peripheral surface of the said trunk | drum is a taper surface where the internal diameter expands continuously toward the said one side from the said other side. According to such a configuration, it is possible to increase the utilization efficiency of the light incident on the body portion of the condenser lens.

In the present invention, when the diameter of the Fresnel lens portion is φFresnel and the diameter of the convex lens surface is φASP, φFresnel and φASP preferably satisfy the following expressions.
φASP ≦ φFresnel
According to such a configuration, the utilization efficiency of light incident on the lens portion of the condenser lens can be increased.

In the present invention, the distance from the most located part of the convex lens surface to the center of the optical element is dAir, the length of the reflecting surface in the optical axis direction is dMirror, and the distance in the Fresnel lens portion is the most. When the distance from the portion located on the other side to the portion located on the most one side in the convex lens surface is dLens, dAir, dMirror, and dLens preferably satisfy the following expressions.
dAir ≦ dMirror−dLens
According to such a configuration, it is possible to increase the utilization efficiency of light incident on the reflecting surface of the condenser lens.

In the present invention, when the refractive index of the medium located between the lens portion and the light emitting element is n1, the refractive index of the lens portion is n2, and the radius of the convex lens surface is r, φFresnel, φASP, n1, n2, dLens, and r preferably satisfy the following equations.
φASP ≦ φFresnel ≦ 2 × dLens × tanθ + φASP
However, θ = Sin ⁻¹ ((n1 × φASP) / (n2 × 2 × r))
According to such a configuration, the utilization efficiency of light incident on the lens portion of the condenser lens can be increased.

In the present invention, when the reflection surface is a conical surface and the angle between the reflection surface and the optical axis is θMirror, θMirror and n2 preferably satisfy the following expressions.
θMirror ≦ π / 2-Sin ⁻¹ (1 / n 2)
According to this configuration, since the incident angle with respect to the reflecting surface can be increased, the light incident on the reflecting surface can be totally reflected without providing a metal layer on the reflecting surface. Therefore, the utilization efficiency of the light incident on the reflecting surface can be increased with a simple configuration.

In the present invention, φLens, φASP, dLens, dMirror, dAir, and θMirror preferably satisfy the following equations, where φLens is the diameter of the portion located on the other side of the body portion.
φLens ≦ φASP + 2 × (dLens + dAir) × tan (θMirror)
According to such a configuration, it is possible to increase the utilization efficiency of the light incident on the condenser lens.

In the present invention, when the curvature radius of each lens surface constituting the Fresnel lens portion is RFresnel and the curvature radius of the convex lens surface is RASP, it is preferable that RFresnel and RASP satisfy the following expressions.
RFresnel ≧ RASP
According to such a configuration, it is possible to easily reduce the aberration of light passing through the lens portion of the condenser lens.

  In the present invention, since the lens part of the condenser lens has a convex lens surface on one side in the optical axis direction and a condensing Fresnel lens part on the other side in the optical axis direction, the lens part has positive power. Have. For this reason, in the light emitting element provided on the optical axis of the lens unit on one side with respect to the lens unit, sufficient light can be emitted over a predetermined angular range. The light receiving element provided on the optical axis of the lens unit on one side with respect to the lens unit has sufficient sensitivity over a predetermined angular range. In addition, the condenser lens includes a translucent barrel projecting to one side in the optical axis direction on the outer peripheral side of the lens unit, and an outer diameter of the outer peripheral surface of the barrel unit from the other side toward the one side. Is provided with a reflective surface that is continuously reduced. For this reason, even when a Fresnel lens portion is provided in the lens portion to reduce the size in the optical axis direction, the amount of emitted light and sensitivity in the front direction are excellent. Therefore, both downsizing in the optical axis direction and realization of appropriate directivity can be achieved.

It is explanatory drawing of the optical unit to which this invention is applied. It is explanatory drawing of the condensing lens of the optical unit to which this invention is applied. It is explanatory drawing which shows the dimension of each location of the condensing lens shown in FIG. It is a graph which shows the directivity of the sensitivity of the optical unit to which this invention is applied.

  DESCRIPTION OF EMBODIMENTS Embodiments for carrying out the present invention will be described with reference to the drawings. In the following description, L1 is attached to one side of the optical axis L, and L2 is attached to the other side. The condensing lens 2 to which the present invention is applied constitutes the optical unit 1 together with the optical element 9 including the light receiving element 91 or the light emitting element 92. In the following description, the case where the optical element 9 is the light receiving element 91 will be mainly described.

(Configuration of optical unit)
FIG. 1 is an explanatory view of an optical unit 1 to which the present invention is applied. FIGS. 1A and 1B are a perspective view of the optical unit 1 viewed from the other side L2 in the optical axis L direction, and the optical unit 1. FIG. FIG. 2 is an explanatory diagram of the condenser lens 2 of the optical unit 1 to which the present invention is applied. FIGS. 2A, 2B, and 2C show the condenser lens 2 on the other side in the optical axis L direction. 2 is a front view as viewed from L2, a cross-sectional view when the condenser lens 2 is cut along the optical axis L, and an enlarged cross-sectional view showing a lens surface in a region surrounded by a line P in the Fresnel lens portion 31. FIG.

  The optical unit 1 shown in FIGS. 1 and 2 includes a condenser lens 2 and an optical element 9 disposed on the optical axis L (central optical axis) of the condenser lens 2. The optical element 9 includes a light receiving element 91 or a light emitting element 92. When the optical element 9 is the light receiving element 91, the optical unit 1 condenses the light incident from the condenser lens 2 side on the light receiving element 91. On the other hand, when the optical element 9 is the light emitting element 92, the optical unit 1 emits the diverging light emitted from the light emitting element 92 with the converging lens 2 narrowing the divergence angle. In this embodiment, the optical element 9 is the light receiving element 91, and condenses near infrared light for communication (wavelength 780 nm to 1100 nm) on the light receiving element 91 by the condenser lens 2. In that case, high sensitivity is calculated | required over the angle range of +/- 30 degree including a front surface (angle 0 degree), for example.

(Configuration of the condenser lens 2)
In this embodiment, the condensing lens 2 includes a lens portion 3 and a translucent cylindrical body portion 4 that protrudes from the outer peripheral side of the lens portion 3 to one side L1 in the optical axis L direction. The element 9 (light receiving element 91) is disposed on the optical axis L (center optical axis) of the lens unit 3 on one side L1 with respect to the lens unit 3. In the present embodiment, the lens unit 3 and the body unit 4 are resin molded products obtained by integrally molding a translucent resin, and are made of acrylic resin, polycarbonate, or the like. The lens unit 3 is circular when viewed from the other side L2 in the optical axis L direction, and the body unit 4 is also circular when viewed from the other side L2 in the optical axis L direction, like the lens unit 3. The end surface 3a on the other side L2 in the optical axis L direction of the lens unit 3 and the end surface 4a on the other side L2 in the optical axis L direction of the body unit 4 are at the same position in the optical axis L direction, and the end surface 3a. 4a constitutes an integral end face 2a on the other side L2 of the condenser lens 2 in the optical axis L direction.

  The surface (end surface 3a) on the other side L2 in the optical axis L direction of the lens unit 3 is a condensing Fresnel lens unit 31, and the surface on the one side L1 in the optical axis L direction of the lens unit 3 is a convex lens. Surface 32 is formed. The Fresnel lens portion 31 has a convex curved surface 315 having a circular center, and a plurality of concentric lens surfaces 310 each having a serrated annular convex portion protruding to the other side L2 are arranged around the convex curved surface 315. Has been. In this embodiment, the annular lens surface 310 has four rows of lens surfaces 311, 312, 313, and 314 formed concentrically, and the width of the lens surface 310 increases from the radially inner side toward the radially outer side. Is narrower. Here, the spherical surface when the convex curved surface 315 and the lens surface 310 are combined to form a continuous surface is an aspherical surface, and the convex lens surface 32 is a spherical surface.

  On the outer peripheral surface 4 b of the body portion 4, a reflecting surface 41 whose outer diameter is continuously reduced from the other side L2 in the optical axis L direction toward the one side L2 is provided. In this embodiment, the reflection surface 41 is a conical surface. In the body portion 4, a rectangular tubular portion 42 is provided on one side L <b> 1 in the optical axis L direction with respect to the reflecting surface 41, and the optical element 9 (light receiving element 91) is disposed inside the tubular portion 42. Has been placed. Here, the reflection surface 41 uses reflection at the interface where the body portion 4 and the air layer are in contact, and a reflection layer such as a metal layer is not formed. Moreover, the inner peripheral surface 43 of the trunk | drum 4 is a taper surface where the internal diameter expands continuously toward the one side L1 from the other side L2 of the optical axis L direction.

  In the present embodiment, the end surface 4a on the other side L2 of the body portion 4 is a flat surface or a convex curved surface. In the present embodiment, the end surface 4a on the other side L2 of the body 4 is a flat surface.

(Operation of the optical unit 1)
In the optical unit 1 configured as described above, the light incident on the end surface 3a of the lens unit 3 out of the light incident on the end surface 2a of the condenser lens 2 from the other side L2 in the optical axis L direction is the Fresnel lens unit 31. After condensing on the convex lens surface 32, the light is condensed toward the light receiving element 91. The light incident on the end surface 4 a of the body 4 is reflected by the reflecting surface 41, is refracted by the inner peripheral surface 43 of the body 4, and is collected on the light receiving element 91. For this reason, the light receiving element 91 has sufficient sensitivity over a predetermined angle range.

(Detailed configuration of the lens portion 3 of the condenser lens 2)
FIG. 3 is an explanatory diagram showing dimensions and the like of each part of the condenser lens 2 shown in FIG.

As shown in FIG. 2, when the diameter of the Fresnel lens portion 31 is φFresnel and the diameter of the convex lens surface 32 is φASP in the condenser lens 2 of this embodiment, φFresnel and φASP satisfy the following equations: Yes.
φASP ≦ φFresnel ・ ・ Condition (1)

When the refractive index of the medium located between the lens unit 3 and the light receiving element 91 is n1, the refractive index of the lens unit 3 is n2, and the radius is r of the convex lens surface 32, φFresnel, φASP, n1, n2 , DLens, and r satisfy the following equation:
φASP ≦ φFresnel ≦ 2 × dLens × tan θ + φASP ·· Condition (2)
However, θ = Sin ⁻¹ ((n1 × φASP) / (n2 × 2 × r))

  For this reason, the utilization efficiency of the light which entered the lens part 3 among the condensing lenses 2 can be improved. That is, even the light that has entered the outermost edge of the lens unit 3 reaches the center 90 of the light receiving element 91 via the convex lens surface 32, and it is necessary to satisfy the following conditions.

  First, when it is assumed that the surface on the one side L1 of the lens unit 3 is a plane passing through the portion of the convex lens surface 32 located on the most one side L1 in the optical axis L direction, one side of the lens unit 3 in the optical axis L direction. The angle formed by the line connecting the outer edge of the surface L1 and the center 90 of the light receiving element 91 with the optical axis L is θ1, and the outer edge of the surface L1 on the one side L1 in the optical axis L direction of the lens unit 3 and the Fresnel lens unit 31 An angle formed by a line connecting the outer edge and the optical axis L is defined as θ. In addition, the distance from the portion of the Fresnel lens portion 31 located on the other side L2 in the optical axis L direction to the portion of the convex lens surface 32 located on the most side L1 in the optical axis L direction is defined as dLens. Let ½ of the difference be Δφ. Here, even if the convex lens surface 32 does not have positive power, in order for the light incident on the outermost edge of the lens portion 3 to reach the center 90 of the light receiving element 91, the light incident on the outermost edge of the lens portion 3. Needs to reach the center 90 of the light receiving element 91, and the following conditions must be satisfied.

First, the following equation holds.
Δφ = (φFresnel−φASP) / 2 = dLens × tan θ
Therefore, the following equation is obtained.
φFresnel = 2 × dLens × tanθ + φASP

Here, in order for the light incident on the outermost edge of the lens unit 3 to reach the center 90 of the light receiving element 91, the following condition is satisfied.
φFresnel ≦ φASP + 2 × dLens × tanθ

Further, since θ <θ1 from Snell's law, the following conditional expressions (1) and (2) are obtained.
φASP ≦ φFresnel ・ ・ Condition (1)
φASP ≦ φFresnel ≦ 2 × dLens × tanθ + ΦASP ·· Condition (2)

Note that the following equation holds for θ according to Snell's law.
n1 × sinθ1 = n2 × sinθ
sin θ = (n1 × sin θ1) / n2
θ = sin ⁻¹ ((n1 × sin θ1) / n2))
θ = Sin ⁻¹ ((n1 × φASP) / (n2 × 2 × r))

(Relationship between the reflecting surface 41 and the convex lens surface 32 of the condenser lens 2)
On the convex lens surface 32, the distance from the portion located on the most one side L in the optical axis L direction to the center 90 of the light receiving element 91 is dAir, the length of the reflecting surface 41 in the optical axis L direction is dMirror, and the Fresnel lens portion 31. Where dLens is the distance from the portion located on the most other side L2 in the optical axis L direction to the portion located on the most one side L1 on the convex lens surface 32, dAir, dMirror, and dLens satisfy the following equations: Yes.
dAir ≦ dMirror−dLens ·· Condition (3)

For this reason, the utilization efficiency of the light which injected into the reflective surface 41 among the condensing lenses 2 can be improved. That is, the distance dAir from the portion located on the most one side L on the convex lens surface 32 to the center 90 of the light receiving element 91 is appropriate, and the reflecting surface 41 needs to extend from the convex lens surface 32 to the one side L1. Yes, the following formula needs to be satisfied.
dLens + dAir ≦ dMirror

Therefore, the following conditional expression (3) can be obtained.
dAir ≦ dMirror−dLens ·· Condition (3)

(Total reflection condition on the reflection surface 41 of the condenser lens 2)
When the angle formed by the reflecting surface 41 and the optical axis L is θMirror, θMirror and n2 satisfy the following expressions.
θMirror ≦ π / 2−Sin ⁻¹ (1 / n 2) ·· Condition (4)

For this reason, since the incident angle with respect to the reflective surface 41 can be made larger than the critical angle, the light incident on the reflective surface 41 can be totally reflected without providing the reflective surface 41 with a reflective layer such as a metal layer. . Therefore, the utilization efficiency of the light incident on the reflecting surface 41 can be increased with a simple configuration. That is, when the light traveling in parallel to the optical axis L is incident on the reflecting surface 41, the critical angle is θn, and when the refractive index of the air layer is 1, the incident angle is θn and the refractive index of the air layer is 1. Then, the following equation holds from Snell's law.
n2 × sin θn = 1 × sin (90 °)
sin θn = 1 / n2
θn = Sin ⁻¹ (1 / n 2)

Therefore, conditional expression (4) is obtained as follows.
θMirror ≦ π / 2−Sin ⁻¹ (1 / n 2) ·· Condition (4)
(Dimensions of the reflecting surface 41 of the condenser lens 2)

When the diameter of the portion located on the most other side L2 of the body portion 4 is φLens, φLens, φASP, dLens, dMirror, dAir, and θMirror satisfy the following expressions.
φLens ≦ φASP + 2 × (dLens + dAir) × tan (θMirror) ·· Condition (5)

For this reason, the utilization efficiency of the light which entered into the condensing lens 2 can be improved. That is, it is preferable that the reflecting surface 41 extends from the surface on the other side L2 of the body portion 4 to a position close to the light receiving element 91 in the optical axis L direction. Here, the following equation holds.
ΦLens / 2 ≦ ΦASP / 2 + (dLens + dAir) × tan (θMirror)

Therefore, the following conditional expression (5) is obtained.
φLens ≦ φASP + 2 × (dLens + dAir) × tan (θMirror) ·· Condition (5)

(Aberration measures)
When the curvature radius of each lens surface 310 (see FIG. 2) constituting the Fresnel lens portion 31 is R Fresnel and the curvature radius of the convex lens surface 32 is R ASP, R Fresnel and R ASP satisfy the following expressions.
RFresnel ≧ RASP

  For this reason, the spherical aberration, the coma aberration, and the astigmatism of the light passing through the lens unit 3 in the condenser lens 2 can be easily reduced. Therefore, the sensitivity can be improved.

(Main effects of this form)
FIG. 4 is a graph showing the directivity of the sensitivity of the optical unit 1 to which the present invention is applied. FIGS. 4A and 4B are simulation results of the directivity of the sensitivity of the optical unit 1 to which the present invention is applied. And a graph showing a simulation result of sensitivity directivity of a reference example using a bullet-shaped lens.

  As described above, in the optical unit 1 according to this embodiment, the lens unit 3 of the condenser lens 2 includes the convex lens surface 32 on the one side L1 in the optical axis L direction and condenses on the other side L2 in the optical axis L direction. The lens part 3 has a positive power because it has the characteristic Fresnel lens part 31. For this reason, the light receiving element 91 provided on the optical axis L of the lens unit 3 on one side L1 with respect to the lens unit 3 has sufficient sensitivity over a predetermined angular range. The condensing lens 2 includes a translucent cylindrical body 4 that protrudes to the one side L1 in the optical axis L direction on the outer peripheral side of the lens part 3, and the outer peripheral surface 4b of the body 4 includes A reflecting surface 41 having an outer diameter continuously decreasing from the other side L2 toward the one side L1 is provided. For this reason, since the light incident on the body 4 can be reflected by the reflecting surface 41 and incident on the light receiving element 91, the sensitivity in the front direction can be increased. Therefore, even if the lens unit 3 is provided with the Fresnel lens unit 31 to reduce the size of the condenser lens 2 in the optical axis L direction, as shown in FIGS. Directivity equivalent to that when a lens is used can be obtained. More specifically, according to the condensing lens 2 of the present embodiment, even when the size in the optical axis L direction is reduced to, for example, 6 mm or less, a bullet-shaped lens having a size in the optical axis L direction of about 11 mm Similarly, high sensitivity can be obtained over an angle range of ± 30 ° including the front (angle 0 °), for example. Therefore, according to this embodiment, it is possible to reduce the size of the optical unit 1 and the condenser lens 2 in the direction of the optical axis L, and to realize appropriate directivity characteristics.

  Further, the reflection surface 41 uses reflection at the interface where the body portion 4 and the air layer are in contact with each other. For this reason, since the reflecting surface 41 can be configured without providing a reflecting layer such as a metal layer on the outer peripheral surface of the body portion 41, the cost of the condenser lens 2 can be reduced.

  Further, in this embodiment, if the configuration such as the inclination of the reflecting surface 41 is optimized, the surface of the other side L2 of the body portion 4 can be a flat surface, so that the configuration of the condenser lens 2 can be simplified. Can be planned.

  Moreover, since the inner peripheral surface 43 of the trunk | drum 4 is a taper surface from which the internal diameter expands continuously toward the one side L1 from the other side L2, it is in the trunk | drum 4 among the condensing lenses 2. FIG. The utilization efficiency of incident light can be increased.

(Other embodiments)
In the above embodiment, the end surface 4a on the other side L2 of the body portion 4 is a flat surface. However, the end surface 4a on the other side L2 of the body portion 4 is curved from the optical axis L side toward the outer peripheral side. It may be a curved surface.

  In the above embodiment, the reflecting surface 41 is a conical surface. However, the reflecting surface 41 has an aspherical surface whose outer diameter is continuously reduced from the other side L2 toward the one side L1, or a parabola in cross section. It may be a paraboloid. In such a configuration, if the reflecting surface 41 is a parabolic surface, the light condensing property to the light receiving element 91 can be improved.

  In the above embodiment, the case where the light receiving element 91 is used as the optical element 9 has been mainly described. However, the present invention may be applied to the case where the light emitting element 92 is used as the optical element 9, and in this case, the optical unit 1 The directivity of the light emitted from can be improved.

DESCRIPTION OF SYMBOLS 1 Optical unit, 2 Condensing lens, 2a, 3a, 4a End surface, 3 Lens part, 4 Torso part, 4b Outer peripheral surface, 9 Optical element, 31 Fresnel lens part, 32 Convex lens surface, 41 Reflecting surface, 43 Inner peripheral surface, 91 Light receiving element, 92 Light emitting element, 310, 311, 312, 313, 314 Lens surface, 315 Convex curved surface, L Optical axis

Claims (18)

A condensing lens comprising a lens part, and a translucent cylindrical body part projecting to one side in the optical axis direction on the outer peripheral side of the lens part;
An optical element comprising a light receiving element or a light emitting element and provided on the optical axis of the lens part on the one side with respect to the lens part;
Have
The other surface of the lens portion in the optical axis direction is a light-collecting Fresnel lens portion,
The one side surface of the lens part is a convex lens surface,
An optical unit, wherein an outer peripheral surface of the body portion is provided with a reflecting surface whose outer diameter is continuously reduced from the other side toward the one side.   The optical unit according to claim 1, wherein the optical element includes a light receiving element.   The optical unit according to claim 1, wherein the reflection surface uses reflection at an interface between the body portion and the air layer.   The optical unit according to any one of claims 1 to 3, wherein the surface on the other side of the body portion is a flat surface or a convex curved surface.   The optical unit according to claim 4, wherein the other surface of the body portion is a flat surface.   6. The inner peripheral surface of the trunk portion is a tapered surface having an inner diameter that continuously increases from the other side toward the one side. The optical unit described. The diameter of the Fresnel lens part is φFresnel,
When the diameter of the convex lens surface is φASP,
φFresnel and φASP are the following formulas φASP ≦ φFresnel
The optical unit according to any one of claims 1 to 6, wherein: The distance from the portion located on the most one side on the convex lens surface to the center of the optical element is dAir,
The length of the reflecting surface in the optical axis direction is dMirror,
When the distance from the portion located on the other side of the Fresnel lens portion to the portion located on the one side of the convex lens surface is dLens,
dAir, dMirror, and dLens are expressed by the following equations: dAir ≦ dMirror−dLens
The optical unit according to claim 7, wherein: The refractive index of the medium located between the lens part and the light emitting element is n1,
The refractive index of the lens part is n2,
When r is the radius of the convex lens surface,
φFresnel, φASP, n1, n2, dLens, and r are the following formulas: φASP ≦ φFresnel ≦ 2 × dLens × tan θ + φASP
However, θ = Sin ⁻¹ ((n1 × φASP) / (n2 × 2 × r))
The optical unit according to claim 8, wherein: The reflective surface comprises a conical surface;
When the angle between the reflection surface and the optical axis is θMirror,
θMirror and n2 are expressed by the following equation: θMirror ≦ π / 2−Sin ⁻¹ (1 / n2)
The optical unit according to claim 9, wherein: When the diameter of the part located on the other side of the trunk part is φLens,
φLens, φASP, dLens, dMirror, dAir, and θMirror are the following formulas: φLens ≦ φASP + 2 × (dLens + dAir) × tan (θMirror)
The optical unit according to claim 9 or 10, wherein: The radius of curvature of each lens surface constituting the Fresnel lens portion is R Fresnel,
When the curvature radius of the convex lens surface is RASP,
RFresnel and RASP are the following formulas: RFresnel ≧ RASP
The optical unit according to any one of claims 1 to 11, wherein: The lens part,
A translucent cylindrical barrel projecting to one side in the optical axis direction on the outer peripheral side of the lens unit;
With
The other surface of the lens portion in the optical axis direction is a light-collecting Fresnel lens portion,
The one side surface of the lens part is a convex lens surface,
A condensing lens, wherein an outer peripheral surface of the body portion is provided with a reflecting surface whose outer diameter is continuously reduced from the other side toward the one side.   The condensing lens according to claim 13, wherein the reflection surface uses reflection at an interface between the body portion and the air layer.   The condensing lens according to claim 13 or 14, wherein the surface on the other side of the body portion is a flat surface or a convex curved surface.   The condensing lens according to claim 15, wherein a surface of the other side of the body portion is a flat surface.   17. The inner peripheral surface of the body portion is a tapered surface having an inner diameter continuously expanding from the other side toward the one side. The condenser lens described. The diameter of the Fresnel lens part is φFresnel,
When the diameter of the convex lens surface is φASP,
φFresnel and φASP are the following formulas φASP ≦ φFresnel
The condensing lens according to claim 13, wherein:

Images