Patent Description:
With development of technology and progress of society, a lighting or signaling apparatus that can only provide a function of illumination or a function of signal indicator will not satisfy the requirements of the people any longer. Instead, more and more customized applications of the lighting or signaling apparatus (for example a vehicle lamp for an automobile vehicle) have been proposed, therefore it needs to provide more diverse patterns and lit aspects of the light beam. In this case, a single light source often cannot satisfy the requirements. Thus, in order to achieve the diverse lit aspects (such as diverse depths of field, plural spots), in the prior art, more light sources are often needed to be provided. Thus, more light sources typically will occupy more space. It will affect the design space of lamps adversely and limit style design.

Japanese patent document <CIT> discloses a collimation optical system having Fresnel lens system to collimate and project the light image. The system disclosed uses multiple Fresnel lens to obtain the final output, this setup though compact has limitations in design and efficiency due to multiple component system adding to the complexity in design.

The present application is intended to provide a light beam adjusting device that can focus a light beam at a plurality of focal points to use a single light source to provide a lit aspect similar to that of a combination of a plurality of light sources.

The present application is also intended to provide an optical assembly including the light beam adjusting device and a lighting and/or signaling apparatus.

An embodiment of present application provides a light beam adjusting device including: a light collimating portion arranged to collimate a light beam; and a multi-focal converging portion arranged to converge the collimated light beam, the multi-focal converging portion comprising two or more converging surfaces, wherein the light collimating portion and the multi-focal converging portion are formed integrally as one single part, wherein the light collimating portion is formed at a light incidence side of the single part and the multi-focal converging portion is formed at a light exit side of the single part and at least two of the two or more converging surfaces have focal points separated spatially from each other,and wherein all of focal points of the two or more converging surfaces are arranged in the same axis of the multi-focal converging portion, the two or more converging surfaces being arranged in sequence along a radial direction of the multi-focal converging portion, and wherein the two or more converging surfaces are arranged at a side surface of the single part, and the single part further comprises a reflective face arranged to direct the light beam collimated by the light collimating portion to the two or more converging surfaces, the reflective face being arranged at a side of the single part opposite to the light collimating portion.

In an embodiment, all of focal points of the two or more converging surfaces are arranged in at least two different planes perpendicular to an axis of the multi-focal converging portion respectively.

In an embodiment, all of peaks of the two or more converging surfaces are arranged in the at least two different planes perpendicular to the axis of the multi-focal converging portion respectively.

In an embodiment, the light beam adjusting device further includes a reflector arranged to reflect a light emitted from the two or more converging surfaces.

In an embodiment, the light beam adjusting device further includes a plurality of mirrors arranged outside the side surface of the single part and arranged in sequence from near to far with respect to the side surface of the single part, to reflect the light beam converged by the two or more converging surfaces respectively.

In an embodiment, the light collimating portion comprises a first light incident face, a second light incident face and a totally reflective face, and wherein the first light incident face is arranged at an intermediate position of the light collimating portion to collimate a central portion of the light beam; the second light incident face is arranged outside the first light incident face in a radial direction to direct a peripheral portion of the light beam to the totally reflective face which is arranged outside the second light incident face in a radial direction to collimate the portion of the light beam incident from the second light incident face.

An embodiment of the present application provides an optical assembly comprising: a light source arranged to emit a light beam; and the light beam adjusting device as described in any one of the above embodiments.

In an embodiment, the optical assembly further includes a light guide device which has a light incidence end arranged toward the two or more converging surfaces and arranged to receive the light emitted from the two or more converging surfaces.

An embodiment of the present application also provides a lighting and/or signaling apparatus, including the optical assembly as described in any one of the above embodiments.

With the light beam adjusting device and the optical assembly as described in any one of the above embodiments, the intensity distribution of a light beam emitted from a single light source can be converted by a plurality of converging surfaces having different focal points into an intensity distribution similar to that of the light beams emitted from a plurality of light sources, so as to improve the lit aspect of the illuminating and/or signaling light of a vehicle lamp.

Embodiments of the present application will below be explained in details by ways of examples with reference to the accompanying drawings. Throughout the description, same or similar reference numerals represent same or similar parts. The following description of the embodiments with reference to the drawings is intended to explain the general inventive concept of the present application, instead of limiting the present invention.

The present invention provides a light beam adjusting device including: a light collimating portion arranged to collimate a light beam; and a multi-focal converging portion arranged to converge the collimated light beam, the multi-focal converging portion comprising two or more converging surfaces, wherein the light collimating portion and the multi-focal converging portion are formed integrally as one single part, wherein the light collimating portion is formed at a light incidence side of the single part and the multi-focal converging portion is formed at a light exit side of the single part and at least two of the two or more converging surfaces have focal points separated spatially from each other,and wherein all of focal points of the two or more converging surfaces are arranged in the same axis of the multi-focal converging portion, the two or more converging surfaces being arranged in sequence along a radial direction of the multi-focal converging portion, and wherein the two or more converging surfaces are arranged at a side surface of the single part, and the single part further comprises a reflective face arranged to direct the light beam collimated by the light collimating portion to the two or more converging surfaces, the reflective face being arranged at a side of the single part opposite to the light collimating portion.

In addition, in the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments.

<FIG> are schematic views showing a light beam adjusting device <NUM> according to an embodiment not claimed. The light beam adjusting device <NUM> includes: a light collimating portion <NUM> and a multi-focal converging portion <NUM>. The light collimating portion <NUM> is arranged to collimate a light beam <NUM>(for example, emitted from a light source <NUM>). The multi-focal converging portion <NUM> is arranged to converge the collimated light beam. The multi-focal converging portion <NUM> includes three converging surfaces <NUM>, <NUM>, <NUM>. The three converging surfaces <NUM>, <NUM>, <NUM> have focal points separated spatially from each other. As illustrated in <FIG>, these focal points are located at three points F1, F2 and F3. In this way, different portions of a light beam <NUM> may be converged at different converging points by the three different converging surfaces <NUM>, <NUM>, <NUM>, respectively. In this case, the focal points F1, F2 and F3 may be considered as virtual source points. In other words, when viewed in a direction opposite to the light exit direction of the light beam adjusting device <NUM> (i.e., viewed from right to left at the right side of F3 in the example shown in <FIG>), the light beam <NUM> seems to be converted into a combination of light beams emitted from focal points (or virtual source points) F1, F2 and F3 after it passes through the light beam adjusting device <NUM>. Thus, the light beam adjusting device <NUM> can provide lit aspect similar to that of a combination of a plurality of point light sources by a single point light source.

The number of the converging surfaces is not limited to three. For example, two or more than three converging surfaces may be provided. At least two of these converging surfaces have focal points separated spatially from each other. In this way, it may achieve the lit aspect similar to that of the combination of a plurality of point light sources.

In the example shown in <FIG>, all of focal points F1, F2, F3 of the three converging surfaces <NUM>, <NUM>, <NUM> are arranged in the same axis y of the multi-focal converging portion <NUM>. The converging surfaces <NUM>, <NUM>, <NUM> may be arranged in sequence in a radial direction of the multi-focal converging portion <NUM>. In this way, the focal points of the converging surfaces <NUM>, <NUM>, <NUM> may be separated from each other in the axis y by adjusting the shape and position of each of the converging surfaces <NUM>, <NUM>, <NUM>. In the example shown in <FIG>, the converging surfaces <NUM>, <NUM>, <NUM> are shown as concentric circles and circular rings in shape. In this way, it is easy to arrange the focal points of the three converging surfaces <NUM>, <NUM>, <NUM> in a same axis. However, the converging surfaces <NUM>, <NUM>, <NUM> may have other forms or structures as long as it allows the focal points of the three converging surfaces <NUM>, <NUM>, <NUM> to be in the same axis.

In the above embodiment in which the focal points of the converging surfaces are located in the same axis, the lit aspect of the single point light source may be converted into a light aspect similar to that of the combination of the plurality of point light sources located in the same axis.

<FIG> shows schematically converging effects of the light beam <NUM> at any position on the converging surfaces <NUM>, <NUM>, <NUM>. In <FIG>, the numeral "<NUM>" represents a tangent line to the converging surface <NUM>, <NUM>, <NUM> at a position and the numeral "<NUM>" represents a normal line to the converging surface <NUM>, <NUM>, <NUM> at the position, α is an angle between an incident light and the tangent line <NUM> at the position. β is an angle between an emergent light and a plane perpendicular to the axis y of the multi-focal converging portion <NUM> at the position. γ is an angle between an emergent light and the normal line <NUM> at the position. N1 is a refractive index of a medium at an inside of the converging surface <NUM>, <NUM>, <NUM>(i.e., the material medium of the multi-focal converging portion <NUM>, such as PMMA (refractive index of <NUM>) or polycarbonate (refractive index of <NUM>)). N2 is a refractive index of a medium at an outside of the converging surface <NUM>, <NUM>, <NUM>(i.e., the external environmental medium, such as air). H is a height between this position and the axis y of the multi-focal converging portion <NUM>. D is a distance between this position and the focal point F along the axis y. In practice, H and D may be given as requirements of design. The angles α, β and γ meet the following equation: <MAT>.

From the above Eq. <NUM>, the angles α, β and y can be obtained. That is, the respective angles of desired incident light and emergent light with respect to the tangent line <NUM> and the normal line <NUM> can be obtained. In this way, the surface shapes of the converging surface <NUM>, <NUM>, <NUM> at respective positions can be determined. As an example, for PMMA, the angle α may be in a range between <NUM> degrees and <NUM> degrees; for polycarbonate, the angle α may be in a range between <NUM> degrees and <NUM> degrees. As an example, H may be in a range between <NUM> and <NUM>, such as <NUM>. D may be in a range between <NUM> and <NUM>, such as <NUM>.

<FIG> and <FIG> show schematically a light beam adjusting device <NUM>' according to another embodiment not claimed. The embodiment is distinguished from those shown in <FIG> in that focal points F1', F2' of the converging surfaces <NUM>', <NUM>', <NUM>', <NUM>', <NUM>' are arranged in the same plane K perpendicular to the axis y of the multi-focal converging portion <NUM>. (For the sake of clarity, <FIG> only shows focal points of two converging surfaces <NUM>', <NUM>'. However, the focal points of the converging surfaces <NUM>', <NUM>', <NUM>' may also be arranged in the plane K). As an example, the converging surfaces <NUM>', <NUM>', <NUM>', <NUM>', <NUM>' may have peaks (i.e., the highest points projecting from the respective converging surfaces <NUM>', <NUM>', <NUM>', <NUM>', <NUM>') P1, P2, P3, P4, P5. All of peaks P1, P2, P3, P4, P5 of the respective converging surfaces <NUM>', <NUM>', <NUM>', <NUM>', <NUM>' may also be arranged in the same plane perpendicular to the axis y of the multi-focal converging portion <NUM>.

For example, as shown in <FIG>, the distance D1' between the peak P1 and a plane Z perpendicular to the axis y is equal to the distance D2' between the peak P2 and the plane Z perpendicular to the axis y, that is, these peaks are located in the same plane perpendicular to the axis y of the multi-focal converging portion <NUM>. As an example, in the example shown in <FIG>, the converging surfaces <NUM>', <NUM>', <NUM>', <NUM>', <NUM>' are shown to occupy the same area of circular sector respectively. By means of such structure, it is easy to arrange the focal points of the converging surfaces <NUM>', <NUM>', <NUM>', <NUM>', <NUM>' in the same plane.

Alternatively, other forms of the converging surfaces <NUM>', <NUM>', <NUM>', <NUM>', <NUM>' may also be applied as long as the focal points of the converging surfaces <NUM>', <NUM>', <NUM>', <NUM>', <NUM>' can be arranged in the same plane perpendicular to the axis y of the multi-focal converging portion <NUM>.

In the above embodiment in which the focal points of the converging surfaces are located in the same plane, the lit aspect of the single point light source may be converted into a light aspect similar to that of the combination of the plurality of point light sources located in the same plane.

<FIG> and <FIG> show schematically a light beam adjusting device <NUM>" according to a further embodiment not claimed. The embodiment is distinguished from those shown in <FIG> in that focal points of the converging surfaces <NUM>", <NUM>", <NUM>", <NUM>", <NUM>" are arranged in two different planes perpendicular to the axis y of the multi-focal converging portion <NUM>. That is, they are not arranged in the same plane perpendicular to the axis y of the multi-focal converging portion <NUM>. (For the sake of clarity, <FIG> only shows focal points of three converging surfaces <NUM>", <NUM>", <NUM>" and focal points of the converging surfaces <NUM>", <NUM>" are not shown. ) As an example, the converging surfaces <NUM>", <NUM>", <NUM>", <NUM>", <NUM>" may have peaks (i.e., the highest points projecting from the respective converging surfaces <NUM>", <NUM>", <NUM>", <NUM>", <NUM>") P1", P2", P3", P4", P5". All of these peaks P1", P2", P3", P4", P5" of the respective converging surfaces <NUM>", <NUM>", <NUM>", <NUM>", <NUM>" may also be arranged in at least two different planes perpendicular to the axis y of the multi-focal converging portion <NUM>. That is, these peaks P1", P2", P3", P4", P5" are also not located in the same plane.

For example, as shown in <FIG>, any one of the distance D1 between the peak P1" and a plane Z perpendicular to the axis y, the distance D2 between the peak P2" and the plane Z perpendicular to the axis y and the distance D3 between the peak P3" and the plane Z perpendicular to the axis y is not equal to the other two of them. The focal points F1", F2", F3" of the converging surfaces <NUM>", <NUM>", <NUM>" are arranged in planes K1, K2, K3 perpendicular to the axis y of the multi-focal converging portion <NUM>, respectively. And as shown in <FIG>, the distances between these peaks P1", P2", P3", P4", P5" and the axis y may also be arranged in any manner as requirement of design. Such arrangement provides more flexible design for configuration of the focal points of the light beam (or virtual source points). In practice, the number and shape of the converging surfaces may be designed freely as requirement of the design.

In the above embodiment in which the focal points of the converging surfaces are located in different planes, the lit aspect of the single point light source may be converted into a light aspect similar to that of the combination of the plurality of point light sources arranged in any manner. It may provide more freedom for the design of the lit aspect of lamps.

In the above three types of embodiments, i. e, focal points in the same axis, focal points in the same plane and focal points in different planes, the arrangement of the focal points in the same axis can provide the maximum optical efficiency (for example up to <NUM>%) for the light beam adjusting device <NUM>, <NUM>', <NUM>" while the arrangement of the focal points in the same plane and the arrangement of the focal points in different planes may provide off-axis illumination effects.

In the above examples given by <FIG>, the surface shapes of the converging surfaces <NUM>', <NUM>', <NUM>', <NUM>', <NUM>', <NUM>", <NUM>", <NUM>", <NUM>", <NUM>" may be determined by means of the method shown in <FIG>. The details will be omitted herein.

In an embodiment not claimed, as shown in <FIG>, the light collimating portion <NUM> may for example have a first light incident face <NUM>, a second light incident face <NUM> and a totally reflective face <NUM>. The first light incident face <NUM> is located in an intermediate position of the light collimating portion <NUM> and is configured to collimate a central portion of the light beam <NUM>. The second light incident face <NUM> is arranged outside the first light incident face <NUM> in a radial direction and configured to direct (for example deflect) a peripheral portion of the light beam <NUM> to the totally reflective face <NUM>. The totally reflective face <NUM> is arranged outside the second light incident face <NUM> in a radial direction and configured to collimate the portion of the light beam incident from the second light incident face <NUM>. Such structure of the light collimating portion <NUM> can allow the position of the light source <NUM> to be closer to the light collimating portion <NUM>, so as to improve the optical efficiency and reduce the size of the lamps. However, the embodiments of the present application are not limited to this. Alternatively, any other forms of the light collimating portion <NUM> may also be applied. For example, the reflective collimator <NUM>' shown in <FIG> (e.g., it has a curve surface shape such as paraboloid) and the transmissive collimator <NUM>" shown in <FIG> may be used as the light collimating portion <NUM>. It should be noted that, in the embodiment shown in <FIG>, the light source <NUM> may be arranged between the light collimating portion <NUM> and the multi-focal converging portion <NUM>.

In an example, as shown in <FIG>, the light collimating portion <NUM> and the multi-focal converging portion <NUM> may be formed integrally as one single part. The light collimating portion <NUM> is formed at a light incidence side <NUM> of the single part and the multi-focal converging portion <NUM> is formed at a light exit side <NUM> of the single part. Forming the light collimating portion <NUM> and the multi-focal converging portion <NUM> as one integral part may reduce the space that the light beam adjusting device occupies and save the costs and reduce work load of calibrating optical paths. As an example, as shown in <FIG> and <FIG>, in the axial direction of the multi-focal converging portion <NUM>, the thickness of the multi-focal converging portion <NUM> (for example the maximum height of the peaks of the converging surfaces) may be less than the thickness of the light collimating portion <NUM>, so as to further reduce the size of the single part.

In an embodiment not claimed, as shown in <FIG>, the light beam adjusting device <NUM> may further include a reflector <NUM>, for example, a planar mirror or a curved mirror (e.g., it has a shape such as paraboloid, ellipsoid, hyperboloid) arranged to reflect a light emitted from the converging surfaces <NUM>, <NUM>, <NUM>. As illustrated in <FIG>, the reflector <NUM> may be arranged outside the multi-focal converging portion <NUM>. Due to difference in focal points of the converging surfaces <NUM>, <NUM>, <NUM>, the light reflected by the reflector <NUM> may provide different depth of field.

<FIG> shows a light beam adjusting device <NUM> according to an embodiment of the present application. In the light beam adjusting device <NUM>, the converging surfaces <NUM>, <NUM>, <NUM> are arranged at a side surface <NUM> of the single part formed integrally by the light collimating portion <NUM> and the multi-focal converging portion <NUM>. The single part further includes a reflective face <NUM> arranged to direct the light beam collimated by the light collimating portion <NUM> to the converging surfaces <NUM>, <NUM>, <NUM>. The reflective face <NUM> is arranged at the side of the single part opposite to the light collimating portion <NUM>. By means of the reflective face <NUM>, the light converged by the converging surfaces <NUM>, <NUM>, <NUM> is directed towards periphery of the light beam adjusting device <NUM> to enlarge the propagation range.

As an example, the light beam adjusting device <NUM> may further include a plurality of mirrors <NUM> arranged outside the side surface <NUM> of the single part and arranged in sequence from near to far with respect to the side surface <NUM> of the single part, to reflect the light beam converged by these converging surfaces <NUM>, <NUM>, <NUM> respectively. Since the converging surfaces <NUM>, <NUM>, <NUM> have different focal points respectively, the light reflected by the plurality of mirrors <NUM> may provide more diverse lit aspect. The orientations of the plurality of mirrors <NUM> may be provided as requirement of the design of optical paths, for example, the plurality of mirrors <NUM> may have the same orientation or different orientations from each other, as shown in <FIG> also shows another surface <NUM> in opposite to the converging surfaces <NUM>, <NUM>, <NUM>. The surface <NUM> may have different converging characteristic from those of the converging surfaces <NUM>, <NUM>, <NUM>, such that the light emitted from the light source <NUM> can have different travel directions or converging degrees on different sides of the light beam adjusting device <NUM>. It may provide more flexibility for the design of the optical paths.

An embodiment of the present application also provides an optical assembly <NUM>. The optical assembly <NUM> includes: a light source arranged to emit a light beam <NUM>; and the light beam adjusting device <NUM>, <NUM>', <NUM>", <NUM>, <NUM> as described in any one of the above embodiments. As an example, as shown in <FIG>, the optical assembly <NUM> may further include a light guide device <NUM> which has a light incidence end <NUM> arranged toward the converging surfaces <NUM>, <NUM>, <NUM> and arranged to receive the light emitted from the converging surfaces <NUM>, <NUM>, <NUM>.

<FIG> shows an exemplary structure of the light guide device <NUM>. In this example, the light guide device <NUM> has an axis coinciding with the axis of the light beam adjusting device <NUM>. It is assumed that R is the radius of the end face of the light incident end <NUM> of the light guide device <NUM>, F1 is a focal point of an optional converging surface <NUM>, D1 is a distance between a position A on the converging surface <NUM> and the light incident end <NUM> in an axial direction of the light beam adjusting device <NUM>, D2 is a distance between the position A on the converging surface <NUM> and the focal point F1 in the axial direction of the light beam adjusting device <NUM>, and H is the height of the position A with respect to the axis of the light beam adjusting device <NUM>. In order that the light from the position A can enter the light incident end <NUM> of the light guide device <NUM>, it needs to satisfy: <MAT>.

In practice, the radius R of the end face of the light incident end <NUM> of the light guide device <NUM> may be set depending on the positions of point on the converging surfaces <NUM>, <NUM>, <NUM>. In order that all of lights from different converging surfaces can enter the light guide device <NUM>, it is desired that there are a plurality of points on the converging surfaces <NUM>, <NUM>, <NUM> located in the range of height H. As an example, H may be in a range between <NUM> and <NUM>, for example, <NUM>. As an example, R may be in a range between <NUM> and <NUM>, for example, <NUM>. As an example, D2 may be in a range between <NUM> and <NUM>, for example, <NUM>. As an example, D1 may be in a range between <NUM> and <NUM>, for example, <NUM>. As the converging surfaces <NUM>, <NUM>, <NUM> have different focal points, the light that enters the light incident end <NUM> of the light guide device <NUM> will have more uniform distribution of intensity and direction. Thus, it is beneficial to enhance uniformity of the light intensity distribution of the light guide device <NUM>, in particular, to enhance the light intensity distribution nearby the light incident end <NUM>.

The term of "light guide device" means a device that can direct a transmission of light therein mainly by internally total reflection. It may have various shapes, for example, of cylinders (may be called as light guide rods), bars (may be called as light guide bars or lamp bars), plates (may be called as light guide plates), rings (may be called as light guide rings), and so on. Because the light guide device directs the light mainly by the internally total reflection, it has high optical efficiency and low optical loss. The light guide device <NUM> directs the light incident from the light incident end <NUM> of the light guide device <NUM> towards its light exit end. Thus, in the light guide device <NUM>, it typically needs the incident light to satisfy the total reflection condition at a side surface <NUM> of the light guide device <NUM>, however, some decoupling structures (such as micro protrusions) may be provided at certain positions where the light is desired to exit on the side surface <NUM>, so as to destroy the total reflection condition to allow the light to exit at the specified positions.

An embodiment of the present application also provides a lighting and/or signaling apparatus, including the optical assembly <NUM> as described in any one of the above embodiments.

In the above embodiments of the present application, the number of the converging surfaces is exemplary. Two or more converging surfaces are applicable. Unless there is technical conflict, various forms of multi-focal converging portion <NUM>, for example those with multiple focal points arranged in the same axis shown in <FIG> and <FIG>, those with multiple focal points arranged in the same plane shown in <FIG> and <FIG>, those with multiple focal points arranged in different planes shown in <FIG> and <FIG>, may be combined with any examples of the light collimating portions <NUM>, the reflector <NUM>, the plurality of mirrors <NUM> and the light guide device <NUM>, or the like given in the embodiments of the present application.

As an example, the light source <NUM> may include a white light LED or a monochromatic light LED. Alternatively, it may also be any other known light sources in the art, such as an incandescent lamp. As an example, the light collimating portion <NUM> and the multi-focal converging portion <NUM> may be made from transparent glass, resin or plastic materials, for example, PMMA (polymethy methacrylate) or polycarbonate.

In the embodiments of the present application, the optical assembly <NUM> may be supported or suspended by any known suitable devices for holding optical elements, for example a supporting seat or a suspension arm.

The lighting and/or signaling apparatus according to embodiments of the present application may include any types of illumination lamps and/or signaling lamps for an automobile vehicle, for example, headlamps, central high mounted stop lamps, turn indicators, position lamps, rear stop lamps and so on. The lighting and/or signaling apparatus according to embodiments of the present application may also be used in any fields other than the vehicle lamps, for example, streetlamps, advertising lamps and so on.

The present disclosure has been explained with reference to drawings. However, the examples shown in drawings are intended to exemplarily illustrate the embodiments of the present application by way of examples, instead of limiting the present invention. Scales in the drawings are only provided by way of examples, and are not intended to limit the present invention.

Claim 1:
A light beam adjusting device (<NUM>) comprising:
a light collimating portion (<NUM>) arranged to collimate a light beam (<NUM>); and
a multi-focal converging portion (<NUM>) arranged to converge the collimated light beam, the multi-focal converging portion (<NUM>) comprising two or more converging surfaces (<NUM>, <NUM>, <NUM>),
and at least two of the two or more converging surfaces (<NUM>, <NUM>, <NUM>) have focal points separated spatially from each other,
and wherein all of focal points of the two or more converging surfaces (<NUM>, <NUM>, <NUM>) are arranged in the same axis (y) of the multi-focal converging portion (<NUM>), the two or more converging surfaces (<NUM>, <NUM>, <NUM>) being arranged in sequence along a radial direction of the multi-focal converging portion (<NUM>),
characterized in that the light collimating portion (<NUM>) and the multi-focal converging portion (<NUM>) are formed integrally as one single part,
wherein the light collimating portion (<NUM>) is formed at a light incidence side (<NUM>) of the single part and the multi-focal converging portion (<NUM>) is formed at a light exit side (<NUM>) of single part,
and wherein the two or more converging surfaces (<NUM>, <NUM>, <NUM>) are arranged at a side surface (<NUM>) of the single part, and the single part further comprises a reflective face (<NUM>) arranged to direct the light beam collimated by the light collimating portion (<NUM>) to the two or more converging surfaces (<NUM>, <NUM>, <NUM>), the reflective face (<NUM>) being arranged at a side of the single part opposite to the light collimating portion (<NUM>).