Illuminating device comprising a pump radiation source

Abstract

An illuminating device includes a pump radiation source for emitting pump radiation as a beam bundle, a phosphor element for converting the pump radiation into conversion light, and a lens system between the pump radiation source and the phosphor element, which is penetrated by the pump beam bundle, wherein the lens system has a focus and the phosphor element is arranged at the focus, and wherein furthermore a lens of the lens system has a scattering means which scattering means the pump beam bundle penetrates and is widened at the same time, so that the pump beam bundle is incident on the phosphor element in a manner widened around a focus point.

Claims

1. An illuminating device comprising: a pump radiation source for emitting pump radiation as a beam bundle, a phosphor element for converting the pump radiation into conversion light, and a lens system between the pump radiation source and the phosphor element, which is penetrated by the pump beam bundle, wherein the lens system has a focus and the phosphor element is arranged at the focus, wherein a lens of the lens system has a scattering means which scattering means the pump beam bundle penetrates and is widened at the same time, so that the pump beam bundle is incident on the phosphor element in a manner widened around a focus point; wherein the lens comprising the scattering means has a spherical light entry surface; and wherein the pump beam bundle is incident on a pump radiation incidence surface of the phosphor element, which has a mean extension x, and a sphere on which the spherical light entry surface is based has a radius R, wherein Rx/2.

2. The illuminating device as claimed in claim 1, wherein the scattering means widens the opening angle of the pump beam bundle by at least 0.5 and at most 10.

3. The illuminating device as claimed in claim 1, wherein the scattering means is provided at a light entry surface of the lens.

4. The illuminating device as claimed in claim 1, wherein the pump beam bundle is incident on a pump radiation incidence surface of the phosphor element and a surface focal point of the pump radiation incidence surface has a distance d taken along a surface normal in relation to the spherical light entry surface and a sphere on which the spherical light entry surface is based has a radius R, wherein d0.9.Math.R, preferably d=R.

5. The illuminating device as claimed in claim 1, wherein the lens is a planar-spherical lens, and wherein the phosphor element is arranged at alight exit surface of the lens.

6. The illuminating device as claimed in claim 1, wherein a sphere on which the spherical light entry surface is based has a center point and the pump beam bundle is incident on the spherical light entry surface convergently in relation to the center point.

7. The illuminating device as claimed in claim 5, wherein the lens has an optical axis, which is perpendicular to the light exit surface, wherein .sub.c is the critical angle for total reflection at the light exit surface, and wherein the pump beam bundle penetrates the spherical light entry surface with a focal point direction which is tilted by an angle .sub.c in relation to the optical axis.

8. The illuminating device as claimed in claim 1, further comprising a plurality of pump radiation sources.

9. The illuminating device as claimed in claim 7, wherein a first pump beam bundle, which originates from a first pump radiation source, and a second pump beam bundle, which originates from a second pump radiation source, are rotationally symmetrical in relation to one another in the planar-spherical lens with respect to the optical axis, specifically precisely in a twofold manner having an angle of rotation of 180.

10. The illuminating device as claimed in claim 1, wherein the light entry surface of the lens is at least regionally provided with a reflection layer.

11. The illuminating device as claimed in claim 10, wherein the reflection layer is reflective both for the conversion light and for the pump radiation, wherein a region of the light entry surface, which the pump beam bundle penetrates, is free of the reflection layer.

12. The illuminating device as claimed in claim 3, wherein the scattering means is provided at the light entry surface of the lens as a coating or surface roughening.

13. The illuminating device as claimed in claim 5, wherein the light exit surface of the lens, which is opposite to the spherical light entry surface, is planar.

14. A use of an illuminating device comprising: emitting pump radiation as a beam bundle with a pump radiation source, converting the pump radiation into conversion light with a phosphor element, and penetrating a lens system between the pump radiation source and the phosphor element with the pump beam bundle, wherein the lens system has a focus and the phosphor element is arranged at the focus, wherein a lens of the lens system has a scattering means which scattering means the pump beam bundle penetrates and is widened at the same time, so that the pump beam bundle is incident on the phosphor element in a manner widened around a focus point; wherein the lens comprising the scattering means has a spherical light entry surface; wherein the pump beam bundle is incident on a pump radiation incidence surface of the phosphor element, which has a mean extension x, and a sphere on which the spherical light entry surface is based has a radius R, wherein Rx/2.

15. An illuminating device comprising: a pump radiation source for emitting pump radiation as a beam bundle, a phosphor element for converting the pump radiation into conversion light, and a lens system between the pump radiation source and the phosphor element, which is penetrated by the pump beam bundle, wherein the lens system has a focus and the phosphor element is arranged at the focus, wherein a lens of the lens system has a scattering means which scattering means the pump beam bundle penetrates and is widened at the same time, so that the pump beam bundle is incident on the phosphor element in a manner widened around a focus point; wherein the lens comprising the scattering means has a spherical light entry surface; and wherein the pump beam bundle is incident on a pump radiation incidence surface of the phosphor element and a surface focal point of the pump radiation incidence surface has a distance d taken along a surface normal in relation to the spherical light entry surface and a sphere on which the spherical light entry surface is based has a radius R, wherein d0.9.Math.R, preferably d=R.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Various embodiments will be explained in greater detail hereafter on the basis of exemplary embodiments, wherein the individual features in the scope of the coordinate claims can also be essential to various embodiments in other combinations and also furthermore differentiation is not always made in detail between the different claim categories.

(2) In the drawings, like reference characters generally refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the disclosed embodiments. In the following description, various embodiments described with reference to the following drawings, in which:

(3) FIG. 1 shows an illuminating device according to various embodiments having four laser diodes in a schematic overview;

(4) FIG. 2 shows a schematic section through a hemispherical lens having scattering means, reflection layer, and phosphor element;

(5) FIG. 3 shows backscatter conversion light emitted at the pump radiation incidence surface of the phosphor element according to FIG. 2;

(6) FIG. 4 shows the coupling in of multiple pump beam bundles.

DETAILED DESCRIPTION

(7) FIG. 1 shows an illuminating device 1 according to various embodiments in a schematic overview. Four laser diodes 2 can be seen as pump radiation sources. The laser diodes emit at approximately 450 nm and have a radiant power of 1.5 W to 3.0 W. A planar convex lens 3 is associated with each of the laser diodes 2, which bundles the pump radiation (blue pump light) emitted from the respective laser diode 2 and guides it onto a hemispherical lens 5.

(8) The pump beam bundles 4 are incident on a light entry surface 6 of the hemispherical lens 5 made of sapphire and penetrate the latter up to an opposing light exit surface 21. The light exit surface is located facing away on the rear side in relation to the observation direction according to FIG. 1, because of which reference is also made to FIG. 2 for the illustration. The pump radiation is incident on a phosphor element 22 via the light exit surface 21. The phosphor element is arranged at the light exit surface 21 of the hemispherical lens 5, specifically bonded thereto via a thin adhesive layer (<50 m).

(9) The pump radiation is incident on a pump radiation incidence surface 23 of the phosphor element 22 and is converted at least in portions thereby (in the present case a yellow YAG:Ce phosphor) into longer-wave conversion light 24. The conversion light 24 and possibly non-converted pump light is emitted at a conversion light emission surface 25 of the phosphor element 22, which is located opposite to the pump radiation incidence surface 23. The respective planar convex lens 3 and the hemispherical lens 5 form a lens system for each laser diode 2, by which the pump radiation is guided onto the phosphor element 22.

(10) FIG. 2 furthermore illustrates that the light entry surface 6 of the hemispherical lens 5 is somewhat roughened in the region in which the pump beam bundle 4 (only one of the four pump beam bundles is shown for the sake of comprehensibility) is incident thereon. This surface roughening 26 represents a scattering means, the pump beam bundle 4 is widened during the passage. The opening angle increases by approximately 5.

(11) The beam propagation in the undisturbed case is indicated in FIG. 2 by dashed lines; the pump beam bundle 4 would be incident on the phosphor element 22 in concentrated form in a focus point 27, which would result in local overheating (hotspot) of the phosphor element 22. To avoid this, the pump beam bundle 4 is widened by scattering, and is thus incident on the phosphor element 22 widened accordingly around the focus point 27. The phosphor element is arranged at the focus 20, but the pump beam bundle 4 is not concentrated in a point thereon.

(12) The light entry surface 6 is furthermore provided with a reflection layer 28, specifically a silver film. Because it would also reflect the pump radiation, the reflection layer 28 is interrupted where the pump beam bundles 4 are coupled in.

(13) FIG. 3 illustrates the function of the reflection layer 28, wherein in this illustration the pump beam bundle 4 incident via the scattering means 26 is not shown for the sake of comprehensibility. The conversion light which is generated in the phosphor element 22 upon the excitation using the pump radiation is also emitted at the pump radiation incidence surface 23, namely as backscatter conversion light 31. The backscatter conversion light 31a emitted in the middle of the pump radiation incidence surface 23, which is thus emitted at the focus point and therefore at the sphere center point, is incident perpendicularly on the reflection layer 28 and is accordingly reflected back to the same point of the pump radiation incidence surface 23.

(14) Backscatter conversion light 31b emitted at the edge of the pump radiation incidence surface 23 is not incident exactly, but is incident at least approximately perpendicularly on the reflection layer 28 and is also largely reflected back to the pump radiation incidence surface 23. The backscatter conversion light thus guided back to the phosphor element 22 can then be used at the conversion light emission surface 25 jointly with the conversion light 24 originally emitted there.

(15) Not only conversion light is backscattered, but rather also a part of the pump radiation. This backscattering takes place comparably with the backscatter conversion light 31 with respect to the directions. The backscatter pump radiation is also reflected at the reflection layer 28 and thus guided back to the pump radiation incidence surface 23, which further increases the efficiency.

(16) The schematic illustration according to FIG. 4 once again shows the same structure, wherein in this case two pump beam bundles 4a, b are shown, i.e., a schematic section through the arrangement according to FIG. 1. Each of the pump beam bundles 4a, b is coupled in via a respective scattering means 26 and is widened accordingly around the focus point 27.

(17) The two pump beam bundles 4a, b are furthermore rotationally symmetrical in relation to the optical axis 41 of the hemispherical lens 5, specifically precisely in a twofold manner. Furthermore, the two beam bundles 4a, b are tilted in relation to the optical axis 41 such that the pump radiation is incident at an angle of incidence >.sub.c on the light exit surface 21 of the hemispherical lens 5.

(18) In case of fault, if the phosphor element 22 falls off of the hemispherical lens 5, the two pump beam bundles 4a, b are therefore totally reflected at the light exit surface 21 and the first pump beam bundle 4a can then leave the hemispherical lens 5 on the path of the second pump beam bundle 4b (in the opposite direction), and vice versa.

(19) While the disclosed embodiments have been particularly shown and described with reference to specific embodiments, it should be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the disclosed embodiments as defined by the appended claims. The scope of the disclosed embodiments is thus indicated by the appended claims and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced.