LASER PHOSPHOR BASED LIGHT SOURCE WITH IMPROVED BRIGHTNESS

Abstract

The invention provides alighting system (1000) configured to generate lighting system light (1001), wherein the lighting system light (1001) comprises one or more of (i) a first lighting system light component (1101) having a first component optical power Wopt,comp1, and (ii) a second lighting system light component (1201) having a second component optical power Wopt,comp2; wherein the lighting system (1000) comprises: —a first light source (110) comprising a first pump light source (10) configured to generate first pump light source light (11) and a luminescent material (200) configured to convert at least part of the first pump light source light (11) into luminescent material light (201), wherein the first light source (110) optionally in combination with first optics (115) is configured to provide the first lighting system light component (1101), wherein the first lighting system light component (1101) comprises at least part of the luminescent material light (201), wherein the first lighting system light component (1101) has a first spectral power distribution with spectral intensity at a first wavelength λ1; —a second light source (120) comprising a laser light source (20) configured to generate laser light source light (21), wherein the second light source (120) optionally in combination with second optics (125) is configured to provide the second lighting system light component (1201), wherein the second lighting system light component (1201) comprises at least part of the laser light source light (21), wherein the second lighting system light component (1201) has a second spectral power distribution, different from the first spectral power distribution, with spectral intensity at a second wavelength λ2, wherein the second wavelength λ2 is selected from the range of λ1−30 nm≤λ2≤λ1+30 nm; —a control system (30) configured to control in one or more control modes the second component optical power Wopt,comp2 of the second lighting system light component (1201) in dependence of the first component optical power Wopt,comp1 of the first lighting system light component (1101).

Claims

1. A lighting system configured to generate lighting system light, wherein the lighting system light comprises one or more of (i) a first lighting system light component having a first component optical power W.sub.opt,comp1, and (ii) a second lighting system light component having a second component optical power W.sub.opt,comp2, wherein the lighting system comprises: a first light source comprising a first pump light source configured to generate first pump light source light and a luminescent material configured to convert at least part of the first pump light source light into luminescent material light, wherein the first light source optionally in combination with first optics is configured to provide the first lighting system light component, wherein the first lighting system light component comprises at least part of the luminescent material light, wherein the first lighting system light component has a first spectral power distribution with spectral intensity at a first wavelength λ.sub.1; a second light source comprising a laser light source configured to generate laser light source light, wherein the second light source optionally in combination with second optics is configured to provide the second lighting system light component, wherein the second lighting system light component comprises at least part of the laser light source light, wherein the second lighting system light component has a second spectral power distribution, different from the first spectral power distribution, with spectral intensity at a second wavelength λ.sub.2, wherein the second wavelength λ.sub.2 is selected from the range of λ.sub.1−30 nm λ.sub.2≤λ.sub.1+30 nm; a control system configured to control in at least one control modes the second component optical power W.sub.opt,comp2 of the second lighting system light component in dependence of the first component optical power W.sub.opt,comp1 of the first lighting system light component, wherein the control system is further configured to control in a first control mode the second component optical power W.sub.opt,comp2 of the second lighting system light component in dependence of the first component optical power W.sub.opt,comp1 of the first lighting system light component only above a predetermined threshold value of the first component optical power W.sub.opt,comp1 of the first lighting system light component and the control system being configured to keep the color point of the combination of the first lighting system light component and the second lighting system light component within a predefined range of +/−0.05 of a predefined color point.

2. The lighting system according to claim 1, wherein the first pump light source has a maximum first optical power W.sub.opt,10,max, wherein the laser light source has a maximum second optical power W.sub.opt,20,max, wherein the second optical power of the laser light source light and the first optical power of the first pump light source light have a ratio WR.sub.opt,max, wherein WR.sub.opt,max=W.sub.opt,20,max/W.sub.opt,10,max, and wherein 0.01≤W.sub.opt,20,max/W.sub.opt,10,max≤1.

3. The lighting system according to claim 1, wherein the first spectral power distribution has a band shape, and wherein the first wavelength λ.sub.1 is a dominant wavelength.

4. The lighting system according to claim 1, wherein the first light source comprises a plurality of first pump light sources and an elongated luminescent concentrator, wherein the plurality of first pump light sources are configured to irradiate with the first pump light source light a radiation input face comprised by a side face of the elongated luminescent concentrator, and wherein the elongated luminescent concentrator is configured to provide the luminescent material light emanating from a radiation exit face comprised by an end face of the elongated luminescent concentrator.

5. The lighting system according to claim 1, wherein the first light source comprises a solid state laser light source, and wherein the second wavelength λ.sub.2 is selected from the range of λ.sub.1−10 nm λ.sub.2≤λ.sub.1+10 nm.

6. The lighting system according to claim 1, wherein the control system is configured to keep the dominant wavelength of the combination of the first lighting system light component and the second lighting system light component within a predefined range of a predefined dominant wavelength +/−10 nm.

7. The lighting system according to claim 1, wherein the first pump light source has a first dimming range over which the first pump light source can be up dimmed and down dimmed, wherein over a first part of the first dimming range there is a linear relation between dimming levels within the first part of the first dimming range and the first component optical power W.sub.opt,comp1 of the first lighting system light component, wherein over a second part of the first dimming range there is a non-linear relation between dimming levels within the second part of the first dimming range and first component optical power W.sub.opt,comp1 of the first lighting system light component, and wherein the laser light source comprises a second dimming range over which the laser light source can be up dimmed and down dimmed.

8. The lighting system according to claim 7, wherein the control system is configured to control in a second control mode a ratio WR.sub.comp of the second component optical power W.sub.opt,comp2 of the second lighting system light component and the first component optical power W.sub.opt,comp1 of the first lighting system light component, WR.sub.comp=W.sub.opt,comp2/W.sub.opt,comp1, wherein in the second control mode WR.sub.comp is larger in the second part of the first dimming range than in the first part of the first dimming range.

9. The lighting system (1000) according to claim 8, wherein over a first dimming level W.sub.10,x of the pump light source the luminescent material light quenches, and wherein the control system is configured to increase WR.sub.comp when a dimming level of the first dimming range is equal to or higher than 0.7*W.sub.10,x.

10. The lighting system according to claim 7, wherein over a third part of the first dimming range there is a negative relation between dimming levels within the third part of the first dimming range and the first component optical power W.sub.opt,comp1 of the first lighting system light component, wherein the control system is configured to control in a third control mode the ratio WR.sub.comp, wherein in the third control mode WR.sub.comp is larger in the third part of the first dimming range than in the second part of the first dimming range.

11. The lighting system according to claim 8, wherein the control system is configured to increase in a fourth control mode the second component optical power W.sub.opt,comp2 with increasing optical power W.sub.opt,sys of the lighting system light, wherein over at least part of a dimming range of the optical power W.sub.opt,sys of the lighting system light there is a linear or non-linear relation between the second component optical power W.sub.opt,comp2 with increasing optical power W.sub.opt,sys of the lighting system light, wherein over at least part of the dimming range of the optical power W.sub.opt,sys of the lighting system light the ratio WR.sub.comp increases with up dimming.

12. The lighting system according to claim 1, wherein both the first pump light source and the second light source light source are configured upstream of the luminescent material, and wherein the luminescent material is transmissive for the laser light source light, wherein an absorption of the laser light source light by the luminescent material is less than 10% of the laser light source light, and wherein the optional first optics comprise a wavelength dependent optical filter.

13. The lighting system according to claim 1, further comprising an optical sensor configured to receive part of the lighting system light, or of the first pump light source light, and to provide a corresponding sensor signal, wherein the control system is configured to control in the one or more control modes the first component optical power W.sub.opt,comp1 of the first lighting system light component and the second component optical power W.sub.opt,comp2 of the second lighting system light component in dependence of the sensor signal.

14. The lighting system according to claim 1, further comprising a third light source configured to generate third light source light, wherein in the one or more controlling modes the lighting system light comprises (a) one or more of the first lighting system light component and the second lighting system light component, and (b) optionally a third lighting system component having a third component optical power W.sub.opt,comp3, wherein the third lighting system light component comprises the third light source light, wherein the third lighting system light component has a third spectral power distribution, different from the first spectral power distribution and the second spectral power distribution, and wherein the control system is further configured to control in the one or more controlling modes also the third component optical power W.sub.opt,comp3 of the third lighting system light component.

15. A projection system or a luminaire comprising the lighting system according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0120] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which:

[0121] FIGS. 1-10b schematically depict some embodiments;

[0122] FIGS. 11a-11b schematically depict some (application) embodiments;

[0123] FIGS. 12a-12d schematically depict some aspects and embodiments; and

[0124] FIGS. 13a-13b schematically depict some aspects of the invention. The schematic drawings are not necessarily to scale.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0125] In the present invention, amongst others it is suggested to use a laser phosphor based light source, which may have an improved brightness. In embodiments, it is proposed to use a phosphor for conversion of blue laser light, such as up to the saturation point (temperature and or intensity saturation whichever comes first). In embodiments, above this point when even higher converted light intensity is required, the laser light can be added to the system. For example, blue laser light may be used in order to obtain green light using a luminescent material that converts the blue light into green light. At the point of saturation, green laser light can be added to the system for obtaining a higher intensity, see e.g. FIG. 1, where on the left (FIG. 1a) no laser light is added, and on the right (FIG. 1b), laser light is added. For instance, in embodiments the phosphor converted light has a peak wavelength λ, the green laser light has a peak wavelength Y. Especially, Y is in the range from X−30 nm and X+30 nm, more especially in the range from X−20 nm and X+20 nm, even more especially in the range from X−10 nm and X+10 nm.

[0126] In the arrangement shown in FIG. 1, the configuration is a transmissive configuration in the sense that the first pump light source is configured upstream of the luminescent material (layer) and luminescent material light that escapes from the opposite side of the luminescent material (layer) is used as at least part of the lighting system light. Further, the arrangement shown in FIG. 1 is also a transmissive configuration as the laser light source light is provided to one side of the luminescent material (layer) is at least partly, more especially essentially completely, transmitted through the luminescent material (layer). Especially, the absorption of laser light is less than 10%, more especially less than 5%, yet even more especially less than about 3%.

[0127] FIG. 1 schematically depicts an embodiment of a lighting system 1000 configured to generate lighting system light 1001. The lighting system light 1001 may comprise one or more of (i) a first lighting system light component 1101 having a first component optical power W.sub.opt,comp1, and (ii) a second lighting system light component 1201 having a second component optical power W.sub.opt,comp2. The optical power W.sub.opt,sys of the lighting system light 1001 may be controllable.

[0128] The lighting system 1000 comprises a first light source 110 and a second light source 120. The first light source 110 may comprise a first pump light source 10 configured to generate first pump light source light 11. The lighting system 1000, such as the first light source, may comprise also a luminescent material 200 configured to convert at least part of the first pump light source light 11 into luminescent material light 201. The first light source 110, optionally in combination with first optics (not shown) may be configured to provide the first lighting system light component 1101. The first lighting system light component 1101 especially comprises at least part of the luminescent material light 201. The first lighting system light component 1101 has a first spectral power distribution with spectral intensity at a first wavelength λ.sub.1 (see also below). A first optical power of the first pump light source light 11 is controllable, whereby the first component optical power W.sub.opt,comp1 of the first lighting system light component 1101 may be controllable. The second light source 120 may comprise a laser light source 20 configured to generate laser light source light 21. The second light source 120, optionally in combination with second optics (not depicted), may be configured to provide the second lighting system light component 1201. The second lighting system light component 1201 especially comprises at least part of the laser light source light 21. The second lighting system light component 1201 has a second spectral power distribution, different from the first spectral power distribution, with spectral intensity at a second wavelength λ.sub.2 (see also below). The second wavelength λ.sub.2 is especially selected from the range of λ.sub.1−30 nm≤λ.sub.2≤λ.sub.1+30 nm. A second optical power of the laser light source light 21 may be controllable, whereby the second component optical power W.sub.opt,comp2 of the second lighting system light component 1201 may be controllable.

[0129] As indicated above, the luminescent material 200 is especially configured to substantially not absorb the laser light source light 21.

[0130] Here, the luminescent material is schematically depicted configured remote from the pump light source. However, the luminescent material may also be in optical contact or even physical contact with the pump light source. When configured remote, as schematically depicted in a number of embodiments, the laser light source light 21 may propagate via the luminescent material 200 (transmission or reflection; here in some embodiments transmission is schematically depicted). In such embodiments it may especially be relevant that the luminescent material 200 is especially configured to substantially not absorb the laser light source light 21.

[0131] The system 1000 may further comprise a control system 30 especially configured to control in one or more control modes the second component optical power W.sub.opt,comp2 of the second lighting system light component 1201 in dependence of the first component optical power W.sub.opt,comp1 of the first lighting system light component 1101.

[0132] In FIG. 1 on the left (FIG. 1a), a mode without the second lighting system light component 1201 is shown; on the right (FIG. 1b) a mode is shown with both the first and the second lighting system light components 1101,1201, respectively.

[0133] FIG. 1, and other figures, also schematically depicts an embodiment of the lighting system 1000, wherein both the first pump light source 10 and the second light source light source 120 are configured upstream of the luminescent material 200. Especially, the luminescent material 200 is transmissive for the laser light source light 21, wherein an absorption of the laser light source light 21 by the luminescent material 200 is less than 10% of the laser light source light 21.

[0134] The first pump light source 10 may have a maximum first optical power W.sub.opt,10,max. The laser light source 20 may have a maximum second optical power W.sub.opt,20,max, wherein the second optical power of the laser light source light 21 and the first optical power of the first pump light source light 11 have a ratio WR.sub.opt,max, wherein WR.sub.opt,max=W.sub.opt,20,max/W.sub.opt,10,max, and wherein 0.01≤W.sub.opt,20,max/W.sub.opt,10,max≤1.

[0135] References 115 and 125 refer to one or more optional first and/or second optics, which may comprise one or more wavelength dependent optical filter, e.g. to fine tune the first lighting system light component and/or second lighting system light component.

[0136] Below some examples are provided of combinations of the first light source and the second light source:

TABLE-US-00001 Pump light source Luminescent material Pump laser light Possible additional light color/λ range light color/λ range color/λ range source color(s)/λ range(s) 1 UV Blue Blue 2 UV Green Green 3 UV Yellow Yellow Blue + optionally red 4 UV Red Red Green and/or yellow + blue 5 Blue Green Green 6 Blue Yellow Yellow 7 Blue Red Red Green and/or yellow + blue 8 Green Yellow Yellow Blue + optionally red 9 Green Red Red Green and/or yellow + blue

[0137] In the last column (italics), possible additional colors, which may be provided by additional light sources, are indicated which could provide white light in combination with the first light source and the second light source. Bold marked options in the table are the most relevant options.

[0138] Hence, the system comprising the first light source and the second light source may e.g. be combined with other light source light, such as a solid state light lighting (SSL) light source, to obtained combined light e.g. white light. For example, the proposed green phosphor based light source may be combined with a blue and a red LED light source. Typically, dichroic mirrors may be used to combine the beams (FIG. 2). In embodiments, the prosed lighting device may be combined with other lasers e.g. a red and a blue laser. Alternatively or additionally, the proposed lighting device may also be combined with a laser and a LED light source e.g. a blue LED and a red laser.

[0139] FIG. 2 schematically depicts that one of the sources comprises the first light source 130a and the second light source 130b. These may e.g. be configured to generate green light. A first further light source 130a, configured to generate first further light source light 131a, which may e.g. be blue light and/or a second further light source 130b, configured to generate second further light source light 131b, which may e.g. be red light, may also be comprised by the system. In this way, in one or more controlling modes the lighting system light 1001 may comprise one or more of the of (i) the first lighting system light component 1101, (ii) the second lighting system light component 1201, (iii) the first further light source light 131a, and (iv) the second further light source light 131b.

[0140] Hence, FIG. 2 schematically depicts an embodiment of the lighting system 1000, further comprising a third light source 130 configured to generate third light source light 131. Especially a third optical power of the third light source light 131 is controllable.

[0141] In the one or more controlling modes, the lighting system light 1001 may comprise (a) one or more of the first lighting system light component 1101 and the second lighting system light component 1201, and (b) optionally a third lighting system component 1301 having a third component optical power W.sub.opt,comp. The third lighting system light component 1301 may comprise the third light source light 131. The third lighting system light component 1301 may have a third spectral power distribution, different from the first spectral power distribution and different from the second spectral power distribution. A third optical power of the third light source light 131 may be controllable, whereby the third component optical power W.sub.opt,comp3 of the third lighting system light component 1301 may be controllable. Especially, the control system 30 may further be configured to control in the one or more controlling modes also the third component optical power W.sub.opt,comp3 of the third lighting system light component 1301.

[0142] Reference 135 refers to an optical element that reflects a part of the light and transmit a part of the light, such as a dichroic filter.

[0143] Of course, often additional optics may be used to establish a beam profile required for an application. These optics are not shown here.

[0144] In fact, FIG. 2 schematically depicts two additional third light sources 130, indicated with references 130a and 130b. Their respective third light source light 131 are indicated with 131a and 131b, respectively. Their respective third lighting system light components 1301 are indicated with references 1301a and 1301b, respectively. Of course, there can be more than two additional third light sources 130. Two or more additional third light sources 130 may refer to two or more essentially identical additional third light sources 130, such as in embodiments from the same bin. However, two or more additional third light sources 130 may also refer to two or more different types of light sources.

[0145] Together with the one or more (optionally different) third light sources 130, the lighting system 1000 may be able in control modes to generate white system light 1001.

[0146] This may e.g. be the case when first light source 110 is e.g. configured to generate green and/or yellow light, and the third light sources are configured to generate blue light or blue and red light.

[0147] In embodiments, two or even three lighting system may be combined; see FIGS. 3-4, respectively. For instance, referring to the above table, (a) option 1, and (b) options 3 and/or 6 and/or 8 may be combined to provide white light (see FIG. 3). For instance, referring to the above table: (a) option 1, and (b) options 2 and/or 5, and (c) options 4 and/or 7 and/or 8, may be combined to provide white light (see FIG. 4). In such configurations the color point e.g. white point may be controlled over a relatively large dimming range of the system. FIG. 3 schematically depicts an embodiment of the lighting system 1000, which actually may comprise two of the herein described lighting systems, indicated with references 1000a and 1000b, which may be configured to generate lighting system light 1001a and 1001b, respectively, having different spectral power distributions. FIG. 4 schematically depicts an embodiment of the lighting system 1000, which actually may comprise three of the herein described lighting systems, indicated with references 1000a, 1000b and 1000c, which may be configured to generate lighting system light 1001a, 1001b and 1001c, respectively, having mutually different spectral power distributions. Likewise, the luminescent material 200 may be indicated as first luminescent material 200a and second luminescent material 200b, respectively. Likewise this may apply to a third luminescent material 200c. Similarly, this applies to the first light sources 110, indicated with references 110a, 110b, 110c, etc.; likewise this applies to the second light sources 120a, 120b, 120c, etc.

[0148] Hence, in embodiments the lighting system may comprise a control system 30 (or controller) for controlling the amount of laser light (FIG. 5).

[0149] In embodiments, the lighting device may comprise a laser-output sensor (embodiment of optical sensor) measuring the amount of laser light (FIG. 6). Alternatively or additionally, the laser sensor may also be formed by a laser driving current monitor adapted for monitoring the laser driving current (FIG. 7). Alternatively or additionally, the lighting system may comprise a converted light sensor (embodiment of optical sensor) measuring the amount of converted light (FIG. 8). A sensor, such as an optical sensor, is indicated with reference 50.

[0150] Hence, FIGS. 6-8 schematically depict embodiments wherein the lighting system 1000 further comprises an (optical) sensor 50, for instance configured to receive part of the lighting system light 1001, or to measure other parameters, such as especially related to W.sub.opt,comp1, and to provide a corresponding sensor signal, wherein the control system 30 is configured to control in the one or more control modes the first component optical power W.sub.opt,comp1 of the first lighting system light component 1101 and the second component optical power W.sub.opt,comp2 of the second lighting system light component 1201 in dependence of the sensor signal.

[0151] Of course, in embodiments multiple (different) light sources may be combined (FIG. 9). Here, by way of example a plurality of first light source 10 are depicted. Alternatively or additionally, a plurality of second light sources may be available. However, alternatively or additionally, also a plurality of second light sources 20 may be available (not depicted).

[0152] One of the light sources, may also be an HLD type light source. Hence, in embodiments instead of a laser light source pumping the phosphor, LEDs may be used to pump a transparent luminescent rod (FIG. 10). FIG. 10 schematically depicts an embodiment of the lighting system 1000, wherein the first light source 110 comprises a plurality of first pump light sources 10 and an elongated luminescent concentrator 100, wherein the plurality of first pump light sources 10 are configured to irradiate with the first pump light source light 11 a radiation input face 111 comprised by a side face 140 of the elongated luminescent concentrator 100, and wherein the elongated luminescent concentrator 100 is configured to provide the luminescent material light 201 emanating from a radiation exit face 112 comprised by an end face 142 of the elongated luminescent concentrator 100. FIG. 10a shows a mode wherein the second light source 120 does not contribute and FIG. 10b schematically depicts an embodiment wherein the second light source 120 does contribute. In the former mode the lighting system light 1001 may comprise only the first component 1101; in the latter mode the lighting system light may comprise both components 1101 and 1201. In FIG. 10a, the second component is not provided; in FIG. 10b the second component is also provided.

[0153] As shown in FIGS. 11a-11b, the lighting system may e.g. be comprised by a projection system 1 (11a) or a luminaire 2 (11b).

[0154] FIG. 12a-12d schematically depict some operation modes in view of possible quenching behavior.

[0155] FIG. 12a shows on the x-axis the power (in Watt) provided to the first laser light source. This is indicated with W.sub.10. W.sub.10 can e.g. vary between 0 (Watt) and W.sub.10,max. Hence, in embodiments the dimming range of the first light source is between 0 and W.sub.10,max. This dimming range is indicated on the x-axis. On the left y-axis W.sub.opt,comp1 is indicated, which may vary between 0 (Watt) and a maximum value, indicated with W.sub.opt,comp1,max. On the right y-axis (also) W.sub.10 is indicated. As it is assumed that basically there is a linear relation between the input power and the optical output power of the pump light source, on the right y-axis also W.sub.opt,10 could have been indicated, varying between 0 and W.sub.opt,10,max. The dashed slanted line from the origin to the right top would then indicate the (essentially) linear relation between W.sub.10 and W.sub.opt,10.

[0156] FIG. 12a schematically depicts an embodiment wherein the first pump light source 10 has a first dimming range over which the first pump light source 10 can be up dimmed and down dimmed, wherein over a first part I of the first dimming range there is a linear relation between dimming levels (W.sub.10) within the first part I of the first dimming range and the first component optical power W.sub.opt,comp1 of the first lighting system light component. However, at the dashed vertical line between I and II, W.sub.opt,comp1 starts to deviate from a linear (positive) relation, such as especially due to quenching. Hence, over a second part II of the first dimming range there is a non-linear (positive) relation between dimming levels within the second part of the first dimming range and first component optical power W.sub.opt,comp1 of the first lighting system light component. Hence, in the first part I there is essentially no quenching, whereas in the second part II there is quenching, which increases with up dimming, such that at the end of the second part II there is even no increase anymore of W.sub.opt,comp1, even when further up dimming. As indicated above, in embodiment the luminous flux from a phosphor material may increases linearly with the input power until saturation effects (thermally and/or optically induced) start to limit the conversion. FIG. 12a also schematically depicts an embodiment wherein over a third part III of the first dimming range there is (even) a negative relation between dimming levels within the third part of the first dimming range and the first component optical power W.sub.opt,comp1 of the first lighting system light component 1101. Hence, there may be a part of the dimming range wherein the quenching reaches such levels, that an increase of the power of the laser light source effectively results in a decrease of the W.sub.opt,comp1. In the third part III, the quenching may thus be relatively severe and has a negative impact on the converted light.

[0157] There is a ratio WR.sub.comp of the second component optical power W.sub.opt,comp2 of the second lighting system light component and the first component optical power W.sub.opt,comp1 of the first lighting system light component WR.sub.comp=W.sub.opt,comp2/W.sub.opt,comp1. On the x-axis the dimming level of the first pump light source is schematically depicted. As indicated above, at the origin, the dimming level may be 0 Watt, and at the right end of the x-axis the dimming level may be indicated as W.sub.10,max (see also above). Over a first dimming level W.sub.10,x (of the pump light source) the luminescent material light may start to quench. This is indicated in the drawing with the vertical dashed line, which is indicated with W.sub.10,x.

[0158] The dimming range of the laser light source is not depicted in FIG. 12a. However, as indicated above, it is assumed that basically there is a linear relation between the input power and the optical output power of the laser light source.

[0159] Further, FIG. 12a also schematically depict some further embodiments. One may e.g. relate the second component optical power W.sub.opt,comp2 of the second lighting system light component 1201 and the first component optical power W.sub.opt,comp1 of the first lighting system light component 1101 on the basis of the dimming level of the first pump light source, i.e. W.sub.10. As it can be predetermined that at a specific value first dimming level W.sub.10,x the luminescent material may start to quench, in embodiments it may be determined that only at a value equal to or larger than W.sub.10,x, or at another value, e.g. a*W.sub.10,x, the second lighting system light component 1201 is generated. The value of a may e.g. be selected from the range of 0.5-1, like e.g. from the range of 0.5-0.9, like 0.5-0.7. However, the value of a may also be approximately 1. The value a=0.7 is indicated with the dashed vertical line at 0.7*W.sub.10,x. The first component optical power W.sub.opt,comp1 associated to the specific dimming levels may be indicated with W.sub.opt,comp1,x. Here, W.sub.opt,comp1,x2 is the first component optical power W.sub.opt,comp1 related W.sub.10,x, and W.sub.opt,comp1,x1 is the first component optical power W.sub.opt,comp1 related 0.7*W.sub.10,x.

[0160] Hence, as will be clear to a person skilled in the art one may e.g. relate the second component optical power W.sub.opt,comp2 of the second lighting system light component 1201 and the first component optical power W.sub.opt,comp1 of the first lighting system light component 1101 (also) on the basis of the W.sub.opt,comp1 (see e.g. also FIG. 6) (though other options may also be possible (see also above)). For instance, in embodiments one may choose to only add the second lighting system light component 1201 only at W.sub.opt,comp1,max, see e.g. also FIG. 12d. However, it may also be possible to only add the second lighting system light component 1201 only at d*W.sub.opt,comp1,max, see e.g. also FIG. 12c. The value of d may e.g. be selected from the range of 0.5-1, like e.g. from the range of 0.5-0.9, like 0.5-0.7. However, the value of d may also be approximately 1. The value d=0.7 is indicated with the dashed horizontal line 0.7*W.sub.opt,comp1,max.

[0161] However, all kind of other embodiments may also be possible. In general, however, when up dimming over a dimming threshold value WR.sub.comp will increase relative to the value of WR.sub.comp below the dimming threshold value. Likewise, hen down dimming under a dimming threshold value WR.sub.comp will decrease relative to the value of WR.sub.comp above the dimming threshold value.

[0162] FIG. 12b schematically depicts the dimming range of the system on the lower x-as, and on the right y-axis the optical power. The straight slanted line is the optical power of the lighting system light. As schematically depicted, such straight line can be obtained by combining the first component and the second component. This can be done in several ways. FIG. 12b very schematically depicts an embodiment wherein the second lighting system optical component is introduced when up dimming leads to quenching. Hence, the second lighting system optical component starts at the vertical dashed line between the first part I and the second part II of the dimming range. The dashed curve indicates the optical power of the second lighting system optical component, i.e. W.sub.opt,comp2. Of course, at the stage that further up dimming of the pump light source introduces an effective decease of the optical power of the first lighting system optical component W.sub.opt,comp1, one may better keep the dimming level of the pump light source constant, and further up dim the lighting system light via the second lighting system optical component, i.e. W.sub.opt,comp2, i.e. especially the laser light source light.

[0163] As indicated above, and as schematically depicted in an embodiment in FIG. 12b, the laser light source comprises a second dimming range over which the laser light source 20 can be up dimmed and down dimmed. Hence, in embodiments in a control mode WR.sub.comp is larger in the second part of the first dimming range than in the first part of the first dimming range.

[0164] The control system is especially configured to control in a one or more controlling modes the ratio WR.sub.comp.

[0165] As schematically (also) depicted in FIG. 12b, the control system may be configured to increase in one or more controlling modes the second component optical power W.sub.opt,comp2 with increasing optical power W.sub.opt,sys of the lighting system light, wherein over at least part of a dimming range of the optical power W.sub.opt,sys of the lighting system light there is a linear or non-linear relation between the second component optical power W.sub.opt,comp2 with increasing optical power W.sub.opt,sys of the lighting system light, wherein over at least part of the dimming range of the optical power W.sub.opt,sys of the lighting system light 1001 the ratio WR.sub.comp increases with up dimming. The maximum power of the lighting system light (at least comprising one or more of, especially at least both, first lighting system light component and the second lighting system light component), may be indicated with W.sub.opt,sys,max. As schematically depicted in FIG. 12b, when the first component optical power W.sub.opt,comp1 shows over part of the dimming range a non-linear behavior, there will also be a non-linear relation between the second component optical power W.sub.opt,comp2 with increasing optical power W.sub.opt,sys of the lighting system light, to compensate for the non-linear behavior of the first component optical power W.sub.opt,comp1. In this way, the color point of the color component provided by the first component and second component may essentially stay the same—in the controlling mode—over the dimming range of W.sub.opt,sys.

[0166] As schematically depicted in FIGS. 12c and 12d, in embodiments the control system may be configured to control in one or more controlling modes the second component optical power W.sub.opt,comp2 of the second lighting system light component 1201 in dependence of the first component optical power W.sub.opt,comp1 of the first lighting system light component 1101 only above a predetermined threshold value of the first component optical power W.sub.opt,comp1 of the first lighting system light component 1101.

[0167] As schematically depicted in FIG. 12c over a first dimming level W.sub.10,x (see FIG. 12a) the luminescent material light 201 quenches, and the control system may be configured to increase WR.sub.comp when a dimming level of the first dimming range is equal to or higher than 0.7*W.sub.10,x. As (thus) also schematically depicted in FIG. 12c, in one or more control modes in the first part of the first dimming range WR.sub.comp>0.

[0168] However, in the embodiments schematically depicted in FIGS. 12b and 12d, in one or more control modes in the first part of the first dimming range WR.sub.comp≈0.

[0169] In FIG. 12d also schematically an embodiment may be depicted wherein WR.sub.comp may be 0 in the dimming range up to the dashed vertical line (see above some non-limiting examples for threshold values). At the dashed vertical line it may be changed between W.sub.opt,comp1 and W.sub.opt,comp2, i.e. below a threshold value W.sub.opt,comp2 is zero and above the threshold value W.sub.opt,comp1 may be zero. In such instances where W.sub.opt,comp1 is zero and W.sub.opt,comp2 is non-zero, WR.sub.comp may be defined at 0.

[0170] Hence, herein also modes may be possible (than e.g. schematically depicted in FIGS. 12c and 12d) wherein essentially only the second lighting system light component 1201 is available, and optionally one or more other lighting system light components (see also below), but not the first lighting system light component 1101.

[0171] In some of the embodiments, with the system it may be possible to create over a large dimming range a linear behavior of the optical power of the lighting system light or of one or more colors within the lighting system light. However, the invention does not exclude non-linearity. For instance, the slanted line in 12B may also be curved, when desired.

[0172] Hence, in embodiments when up dimming, WR.sub.comp may be increased over a specific threshold value of one or more of W.sub.10, W.sub.opt,10, W.sub.opt,sys, and W.sub.opt,comp1. When down dimming, WR.sub.comp may be decreased under a specific threshold value of one or more of W.sub.10, W.sub.opt,10, W.sub.opt,sys, and W.sub.opt,comp1. Hence, below the specific threshold value(s) the WR.sub.comp value(s) may be lower than above the threshold value(s).

[0173] Referring to FIG. 12d, when W.sub.opt,comp1 reaches the threshold value of W.sub.opt,comp1,max, and would pass this value when further up dimming would be possible, then WR.sub.comp is increased. In fact, in embodiments WR.sub.comp may be zero left from the vertical dashed line and may be ∞right from the vertical dashed line.

[0174] FIGS. 13a-13b schematically depict some aspects of the invention. As schematically depicted the first lighting system light component 1101 has a first spectral power distribution with spectral intensity at a first wavelength λ.sub.1. Further, the second lighting system light component 1201 has a second spectral power distribution, different from the first spectral power distribution, with spectral intensity at a second wavelength λ.sub.2, wherein the second wavelength λ.sub.2 is selected from the range of λ.sub.1−30 nm≤λ.sub.2≤λ.sub.1+30 nm. As schematically depicted, in embodiments the first spectral power distribution may have a band shape. For instance, the first wavelength λ.sub.1 is a dominant wavelength. Also the second wavelength λ.sub.2 may in embodiments be a dominant wavelength. In embodiments, λ.sub.2 may be selected from the range of λ.sub.1−10 nm≤λ.sub.2≤λ.sub.1+10 nm. The first light component 1101 and the second light component 1201 may in embodiments essentially have the same color point.

[0175] The dashed emission band refers to a third light source light 131, providing a third lighting system light component 1301, which may also be controlled by the control system.

[0176] Instead of a single peak of laser light source light 21, also a plurality of peaks may be provided, see FIG. 13b. References 21a and 21b indicate different laser light source lights, respectively. The relevant second wavelengths are indicated with λ.sub.2a and λ.sub.2b, and the relevant second lighting system light component 1201 with references 1201a and 1201b, respectively.

[0177] Hence, the invention provides in embodiments a laser phosphor based light source with improved brightness.

[0178] The term “plurality” refers to two or more.

[0179] The terms “substantially” or “essentially” herein, and similar terms, will be understood by the person skilled in the art. The terms “substantially” or “essentially” may also include embodiments with “entirely”, “completely”, “all”, etc. Hence, in embodiments the adjective substantially or essentially may also be removed. Where applicable, the term “substantially” or the term “essentially” may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, even more especially 99.5% or higher, including 100%.

[0180] The term “comprise” includes also embodiments wherein the term “comprises” means “consists of”.

[0181] The term “and/or” especially relates to one or more of the items mentioned before and after “and/or”. For instance, a phrase “item 1 and/or item 2” and similar phrases may relate to one or more of item 1 and item 2. The term “comprising” may in an embodiment refer to “consisting of” but may in another embodiment also refer to “containing at least the defined species and optionally one or more other species”.

[0182] Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

[0183] The devices, apparatus, or systems may herein amongst others be described during operation. As will be clear to the person skilled in the art, the invention is not limited to methods of operation, or devices, apparatus, or systems in operation.

[0184] It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims.

[0185] In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

[0186] Use of the verb “to comprise” and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”.

[0187] The article “a” or “an” preceding an element does not exclude the presence of a plurality of such elements.

[0188] The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In a device claim, or an apparatus claim, or a system claim, enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0189] The invention also provides a control system that may control the device, apparatus, or system, or that may execute the herein described method or process. Yet further, the invention also provides a computer program product, when running on a computer which is functionally coupled to or comprised by the device, apparatus, or system, controls one or more controllable elements of such device, apparatus, or system.

[0190] The invention further applies to a device, apparatus, or system comprising one or more of the characterizing features described in the description and/or shown in the attached drawings. The invention further pertains to a method or process comprising one or more of the characterizing features described in the description and/or shown in the attached drawings.

[0191] The various aspects discussed in this patent can be combined in order to provide additional advantages. Further, the person skilled in the art will understand that embodiments can be combined, and that also more than two embodiments can be combined. Furthermore, some of the features can form the basis for one or more divisional applications.