A RADIATION GENERATING SYSTEM COMPRISING AN OPTICAL ARRANGEMENT FOR A FAR UV LIGHT SOURCE MINIMIZING THE IMPACT OF UNFILTERED UNDESIRED WAVELENGTHS

Abstract

The present invention relates to a radiation generating system (1) comprising a radiation unit (2), wherein the radiation unit (2) comprises a light source (3), a first collimator (4), and an optical arrangement (5). The light source (3) is configured to generate light source radiation (100) having a first spectral power distribution having an intensity I.sub.1,1 at a first wavelength .sub.1 and an intensity I.sub.1,2 at a second wavelength .sub.2. The first collimator (4) is configured in a light receiving relationship with the light source (3), wherein the first collimator (4) is configured to collimate the light source radiation (100) into collimated light source radiation (101) having an initial spatial light distribution (ISLD). The optical arrangement (5) is arranged downstream of the first collimator (4) and comprises an optical filter (6) and a diffuser (7). The optical filter (6) has a higher transmission for the first wavelength .sub.1 than for the second wavelength Xi when irradiated under a predefined angle 0. The first wavelength Xi is selected from the range of 190-230 nm and the second wavelength Xi is selected from the range of 100-190 nm and/or 230-300 nm. The optical filter (6) is configured to filter at least part of the collimated light source radiation (101) into filtered radiation (102) comprising at least portion of the light source radiation (100) of the first wavelength Xi having a first spatial light distribution (SLD1) and at least portion of the light source radiation (100) of the second wavelength .sub.2 having a second spatial light distribution (SLD2) different from the first spatial light distribution (SLD1). The diffuser (7) is configured downstream of the optical filter (6). The diffuser (7) is configured to diffuse at least part of the filtered radiation (102) into diffused radiation (103) comprising at least a portion of the light source radiation (100) of the first wavelength .sub.1 having a third spatial light distribution (SLD3) and at least portion of the light source radiation (100) of the second wavelength .sub.2 having a fourth spatial light distribution (SLD4) different from the second spatial light distribution (SLD2).

Claims

1. A radiation generating system comprising a radiation unit, wherein said radiation unit comprises a light source, a first collimator, and an optical arrangement, wherein: said light source is configured to generate light source radiation having a first spectral power distribution having an intensity I.sub.1,1 at a first wavelength .sub.1 and an intensity I.sub.1,2 at a second wavelength .sub.2; said first collimator is configured in a light receiving relationship with said light source, wherein said first collimator is configured to collimate said light source radiation into collimated light source radiation having an initial spatial light distribution (ISLD); said optical arrangement is arranged downstream of said first collimator and comprises an optical filter and a diffuser, wherein: said optical filter has a higher transmission for said first wavelength .sub.1 than for said second wavelength .sub.2 when irradiated under a predefined angle ; said first wavelength .sub.1 is selected from the range of 190-230 nm and said second wavelength .sub.2 is selected from the range of 100-190 nm and/or 230 nm; said optical filter is configured to filter at least part of said collimated light source radiation into filtered radiation comprising at least portion of said light source radiation of said first wavelength .sub.1 having a first spatial light distribution and at least portion of said light source radiation of said second wavelength .sub.2 having a second spatial light distribution different from said first spatial light distribution; said diffuser is configured downstream of said optical filter; said diffuser is configured to diffuse at least part of said filtered radiation into diffused radiation comprising at least a portion of said light source radiation of said first wavelength .sub.1 having a third spatial light distribution and at least portion of said light source radiation of said second wavelength .sub.2 having a fourth spatial light distribution different from said second spatial light distribution, and wherein said radiation generating system further comprises a second collimator being arranged downstream of said diffuser; wherein said second collimator is a reflective collimator configured to collimate said diffused radiation into arrangement radiation having a narrower spatial light distribution than said diffused radiation.

2. The radiation generating system according to claim 1, wherein a beam-shaping optical element is arranged downstream said second collimator to beam-shape said arrangement radiation into beam-shaped radiation.

3. The radiation generating system according to claim 2, wherein said beam-shaping optical element is a refractive optical element.

4. The radiation generating system according to claim 3, wherein said refractive optical element comprises an array of refractive optical structures.

5. The radiation generating system according to claim 2, wherein said beam-shaped radiation has a narrower spatial light distribution than said arrangement radiation.

6. The radiation generating system according to claim 2, wherein said beam-shaped radiation has an elongated beam shape.

7. The radiation generating system according to claim 1, wherein 2I.sub.1,1/I.sub.1,2100.

8. The radiation generating system according to claim 1, wherein the reflectivity of the diffuser is in the range from 15% to 35% for said light source radiation.

9. The radiation generating system according to claim 1, wherein said diffuser is in optical contact with said optical filter.

10. The radiation generating system according to claim 1, wherein the dominant peak wavelength of said first wavelength .sub.1 is 207 nm and/or 222 nm, and/or the dominant peak wavelength of said second wavelength .sub.2 is in a wavelength range from 285 nm to 295 nm and/or from 255 to 260 nm.

11. The radiation generating system according to claim 1, wherein said first collimator is a light mixing chamber or a reflector.

12. The radiation generating system according to claim 1, wherein said optical filter has a transmittance characteristic with a high transmission for said first wavelength .sub.1 for the predefined angle with in an angle range of 30 to +30 with respect to the normal to said filter, and wherein said optical filter has substantially no transmittance for said second wavelength .sub.2 in said angle range of 30 to +30 with respect to the normal to the filter.

13. The radiation generating system according to claim 1, wherein said light source comprises an excimer discharge based light source.

14. A method for treating at least part of a space or of an object, wherein said method comprises providing system radiation having said first wavelength .sub.1 in a space or to an object using said radiation generating system as defined in claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Embodiments of the invention will now be described by way of example with reference to the accompanying drawings, of which:

[0067] FIG. 1a illustrates a radiation generating system according to the present invention;

[0068] FIG. 1b depicts a radiation generating system according to another embodiment of the present invention;

[0069] FIGS. 2a-2e illustrate spatial light distribution after each element of the radiation generating system, wherein intensity of the radiation is plotted as a function of the angle.

[0070] All the figures are schematic, not necessarily to scale, and generally only show parts which are necessary in order to elucidate embodiments of the present invention, wherein other parts may be omitted or merely suggested.

DETAILED DESCRIPTION

[0071] The present invention will now be described hereinafter with reference to the accompanying drawings, in which exemplifying embodiments of the present invention are shown. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments of the present invention set forth herein; rather, these embodiments of the present invention are provided by way of example so that this disclosure will convey the scope of the invention to those skilled in the art. In the drawings, identical or similar reference numerals denote the same or similar components having a same or similar function, unless specifically stated otherwise.

[0072] FIG. 1a illustrates a radiation generating system 1 comprising a radiation unit 2 comprising a light source 3, a first collimator 4, and an optical arrangement 5. The light source 3 is configured to generate light source radiation 100 having a first spectral power distribution having an intensity I.sub.1,1, which may be referred to as a primary intensity, at a first wavelength .sub.1 and an intensity I.sub.1,2, referred to as a secondary intensity, at a second wavelength .sub.2. The light source radiation 100 has a source spatial light distribution depicted in FIG. 2a. As mentioned above, the x-axis represents the incidence angle, while the y-axis represents intensity I.sub.1,1 at a first wavelength .sub.1 and an intensity I.sub.1,2, at a second wavelength .sub.2. As may be seen in FIG. 2a, the intensities I.sub.1,1 and I.sub.1,2 of the light source radiation 100 are substantially equal.

[0073] The first collimator 4 is configured in a light receiving relationship with the light source 3, wherein the first collimator 4 is configured to collimate the light source radiation 100 into collimated light source radiation 101.

[0074] The first collimator 4 is configured upstream of the light source 3. The first collimator 4 comprises a reflective collimator, especially a light reflective collimator. The first collimator 4 may especially narrow the beam of radiation. The beam width may be expressed in the full width of the beam at half its maximum intensity (FWHM). The light source 3 may emit light source radiation 100 in substantially all directions. The first collimator 4 substantially redirects part of the light source radiation 100 into collimated light source radiation 101 directed to the optical arrangement 5. As may be seen in FIG. 1a, some light source radiation 100 may already be directed to the optical arrangement 5 and may not interact with the first collimator 4. Hence, the radiation that enters the optical arrangement 5 may comprise both light source radiation 100 and collimated light source radiation 101. Hence, the collimated light source radiation 101 is collimated relative to the light source radiation 100.

[0075] Further, the optical arrangement 5 of the radiation generating system 1 according to the present invention is configured downstream of the first collimator 4. The optical arrangement 5 is configured downstream of the first collimator 4 and the light source 3. As the first collimator 4 in embodiments may comprise a reflective collimator, the light source 3 is positioned in between the first collimator 4 and the optical arrangement 5. The optical arrangement 5 may receive the collimated light source radiation 101 from the first collimator 4, and optionally light source radiation 100 from the light source 3. The optical arrangement 5 comprises an optical filter 6 and a diffuser 7.

[0076] The optical filter 6 has a higher transmission for the first wavelength .sub.1 than for the second wavelength .sub.2, especially when irradiated under the predefined angle or range of angles. The optical filter 6 may comprise an interference filter. The interference filter may specifically transmit wavelengths in the range of 190-230 nm at the predefined angle. The interference filter may specifically absorb wavelengths in the range of 100-190 nm at the predefined angle. Additionally, or alternatively, the interference filter may specifically reflect wavelengths in the range of 100-190 nm at the predefined angle. Especially, the interference filter may have a lower transmission for a wavelength in the range of 100-190 nm. Additionally, or alternatively, the interference filter may specifically absorb wavelengths in the range of 230-280 nm at the predefined angle or have a lower transmission for a wavelength in such range.

[0077] The optical filter 6 is configured to filter at least part of the collimated light source radiation 101 into filtered radiation 102 comprising at least portion of the light source radiation 100 of the first wavelength .sub.1 having a first spatial light distribution (SLD1) and at least portion of the light source radiation 100 of the second wavelength .sub.2 having a second spatial light distribution (SLD2). As may be seen in FIG. 2b, there is only filtered radiation 102 at the first wavelength .sub.1 at the angle =0, since the optical filter 6 has reflected and/or absorbed the collimated light source radiation 101 at the second wavelength .sub.2. However, at higher angles, the collimated light source radiation 101 at the second wavelength .sub.2 is still present.

[0078] An optical axis O1 of the collimated light source radiation 101 may be aligned with a normal N to the optical filter 6. The optical axis O1 of the collimated light source radiation 101 may be defined as an imaginary axis that runs through a center of the light source 3 and through the second collimator 8. The normal N to the optical filter 6 may be defined as an axis perpendicular to a surface of the optical filter 6 configured for the incidence of the collimated radiation 101. Hence, the radiation generating system 1 is configured such that the optical axis O1 of the collimated light source radiation 101 and the normal (N) to the optical filter 6 have a first angle 1 equal to 0.

[0079] The diffuser 7 is configured downstream of the optical filter 6. The diffuser 7 is configured to diffuse at least a part of the filtered radiation 102 into diffused radiation 103 comprising at least a portion of the light source radiation 100 of the first wavelength .sub.1 having a third spatial light distribution (SLD3) and at least portion of the light source radiation 100 of the second wavelength .sub.2 having a fourth spatial light distribution (SLD4) different from the second spatial light distribution (SLD2). In other words, the diffuser 7 redirects at least portion of the light source radiation 100 of the second wavelength .sub.2, i.e. the harmful radiation, to another direction, such that this portion of radiation 103 may be collimated once more by the first collimator 4, and subsequently pass through the optical filter 6, wherein this radiation is filtered. SLD3 and SLD4 are shown in in FIG. 2c. As may be seen in FIG. 2c, the collimated light source radiation 101 at the second wavelength .sub.2 has been redirected by the diffuser 7 from the higher angles back to a more narrow distribution, such that the collimated light source radiation 101 at the second wavelength .sub.2 is filtered once more by the optical filter 6. At the same time, the filtered radiation 102 at the first wavelength .sub.1 has been diffused to have a wider spatial light distribution.

[0080] The optical arrangement 5 comprises a second collimator 8 being arranged downstream of the diffuser 7. The second collimator 8 may be a reflective collimator configured to collimate the diffused radiation 103 into arrangement radiation 104. The arrangement radiation 104 has an arrangement spatial light distribution depicted in FIG. 2d. As is evident from FIG. 2d, the second collimator 8 narrows the spatial light distribution of the arrangement radiation 104 compared to the diffused radiation 103. Further, it may be seen that the intensity of the radiation at the first wavelength .sub.1 is greater than the intensity of the radiation at the first wavelength .sub.2.

[0081] FIG. 1b illustrates a radiation generating system 201 comprising a radiation unit 202 comprising a light source 203, a first collimator 204, and an optical arrangement 205. The light source 203 is configured to generate light source radiation 2100 having a first spectral power distribution having an intensity I.sub.1,1, which may be referred to as a primary intensity, at a first wavelength .sub.1 and an intensity I.sub.1,2, referred to as a secondary intensity, at a second wavelength .sub.2. As may be seen in FIG. 2a, the intensities I.sub.1,1 and I.sub.1,2 of the light source radiation 2100 are substantially equal.

[0082] The first collimator 204 is configured in a light receiving relationship with the light source 3, wherein the first collimator 204 is configured to collimate the light source radiation 2100 into collimated light source radiation 2101.

[0083] The first collimator 204 is configured upstream of the light source 203. The first collimator 204 comprises a reflective collimator, especially a light reflective collimator. The first collimator 204 may especially narrow the beam of radiation. The beam width may be expressed in the full width of the beam at half its maximum intensity (FWHM). The light source 203 may emit light source radiation 2100 in substantially all directions. The first collimator 204 substantially redirects part of the light source radiation 2100 into collimated light source radiation 2101 directed to the optical arrangement 205. As may be seen in FIG. 1a, some light source radiation 2100 may already be directed to the optical arrangement 205 and may not interact with the first collimator 204. Hence, the radiation that enters the optical arrangement 205 may comprise both light source radiation 2100 and collimated light source radiation 2101. Hence, the collimated light source radiation 2101 is collimated relative to the light source radiation 2100.

[0084] Further, the optical arrangement 205 of the radiation generating system 201 according to the present invention is configured downstream of the first collimator 204. The optical arrangement 205 is configured downstream of the first collimator 204 and the light source 203. As the first collimator 204 in embodiments may comprise a reflective collimator, the light source 203 is positioned in between the first collimator 204 and the optical arrangement 205. The optical arrangement 205 may receive the collimated light source radiation 2101 from the first collimator 204, and optionally light source radiation 2100 from the light source 203. The optical arrangement 205 comprises an optical filter 206 and a diffuser 207.

[0085] The optical filter 206 has a higher transmission for the first wavelength .sub.1 than for the second wavelength .sub.2, especially when irradiated under the predefined angle or range of angles. The optical filter 6 may comprise an interference filter. The interference filter may specifically transmit wavelengths in the range of 190-230 nm at the predefined angle. The interference filter may specifically absorb wavelengths in the range of 100-190 nm at the predefined angle. Additionally, or alternatively, the interference filter may specifically reflect wavelengths in the range of 100-190 nm at the predefined angle. Especially, the interference filter may have a lower transmission for a wavelength in the range of 100-190 nm. Additionally, or alternatively, the interference filter may specifically absorb wavelengths in the range of 230-280 nm at the predefined angle or have a lower transmission for a wavelength in such range.

[0086] The optical filter 206 is configured to filter at least part of the collimated light source radiation 2101 into filtered radiation 2102 comprising at least portion of the light source radiation 2100 of the first wavelength .sub.1 having a first spatial light distribution (SLD1) and at least portion of the light source radiation 2100 of the second wavelength .sub.2 having a second spatial light distribution (SLD2). As may be seen in FIG. 2b, there is only filtered radiation 2102 at the first wavelength .sub.1 at the angle =0, since the optical filter 206 has reflected and/or absorbed the collimated light source radiation 2101 at the second wavelength .sub.2. However, at higher angles, the collimated light source radiation 2101 at the second wavelength .sub.2 is still present.

[0087] An optical axis O1 of the collimated light source radiation 2101 may be aligned with a normal N to the optical filter 206. The optical axis O1 of the collimated light source radiation 2101 may be defined as an imaginary axis that runs through a center of the light source 203 and through the second collimator 208. The normal N to the optical filter 206 may be defined as an axis perpendicular to a surface of the optical filter 206 configured for the incidence of the collimated radiation 2101. Hence, the radiation generating system 201 is configured such that the optical axis O1 of the collimated light source radiation 2101 and the normal (N) to the optical filter 206 have a first angle 1 equal to 0.

[0088] The diffuser 207 is configured downstream of the optical filter 206. The diffuser 207 is configured to diffuse at least a part of the filtered radiation 2102 into diffused radiation 2103 comprising at least a portion of the light source radiation 2100 of the first wavelength .sub.1 having a third spatial light distribution (SLD3) and at least portion of the light source radiation 2100 of the second wavelength .sub.2 having a fourth spatial light distribution (SLD4) different from the second spatial light distribution (SLD2). In other words, the diffuser 207 redirects at least portion of the light source radiation 2100 of the second wavelength .sub.2, i.e. the harmful radiation, to another direction, such that this portion of radiation 2103 may be collimated once more by the first collimator 204, and subsequently pass through the optical filter 206, wherein this radiation is filtered. SLD3 and SLD4 are shown in FIG. 2c. As may be seen in FIG. 2c, the collimated light source radiation 2101 at the second wavelength .sub.2 has been redirected by the diffuser 207 from the higher angles back to a more narrow distribution, such that the collimated light source radiation 2101 at the second wavelength .sub.2 is filtered once more by the optical filter 206. At the same time, the filtered radiation 2102 at the first wavelength .sub.1 has been diffused to have a wider spatial light distribution.

[0089] The optical arrangement 205 comprises a second collimator 208 being arranged downstream of the diffuser 207. The second collimator 208 may be a reflective collimator configured to collimate the diffused radiation 2103 into arrangement radiation 2104. The arrangement radiation 2104 has an arrangement SLD depicted in FIG. 2d. As is evident from FIG. 2d, the second collimator 208 narrows the spatial light distribution of the arrangement radiation 2104 compared to the diffused radiation 2103. Further, it may be seen that the intensity of the radiation at the first wavelength .sub.1 is greater than the intensity of the radiation at the first wavelength .sub.2.

[0090] As may be seen in FIG. 1b, the diffuser 207 is in optical contact with the optical filter 106. In such an embodiment, the light loss due to reflection losses inherent to difference in refractive index with air are eliminated. Alternatively, or additionally, adhesive may be applied between the diffuser and the optical filter.

[0091] The radiation generating system 201 shown in FIG. 1b comprises a beam-shaping optical element 209 being arranged downstream from the second collimator 204 to beam-shape the arrangement radiation 2104 into beam-shaped radiation 2105. The beam-shaping optical element 209 is a refractive optical element comprising an array of refractive optical structures that may comprise semispherical lenses.

[0092] The beam-shaped radiation 2105 may have a narrower spatial light distribution than the arrangement radiation 2104. The beam-shaped radiation 2105 has a beam-shaped spatial light distribution shown in FIG. 2e.

[0093] Although the present invention has been described with reference to various embodiments, those skilled in the art will recognize that changes may be made without departing from the scope of the invention. It is intended that the detailed description be regarded as illustrative and that the appended claims including all the equivalents are intended to define the scope of the invention. While the present invention has been illustrated in the appended drawings and the foregoing description, such illustration is to be considered illustrative or exemplifying and not restrictive; the present invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the appended claims, the word comprising does not exclude other elements or steps, and the indefinite article a or an does not exclude a plurality. 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. Any reference signs in the claims should not be construed as limiting the scope.