Dual-output light source and method of generating light

Abstract

This invention discloses a dual-output light source comprising a laser-driven light source that generates light from a thermoplasm within an emission angle range of at least 180 degrees. A first and a second off-axis conical mirror are positioned within the at least 180-degree emission range of the thermoplasm such that light propagating from a first region of self-emission generated by the plasma illuminates a first focal point of the first off-axis conical mirror, and light propagating from a second region of self-emission generated by the plasma illuminates a first focal point of the second off-axis conical mirror. The first and second off-axis conical mirrors reflect light in their respective first and second optical paths. A first filter with a first bandwidth is positioned in the first optical path. A second filter with a second bandwidth is positioned in the second optical path.

Description

Dual-output laser driving light source The section headings used in this document are for organizational purposes only and should not be construed as limiting the subject matter described in this application in any way. Many commercial and academic applications require broadband high-brightness light in the spectral range of 170 nm to 2.1 microns. For example, many industrial applications including photolithography, metrology, accelerated life testing, photoresist development and testing, defect detection, and microscopy require broadband high-brightness light. Other applications of broadband high-brightness light include spectroscopy, aerial imaging, and blank mask detection. These and other applications require a broadband high-brightness light source with high reliability, small physical size, low fixed cost, low operating cost, flexible operating space to optimize the operation to the desired application, and low complexity. Due to various engineering difficulties, known broadband high-brightness light sources have limited efficacy and uses. Also, known broadband high-brightness light sources are typically single-output light sources with limited functionality. A dual-output light source includes a laser driving light source that generates light from a thermal plasma within an emission angle range of at least 180 degrees. A first and a second off-axis conical mirror are positioned within the at least 180-degree emission of the thermal plasma such that light propagating from a first region of spontaneous emission generated by the plasma irradiates a first focus of the first off-axis conical mirror and light propagating from a second region of spontaneous emission generated by the plasma irradiates a first focus of the second off-axis conical mirror. The first and second off-axis conical mirrors reflect light in respective first and second optical paths. The first and second off-axis conical mirrors may include filters with different filter functions. A first filter having a first filter function is positioned in the first optical path such that light having a first spectrum is transmitted to a first output positioned at a second focus of the first off-axis conical mirror. Similarly, a second filter is positioned in the second optical path such that light having a second spectrum is transmitted to a second output positioned at a second focus of the second off-axis conical mirror. A method of generating light according to this disclosure includes generating a thermal plasma that generates light within an emission angle range of at least 180 degrees. Propagating the generated light to a first focus of a first mirror such that the generated light is reflected in a first optical path, and propagating to a first focus of a second mirror such that the generated light is reflected in a first optical path. Filtering the light in the first optical path to form a first output beam having a first spectrum. Filtering the light in the second optical path to form a second output beam having a second spectrum. Propagating the first output beam to a first output at a second focus of the first mirror. Propagating the second output beam to a second output at a second focus of the second mirror. The present teachings will now be described in more detail with reference to its exemplary embodiments shown in the accompanying drawings. Although the present teachings are described in conjunction with various embodiments and examples, the present teachings are not intended to be limited to these embodiments. On the contrary, the present teachings encompass various alternatives, modifications, and equivalents, as will be understood by those skilled in the art. Those of ordinary skill in the art who have access to the teachings herein will recognize additional embodiments, modifications, and implementations within the scope of the invention as described herein, as well as other fields of use. The mention of "an embodiment" or "an implementation" in the specification means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the teachings. The appearances of the phrase "in an embodiment" in various places in the specification are not necessarily all referring to the same embodiment. It should be understood that the individual steps of the methods of the present teachings can be performed in any order and / or simultaneously, as long as the teachings remain operable. In addition, it should be understood that the devices and methods of the present teachings can include any number or all of the described embodiments, as long as the teachings remain operable. The present teachings relate to broadband light that can operate at relatively high brightness. As used herein, the term "broadband" light refers to light having a wavelength within the spectral range of 170 nm to 2.1 micrometers. That is, the term "broadband" light refers to light in the deep ultraviolet to infrared regions of the electromagnetic spectrum. It is technically difficult to generate high-brightness light over such a large range of the electromagnetic spectrum. It is particularly difficult to generate light with different spectral characteristics at multiple outputs within such a large range of the electromagnetic spectrum. Broadband high-brightness light sources are used in many current state-of-the-art optical metrology and exposure applications. It is desirable that these broadband high-brightness light sources be configured to accommodate many usage scenarios, some of which require providing dual or multiple outputs of light with different optical properties. Currently, broadband high-brightness light sources with such multiple outputs and high performance are not available on the market. It should be understood that many aspects of the present teachings are described in connection with a dual-output light source. However, it should be understood that the present teachings can be extended to include plural outputs of three or more outputs that can be used in many applications that require outputs with different spectral properties and / or that use parallel operation. Plasmas can be used to generate photons over a broad spectral range. For example, plasmas generated in accordance with the present teachings can generate light from the deep ultraviolet spectrum to the infrared spectrum. The methods and devices of the present teachings relate to plasma-generated light sources. FIG. 1A illustrates a side view of an embodiment of a dual-output light source system 100 configured in accordance with the present teachings. In one embodiment, the light source system 100 includes a laser-driven light source 102 that generates broadband light from a thermal plasma formed at the center of a bulb or chamber, assuming that the bulb or chamber has some regions that are substantially transparent to electromagnetic radiation having the desired wavelengths to allow light to pass through the chamber or bulb. In various embodiments, the laser-driven light source 102 includes a broadband light source that emits ultraviolet light, visible light, and / or near-infrared light. Light is emitted from the plasma at the center of the bulb in all directions. The bulb or chamber is transparent to electromagnetic radiation having a desired wavelength within an emission angle range of at least 180 degrees. For an example of a state-of-the-art laser-driven light source, see, for example, U.S. Patent No. 11,587,781, titled "Laser-Driven Light Source with Electrodeless Ignition," assigned to the present assignee. Such electrodeless light sources are available from Energetiq, a Hamamatsu Company, Wilmington, Massachusetts. These light sources are based on a Z-pinch plasma and completely avoid electrodes by inductively coupling current into the plasma. The plasma in these light sources is magnetically confined away from the source walls, thereby minimizing the thermal load and reducing debris and providing excellent open-loop spatial stability and a stable, repeatable power output. These light sources are highly desirable for applications that require a high brightness with a compact physical footprint. The light source system 100 also includes first and second off-axis conical mirrors 104, 104' that couple the light flux from the plasma light source 102 into first and second separate optical output channels 106, 106'. The first and second separate optical output channels 106, 106' may be referred to as a first and a second optical path 106, 106'. In some embodiments of the light source according to the present teachings, at least one of the first and second off-axis conical mirrors 104, 104' may be movable such that a plane perpendicular to a surface of the first off-axis conical mirror moves relative to the output aperture at the outputs 116, 116' of the light source. Also, in one embodiment of the light source, at least one of the first and second off-axis conical mirrors 104, 104' is an off-axis ellipsoidal mirror. In another embodiment of the light source, at least one of the first and second off-axis conical mirrors 104, 104' is an off-axis parabolic mirror. The first off-axis conical mirror 104 includes a reflective surface 108 positioned adjacent a first emission region 110 of the laser-driven light source 102 such that light generated by the thermal plasma and propagating from the first emission region 110 of the laser-driven light source 102 impinges on a first focus of the first off-axis conical mirror 104 and is then reflected away in a first optical path 106, where dots show beam tracing. Similarly, the second off-axis conical mirror 104’ includes a reflective surface 108’ positioned within a second emission region 110’ that is within an emission angle range of at least 180 degrees near the laser drive light source 102. Light from the second emission region 110’ is reflected by the reflective surface 108’ into a second optical path 106’, where the dots illustrate beam tracing. The generated light propagating from the second emission region 110’ of the laser drive light source 102 illuminates a first focal point of the second off-axis conical mirror 104’. In many embodiments, the reflective surface comprises a material that is highly reflective within the spectral region of interest. For example, gold and aluminum coatings can be used. At least one of the reflective surface 108 positioned within the first emission region 110 near the laser drive light source 102 on the first off-axis conical mirror 104 and the reflective surface 108’ positioned within a second emission region 110’ on the second off-axis conical mirror 104’ includes an optical coating in addition to a mirror coating. For example, at least one of these surfaces 108, 108’ can include an optical coating that forms a filter. These filters can have the same filter function for each of the surfaces 108, 108’, or the filters can have one filter for one surface 108 and a different filter function for the other surface 108’. The filter function can be, for example, a bandpass filter function or a high-pass or low-pass filter function. In many embodiments of the light source 100 of the present teachings, both the surface 108 positioned within the first emission region 110 near the laser drive light source 102 on the first off-axis conical mirror 104 and the surface 108’ positioned within a second emission region 110’ on the second off-axis conical mirror 104’ include a coating that forms a filter such that the first off-axis conical mirror 104 includes a filter having a first optical bandwidth and the second off-axis conical mirror 104’ includes a filter having a second optical bandwidth, where the first and second optical bandwidths are not equal and do not have the same center wavelength. For example, in one particular embodiment of the light source of the present teachings, the first off-axis conical mirror 104 includes an optical coating configured to have a filter with a bandwidth in the ultraviolet region of the electromagnetic spectrum, and the second off-axis conical mirror 104' is configured to have an optical coating with a bandwidth in the visible region of the electromagnetic spectrum. In another particular embodiment, the first off-axis conical mirror 104 includes an optical coating configured to have a filter with a bandwidth in the ultraviolet region of the electromagnetic spectrum, and the second off-axis conical mirror 104' is configured to have an optical coating with a bandwidth in the near-infrared region of the electromagnetic spectrum. In yet another particular embodiment, the first off-axis conical mirror 104 includes an optical coating configured to have a filter with a bandwidth in the near-infrared region of the electromagnetic spectrum, and the second off-axis conical mirror 104' is configured to have an optical coating with a bandwidth in the visible region of the electromagnetic spectrum. In another particular embodiment, both the first off-axis conical mirror 104 and the second off-axis conical mirror 104' include optical coatings configured to have filters with the same bandwidth. In yet another particular embodiment, a first filter 114 and a second filter 114' are configured to filter electromagnetic spectra of substantially the same bandwidth. A first filter 114 is positioned in the first optical path 106. The first filter 114 includes a first filter function that transmits light having a first spectrum to a first output 116 located at a second focal point of the first off-axis conical mirror 104. Similarly, a second filter 114' is positioned in the second optical path 106'. The second filter 114' includes a second filter function that transmits light having a second spectrum to a second output 116' located at a second focal point of the second off-axis conical mirror 104'. In one practical configuration, a mechanical frame 112 supports the first and second filters 114, 114'. The first and second filters 114, 114' can be separate and independent filters, which can have filter functions different from or the same as the filter functions of any filters configured on the first off-axis conical mirror 104 and configured on the second off-axis conical mirror 104'. The first and second optical outputs 116, 116' can be configured in various ways suitable for specific applications of the dual-output light source 100. In some embodiments, the first optical output 116 is configured to have a first numerical aperture, and the second optical output 116' is configured to have a second numerical aperture different from the first numerical aperture such that the dual-output light source 100 can couple the generated light into two different systems with different optical input configurations. Also, in various embodiments according to the present teachings, one or two optical fibers may be coupled to one or both of the first and second outputs 116, 116' such that EUV light generated by the light source system 100 propagates in the one or two optical fibers, as described more in connection with FIG. 2. Possible configurations of the outputs 116, 116' according to the present teachings may include any combination of free space and optical fibers. FIG. 1B depicts a top view of an embodiment of a dual-output light source optical system 130 configured according to the present teachings in combination with FIG. 1A to include coupling the flux from the laser-driven light source 102 to two separate output channels 106, 106' via a first and a second off-axis conical mirror 104, 104'. As described in connection with FIG. 1A, the light source optical system 100 shows a mechanical frame 112 that supports the first and second filters 114, 114'. The first and second off-axis conical mirrors 104, 104' are positioned below the first and second filters 114, 114' in their respective first and second optical paths 106, 106'. Reflective surfaces 108, 108' are shown directly below the first and second filters 114, 114'. A group of points at the center of the first and second filters 114, 114' are generated from beam tracing and are positioned at the respective second foci 132, 132' of the first and second off-axis conical mirrors 104, 104'. FIG. 1C depicts a perspective view of an embodiment of a dual-output light source optical system 160 configured according to the present teachings in combination with FIG. 1A to include coupling the flux from a laser-driven light source 102 to two separate output channels 116, 116' via a first and a second off-axis conical mirror 104, 104'. The perspective view shown in FIG. 1C is similar to the side view described in detail in connection with FIG. 1A. However, the perspective view shows a more detailed beam tracing depicting the first and second foci of the first and second off-axis conical mirrors 104, 104'. As described in connection with FIG. 1A, the light source optical system 160 shows a mechanical frame 112 that supports the first and second filters 114, 114'. The laser-driven light source 102 is positioned close to the first and second off-axis conical mirrors 104, 104' to couple the light flux from the plasma light source 102 into the first and second optical output channels 106, 106'. The points in the beam tracing on the first and second off-axis conical mirrors 104, 104' indicate the position of the first focus on the reflective surfaces 108, 108' of the conical mirrors 104, 104' where the beam impinges. Similarly, the points in the beam tracing on the first and second filters 114, 114' indicate the position on the filters 114, 114' where the beam impinges when transmitted to the second focus of the conical mirrors 104, 104'. The outputs 116, 116' show the second of the two foci 162, 162' formed by the conical mirrors 104, 104' where the beam impinges. FIG. 2 shows a side view of an embodiment of a high-brightness broadband dual-output light source optical system 200 including a pair of off-axis conical mirrors 104, 104' that couple flux from a plasma to two separate output channels 106, 106' combined into a single fiber optic channel according to the configurations of the present teachings. The dual-output broadband light source optical system 200 is similar to the dual-output broadband light source optical system 100 described in conjunction with FIGS. 1A - 1C, but also includes output fiber coupling and fiber combination that combines beams having different spectral properties. More specifically, the light source system 200 includes first and second off-axis conical mirrors 104, 104' that couple the light flux from the plasma light source 102 to a first and a second separate optical output channels 106, 106'. At least one of the first and second off-axis conical mirrors 104, 104' can be movable. At least one of the first and second off-axis conical mirrors 104, 104' can be an off-axis ellipsoidal mirror or an off-axis parabolic mirror. Each of the first and second off-axis conical mirrors 104, 104' includes a reflective surface 108, 108' positioned adjacent to respective first and second emission regions 110, 110' within an emission angle range of at least 180 degrees such that light generated by the thermal plasma and propagating from these emission regions illuminates respective first foci of the first and second off-axis conical mirrors 104, 104' and then reflects away in respective first and second optical paths 106, 106'. As in FIGS. 1A - 1C, dots show the beam tracing of the light beams reflected from the reflective surfaces 108, 108'. At least one of the reflective surfaces 108, 108' positioned adjacent to respective first and second emission regions 110, 110 of the first and second off-axis conical mirrors 104, 104' includes an optical coating that forms a filter. The filter function of one or both of these filters can be, for example, a band-pass filter function or a high-pass or low-pass filter function. In many embodiments of the light source of the present teachings, both the surface on the first off-axis conical mirror 104 and the surface on the second off-axis conical mirror 104' include a coating that forms a filter such that the first off-axis conical mirror 104 includes a filter having a first optical bandwidth and the second off-axis conical mirror 104' includes a filter having a second optical bandwidth, where the first and second optical bandwidths are not equal. A first filter 114 that transmits light having a first spectrum is positioned in the first optical path 106. Similarly, a second filter 114' that transmits light having a second spectrum is positioned in the second optical path 106'. A mechanical frame 112 supports the first and second filters 114, 114'. The first and second optical outputs 116, 116' are positioned at the respective second foci of the first and second off-axis conical mirrors 104, 104'. In the fiber-coupled configuration shown in FIG. 2, the first optical output 116 is coupled to a first fiber 202, and the second optical output 116' is coupled to a second fiber 202'. A fiber combiner 204 includes a first input coupled to the first fiber 202 and a second input coupled to the second fiber 202'. An output of the fiber combiner 204 transmits a combined beam including the spectra of the beams in the first and second optical paths 106, 106'. The combined spectrum includes a first beam that has been filtered by any filter on the surface of the first off-axis conical mirror 104 and then by the first filter 114. Also, the combined spectrum includes a second beam that has been filtered by any filter on the surface of the second off-axis conical mirror 104' and then by the second filter 114'. In many embodiments, the filter functions of the filters formed on the surfaces of the first and second off-axis conical mirrors 104, 104' and / or the filter functions of the first and second filters 114, 114' are different such that beams having two different spectra are combined in the optical combiner 204 to produce a combined spectrum having a more complex spectrum for a desired application. FIG. 3 depicts a side view of an embodiment of a dual-output light source optical system 300 including a pair of off-axis conical mirrors 104, 104' that couple flux from a plasma to two separate output channels 106, 106' that are combined into a single free-space optical channel according to the teachings of the present disclosure. The dual-output broadband light source optical system 300 is similar to the dual-output broadband light source optical system 200 described in connection with FIG. 2, but includes a free-space optical combiner 304 that produces a combined beam that can have different spectral properties. Also, different numerical apertures in the first and second outputs can transmit beams having different beam profiles. More specifically, the light source system 300 includes first and second off-axis conical mirrors 104, 104' that couple the light flux from the plasma light source 102 into first and second separate optical output channels 106, 106', as described herein. As in the previous figures, dots represent beam tracing. The first and second off-axis conical mirrors 104, 104' each include respective reflective surfaces 108, 108' positioned proximate respective first and second emission regions 110, 110' of the laser drive light source 102. The surfaces 108, 108' may include an optical coating that forms a filter. The filter function of these filters may be, for example, a band-pass filter function or a high-pass or low-pass filter function. In many embodiments of the light source of the present teachings, both the surface on the first off-axis conical mirror 104 and the surface on the second off-axis conical mirror 104' include a coating that forms a filter, such that the first off-axis conical mirror 104 includes a filter having a first optical bandwidth, and the second off-axis conical mirror 104' includes a filter having a second optical bandwidth, where the first and second optical bandwidths are not equal. As described in the previous figures, a first filter 114 that transmits light having a first spectrum is positioned in the first optical path 106. Similarly, a second filter 114' that transmits light having a second spectrum is positioned in the second optical path 106'. The mechanical frame 112 supports the first and second filters 114, 114'. First and second optical outputs 116, 116' are positioned at respective second foci of the first and second off-axis conical mirrors 104, 104'. In some embodiments, the first optical output 116 is configured to have a first numerical aperture, and the second optical output 116' is configured to have a second numerical aperture that is different from the first numerical aperture. In the fiber optic coupling configuration shown in FIG. 3, the first optical output 116 is coupled to a first optical fiber 302, and the second optical output 116' is coupled to a second optical fiber 302'. The first optical fiber 302 is coupled to a first input of a beam combiner 304, and the second optical fiber 302' is coupled to a second input of the beam combiner 304. In a particular embodiment, the optical combiner 304 may include a dichroic mirror. A first beam propagating in the first optical fiber 302 from the first output 116 configured to have a first numerical aperture is combined with a second beam propagating in the second optical fiber 302' from the second output 116' configured to have a second numerical aperture at the beam separation interface 306 of the optical combiner 304. FIG. 3 shows a first beam 308 and a second beam 308' having different beam properties associated with the first and second numerical apertures. In many operating methods according to the present teachings, the first and second beams 308, 308' having different beam profiles also have different spectral properties. Figure 4 shows data 400 of the percentage of reflectance varying with wavelength (in micrometers) of various reflective materials suitable for use as a reflective surface of the first and second off-axis conical mirrors 104, 104' in some embodiments of the dual-output broadband light source optical system of the present teachings. The use of a particular one of the various reflective materials may depend on, for example, a particular application. Percentage reflectance data for infrared to ultraviolet wavelengths for five metal coatings including UV-enhanced aluminum, enhanced aluminum, protected aluminum, protected gold, and protected silver are presented. Embodiments of the dual-output broadband light source optical system are not limited to the reflective materials described in connection with Figure 4. In operation, one method of generating light according to the present teachings includes generating a thermal plasma that generates light within an emission angle range of at least 180 degrees. Light within a broadband spectrum can be generated. Propagate the generated light to a first focal point of a first off-axis conical mirror, where the generated light is reflected at the first focal point in a first optical path. Some methods include moving the first off-axis conical mirror. In some methods, filtering can be performed when reflected in the first optical path. The light in the first optical path can be filtered to form a first output beam having a first spectrum. Then propagate the first beam to an optical output at a second focal point of the first off-axis conical mirror. Similarly, propagate the generated light to a first focal point of a second off-axis conical mirror, where the generated light is reflected at the first focal point in a second optical path. Some methods include moving the second off-axis conical mirror. Filter the light in the second optical path to form a second output beam having a second spectrum. In some methods, filtering can be performed when reflected in the second optical path. Then propagate the second beam to a second optical output at a second focal point of the second off-axis conical mirror. Some methods include coupling at least one of the first and second optical outputs to an optical fiber. Also, some methods include combining the first and second output beams into a combined beam that propagates in free space or in an optical fiber. The methods of the present teachings may include performing many different types of filtering at the first and / or second off-axis conical mirrors and / or in the first and second optical paths to produce only light having the desired spectral properties. For example, filtering can be performed such that only ultraviolet light propagates through the first output and only visible light propagates through the second output. Also, filtering can be performed such that only near-infrared light propagates through the first output and only ultraviolet light propagates through the second output. Also, filtering can be performed such that only visible light propagates through the first output and only near-infrared light propagates through the second output. In one method, the filtering in the first and second optical paths is substantially the same. Equivalents Although the applicant's teachings are described in connection with various embodiments, the applicant's teachings are not intended to be limited to these embodiments. On the contrary, the applicant's teachings cover various alternatives, modifications, and equivalents that may be made herein without departing from the spirit and scope of the teachings as would be understood by one of ordinary skill in the art. 100: Dual-output light source system 102: Laser drive light source / Plasma light source 104: First off-axis conical mirror 104’: Second off-axis conical mirror 106: First optical output channel / First optical path 106’: Second optical output channel / Second optical path 108: Reflective surface 108’: Reflective surface 110: First emission region 110’: Second emission region 112: Mechanical frame 114: First filter 114’: Second filter 116: First output 116’: Second output 130: Dual-output light source optical system 132: Second focal point 132’: Second focal point 160: Dual-output light source optical system 162: Focal point 162’: Focal point 200: High-brightness broadband dual-output light source optical system 202: First optical fiber 202’: Second optical fiber 204: Fiber optic combiner 300: Dual-output light source optical system 302: First optical fiber 302’: Second optical fiber 304: Free-space optical combiner 306: Beam separation interface 308: First beam 308’: Second beam 400: Data The teachings of the present disclosure, along with its further advantages, are described in more particularity in the following detailed description taken in conjunction with the accompanying drawings. Those of ordinary skill in the art will understand that the drawings described below are for illustrative purposes only. The drawings are not necessarily to scale; instead, emphasis is generally placed on illustrating the principles of the teachings. The drawings are not intended to limit the scope of the applicant's teachings in any way. FIG. 1A shows a side view of an embodiment of a dual-output light source optical system according to the configuration of the present disclosure that includes a pair of off-axis conical mirrors that couple the flux from a plasma to two separate output channels. FIG. 1B shows a top view of an embodiment of a dual-output light source optical system according to the configuration of the present disclosure that includes a first and a second off-axis conical mirror that couple the flux from a laser drive light source to two separate output channels, as described in connection with FIG. 1A. FIG. 1C shows a perspective view of an embodiment of a dual-output light source optical system according to the configuration of the present disclosure that includes a first and a second off-axis conical mirror that couple the flux from a laser drive light source to two separate output channels, as described in connection with FIG. 1A. FIG. 2 shows a side view of an embodiment of a dual-output light source optical system according to the configuration of the present disclosure that includes a pair of off-axis conical mirrors that couple the flux from a plasma to two separate output channels that are combined into a single fiber optic channel. FIG. 3 shows a side view of an embodiment of a dual-output light source optical system according to the present teachings that includes a pair of off-axis conical mirrors that couple flux from a plasma to two separate output channels that are combined into a single free-space optical channel. FIG. 4 shows data of the percentage of reflectivity that varies with wavelength (in micrometers) of various reflective materials suitable for use as a reflective surface of the first and second off-axis conical mirrors in some embodiments of the dual-output light source optical system of the present teachings. 100: Dual-output light source system 102: Laser-driven light source / Plasma light source 104: First off-axis conical mirror 104’: Second off-axis conical mirror 106: First optical output channel / First optical path 106’: Second optical output channel / Second optical path 108: Reflective surface 108’: Reflective surface 110: First emission region 110’: Second emission region 112: Mechanical frame 114: First filter 114’: Second filter 116: First output 116’: Second output

Claims

1. A dual-output light source, comprising: a) A laser-driven light source that generates light from a thermoplasm within an emission angle range of at least 180 degrees; b) A first off-axis conical mirror having a surface having a first coating and positioned close to the thermoplasm such that light generated from a first region of the at least 180-degree emission angle range illuminates a first focal point of the first off-axis conical mirror, the first off-axis conical mirror reflecting light in a first optical path; c) A second off-axis conical mirror having a surface having a second coating and positioned close to the thermoplasm such that light generated by the laser-driven light source from a second region of the at least 180-degree emission angle range illuminates a first focal point of the surface of the second off-axis conical mirror, the second off-axis conical mirror reflecting light in a second optical path; d) A first filter having a first bandwidth and having an input positioned in the first optical path, wherein light transmitted through an output of the first filter has a first spectrum; e) A first optical output positioned at a second focal point of the first off-axis conical mirror in an optical path of the output light transmitted through the first filter; f) a second filter having a second bandwidth and an input positioned in the second optical path, wherein the output light transmitted through the second filter has a second spectrum; and g) a second optical output positioned at a second focal point of the second off-axis conical mirror in an optical path of the output light transmitted through the second filter.

2. The light source as claimed in claim 1, wherein at least one of the first and second off-axis conical mirrors comprises an off-axis ellipsoidal mirror.

3. The light source as claimed in claim 1, wherein at least one of the first and second off-axis conical mirrors comprises an off-axis parabolic mirror.

4. The light source as claimed in claim 1, wherein the laser-driven light source includes a broadband light source that emits ultraviolet light.

5. The light source as claimed in claim 1, wherein the laser-driven light source includes a broadband light source that emits visible light.

6. The light source as claimed in claim 1, wherein the laser-driven light source includes a broadband light source that emits near-infrared light.

7. The light source of claim 1, further comprising an optical fiber having an end optically coupled to one end of the first optical output.

8. The light source of claim 1, further comprising a first optical fiber having an optically coupled end to the first optical output and a second optical fiber having an optically coupled end to the second optical output.

9. The light source of claim 1, wherein the first bandwidth includes a bandwidth in the ultraviolet region of the electromagnetic spectrum and the second bandwidth includes a bandwidth in the visible light region of the electromagnetic spectrum.

10. The light source of claim 1, wherein the first bandwidth includes a bandwidth in the ultraviolet region of the electromagnetic spectrum and the second bandwidth includes a bandwidth in the near-infrared region of the electromagnetic spectrum.

11. The light source of claim 1, wherein the first bandwidth includes a bandwidth in the near-infrared region of the electromagnetic spectrum and the second bandwidth includes a bandwidth in the visible region of the electromagnetic spectrum.

12. The light source of claim 1, wherein the first and second filters are configured to have the same bandwidth.

13. The light source of claim 1, wherein the first optical output is configured to have a first numerical aperture and the second optical output is configured to have a second numerical aperture different from the first numerical aperture.

14. The light source of claim 1, further comprising an optical combiner having a first input optically coupled to the first optical output and a second input optically coupled to the second optical output, wherein one output of the optical combiner provides a combined output beam.

15. The light source of claim 14, wherein the optical combiner includes an optical fiber combiner.

16. The light source of claim 14, wherein the optical combiner includes a dichroic mirror.

17. The light source of claim 1, wherein the first coating includes a first filter and the second coating includes a second filter, wherein one of the filtering functions of the first filter is different from one of the filtering functions of the second filter.

18. The light source of claim 1, wherein the first coating includes a first filter and the second coating includes a second filter, wherein a bandwidth of the first filter is the same as a bandwidth of the second filter.

19. The light source of claim 1, wherein the first coating is the same as the second coating.

20. The light source of claim 1, wherein at least one of the first and second off-axis conical mirrors comprises a coating including gold.

21. The light source of claim 1, wherein at least one of the first and second off-axis conical mirrors comprises a coating including aluminum.

22. The light source of claim 1, wherein the first off-axis conical mirror is movable such that a plane perpendicular to one of the surfaces of the first off-axis conical mirror moves relative to the output aperture of the light source.

23. The light source of claim 1, wherein the first off-axis conical mirror is movable such that a plane perpendicular to one of the surfaces of the first off-axis conical mirror moves relative to one of the output apertures of the light source, and the second off-axis conical mirror is movable such that a plane perpendicular to one of the surfaces of the second off-axis conical mirror moves relative to one of the output apertures of the light source.

24. A method for generating light, the method comprising: a) Generate a thermoplasm that generates light within an emission angle range of at least 180 degrees; b) Propagate the generated light via the thermoplasm to a first mirror that reflects the generated light in a first optical path; c) Filter the light in the first optical path to form a first output beam having a first spectrum; d) Propagate the first output beam to a second focal point of the first mirror; e) Propagate the generated light to a second mirror that reflects the generated light in a second optical path; f) Filter the light in the second optical path to form a second output beam having a second spectrum; and g) Propagate the second output beam to a second focal point of the second mirror.

25. The method of claim 24, wherein propagating the generated light to the first mirror includes propagating to one focal point of the first mirror.

26. The method of claim 24, further comprising performing filtering at the first mirror.

27. The method of claim 24, further comprising performing filtering at the first and second mirrors.

28. The method of claim 24, further comprising combining the first and second output beams.

29. The method of claim 24, further comprising moving at least one of the first and second mirrors.

30. The method of claim 24, wherein generating a thermoelectric plasma for generating light includes generating light using a broadband light source.

31. The method of claim 24, further comprising coupling at least one of the first and second output beams to an optical fiber.

32. The method of claim 24, further comprising coupling the first output beam to an optical device having a first numerical aperture and coupling the second output beam to an optical device having a second numerical aperture not equal to the first numerical aperture.

33. The method of claim 24, further comprising coupling the first output beam to a first input of a beam splitter and coupling the second output beam to a second input of the beam splitter.

34. The method of claim 24, further comprising coupling the first and second output beams to a single optical fiber.

35. The method of claim 24, wherein filtering the light in the first optical path to form the first output beam having the first spectrum includes filtering to transmit only ultraviolet light and filtering the light in the second optical path to form the second output beam having the second spectrum includes filtering to transmit only visible light.

36. The method of claim 24, wherein filtering the light in the first optical path to form the first output beam having the first spectrum includes filtering to transmit only ultraviolet light, and filtering the light in the second optical path to form the second output beam having the second spectrum includes filtering to transmit only near-infrared light.

37. The method of claim 24, wherein filtering the light in the first optical path to form the first output beam having the first spectrum includes filtering to transmit only visible light, and filtering the light in the second optical path to form the second output beam having the second spectrum includes filtering to transmit only near-infrared light.

38. The method of claim 24, wherein the first spectrum and the second spectrum are the same spectrum.

39. The method of claim 24, wherein the first spectrum is different from the second spectrum.

Images