Patent Publication Number: US-2022229307-A1

Title: Spectrally Shaped Light Source

Description:
CROSS REFERENCE TO RELATED APPLICATIONS SECTION 
     This application is a non-provisional of U.S. Provisional Patent Application Ser. No. 63/140,145, filed on Jan. 21, 2021, entitled “Spectrally Shaped Light Source”. The entire contents of U.S. Provisional Patent Application Ser. No. 63/140,145 are herein incorporated by reference. 
    
    
     INTRODUCTION 
     Numerous commercial and academic applications have need for high brightness light over a broad wavelength range. For example, laser-driven light sources are available that provide high brightness over spectral ranges from the extreme UV through visible and into the infrared regions of the spectrum with high reliability and long lifetimes. Various types of such high-brightness light sources are commercially available from Energetiq, a Hamamatsu Company, located in Wilmington, Mass. 
     The widespread availability of high-brightness light sources, together with growing applications that use high brightness light, has driven the need for systems that shape the spectrum of the optical output of the high-brightness light source. Spectral shaping systems are needed that can provide, for example, specific wavelength distributions. This includes systems that can provide nearly arbitrary shapes of the output spectrum from UV to infrared and also enable programmable and controllable wavelength spectrums of light at an output. 
     SUMMARY 
     The present teaching relates to spectrally shaped sources that shape the spectrum of light generated by a high-intensity broadband light source to provide a high-brightness output optical illumination with a desired spectrum. More specifically, the present teaching relates to various embodiments of a high-intensity broadband light source that produce a round-shaped optical beam that is transformed by an input optical element into a rectangular shaped optical beam. An imaging dispersive optical element angularly disperses the wavelengths of the rectangular optical beam in one dimension and images the rectangular optical beam to illuminate a pixelated Spatial Light Modulator (SLM). Selective reflection of the pixelated spatial light modulator illuminated by the dispersed imaged optical beam produces various desired intensities of spectral output in a particular reflected direction towards a toroidal mirror. 
     In some embodiments of apparatus according to the present teaching, each column of an array of pixels in the pixelated spatial light modulator is illuminated at the same height by a different wavelength in the optical beam. Each column of the array of pixels in the spatial light modulator array that is illuminated is controlled to selectively reflect a desired portion of the light illuminating each column to the toroidal mirror. The toroidal mirror serves to simultaneously focus in the dispersion direction and image the rectangular shaped optical beam at an output plane. This action of the toroidal optic results in the selected portions of the dispersed wavelengths that are reflected toward the toroidal optic being overlapped in an image of the rectangular shape at an output port of the spectrally shaped source, and thus provides output optical illumination comprising a desired spectrum at the output port. 
     One feature of the spectrally shaped source of the present teaching is that it exhibits very high optical efficiency and can be constructed to be easy to assemble and physically compact. In addition, the spectrally shaped source generates a desired output spectrum that has high resolution and high precision and accuracy. More specifically, the use of a transformed rectangular shape optical beam of the present teaching has at least three key advantages over known systems. First, it improves a resolution of the spectral selectivity of the spectral shaper, much like a slit is used to improve a resolution of a spectrometer. Second, the rectangular shape simplifies the operation of the pixelated spatial light modulator because the modulator is illuminated by rectangular shaped images of the input beam that are separated in wavelength by the dispersive device. Thus, only a height of the illuminated columns of the array needs to be determined to provide a desired intensity of a reflected portion of an optical beam of a given wavelength. Third, the rectangular shape improves the integrity of the provided spectral profile because each reflected portion of a particular wavelength in the spectrum is independent of another reflected portion. In various embodiments, different lengths and positions for the selected portion of the pixel column that are chosen to reflect the optical illumination are used. 
     The spectrally shaped source of the present teaching includes optical elements positioned so as to support appropriate orientation and position of the various input and output planes as well as the plane of the spatial light modulator for various features, such as compact design, ease of assembly, high resolution, high precision, and high accuracy of spectral output. Various shapes and numbers of pixels, in one or more columns, can be controlled to reflect the portion of the optical beam to the toroidal optic to provide tailoring of the spectrum of the output illumination. Also, a spectral extension source can be optionally coupled to the output of the spectrally shaped source to expand the output spectrum wavelength range of the optical signal. The spectral extension source can be a light emitting diode (LED). The spectral extension source can also be a NIR LED. In addition, a fiber bundle can be used to transform the optical beam shape to provide a highly accurate beam shape with low loss. In addition, optical elements are positioned such that the toroidal optics configuration accommodates “off-axis” mirrors, i.e. 45-degree axis, for Digital Light Processing (DLP) micro-mirror embodiments. Furthermore, various techniques can be employed to provide stray light suppression. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present teaching, in accordance with preferred and exemplary embodiments, together with further advantages thereof, is more particularly described in the following detailed description, taken in conjunction with the accompanying drawings. The skilled person in the art will understand that the drawings, described below, are for illustration purposes only. The drawings are not necessarily to scale; emphasis instead generally being placed upon illustrating principles of the teaching. The drawings are not intended to limit the scope of the Applicant&#39;s teaching in any way. 
         FIG. 1  illustrates a system diagram of an embodiment of a spectrally shaped light source according to the present teaching. 
         FIG. 2A  illustrates a schematic of an embodiment of the input optics and light source for a spectrally shaped source according to the present teaching. 
         FIG. 2B  illustrates an input cross section of an embodiment of a fiber bundle for a spectrally shaped source according to the present teaching. 
         FIG. 2C  illustrates an output cross section of an embodiment of a fiber bundle for a spectrally shaped source according to the present teaching. 
         FIG. 3  illustrates a perspective view of an embodiment of part of the spectral shaper system that includes the input fiber plane, image forming dispersive device, and spatial light modulator plane of a spectrally shaped source according to the present teaching. 
         FIG. 4  illustrates another perspective view of the embodiment of the spectral shaper system that includes the input fiber plane, image forming grating, and spatial light modulator plane of the spectrally shaped source of  FIG. 3 . 
         FIG. 5  illustrates another perspective view of the embodiment of the spectral shaper system that includes the input fiber plane, image forming grating, spatial light modulator plane, toroidal mirror, and output optics of the spectrally shaped source of  FIG. 3 . 
         FIG. 6  illustrates another perspective view of the embodiment of the spectral shaper system including the input fiber plane, image forming grating, spatial light modulator plane, toroidal mirror and output optics of the spectrally shaped source of  FIG. 3  that illustrates the input. 
         FIG. 7A  illustrates a perspective view of an embodiment of the input planes, image forming dispersive device, and spatial light modulator plane of a spectral shaper system for an infrared-extended spectrally shaped source according to the present teaching. 
         FIG. 7B  illustrates another perspective view of the embodiment of the spectral shaper system for an infrared-extended spectrally shaped source of  FIG. 7A . 
         FIG. 7C  illustrates yet another perspective view of the embodiment of the spectral shaper system for an infrared-extended spectrally shaped source of  FIG. 7A . 
         FIG. 8A  illustrates the illumination of a modulator showing the light from the visible spectrum and the NIR spectrum of a spectral shaper of the present teaching. 
         FIG. 8B  illustrates the illumination of modulator regions of visible and NIR light from a face-on view of the system of  FIG. 8A . 
         FIG. 9A  illustrates a simulation of the spatial distribution of an output beam spot in the near-infrared region of the spectrum of an embodiment of the spatial shaper system of the present teaching. 
         FIG. 9B  illustrates a simulation of the spatial distribution of an output beam spot in the visible region of the spectrum of an embodiment of the spatial shaper system of the present teaching. 
         FIG. 9C  illustrates a simulation of the composite spatial distribution of an output beam spot in the near-infrared and visible regions of the spectrum of the embodiment of the spatial shaper system of  FIGS. 9A and 9B . 
         FIG. 10A  illustrates results of a model of the modulator plane in an embodiment of a near-IR extended spectral shaper of the present teaching. 
         FIG. 10B  illustrates photographs of the modulator plane for two measurements of embodiments of a near-IR extended spectral shaper of the present teaching. 
         FIG. 11A  illustrates a graph of spectra from an embodiment of the spectral shaper of the present teaching with particular rows of mirrors configured in the “on state” and showing a comparison of the visible spectrum and the NIR spectrum. 
         FIG. 11B  illustrates a graph of spectra from the embodiment of the spectral shaper system of  FIG. 11A  showing the output with all the mirrors in the “on state” for the visible spectrum and/or the NIR spectrum. 
         FIG. 12A  illustrates a graph of a spectrum from an embodiment of the spectral shaper system of the present teaching with particular rows of mirrors in the visible region in the on state. 
         FIG. 12B  illustrates a graph of a spectrum from an embodiment of the spectral shaper system of the present teaching with particular rows of mirrors in the NIR region in the on state. 
         FIG. 12C  illustrates a graph of the spectra of  FIGS. 12A and 12B  on a shared axis. 
         FIG. 13A  illustrates a graph of a spectrum from an embodiment of the spectral shaper system of the present teaching with five peaks in the NIR region using five rows of mirrors in the NIR region in the on state. 
         FIG. 13B  illustrates a graph of the spectrum of  FIG. 13A  with calculated FWHM information. 
         FIG. 14A  illustrates a front view of an optical source that generates visible light and NIR optical light from a broadband point source of light. 
         FIG. 14B  illustrates a top view of the optical source of  FIG. 14A  that generates visible light and NIR optical light. 
         FIG. 14C  illustrates a side top view of the optical source of  FIG. 14A  that generates visible light and NIR optical light. 
         FIG. 15  illustrates a graph of spectra of the output for different embodiments of the optical source for a spectral shaper system according to present teaching that use different filters and/or mirror coatings on the optical elements and a Xenon-based high-brightness plasma to generate the point source illumination. 
         FIG. 16  illustrates an alignment and characterization system for an optical source for the spectral shaper system of the present teaching. 
     
    
    
     DESCRIPTION OF VARIOUS EMBODIMENTS 
     The present teaching will now be described in more detail with reference to exemplary embodiments thereof as shown in the accompanying drawings. While the present teaching is described in conjunction with various embodiments and examples, it is not intended that the present teaching be limited to such embodiments. On the contrary, the present teaching encompasses various alternatives, modifications and equivalents, as will be appreciated by those of skill in the art. Those of ordinary skill in the art having access to the teaching herein will recognize additional implementations, modifications, and embodiments, as well as other fields of use, which are within the scope of the present disclosure as described herein. 
     Reference in the specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the teaching. The appearances of the phrase “in one 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 method of the present teaching can be performed in any order and/or simultaneously as long as the teaching remains operable. Furthermore, it should be understood that the apparatus and method of the present teaching can include any number or all of the described embodiments as long as the teaching remains operable. 
       FIG. 1  illustrates a system diagram of an embodiment of a spectrally shaped source  100  according to the present teaching. A high intensity optical source  102  produces high-brightness light at an output. The optical source  102  can be, for example, a high-brightness laser driven light source (LDLS), such as a laser driven xenon lamp, that provides broadband light supplied by a high-intensity plasma at an output. The source  102  can also be, for example, a super continuum fiber laser. 
     The output light is collected by input optics  104  and directed to an image forming grating  106 . The image forming grating  106  in some embodiments is an image forming dispersive device. The input optics  104  can include various optical elements including, for example, bulk optical components and/or fiber optic components. The input optics  104  can transform the spatial output of the light from the source  102  into a desired spatial profile at an input plane of the spectral shaper system  108 . The image forming grating spatially separates the wavelengths of the light from the input and directs the light to a spatial light modulator  110 . 
     The spatial light modulator  110  modulates the light in the spatially separated wavelengths of light independently and directs them to a toroidal optic element  112 . In some embodiments, the spatial light modulator is a pixelated spatial light modulator. In some embodiments the pixels form a one-dimensional array. In some embodiments, the pixels form a two-dimensional array. In some embodiments, the pixelated spatial light modulator  110  comprises a digital micro-mirror device (DMD). In some embodiments, the pixelated spatial light modulator comprises a liquid crystal on silicon (LCOS) device. Also, in some embodiments, the pixelated spatial light modulator  110  includes an order-sorting filter that increases spectral purity. 
     The toroidal optic element  112  directs the light reflected toward the toroidal optical element  112  by the spatial light modulator  110  to output optics  114 . The toroidal optic element  112  collects and focuses light from the spatial light modulator  110 . Some embodiments of the toroidal optic element utilize a reflective surface with a toroidal shape that recombines the spatially separated wavelengths of light and images the light from the surface of the modulator that are directed to the toroidal optic to an output plane. The output optics  114  can include various optical elements including, for example, bulk optical components and/or fiber optic components and can be used, for example, to couple the imaged optical light into an optical fiber or other lightguide. 
     A controller  116  is connected to the high-intensity light source and/or the spatial light modulator  110  to control the modulation of the light to provide a desired optical spectrum at the output of the output optics  114 . In some embodiments, the controller  116  operates in an open-loop configuration, and uses, for example, pre-loaded spectrum files to determine how to control the spatial light modulator. For example, the pre-loaded spectrum files can include how many pixels in a column of the modulator  110  associated with a particular wavelength are directing light toward the toroidal optical element  112 . In these embodiments, no external sensor and/or spectrometer is needed to adjust the spectral profile. This feature is possible because of the precise shaping and spectral imaging of the optical beams in the system. The input beam and the image forming grating  106  are configured to illumination a precise shape and size of a region on the modulator with a particular desired wavelength. Because of the precise illumination region size and shape, the number and position of pixels illuminated by the desired wavelength in the region can be determined. A pixel in the “on state” reflects light, while a pixel in the “off state” does not reflect light. Therefore, the intensity of light reflected from the region is controlled by controlling the number of pixels in the “on state”. Thus, it is possible to produce a desired intensity of a particular wavelength at the output only by controlling the number of pixels in the “on state” in the illuminated region. In some embodiments, the size and shape of the image beam is a rectangular shape that illuminates one column of a two dimensional array of pixels in the modulator. 
     Various embodiments of the spectral shaper system  108  may or may not include specific input optics  104  or output optics  114 , depending on the application. Some embodiments of the spectral shaper systems  108  can include an internal controller with pre-loaded control algorithms for controlling the spatial light modulator to provide desired spectral shapes of the output light. 
     One feature of the present teaching is that the spectrally shaped source  100  can include input optics  104  that spatially shape the high-brightness light from the optical source  102  to provide a spatial profile at an input plane of the shaper that produces a desired image at the plane of the spatial light modulator  110  after transformation by the image forming grating 106 . For example, in some embodiments, it is desirable that the spatial profile of light at an input plane of the shaper optical system  108  have a substantially rectangular shape. The light that emerges from the high-brightness source  102  can be, for example, generally a circular shape. Thus, in some embodiments, the input optics  104  performs a transformation from a circular shape input to a rectangular shape output. 
       FIG. 2A  illustrates a schematic of some elements  200  including the input optics  202  and light source  204  for an embodiment of a spectrally shaped source according to the present teaching. The light source  204  generates light from a high-intensity plasma  206  that diverges from the light source  204 . Focusing optics  208  in the input optics  202  collect the divergent light from the light source  204  and focus the light to an input of an optical fiber bundle  210 . In some embodiments, the fiber bundle  210  is configured to transform a shape of the focused beam that is coupled at the input of the fiber to a desired output shape. 
       FIG. 2B  illustrates an input cross section  230  of an embodiment of a fiber bundle  210  for a spectrally shaped source according to the present teaching. Individual fibers  232  in the bundle are arranged in a nominally circular shape at the input. 
       FIG. 2C  illustrates an output cross section of an embodiment of the fiber bundle  210  for a spectrally shaped source according to the present teaching. Individual fibers  232  in the bundle are arranged in a nominally rectangular shape at the input. In this embodiment, that shape is provided by a single column of 24 fibers. Other embodiments can use different aspect ratios of height-to-width of the rectangular shape and/or different numbers of fibers. The transformation from circular shape to rectangular shape is achieved by rearranging the positions of the fibers  232  over the length of the bundle  210  to realize the desired shape transformation. As understood by those skilled in the art, numerous shapes and shape transformations can be achieved using a fiber bundle. In some embodiments, a shape of an input cross-section of the fiber bundle is provided that closely matches an image of a plasma  206  or other light-generating element in the source  204 . In some embodiments, a shape of the output cross-section of the fiber bundle  210  is provided that has a rectangular shape that is matched to a shape of a pixel, or group of pixels, in the spatial light modulator in the shaper system. 
       FIG. 3  illustrates a perspective view of an embodiment of part of a spectral shaper system  300  that includes the input fiber plane  302 , image forming dispersive device  304 , and spatial light modulator plane  306  of a spectrally shaped source according to the present teaching. A length scale  310  is indicated. This length scale  310  is exemplary and shaper systems of the present teaching are not limited to this size or shape as understood by those skilled in the art. 
     Input light, which can be white light or other broadband light, is introduced into the shaper as an optical beam  308  having a particular shape. The shape may be provided by passing the optical beam  308  through a fiber array. While a fiber array is described herein, other input optics can be used to provide an input optical beam  308  with a desired shape at the input plane  302 . The fiber array can be, for example, a straight-line fiber-array or a rectangular array or other shape. In some embodiments, the fiber array is a straight-line fiber-array constructed from a multi-strand fiber bundle with a circular input bundle cross-section and a straight-line output end. In some embodiments, the light from the array is formed in a shape of a rectangular optical beam  308 . 
     The light in the optical beam  308  from the array is then directed to the image forming dispersive device  304  that separates the spectrum of the light in the shaped optical beam into spatially separated beams. Thus, the image forming dispersive device  304  angularly disperses wavelengths of the optical beam in a dispersion direction and images the shape of the optical beam at a modulation plane  306 . In some configurations according to the present teaching, the optical beam is formed in a rectangular shape. In some embodiments, the image forming dispersive device  304  is a concave, aberration-corrected, image-forming grating. The use of a curved dispersive element to image the input optical beam can eliminate the need for an extra optical element, such as a lens, needed in the shaper system to perform the imaging. 
     The image forming dispersive device  304  produces an image of the fiber-array  308  output at the input plane  302  onto a surface of a spatial light modulator (not shown) positioned in a modulator plane  306 . Different wavelengths of light separated by the dispersive device  304  are separately imaged onto different modulator regions. In some configurations according to the present teaching, the input light is a rectangle shape and modulator regions are columns of an array of pixels that form the modulator. For example, for an individual wavelength of input light, the dispersive element forms an image of the input light beam shape onto a specific column of a modulator. 
     For a broadband light input, images of the input shape at different wavelengths are formed on different columns of the pixelated modulator, forming a rainbow across the columns. In some embodiments, the modulator is a DMD modulator, and the different wavelength images coincide with different micro-mirror pixel columns. Various descriptions herein will refer to particular rows and/or columns of pixels as representing one dimension of the array without loss of generality, as the relative orientation of the array is arbitrary as understood by those skilled in the art. 
     In some embodiments, the input plane  302  and the modulator plane  306  are different planes, and a normal to the input plane  302  is not collinear with a normal to the modulator plane  306 . This configuration assists in providing a compact three-dimensional package for the optical system, which maintains a high-quality image of the optical input shape at the modulator plane  306 . 
       FIG. 4  illustrates another perspective view of the embodiment of the spectral shaper system  400  including the input fiber plane  302 , image forming dispersive device  304 , and spatial light modulator plane  306  for the spectrally shaped source of  FIG. 3 . The length scale  310  is also shown. The fiber array  308  and modulator  312  are shown. This view shows the three surfaces of the array, a view at the input plane  302 , a view at the concave surface of the dispersive device  304  that spreads the individual wavelengths in space to form images at different wavelengths, and a view at the plane  306  of the input to the modulator  312 . Each wavelength that emerges at a different angle from the dispersive device  304  forms a separate image of the input array  308  in different regions of the modulator  312  based on the wavelength separation provided by the grating and the curvature of the dispersive device  304 . In some embodiments, the dispersive device  304  also provides correction for spherical aberration. 
     In some embodiments, an order-sorting filter is positioned in the path between the image forming dispersive device  304  and the modulator  312 . The order-sorting filter can be positioned on or integrated into the image forming dispersive device  304  and/or the modulator  312 . The order-sorting filter enhances the spectral purity of the spectrum in the image plane by rejecting the second-order of shorter-wavelength light from mixing with the first-order light. The first and second orders have a wavelength difference of a factor of two. For example, a 400 nm second order wavelength is rejected and will not overlap with the 800 nm first order wavelength of light. 
       FIG. 5  illustrates another perspective view of the embodiment of the spectral shaper system  500  including the input fiber plane  302 , image forming dispersive device  304 , spatial light modulator plane  306 , toroidal mirror  314 , and output optics  316  for the spectrally shaped source of  FIG. 3 . The length scale  310  is also shown. The system includes the fiber array  308  and the modulator  312  shown in  FIG. 4 . A toroidal mirror  314  and output optics  316 , which in this embodiment is a lens, are used to project the optical light directed from the modulator  312  to the toroidal mirror  314  to an output plane  318  of the shaper system  500 . The modulator  312  is controlled to direct light from some regions of the modulator  312  toward the toroidal mirror  314  while directing light from other regions of the modulator  312  away from the toroidal mirror  314 . For example, in some embodiments, light from one or more pixels of a DMD is directed toward the mirror  314  and light from other pixels is directed away from the mirror  314 . 
     In some embodiments, the modulator  312  is a two-dimensional array of pixels comprising rows and columns of pixels. Light from a rectangular shaped optical beam at the input plane  312  is imaged such that a width and height of the imaged rectangle at the modulator plane  306  corresponds to a width and height of a column of pixels. The spatial separation of wavelengths by the dispersive device  304  causes different wavelengths of light to illuminate different columns of pixels. A controller (not shown in  FIG. 5 ) is used to configure each of the pixels in the modulator  312  to direct light toward or away from the toroidal mirror  314 . 
     The dispersive device  304  configuration determines the central wavelength and spectral bandwidth around the central wavelength, which can be referred to as a spectral segment, that is directed to each column of pixels in the modulator  312 . A certain fraction of the pixels in a column are then controlled to direct the light to the mirror  314 , while the remaining pixels direct light away from the mirror  314 . Different columns correspond to different spectral segments of light. In this way, a controlled fraction of the intensity of light in a particular spectral segment that is directed to the mirror  314  is then reflected by the mirror  314  to the output, thereby providing a controlled intensity of light in the spectral segment at the shaper output. Because different spectral segments associated with different columns are independently controlled, this feature provides a controlled shape of the intensity as a function of wavelength at the shaper system output. 
     One feature of using the rectangular shape of the optical light at the input plane  302  as described is that a very low loss, or high throughput efficiency can be realized. This occurs because the image efficiently illuminates the surface of a rectangular modulator  312  so nearly all the input light impinges to a pixel and nearly all light directed by the modulator to the toroidal mirror  314  appears at the output plane  318 . Also, high accuracy of intensity is provided because the pixels are uniformly illuminated. It should be understood that in various embodiments, different shapes of image from the input plane  302  to the modulator plane  306 , as well as different shapes of illuminated regions on the modulator  312 , are also possible. 
     One feature of the present teaching is that the image formed by the image forming dispersive device  304  of the rectangular shaped input optical beam illuminates the pixels in columns of the modulator  312  at a uniform height. In this case, a height of pixels in a column associated with a particular wavelength that are controlled to reflect the light from the surface of the modulator  312  toward the toroidal mirror  314  determines the fraction of the illumination in that wavelength that appears at the output. Controlling the various heights of the columns of the pixels in the modulator then provides a desired spectral shape of the illumination at the output plane  318 . 
     Also, the amount of light reflected toward the toroidal mirror in a given wavelength band associated with a column of the spatial light modulator  312  can be determined by a number of pixels in that column that are controlled to direct light to the toroidal mirror  314 . Thus, in some embodiments, a number of pixels in at least one column of pixels that is illuminated by the angularly dispersed wavelengths of the rectangular optical beam imaged by the image forming dispersive device is chosen to provide a desired spectral shape of the output optical illumination at the output plane  318 . 
     The toroidal mirror  314  is configured with a reflective surface in a shape that spatially recombines the wavelengths from the spatial light modulator  312  that are directed to the surface of the mirror  314  and direct them to the output optics  316 . The output optics  316  couple the spatially recombined light into a desired receiving optical system (not shown) positioned at an output plane  318  of the shaper system  500 . The output optics  316  in some embodiments is an output lens that couples the output light directed off of the toroidal mirror  314  to a liquid light guide (not shown). Other optical systems for receiving the optical beam from the output plane  318  are also possible as can be based on a particular application. 
       FIG. 6  illustrates another perspective view of the spectral shaper system  600  including the input fiber plane  302 , image forming dispersive device  304 , spatial light modulator plane  306 , toroidal mirror  314 , and output optics  316  of the spectrally shaped source of  FIG. 3 . This view of the shaper system  600  illustrates an optical axis through the input plane  302  to the dispersive device  304  and how the dispersive device  304  directs the light to the modulator plane  306  with a normal that is non-collinear with the optical axis through the input plane  302  to the dispersive element  304 . This view of the shaper system  600  also shows how the toroidal mirror  314  has a three-dimensional toroidal surface shape that both spatially recombines the wavelengths that are directed toward the mirror  314  and directs them towards the output plane  318 . 
     The embodiment of the spectral shaping system shown in  FIGS. 3-6  is illustrated with the dispersive device, modulator, and toroidal optical elements configured as reflective devices. It should be understood that one or more of those elements can be configured as a transmissive device with well understood modifications to the optical system and still be consistent with a spectral shaper system of the present teaching. 
     One feature of the spectral shaping system of the present teaching is that it can be designed to accommodate multiple wavelength ranges of interest. For example, embodiments of the system operate over a wavelength range from ˜380 nm to ˜760 nm. This may be referred to as the UV and visible region of the spectrum. Embodiments of the system also operate over a wavelength range from ˜380 nm to ˜1100 nm. This extended wavelength range includes spectral components in the near infrared (NIR) region of the spectrum, nominally from ˜760 nm to ˜1100 nm. 
     Some embodiments of the spectral shaper according to the present teaching produce spectral shaping in the NIR region of the spectrum that share the image-forming dispersive element and modulator, but have different input configurations for the UV and/or visible light and the NIR light. These embodiments locate the shaped optical beam in the NIR region of the spectrum at a position that generates astigmatism aberrations from the image forming dispersive device, and then these aberrations are used to locate the NIR spectrum at a different position on the surface of the spatial light modulator from the visible/UV spectrum. Thus, the NIR spectral components and visible and/or UV components can be independently controlled because they illuminate different pixel columns. 
       FIG. 7A  illustrates a perspective view of an embodiment of a spectral shaper system  700  including the input planes  702 ,  704 , image forming dispersive device  706 , and spatial light modulator plane  708  of an infrared-extended spectrally shaped source according to the present teaching. The shaper system  700  shown in perspective view  700  has a length scale  711  indicated. This length scale  710  is exemplary and NIR-extended shaper systems of the present teaching are not limited to this size or shape as understood by those skilled in the art. 
     Visible and/or ultraviolet input light is introduced into the shaper system  700  as an optical beam having a rectangular shape at the visible input plane  702 . In some embodiments, the visible light is a line shape. Near infrared light is input at a NIR input plane  704 . In some embodiments, the NIR light is input as a point source shape. The light from the visible input plane  702  and the light from the NIR input plane  704  is directed to the image forming dispersive device  706 . The image forming dispersive device  706  separates the spectrum of the light in the shaped optical beams from the NIR and visible planes  702 ,  704  into spatially separated beams and directs them to the spatial light modulator window  710  positioned at a spatial light modulator plane  708  such that the NIR spectrum is parallel to the visible spectrum on the modulator  712  positioned just behind the window  710 . The NIR subsystem shares the same optical path with the visible system. In some embodiments, the visible light is provided by a fiber bundle with a linear array of fibers at the output cross section. This produces a line shape. In some embodiments, the NIR system is nominally a point source. This point source can be provided, for example, from a single optical fiber output. 
     The NIR shares this path until it is coupled into an output optical device, which may be a liquid light guide. Both of the visible and NIR spectra are located on the spatial light modulator with a spatial gap, so they can be independently manipulated by the spatial light modulator  712  and controller (not shown). In this embodiment, the NIR input is offset from an optimum input position that would have no aberration. The offset position introduces astigmatism from the image forming dispersive device  706 , which serves to generate a line shape of NIR light at the spatial light modulator  712  from the point source shape of the NIR input light. The aberrations also serve to locate the NIR spectrum at a different position from the visible light on the modulator  712 . In contrast, the visible input, which is a line source shape is imaged with no aberration. 
     Similar to the embodiment described in connection with  FIG. 3 , the image forming dispersive device  706  of the embodiment of  FIG. 7A  produces an image of the shaped optical beam at the visible input plane  702  and the NIR input plane  704  at the modulator plane  306  ( FIG. 3 ). Different wavelengths of light separated by the dispersive device  706  are separately imaged onto different modulator pixel regions. In some embodiments, the modulator is a DMD modulator, and the different wavelength images coincide with different DMD pixel columns. In some embodiments, the input planes  702 ,  704  and the modulator plane  708  are different planes, providing a compact three-dimensional package for the optical system. Optionally, an optical wedge  714  can be used to project the NIR optical beam, and an optical aperture  716  can be used to aperture the visible and/or UV optical beam from the input planes  702 ,  704 . 
       FIG. 7B  illustrates another perspective view  730  of the spectral shaper system for an infrared-extended spectrally shaped source of  FIG. 7A . The length scale  711  is shown. This view  730  shows the visible input plane  702  and the visible line source optical beam that enters the system at that plane  702 . The NIR optical beam input is a point source at the NIR plane  704  that passes through the optical wedge  714 . The NIR light passes an aperture  724  and the visible light also passes and aperture  716  and then both beams impinge the image-forming dispersive device  706 . The image-forming dispersive device  706  spatially separates the wavelengths of light of both the visible and NIR light. The image-forming dispersive device  706  images different color points of light from the NIR light and different colored lines of light from the visible light to the spatial light modulator  712  after passing through the window  710 . 
     A controller (not shown) is used to control the spatial light modulator  712  such that a desired amount of light from each color is directed to the toroidal mirror  718  that spatially recombines the wavelengths and directs the desired amount of light from each color to a collection lens  720 . The collection lens provides an optical beam at an output plane  722  with a desired spectral shape of the output optical illumination. 
       FIG. 7C  illustrates a portion of yet another perspective view of the spectral shaper system  750  for the infrared-extended spectrally shaped source of  FIG. 7A . The visible input plane  702 , NIR input plane  704 , image forming dispersive device  706 , spatial light modulator plane  708 , spatial light modulator window  710 , spatial light modulator  712 , toroidal optical mirror  718 , collection lens  720 , and output plane  722  are shown. The scale  711  is indicated. This view of the spectral shaper system  750  illustrate the complex three-dimensional trajectories of the optical beams that pass through the system. This is why a toroidal mirror  718  is needed to both spatially recombine the wavelengths dispersed by the dispersive device  706  and to re-image the light at the output plane  722 . 
       FIG. 8A  illustrates the illumination  800  of a modulator  802  showing the illumination from the visible spectrum  804  and the NIR spectrum  806  of a spectral shaper system of the present teaching. A length scale  801  is provided. The light from the visible spectrum  804  and the NIR spectrum  806  share the same modulator  802 . The visible light  804  impinges the top half of the modulator  802 , and exhibits high resolution due to lower aberrations from the imaging dispersive device. The NIR light  806  impinges on the bottom half of the modulator  802  and exhibits lower resolution due to aberration in the imaging dispersive device. Thus, the two spectra  804 ,  806  are spatially separated and there is only minimal wavelength range overlap. In some embodiments, bandpass filters are used. 
       FIG. 8B  illustrates the illumination  850  of the modulator regions  852 ,  856  from a face-on view of the system of  FIG. 8A . A wavelength scale  856  is shown, with different wavelengths of light having different symbols and different grey scale levels in the simulation in the regions  852 ,  854 . In the NIR spectrum region  854 , for each wavelength, the spectral lines  860  are tilted and parallel with the spectral lines of other wavelengths. As a result, the output for the NIR is a line image when these lines are recombined in the toroidal mirror. The visible light  858  has higher resolution, and the input array shape is imaged on the modulator  802  and also at the output of the shaper system after being recombined in the toroidal mirror. Note that although individual circular array elements from a linear array of optical fibers provided at the input are resolved as three individual spots, such a pattern can be referred to as a line shape or a rectangular shape. Generally, in connection with the apparatus according to the present teaching, the visible spectrum  804  covers a range from ˜380 nm to ˜750 nm, and the NIR spectrum  806  covers a range from ˜700 nm to ˜1100 nm. 
       FIG. 9A  illustrates a simulation of the spatial distribution  900  of an output beam spot in the near-infrared region of the spectrum of an embodiment of the spectral shaper system of the present teaching. The grid squares  902  are one-millimeter square. The legend  904  refers to the grey scale in the figure which shows different wavelengths from 0.7 micrometers to 1.1 micrometers. The spatial distribution  900  represents the spot size at the input surface to, for example, an output liquid light guide coupled to the shaper system (not shown). 
       FIG. 9B  illustrates a simulation of the spatial distribution  930  of an output beam spot in the visible region of the spectrum of an embodiment of the spatial shaper system of the present teaching. The grid squares  932  are one-millimeter square. The legend  934  refers to the grey scale representing different wavelengths from 0.38 micrometers to 0.75 micrometers. The spatial distribution  930  represents the spot size at the input surface to, for example, an output liquid light guide coupled to the shaper (not shown). 
       FIG. 9C  illustrates a simulation of the composite spatial distribution  950  of an output beam spot in the near-infrared and visible regions of the spectrum of the embodiment of the spatial shaper system of  FIGS. 9A and 9B . The grid squares  952  are one-millimeter square. The legend  954  refers to the grey scale in the figure representing different wavelengths from 0.38 micrometers to 1.0 micrometers. The spatial distribution  950  represents the spot size at the input surface to, for example, an output liquid light guide coupled to the shaper system (not shown). This result is achieved with visible and NIR that share the same optics in the spectral shaper system. The output of the shaper system has the visible and NIR light overlapped onto a small area. The area has a dimension of approximately four millimeters by five and a half millimeters. This size and shape of a spatial distribution  950  at the output plane of the spectral shaper can be efficiently collected by a liquid light guide. 
       FIG. 10A  illustrates the results of a Zemax™ model simulator output  1000  of the modulator plane in an embodiments of a near-IR extended spectral shaper system of the present teaching. The NIR region  1001  of the modulator shows illumination patterns  1002 ,  1004 ,  1006 ,  1008 ,  1010  for five different individual NIR wavelengths with a line shape that is slightly tilted as a result of some aberration in the imaging dispersive element because of the offset placement of the input NIR point source at the NIR input plane. The visible region  1011  of the modulator shows illumination patterns  1012 ,  1014 ,  1016 ,  1018 ,  1020  for five different individual visible wavelengths with a higher-resolution image of a three-element linear fiber array input at the visible input plane, as imaged by the imaging dispersive element with aberration correction. The Model  1000  shows a clear gap between individual NIR spectral images  1002 ,  1004 ,  1006 ,  1008 ,  1010  and visible images  1012 ,  1014 ,  1016 ,  1018 ,  1020 . 
       FIG. 10B  illustrates photographs  1030 ,  1050  of the modulator plane for two measurements of embodiments of a near-IR extended spectral shaper system of the present teaching. The NIR regions  1032 ,  1052  and the visible regions  1034 ,  1054  of the modulator for each photograph  1030 ,  1050  are indicated. Each photograph is illuminated with different input illumination that extends from the visible through the NIR portion of the spectrum. The entire spectrum of illumination for each measurement is shown in the photographs  1030 ,  1050 . The illumination for the entire measured spectrum shares the same imaging dispersive element and all spectral components separated by the dispersive element fall onto the same modulator element. A clear spatial gap is apparent between the illuminated regions  1032 ,  1034  in the first photograph  1030  and also between the illuminated regions  1052 ,  1054  in the second photograph  1050 . This is necessary to provide independent spectral control for the NIR regions  1032 ,  1052  and the visible regions  1034 ,  1054 . For modulators that are pixelated modulators with a two dimensional array of pixels, it is clear that the pixels for the NIR region  1032 ,  1052  are different from the pixels for the visible region  1034 ,  1054 . It is also clear that individual spectral components of the visible and/or the NIR regions are distinct, and also can be independently controlled by controlling different regions of pixels on the pixelated modulator. 
       FIG. 11A  illustrates a graph  1100  of spectra from an embodiment of the spectral shaper system of the present teaching with rows of mirrors configured in the “on state” showing a comparison of the visible spectrum and the NIR spectrum. The spectral shaper system used for these measurements included a DMD with micro-mirrors as pixels at the modulator plane. These measurements were taken at the output of a liquid light guide that was optically coupled to the output of the spectral shaper system. For this measurement, eight rows of mirrors, with each row having a five-mirror width, was turned on. The visible spectrum  1102  is shown in short dashed line and the NIR spectrum  1104  is shown in a longer dash line. The combined spectrum  1106  is also shown with a solid line. The eight peaks apparent in the visible spectrum  1102  have a small full width at half maximum (FWHM). Five of the eight peaks of the NIR spectrum  1104  have lower counts and slightly broader FWHM. Some imbalance of the intensity of the spectra in the graph  1100  are due to attenuation in the liquid light guide, which has low transmission for wavelengths greater than 730 nm that collected the output light. 
       FIG. 11B  illustrates a graph  1150  of spectra from the spectral shaper system described in connection with of  FIG. 11A  showing the output with all the mirrors in the “on state” for the visible spectrum and/or the NIR spectrum. The visible spectrum  1152  with all mirrors in the “on state” in the visible region of the modulator is shown in short dashed line and the NIR spectrum  1154  with all mirrors in the “on state” in the NIR region is shown in a longer dash line. The combined spectrum  1156  with all mirrors in the “on state” in both regions is also shown with a solid line. With all mirrors in the “on state”, the output exhibits a higher count rate with individual spectral components not distinguished, and the total wavelength range is lower than the rows in on state of graph  1100 . 
       FIG. 12A  illustrates a graph  1200  of a spectrum from an embodiment of the spectral shaper system of the present teaching with rows of mirrors in the “on state” in the visible region. This graph shows results with eight rows of five mirror with each mirror in the “on state”. The high resolution provided by the aberration-corrected imaging is illustrated by the small FWHM. 
       FIG. 12B  illustrates a graph  1230  of a spectrum from an embodiment of the spectral shaper of the present teaching with rows of mirrors in the NIR region in the on state. The NIR peaks have a wider FWHM. 
       FIG. 12C  illustrates a graph  1250  of both the visible spectrum and the NIR spectrum of  FIGS. 12A and 12B  on the same plot. The comparison shows lower throughput for the NIR light, and the larger FWHM. The liquid light guide used for this measurement had low transmission for the NIR region, but extended transmission liquid light guides are available with over 70% transmission throughout the near infrared region. Throughput of the spectral shaping system can be improved by extending the reflectivity of the imaging dispersive device by using, for example, a gold coated reflective surface that can result in as much as 10% higher flux. Also, changes in the aberration condition can modify the tilt of the individual lines in the NIR spectrum. 
       FIG. 13A  illustrates a graph  1300  of a spectrum from an embodiment of the spectral shaper system of the present teaching with five peaks in the NIR region using five rows of mirrors in the “on state” in the NIR region. The sample peaks are at 716 nm, 754 nm, 791 nm, 835 nm and 905 nm. 
       FIG. 13B  illustrates a graph  1350  of the spectrum of  FIG. 13B  with calculated FWHM information. The peak at 716 nm has a FWHM of 13.72 nm. The peak at 754 nm has a FWHM of 14.26 nm. The peak at 791 nm has a FWHM of 14.46 nm. The peak at 835 nm has a FWMH of 14.22 nm. The peak at 905 nm has a FWHM of 13.21 nm. Thus, the FWHM ranges from 13 nm to 14 nm. 
     One feature of the present teaching is that it is possible to have both the NIR optical source light and the visible source light be generated by the same optical source. The optical source is constructed so that the visible source light is provided at a plane consistent with the visible input plane of the spectral shaper and the NIR source light is provided at a plane consistent with the NIR input plane of the spectral shaper as described herein. One advantage of this embodiment is that both complexity and cost are reduced by using a single source to power both the visible and NIR illumination. This design makes it possible to provide a compact NIR-extended programmable light source using the spectral shaping system. 
       FIG. 14A  illustrates a front view  1400  of an optical source that generates visible light  1402  and NIR optical light  1404  from a broadband point source  1406  of light. The broadband point source  1406  of light can be, for example, generated by a high-intensity plasma of a laser driven light source. A first elliptical mirror  1408  reflects and focuses light from the point source  1406  to a visible output  1410  optical beam with a desired shape at a visible output plane  1412 . A short pass filter  1414  is positioned in the path of the light reflected from the first elliptical mirror  1408 . A second elliptical mirror  1416  reflects and focuses light from the point source  1406  to a NIR output  1418  optical beam with a desired shape at a NIR output plane  1420 . A long pass filter  1422  is positioned in the path of the light reflected from the second elliptical mirror  1416 . The shape of the visible output  1410  and the shape of the NIR output  1418  is elliptical, which, when coupled into the spectral shaper, serves to balance and smooth the spectrum of the visible and NIR parts of the spectrum at the shaper output. 
       FIG. 14B  illustrates a top view  1430  of the optical source that generates visible light  1402  and NIR optical light  1404  of  FIG. 14A . The first and second elliptical mirrors  1408 ,  1416 , short-pass filter  1414  and long pass filter  1422  are shown as well as the visible output plane  1412  and the NIR output plane  1420 . 
       FIG. 14C  illustrates a side top view  1450  of the optical source that generates visible light  1402  and NIR optical light  1404  ( FIG. 14A ). The first and second elliptical mirrors  1408 ,  1416 , short-pass filter  1414  and long pass filter  1422  are shown as well as the visible output plane  1412  and the NIR output plane  1420 . 
     In various embodiments, the relative flux from the visible and NIR optical illumination can be achieved based on the reflectivity of various components used in the source. For example, it is possible to have nominally the same flux level for each channel of visible and/or NIR light. It is also possible to have higher flux in either the visible or the NIR regions. For example, using gold coating on reflective surfaces increases reflected flux of the infrared light. For example, a long-pass filter can flatten the Xenon spectrum response, reducing the peaks of Xenon spectrum in the near infrared. These two aspects can help improve the balance of the NIR part of the spectrum, especially as compared to the visible part of the spectrum of the output light of the optical source. For the visible light path, some embodiments use a first elliptical mirror  1408  with an enhanced aluminum coating and a short pass filter  1414  with a cutoff at 760 nm. For the NIR light path, some embodiments use a second elliptical mirror  1416  with an enhanced gold coating and a long-pass filter  1422  with a cutoff at 740 nm wavelength. 
       FIG. 15  illustrates a graph  1500  of spectra of the output for different embodiments of the optical source for a spectral shaper system of the present teaching that use different filters and/or mirror coatings on the optical elements and a Xenon-based high-brightness plasma to generate the point source illumination. The first spectrum  1502  illustrates the output of the Xenon plasma, with high peaks in the near infrared region. The second spectrum  1504  illustrates the reduction of the NIR peaks using a long pass Xenon spectrum flattening filter with a cutoff wavelength of 740 nm. 
       FIG. 16  illustrates an alignment and characterization system  1600  for an optical source  1602  for the spectral shaper system of the present teaching. An optical point source  1612  generates visible light  1604  at a visible output plane  1606  and NIR optical light  1608  at a NIR output plane  1610  from the optical point source  1612 . The optical point source  1612  for this embodiment is a high-intensity Xenon plasma driven by a laser. The visible light  1604  at a visible output plane  1606  and NIR optical light  1608  at a NIR output plane  1610  have nominally elliptical shapes. The visible light  1604  or the NIR light  1608  is coupled into an alignment tool  1614  that includes an imaging fiber bundle  1616  and a one-times magnifying lens pair  1618  that images the bundle onto a camera  1620 . A position of either the visible beam or the NIR beam on the camera is used to adjust the respective elliptical mirrors. As an example, if the optical point source  1612  has a plasma size of between 80 to 240 micrometers, it is imaged by a three-factor ellipsoidal mirror to a size between 240 and 720 micrometers at the output planes  1606 ,  1608 . The inset picture  1622  shows a point source generated by an optical fiber as imaged at the camera to show the operation of the alignment tool  1614  in an ideal case. 
     EQUIVALENTS 
     While the Applicant&#39;s teaching is described in conjunction with various embodiments, it is not intended that the Applicant&#39;s teaching be limited to such embodiments. On the contrary, the Applicant&#39;s teaching encompasses various alternatives, modifications, and equivalents, as will be appreciated by those of skill in the art, which may be made therein without departing from the spirit and scope of the teaching.