Spectrally shaped light source

Abstract

To provide a spectral shaping system that shapes a spectrum of optical output of a high-brightness light source.SOLUTION: A spectrally-shaped light source includes a light source that generates a round beam. An optical element transforms the round beam into a rectangular beam. An image forming dispersive device angularly disperses wavelengths and images a rectangular beam at a modulation plane. A pixelated SLM is illuminated by the dispersed wavelengths of the rectangular beam such that each column of illuminated pixels is illuminated by a different wavelength. A toroidal optic projects light directed from the SLM to an output plane and focuses the angularly dispersed wavelengths of the beam so that a selected portion of the optical beam is reflected toward the toroidal optic by the SLM. A controller instructs the pixelated SLM to selectively reflect one portion of the optical beam toward the toroidal optic and to selectively reflect the other portion of the beam away from the toroidal optic so as to form a desired spectral shape.SELECTED DRAWING: Figure 1

Description

[Background technology]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application is a non-provisional adaptation of U.S. Provisional Patent Application No. 63 / 140,145, entitled "Spectrally Shaped Light Source," filed January 21, 2021. The entire contents of U.S. Provisional Patent Application No. 63 / 140,145 are incorporated herein by reference.

[0002] [Introduction]

[0002] Many commercial and academic applications require high-intensity light over a wide wavelength range. For example, laser-pumped light sources are available that provide high brightness across the spectral range from extreme ultraviolet to visible light to infrared, with high reliability and long life. Various types of such high-intensity light sources are available from Energetiq Technology, Inc., a subsidiary of Hamamatsu Photonics, located in Wilmington, Massachusetts.

[0003]

[0003] The widespread availability of high-brightness light sources, coupled with the growing number of applications using high-brightness light, has created a growing need for systems that can spectrally shape the light output of high-brightness light sources. For example, there is a need for spectral shaping systems that can generate unique wavelength distributions. These spectral shaping systems include systems that can create output spectra of nearly any shape, from ultraviolet (UV) to infrared, and also allow for programmable control of the wavelength spectrum of the output light. Summary of the Invention

[0004] The present teachings relate to a spectrally shaped light source that shapes the spectrum of light generated by a high-brightness broadband light source to produce a high-brightness output light illumination with a desired spectrum. More particularly, the present teachings relate to various embodiments of a high-brightness broadband light source that produces a circular light beam that is converted into a rectangular-shaped light beam by an input optical element. An imaging dispersive optical element angularly disperses the wavelengths of the rectangular light beam in one dimension and images the rectangular light beam to illuminate a pixelated spatial light modulator (SLM). Selective reflection of the pixelated spatial light modulator illuminated by the dispersed imaged light beam achieves various desired intensities of spectral output in specific reflected directions toward a toroidal mirror.

[0005] In some embodiments of devices according to the present teachings, each column of an array of pixels of a pixelated spatial light modulator is illuminated at the same height by a different wavelength of a light beam. Each illuminated column of the array of pixels of the spatial light modulator array is controlled to selectively reflect a desired portion of the light illuminating each column onto a toroidal mirror. The toroidal mirror simultaneously serves to focus the light in the dispersion direction and to image the rectangular-shaped light beam onto an output surface. This action of the toroidal optic causes the selected portion of the dispersed wavelengths reflected towards the toroidal optic to be superimposed onto a rectangular-shaped image at the output port of the spectrally shaped light source, providing light illumination at the output port containing the desired spectrum.

[0006] One feature of the spectrally shaped light source of the present teachings is that it exhibits very high optical efficiency and can be constructed to be easily assembled and physically compact. Additionally, the spectrally shaped light source produces a desired output spectrum with high resolution and high precision and accuracy. More specifically, the use of the converted rectangular-shaped light beam of the present teachings has at least three important advantages over known systems. First, the use of the converted rectangular-shaped light beam of the present teachings increases the resolution of the spectral selectivity of the spectral shaper, similar to using a slit to improve the resolution of a spectrometer. Second, the rectangular shape simplifies the operation of pixelated spatial light modulators because the modulator is illuminated by a rectangular image of an input beam separated by wavelength by a dispersive device. Therefore, to achieve a desired intensity of the reflected portion of a light beam of a given wavelength, only the height of the illuminated column of the array needs to be determined. Third, the rectangular shape improves the integrity of the resulting spectral profile because each reflected portion of a particular wavelength of the spectrum is independent of other reflected portions. In various embodiments, different lengths and positions are used for the selected portions of the pixel columns selected to reflect the light illumination.

[0007] The spectrally shaped light source of the present teachings includes optical elements arranged to appropriately support various input and output surface orientations and positions, as well as the plane of a spatial light modulator, for various features, such as compact design, ease of assembly, and high resolution, high precision, and high accuracy of the spectral output. Various shapes and numbers of pixels in one or more columns can be controlled to reflect portions of the light beam toward the toroidal optics to adjust the spectrum of the output illumination. Furthermore, a spectrally expanded light source can optionally be coupled to the output of the spectrally shaped light source to expand the output spectral wavelength range of the optical signal. The spectrally expanded light source can be a light emitting diode (LED). The spectrally expanded light source can also be a near-infrared (NIR) LED. Additionally, a fiber bundle can be used to transform the light beam shape, creating a low-loss, highly accurate beam shape. Additionally, the optical elements are arranged so that the toroidal optics configuration accommodates an "off-axis" mirror, i.e., a 45-degree axis, for DLP (Digital Light Processing) micromirror embodiments. Additionally, various techniques can be employed to provide stray light suppression.

[0008] The present teachings, in accordance with preferred and exemplary embodiments, as well as further advantages thereof, are more particularly described in the following detailed description taken in conjunction with the accompanying drawings. Those skilled in the art will understand that the drawings described below are for illustrative purposes only. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the teachings as a whole. The drawings are not intended to limit the scope of applicant's teachings in any way. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 illustrates a system diagram of one embodiment of a spectrally shaped light source in accordance with the present teachings. [Figure 2A] 1A and 1B show schematic diagrams of embodiments of input optics and a light source for a spectrally shaped light source in accordance with the present teachings. [Figure 2B] FIG. 1 illustrates an input cross section of one embodiment of a fiber bundle for a spectrally shaped light source in accordance with the present teachings. [Figure 2C] FIG. 1 illustrates an output cross section of one embodiment of a fiber bundle for a spectrally shaped light source in accordance with the present teachings. [Figure 3] FIG. 1 illustrates a perspective view of one embodiment of a portion of a spectral shaping system including an input fiber surface of a spectrally shaped light source, an imaging dispersion device, and a spatial light modulator surface in accordance with the present teachings. [Figure 4] 4 shows another perspective view of an embodiment of a spectral shaper system including an input fiber surface of the spectrally shaped light source of FIG. 3, an imaging grating, and a spatial light modulator surface. [Figure 5] 4 shows another perspective view of an embodiment of a spectral shaper system including the input fiber facet of the spectrally shaped light source of FIG. 3, an imaging grating, a spatial light modulator facet, a toroidal mirror, and output optics. [Figure 6] 4 illustrates another perspective view of an embodiment of a spectral shaper system including an input fiber facet, an imaging grating, a spatial light modulator facet, a toroidal mirror, and output optics of the spectrally shaped light source of FIG. 3 showing the input. [Figure 7A] FIG. 1 illustrates a perspective view of one embodiment of an input plane, an imaging dispersion device, and a spatial light modulator plane of a spectral shaper system for an infrared extended spectrally shaped light source in accordance with the present teachings. [Figure 7B] FIG. 7B illustrates another perspective view of an embodiment of a spectral shaper system for the infrared extended spectrally shaped light source of FIG. 7A. [Figure 7C] FIG. 7B illustrates yet another perspective view of an embodiment of a spectral shaper system for the infrared extended spectrally shaped light source of FIG. 7A. [Figure 8A] FIG. 10 illustrates illumination of a modulator showing light from the visible and NIR spectrum of a spectral shaper of the present teachings. [Figure 8B]8B illustrates illumination of the modulator region with visible and NIR light from a frontal viewpoint of the system of FIG. 8A. FIG. [Figure 9A] FIG. 10 illustrates a simulation of the spatial distribution of the output beam spot in the near-infrared region of the spectrum for one embodiment of a spatial shaper system of the present teachings. [Figure 9B] FIG. 10 illustrates a simulation of the spatial distribution of the output beam spot in the visible region of the spectrum of one embodiment of a spatial shaper system of the present teachings. [Figure 9C] 9C shows a simulation of the combined spatial distribution of the output beam spots in the near-infrared and visible regions of the spectrum of the embodiment of the spatial shaper system of FIGS. 9A and 9B. FIG. [Figure 10A] 10A-10C illustrate the results of a model of a modulator surface in one embodiment of a near-infrared extended spectrum shaper of the present teachings. [Figure 10B] 10A-10C show photographs of the modulator face for two measurements of an embodiment of a near-infrared extended spectrum shaper of the present teachings. [Figure 11A] 10 is a graph of the spectrum from one embodiment of a spectral shaper of the present teachings with a particular row of mirrors set to the "on state," showing a comparison of the visible spectrum with the NIR spectrum. [Figure 11B] 11B shows graphs of spectra from the embodiment of the spectral shaper system of FIG. 11A, illustrating the output with all mirrors in the "on" state for the visible and / or NIR spectrum. [Figure 12A] FIG. 10 shows a graph of a spectrum from one embodiment of a spectral shaper system of the present teachings with a particular row of mirrors in the visible region in the on state. [Figure 12B] FIG. 10 shows a graph of a spectrum from one embodiment of a spectral shaper system of the present teachings with a particular row of mirrors in the NIR region in the on state. [Figure 12C] FIG. 12C is a graph showing the spectra of FIGS. 12A and 12B on a common axis. [Figure 13A]FIG. 10 shows a graph of a spectrum from one embodiment of a spectral shaper system of the present teachings with five peaks in the NIR region using five rows of mirrors in the NIR region in the on state. [Figure 13B] FIG. 13B shows a graph of the spectrum of FIG. 13A with the addition of calculated FWHM information. [Figure 14A] FIG. 1 is a front view of a light source that generates visible and NIR light from a broadband point source. [Figure 14B] FIG. 14B is a top view of the light source of FIG. 14A that generates visible and NIR light. [Figure 14C] FIG. 14B is a side top view of the light source of FIG. 14A that generates visible and NIR light. [Figure 15] 10A-10C show graphs of the spectra of the output of various embodiments of light sources for a spectral shaper system according to the present teachings, using various filter and / or mirror coatings on optical elements and a xenon-based high-intensity plasma to generate point source illumination. [Figure 16] FIG. 1 illustrates an alignment and characterization system for a light source for a spectral shaper system of the present teachings. DETAILED DESCRIPTION OF THE INVENTION

[0010] Description of Various Embodiments

[0039] The present teachings will now be described in more detail with reference to exemplary embodiments of the present teachings, as illustrated in the accompanying drawings. While the present teachings are described in conjunction with various embodiments and examples, it is not intended that the present teachings be limited to such embodiments. On the contrary, the present teachings encompass various alternatives, modifications, and equivalents, as will be appreciated by those skilled in the art. Those skilled in the art and having access to the teachings herein will recognize additional implementations, modifications, and embodiments, as well as other fields of use, that are within the scope of the present disclosure as described herein.

[0011]

[0040] References in the specification to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment of the present teachings. Note that appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment.

[0012]

[0041] It should be understood that the individual steps of the methods of the present teachings can be performed in any order and / or simultaneously so long as the teachings remain operable. Furthermore, it should be understood that the apparatus and methods of the present teachings can include some or all of the described embodiments so long as the teachings remain operable.

[0013]

[0042] 1 shows a system diagram of one embodiment of a spectrally shaped light source 100 in accordance with the present teachings. A high-intensity light source 102 generates high-intensity light at its output. The light source 102 can be, for example, a high-intensity laser-driven light source (LDLS), such as a laser-pumped xenon lamp, which provides broadband light at its output supplied by a high-intensity plasma. The light source 102 can also be, for example, a supercontinuum fiber laser.

[0014]

[0043] The output light is collected by input optics 104 and directed to imaging grating 106. In some embodiments, imaging grating 106 is an imaging dispersive device. Input optics 104 can include various optical elements, including, for example, bulk optics and / or fiber optic components. Input optics 104 can convert the spatial output of light from light source 102 into a desired spatial profile at the input plane of spectral shaper system 108. The imaging grating spatially separates the wavelengths of light from the input and directs the light to spatial light modulator 110.

[0015]

[0044] The spatial light modulator 110 independently modulates the spatially separated wavelengths of light and directs the modulated light toward the toroidal optical 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 micromirror device (DMD). In some embodiments, the pixelated spatial light modulator comprises a liquid crystal on silicon (LCOS) device. Additionally, in some embodiments, the pixelated spatial light modulator 110 includes an order sorting filter to enhance spectral purity.

[0016]

[0045] The toroidal optical element 112 directs light reflected by the spatial light modulator 110 toward the toroidal optical element 112 to output optics 114. The toroidal optical element 112 collects and focuses the light from the spatial light modulator 110. Some embodiments of the toroidal optical 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 directed toward the toroidal optic onto an output surface. The output optics 114 can include a variety of optical elements, including, for example, bulk optics and / or fiber optic components, and can be used, for example, to couple the imaged light into an optical fiber or other light guide.

[0017]

[0046] The 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 generate a desired light spectrum at the output of the output optics 114. In some embodiments, the controller 116 operates in an open-loop configuration, using, for example, a preloaded spectral file to determine how to control the spatial light modulator. For example, the preloaded spectral file may include information about how many pixels in a column of the modulator 110, associated with a particular wavelength, should send light toward the toroidal optical element 112. In these embodiments, external sensors and / or spectrometers are not required to tailor the spectral profile. This feature is made possible by the precise shaping and spectral imaging of the light beam within the system. The input beam and imaging grating 106 are configured to illuminate an area of ​​a precise shape and size on the modulator at a specific desired wavelength. The precise size and shape of the illuminated area allows for the determination of the number and location of pixels illuminated at the desired wavelength in that area. Pixels in an "on" state reflect light, while pixels in an "off" state do not. Therefore, the intensity of light reflected from that region is controlled by controlling the number of "on" pixels. Thus, only by controlling the number of "on" pixels in the illuminated region can a desired intensity of a particular wavelength be produced at the output. In some embodiments, the size and shape of the image beam is rectangular, illuminating one column of the two-dimensional array of pixels of the modulator.

[0018]

[0047] 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 system 108 may include an internal controller pre-loaded with control algorithms for controlling the spatial light modulator to form a desired spectral shape of the output light.

[0019]

[0048] One feature of the present teachings is that the spectrally shaped light source 100 includes input optics 104 that spatially shape high-brightness light from the light source 102 to form a spatial profile at the input plane of the shaper that, after transformation by the imaging grating 106, produces a desired image at the plane of the spatial light modulator 110. For example, in some embodiments, it is desirable for the spatial profile of the light at the input plane of the shaper optics 108 to have a substantially rectangular shape. The light emerging from the high-brightness light source 102 may, for example, be generally circular in shape. Thus, in some embodiments, the input optics 104 performs a transformation from a circular-shaped input to a rectangular-shaped output.

[0020]

[0049] 2A shows a schematic of some elements 200, including input optics 202 and light source 204, for one embodiment of a spectrally shaped light source in accordance with the present teachings. Light source 204 generates light from a high-intensity plasma 206 that diverges from light source 204. Collection optics 208 in input optics 202 collect the diverging light from light source 204 and focus it at the input of fiber optic bundle 210. In some embodiments, fiber bundle 210 is configured to transform the shape of the focused beam coupled into the fiber input to a desired output shape.

[0021]

[0050] 2B shows an input cross section 230 of one embodiment of a fiber bundle 210 for a spectrally shaped light source in accordance with the present teachings. The individual fibers 232 of the bundle are arranged in a nominally circular shape at the input.

[0022]

[0051] FIG. 2C illustrates the output cross section of one embodiment of a fiber bundle 210 for a spectrally shaped light source in accordance with the present teachings. The individual fibers 232 of the bundle are arranged in a nominally rectangular shape at the input. In this embodiment, the shape at the input of the individual fibers 232 of the bundle is formed by a single column of 24 fibers. In other embodiments, different aspect ratios of the height and width of the rectangular shape and / or different numbers of fibers can be used. The transformation from a circular shape to a rectangular shape is achieved by rearranging the position of the fibers 232 along the length of the bundle 210 to achieve the desired shape transformation. As will be appreciated by those skilled in the art, numerous shapes and shape transformations can be achieved using fiber bundles. In some embodiments, the shape of the input cross section of the fiber bundle is shaped to closely match the image of the plasma 206 or other light-generating element of the light source 204. In some embodiments, the shape of the output cross section of the fiber bundle 210 is given a rectangular shape that matches the shape of a pixel or group of pixels in a spatial light modulator in the shaper system.

[0023]

[0052] 3 shows a perspective view of a portion of an embodiment of a spectral shaping system 300 including an input fiber surface 302 for a spectrally shaped light source in accordance with the present teachings, an imaging dispersion device 304, and a spatial light modulator surface 306. A length scale 310 is shown. This length scale 310 is exemplary, and the shaper system of the present teachings is not limited to this size or shape, as will be understood by those skilled in the art.

[0024]

[0053] Input light, which may be white light or other broadband light, is introduced to the shaper as a light beam 308 having a particular shape. The shape may be formed by passing the light beam 308 through a fiber array. While a fiber array is described herein, other input optics may be used to form the input light beam 308 with a desired shape at the input face 302. The fiber array may be, for example, a linear fiber array or a rectangular array, or other shape. In some embodiments, the fiber array is a linear fiber array constructed from multi-strand fiber bundles with a circular input bundle cross-section and a straight output end. In some embodiments, the light from the array is formed in the shape of a rectangular light beam 308.

[0025]

[0054] The light in the light beam 308 from the array is then directed to an imaging-dispersive device 304, which separates the spectrum of light in the shaped light beam into spatially separated beams. Thus, the imaging-dispersive device 304 angularly disperses the wavelengths of the light beam in the dispersion direction and images the shape of the light beam onto the modulation surface 306. In some configurations according to the present teachings, the light beam is shaped into a rectangular shape. In some embodiments, the imaging-dispersive device 304 is a concave, aberration-corrected imaging grating. Using a curved dispersive element to image the input light beam can eliminate the need for extra optical elements, such as lenses, required in a shaper system to perform the imaging.

[0026]

[0055] The imaging dispersion device 304 generates an image of the fiber array 308 output at the input face 302 onto the surface of a spatial light modulator (not shown) located at the modulator face 306. The various wavelengths of light separated by the dispersion device 304 are separately imaged onto different modulator regions. In some configurations according to the present teachings, the input light is rectangular in shape, and the modulator regions are columns of an array of pixels that form the modulator. For example, for each wavelength of the input light, the dispersion element images the beam shape of the input light onto a particular column of the modulator.

[0027]

[0056] For broadband optical inputs, the input shape at different wavelengths is imaged onto 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 correspond to different micromirror pixel columns. Various descriptions herein refer, without loss of generality, to particular rows and / or columns of pixels as representing one dimension of the array, since the corresponding orientation of the array is arbitrary, as will be understood by those skilled in the art.

[0028]

[0057] In some embodiments, input surface 302 and modulator surface 306 are different planes, and the normal to input surface 302 is not collinear with the normal to modulator surface 306. This configuration facilitates achieving a compact three-dimensional package for the optical system while maintaining a high-quality image of the optical input shape at modulator surface 306.

[0029]

[0058] FIG. 4 shows another perspective view of an embodiment of a spectral shaping system 400 including the input fiber face 302, imaging dispersion device 304, and spatial light modulator face 306 for the spectrally shaped light source of FIG. 3. A length scale 310 is also shown. The fiber array 308 and modulator 312 are shown. The view shows three faces of the array: the input face 302; the concave face of the dispersion device 304, which spreads the individual wavelengths in space to form images of each different wavelength; and the face 306 of the input to the modulator 312. Each wavelength emerging from the dispersion device 304 at a different angle forms a separate image of the input array 308 in a different region of the modulator 312 based on the wavelength separation provided by the grating and the curvature of the dispersion device 304. In some embodiments, the dispersion device 304 also corrects for spherical aberration.

[0030]

[0059] In some embodiments, an order sorting filter is placed in the path between the imaging-dispersive device 304 and the modulator 312. The order sorting filter may be placed on or integrated into the imaging-dispersive device 304 and / or the modulator 312. The order sorting filter increases the spectral purity at the image plane by removing second-order, shorter wavelength light from mixing with the first-order light. The first and second orders have a wavelength difference of two times. For example, the second-order wavelength of 400 nm is removed and does not overlap with the first-order wavelength light of 800 nm.

[0031]

[0060] FIG. 5 shows another perspective view of an embodiment of a spectral shaper system 500 including the input fiber face 302, imaging dispersion device 304, spatial light modulator face 306, toroidal mirror 314, and output optics 316 for the spectrally shaped light source of FIG. 3. A length scale 310 is also shown. The system includes the fiber array 308 and modulator 312 shown in FIG. 4. The toroidal mirror 314 and output optics 316, which in this embodiment is a lens, are used to project light directed from the modulator 312 to the toroidal mirror 314 onto the output face 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 and 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 the DMD is directed towards mirror 314 , while light from other pixels is directed away from mirror 314 .

[0032]

[0061] In some embodiments, the modulator 312 is a two-dimensional array of pixels having rows and columns of pixels. Light from a rectangular shaped light beam at the input face 312 is imaged onto the modulator face 306 such that the width and height of the imaged rectangle correspond to the width and height of a column of pixels. Spatial separation of wavelengths by the dispersing device 304 causes light of different wavelengths to illuminate different columns of pixels. A controller (not shown in FIG. 5) is used to configure each of the pixels of the modulator 312 to direct light toward or away from the toroidal mirror 314.

[0033]

[0062] The configuration of the dispersive device 304 determines the center wavelength and the spectral bandwidth around the center wavelength, sometimes referred to as the spectral segment, that is directed to each column of pixels in the modulator 312. A certain percentage of the pixels in the column are then controlled to direct light toward the mirror 314, while the remaining pixels are controlled to direct light away from the mirror 314. Different columns correspond to different spectral segments of light. In this manner, a controlled percentage of the intensity of light in a particular spectral segment that is directed toward the mirror 314 is then reflected by the mirror 314 to the output, thereby providing a controlled intensity of light for that spectral segment at the shaper output. Because the different spectral segments associated with different columns are controlled independently, this function provides a controlled shape of the intensity as a function of wavelength at the shaper system output.

[0034]

[0063] As described, one advantage of using a rectangular light shape at the input face 302 is that very low loss or high throughput efficiency can be achieved. This very low loss or high throughput efficiency occurs because the image efficiently illuminates the surface of the rectangular modulator 312, so that nearly all of the input light is incident on a pixel, and nearly all of the light directed by the modulator to the toroidal mirror 314 emerges at the output face 318. Also, because the pixel is uniformly illuminated, high intensity accuracy is achieved. It should be understood that in various embodiments, in addition to various shapes of the illuminated area on the modulator 312, various shapes of the image from the input face 302 to the modulator face 306 are also possible.

[0035]

[0064] One feature of the present teachings is that the image of the rectangularly shaped input light beam focused by the imaging-dispersive device 304 illuminates the pixel columns of the modulator 312 at a uniform height. In this case, the height of the pixel columns associated with a particular wavelength, which are controlled to reflect light from the surface of the modulator 312 toward the toroidal mirror 314, determines the percentage of illumination of that wavelength that appears at the output. Controlling the various heights of the pixel columns of the modulator creates a desired spectral shape for illumination at the output surface 318.

[0036]

[0065] Furthermore, the amount of light of a given wavelength band associated with a column of the spatial light modulator 312 that is reflected toward the toroidal mirror 314 can be determined by the number of pixels in that column that are controlled to direct light toward the toroidal mirror 314. Thus, in some embodiments, the number of pixels in at least one column of pixels illuminated by the angularly dispersed wavelengths of the rectangular light beam imaged by the imaging-dispersive device is selected to form a desired spectral shape of the output light illumination at the output face 318.

[0037]

[0066] The toroidal mirror 314 is comprised of a reflective surface shaped to spatially recombine wavelengths from the spatial light modulator 312 directed onto the surface of the mirror 314 and direct the spatially recombined light to output optics 316. The output optics 316 couple the spatially recombined light to desired receiving optics (not shown) located at an output surface 318 of the shaper system 500. In some embodiments, the output optics 316 is an output lens that couples the output light directed from the toroidal mirror 314 into a liquid light guide (not shown). Other optics for receiving the light beam from the output surface 318 are possible, as can be based on the particular application.

[0038]

[0067] Figure 6 is another perspective view of a spectral shaper system 600, including the input fiber face 302 of the spectrally shaped light source of Figure 3, the imaging dispersive device 304, the spatial light modulator face 306, the toroidal mirror 314, and the output optics 316. This view of shaper system 600 shows the optical axis through the input face 302 to the dispersive device 304 and how the dispersive device 304 directs light to the modulator face 306 with a normal that is not collinear with the optical axis through the input face 302 to the dispersive device 304. This view of shaper system 600 also shows that the toroidal mirror 314 has a three-dimensional toroidal surface shape that spatially recombines the wavelengths directed at it and directs the recombined light to the output face 318.

[0039]

[0068] The spectral shaping system embodiments shown in Figures 3-6 are illustrated with the dispersive device, modulator, and toroidal optical element configured as reflective devices. It should be understood that one or more of the dispersive device, modulator, and toroidal optical element can be configured as transmissive devices with well-understood modifications to the optics and still be consistent with the spectral shaper system of the present teachings.

[0040]

[0069] One feature of the spectral shaping systems of the present teachings is that they can be designed to accommodate multiple wavelength ranges of interest. For example, embodiments of the systems operate over a wavelength range from about 380 nm to about 760 nm. This wavelength range is sometimes referred to as the UV and visible regions of the spectrum. Embodiments of the systems also operate over a wavelength range from about 380 nm to about 1100 nm. This expanded wavelength range includes spectral components in the near-infrared (NIR) region of the spectrum, nominally from about 760 nm to about 1100 nm.

[0041]

[0070] Some embodiments of the spectral shaper according to the present teachings perform spectral shaping in the NIR region of the spectrum by sharing an imaging dispersive element and modulator but having separate input configurations for UV and / or visible light and NIR light. These NIR spectral shaper embodiments position a shaped light beam in the NIR region of the spectrum at a location that creates astigmatism in the imaging dispersive device, which then uses the astigmatism of the imaging dispersive device to position the NIR spectrum at a different location on the spatial light modulator surface from the visible / UV spectrum. Thus, the NIR spectral component and the visible and / or UV component illuminate separate pixel columns and can be controlled independently.

[0042]

[0071] 7A is a perspective view of one embodiment of a spectral shaper system 700 including input surfaces 702, 704 of an infrared extended spectrum shaped light source in accordance with the present teachings, an imaging dispersive device 706, and a spatial light modulator surface 708. Shaper system 700 shown in perspective view 700 is shown with a length scale 711. This length scale 710 is exemplary, and the NIR extended shaper system of the present teachings is not limited to this size or shape, as will be understood by those skilled in the art.

[0043]

[0072] Visible and / or ultraviolet input light is introduced into the shaper system 700 as a light beam having a rectangular shape at the visible light input face 702. In some embodiments, the visible light is line-shaped. Near-infrared light is input at the NIR input face 704. In some embodiments, the NIR light is input as a point source shape. The light from the visible light input face 702 and the light from the NIR input face 704 are directed to an imaging dispersion device 706. The imaging dispersion device 706 separates the light spectra of the shaped light beams from the NIR and visible light input faces 702, 704 into spatially separated beams and directs the spatially separated beams to a spatial light modulator window 710 located at the spatial light modulator face 708 so that the NIR spectrum is parallel to the visible spectrum on the modulator 712 located immediately behind the window 710. The NIR subsystem shares the same optical path as the visible system. In some embodiments, the visible light is supplied by a fiber bundle with a linear array of fibers at the output cross-section. This fiber bundle generates the line shape. In some embodiments, the NIR system is nominally a point source, which can be supplied, for example, from a single fiber optic output.

[0044]

[0073] The NIR shares this path until it is coupled to the output optical device, which may be a liquid light guide. Because both the visible and NIR spectra are spatially spaced on the spatial light modulator, they can be independently manipulated by the spatial light modulator 712 and a controller (not shown). In this embodiment, the NIR input is offset from an optimal input position where no aberrations would occur. The offset position introduces astigmatism from the imaging dispersion device 706, which acts to produce a line shape of NIR light at the spatial light modulator 712 from the point source shape of the NIR input light. The aberration also acts to position the NIR spectrum at a different position on the modulator 712 than the visible light. Meanwhile, the visible light input, which is a line source shape, is imaged aberration-free.

[0045]

[0074] Similar to the embodiment described in connection with FIG. 3, the imaging dispersion device 706 of the embodiment of FIG. 7A generates images of the shaped light beams at the visible light input surface 702 and the NIR light input surface 704 at the modulator surface 306 (FIG. 3). The various wavelengths of light separated by the dispersion device 706 are separately imaged onto different modulator pixel regions. In some embodiments, the modulators are DMD modulators, and the different wavelength images correspond to different DMD pixel columns. In some embodiments, the input surfaces 702, 704 and the modulator surface 708 are in different planes, resulting in a compact three-dimensional package for the optical system. Optionally, an optical wedge 714 can be used to project the NIR light beam, and an optical aperture 716 can be used to narrow the visible and / or UV light beams from the input surfaces 702, 704.

[0046]

[0075] FIG. 7B shows another perspective view 730 of the spectral shaper system for the infrared extended spectrally shaped light source of FIG. 7A. A length scale 711 is shown. This view 730 shows a visible light input face 702 and a visible line source light beam entering the system at the visible light input face 702. The NIR light beam input is a point source at the NIR input face 704 that passes through an optical wedge 714. The NIR light passes through an aperture 724, and the visible light also passes through an aperture 716, after which both beams enter an imaging-dispersive device 706. The imaging-dispersive device 706 spatially separates the wavelengths of light, both visible and NIR. The imaging-dispersive device 706 images various colored points of light from the NIR light and various colored lines of light from the visible light onto a spatial light modulator 712 after passing through a window 710.

[0047]

[0076] A controller (not shown) is used to control spatial light modulator 712 so that the desired amount of light from each color is directed to toroidal mirror 718, which spatially recombines the wavelengths and directs the desired amount of light from each color to collection lens 720. The collection lens provides a light beam at output face 722 with the desired spectral shape of the output light illumination.

[0048]

[0077] FIG. 7C shows a portion of yet another perspective view of a spectral shaper system 750 for the infrared-extended, spectrally shaped light source of FIG. 7A . Shown are the visible light input surface 702, the NIR input surface 704, the imaging dispersion device 706, the spatial light modulator surface 708, the spatial light modulator window 710, the spatial light modulator 712, the toroidal optical mirror 718, the collection lens 720, and the output surface 722. A scale 711 is shown. This view of the spectral shaper system 750 illustrates the complex three-dimensional path of the light beams through the system. This is why the toroidal mirror 718 is needed both to spatially recombine the wavelengths dispersed by the dispersion device 706 and to reimage the light at the output surface 722.

[0049]

[0078] 8A is a diagram illustrating illumination 800 of a modulator 802 showing illumination from the visible spectrum 804 and the NIR spectrum 806 of a spectral shaper system of the present teachings. A length scale 801 is provided. Light in the visible spectrum 804 and light in the NIR spectrum 806 share the same modulator 802. Visible light 804 is incident on the top half of the modulator 802 and exhibits high resolution due to small aberrations from the imaging and dispersive device. NIR light 806 is incident on the bottom half of the modulator 802 and exhibits low resolution due to aberrations from the imaging and dispersive device. Thus, the two spectrums 804, 806 are spatially separated, with minimal overlap in wavelength range. In some embodiments, bandpass filters are used.

[0050]

[0079] Figure 8B illustrates illumination 850 of modulator regions 852, 856 from a front-on perspective of the system of Figure 8A. The wavelength order 856 is shown, with different wavelengths of light having different symbols and different grayscale levels in the simulation of regions 852, 854. In the NIR spectral region 854, for each wavelength, the spectral lines 860 are tilted and parallel to the spectral lines of other wavelengths. As a result, the NIR output becomes a line image when these lines are recombined by the toroidal mirror. Visible light 858 has high resolution, and the shape of the input array is imaged by the modulator 802 and also at the output of the shaper system after recombination by the toroidal mirror. Note that although the individual circular array elements from the linear array of optical fibers at the input are resolved as three separate spots, such patterns are sometimes referred to as line or rectangular shapes. Generally, in the context of devices according to the present teachings, the visible spectrum 804 encompasses a range from about 380 nm to about 750 nm, and the NIR spectrum 806 encompasses a range from about 700 nm to about 1100 nm.

[0051]

[0080] 9A shows a simulation of the spatial distribution 900 of the output beam spot in the near-infrared region of the spectrum for one embodiment of a spectral shaper system of the present teachings. The grid squares 902 are 1 millimeter square. Legend 904 indicates the grayscale of the diagram, which shows various wavelengths from 0.7 micrometers to 1.1 micrometers. The spatial distribution 900 represents the spot size at the input surface for, for example, a liquid light guide (not shown) of the output coupled into the shaper system.

[0052]

[0081] 9B shows a simulation of the spatial distribution 930 of the output beam spot in the visible region of the spectrum for one embodiment of a spatial shaper system of the present teachings. The grid squares 932 are 1 millimeter square. The legend 934 shows a gray scale representing various wavelengths from 0.38 micrometers to 0.75 micrometers. The spatial distribution 930 represents the spot size at the input surface for, for example, a liquid light guide (not shown) of the output coupled into the shaper.

[0053]

[0082] FIG. 9C shows a simulation of the combined spatial distribution 950 of the output beam spots in the near-infrared and visible regions of the spectrum for the embodiment of the spatial shaper system of FIGS. 9A and 9B. The grid squares 952 are 1 millimeter square. Legend 954 indicates the grayscale of the diagram, showing various wavelengths from 0.38 micrometers to 1.0 micrometers. The spatial distribution 950 represents the spot size at the input surface of a liquid light guide (not shown) for the output coupled into the shaper system. This result is obtained with the visible and NIR sharing the same optics in the spectral shaper system. The output of the shaper system is a small overlap of visible and NIR light over a small area, approximately 4 millimeters by 5.5 millimeters in size. This size and shape of the spatial distribution 950 at the output face of the spectral shaper allows for efficient collection by the liquid light guide.

[0054]

[0083] 10A shows the results of a Zemax™ model simulator output 1000 of a modulator face in one embodiment of a near-infrared extended spectrum shaper system of the present teachings. The NIR region 1001 of the modulator shows illumination patterns 1002, 1004, 1006, 1008, 1010 assigned to five different, distinct NIR wavelengths with slightly tilted line shapes as a result of some aberrations in the imaging dispersive element due to the offset placement of the input NIR point source at the NIR input face. The visible region 1011 of the modulator shows illumination patterns 1012, 1014, 1016, 1018, 1020 assigned to five different, distinct visible wavelengths with a high-resolution image of a three-element linear fiber array input at the visible light input face, imaged by the imaging dispersive element with aberration correction. The model 1000 shows clear gaps between the individual NIR spectral images 1002, 1004, 1006, 1008, 1010 and the visible images 1012, 1014, 1016, 1018, 1020.

[0055]

[0084] FIG. 10B shows photographs 1030, 1050 of the modulator face for two measurements of an embodiment of a near-infrared extended spectrum shaper system of the present teachings. The NIR region 1032, 1052 and visible region 1034, 1054 of the modulator for each photograph 1030, 1050 are shown. Each photograph is illuminated with a different input illumination, ranging from the visible to the NIR portion of the spectrum. The entire spectrum of illumination for each measurement is shown in photographs 1030, 1050. Illumination across the measured spectrum shares the same imaging dispersive element, and all spectral components separated by the dispersive element fall on the same modulator element. A distinct spatial gap is readily 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 spatial gap is necessary for independent spectral control of the NIR region 1032, 1052 and the visible region 1034, 1054. For modulators that are pixelated modulators with a two-dimensional array of pixels, it will be apparent that the pixels in the NIR region 1032, 1052 will be different from the pixels in the visible region 1034, 1054. It will also be apparent that the individual spectral components in the visible and / or NIR region will be different and may further be independently controlled by controlling different regions of the pixels of the pixelated modulator.

[0056]

[0085] FIG. 11A shows a graph 1100 of spectra from one embodiment of a spectral shaper system of the present teachings, comparing the visible spectrum with the NIR spectrum using mirror rows set to the "on" state. The spectral shaper system used for these measurements included a DMD with micromirrors as pixels on the modulator face. These measurements were taken at the output of a liquid light guide optically coupled to the output of the spectral shaper system. For the measurements in FIG. 11A, eight rows of mirrors were set to on, with each row having a width of five mirrors. The visible spectrum 1102 is shown by the short dashed line, and the NIR spectrum 1104 is shown by the long dashed line. The summed spectrum 1106 is also shown by the solid line. The eight peaks seen in the visible spectrum 1102 have small full width at half maximum (FWHM). Five of the eight peaks in the NIR spectrum 1104 have lower counts and slightly broader FWHMs. The slight imbalance in the spectral intensities in graph 1100 is due to attenuation in the liquid light guide that collected the output light, as the liquid light guide has low transmittance for wavelengths above 730 nm.

[0057]

[0086] Figure 11B shows a graph 1150 of the spectrum from the spectral shaper system described in connection with Figure 11A, showing the output with all mirrors in the "on" state for the visible and / or NIR spectrum. The visible spectrum 1152 with all mirrors in the "on" state in the visible region of the modulator is shown by the short dashed line, and the NIR spectrum 1154 with all mirrors in the "on" state in the NIR region is shown by the long dashed line. The summed spectrum 1156 with all mirrors in the "on" state in both regions is also shown by the solid line. With all mirrors "on," the individual spectral components are not distinguishable, and the output exhibits a high count rate and a lower total wavelength range than the on-state low in graph 1100.

[0058]

[0087] 12A shows a graph 1200 of the spectrum from one embodiment of a spectral shaper system of the present teachings with mirror rows in the "on" state in the visible region. The graph is the result of using eight rows of five mirrors, each in the "on" state. The high resolution achieved by aberration-corrected imaging is indicated by the small FWHM.

[0059]

[0088] 12B shows a plot 1230 of the spectrum from one embodiment of a spectral shaper of the present teachings with the mirror row in the NIR region in the on state. The NIR peak has a broad FWHM.

[0060]

[0089] Figure 12C shows a graph 1250 of both the visible and NIR spectra of Figures 12A and 12B on the same plot. The comparison reveals lower throughput and a larger FWHM for NIR light. While the liquid light guide used for this Figure 12C measurement had low transmittance in the NIR region, extended transmission liquid light guides are available with transmittance greater than 70% across the entire near-infrared range. The throughput of the spectral shaping system can be improved by increasing the reflectivity of the imaging dispersion device, for example, by using a gold-coated reflective surface, which can achieve a 10% higher flux. Changes in aberration conditions can also change the slope of the individual lines in the NIR spectrum.

[0061]

[0090] 13A shows a graph 1300 of a spectrum from one embodiment of a spectral shaper system of the present teachings with five peaks in the NIR region using five rows of mirrors "on" in the NIR region. The sample peaks are at 716 nm, 754 nm, 791 nm, 835 nm, and 905 nm.

[0062]

[0091] FIG. 13B shows a graph 1350 of the spectrum of FIG. 13A with the addition of calculated FWHM information. The 716 nm peak has an FWHM of 13.72 nm. The 754 nm peak has an FWHM of 14.26 nm. The 791 nm peak has an FWHM of 14.46 nm. The 835 nm peak has an FWHM of 14.22 nm. The 905 nm peak has an FWHM of 13.21 nm. Therefore, the FWHMs are in the range of 13 nm to 14 nm.

[0063]

[0092] One feature of the present teachings is that both NIR and visible light can be generated by the same light source. The light source is constructed so that the visible light is provided at a plane coincident with the visible light input face of the spectral shaper, and the NIR light is provided at a plane coincident with the NIR input face of the spectral shaper described herein. One advantage of this embodiment is that using a single light source for both visible and near-infrared illumination reduces both complexity and cost. This single light source design makes it possible to provide a compact, NIR-extended programmable light source with a spectral shaping system.

[0064]

[0093] FIG. 14A shows a front view 1400 of a light source that generates visible light 1402 and NIR light 1404 from a broadband point source of light 1406. The broadband point source of light 1406 may be generated, for example, by the high-intensity plasma of a laser-pumped light source. A first elliptical mirror 1408 reflects the light from the point source 1406 and focuses it into a visible output 1410 light beam with a desired shape at a visible output surface 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 the light from the point source 1406 and focuses it into a NIR output 1418 light beam with a desired shape at a NIR output surface 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 are elliptical, which when coupled to a spectral shaper serves to balance and smooth the visible and NIR portions of the spectrum at the shaper output.

[0065]

[0094] Figure 14B shows a top view 1430 of the light source generating the visible light 1402 and NIR light 1404 of Figure 14A. The first elliptical mirror 1408, the second elliptical mirror 1416, the shortpass filter 1414 and the longpass filter 1422 are shown, as are the visible output surface 1412 and the NIR output surface 1420.

[0066]

[0095] Figure 14C shows a side top view 1450 of a light source generating visible light 1402 and NIR light 1404 (Figure 14A). A first elliptical mirror 1408, a second elliptical mirror 1416, a shortpass filter 1414, and a longpass filter 1422 are shown, as are a visible output surface 1412 and a NIR output surface 1420.

[0067]

[0096] In various embodiments, the relative flux from the visible and NIR illumination can be achieved based on the reflectivity of the various components used in the light source. For example, the flux levels for each visible and / or NIR channel can be nominally the same. It is also possible to increase the flux in either the visible or NIR region. For example, using a gold coating on a reflective surface can increase the reflected flux of infrared light. For example, a long-pass filter can flatten the spectral response of xenon and suppress its spectral peak in the near infrared. These two aspects can help improve the balance of the NIR portion of the spectrum, particularly compared to the visible portion of the light source output spectrum. 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.

[0068]

[0097] 15 shows a graph 1500 of the spectra of the output of various embodiments of light sources for the spectral shaper system of the present teachings, using various filter and / or mirror coatings on optical elements and a xenon-based high-intensity plasma to generate point source illumination. The first spectrum 1502 shows the output of the xenon plasma, which has a high peak in the near-infrared region. The second spectrum 1504 shows the reduction of the NIR peak using a long-pass xenon spectral-flattening filter with a cutoff wavelength of 740 nm.

[0069]

[0098] FIG. 16 shows an alignment and characterization system 1600 for a light source 1602 for a spectral shaper system of the present teachings. A light point source 1612 generates visible light 1604 at a visible output face 1606 and NIR light 1608 at a NIR output face 1610. The light point source 1612 for this embodiment is a high-intensity laser-pumped xenon plasma. The visible light 1604 at the visible output face 1606 and the NIR light 1608 at the NIR output face 1610 have nominally elliptical shapes. The visible light 1604 or NIR light 1608 is coupled into an alignment tool 1614, which includes an imaging fiber bundle 1616 and a 1× magnification lens pair 1618 that images the bundle onto a camera 1620. The position of either the visible or NIR light beam on the camera is used to adjust the respective elliptical mirror. As an example, if the optical point source 1612 has a plasma size between 80 and 240 micrometers, that plasma size is imaged by a three-factor ellipsoidal mirror to a size between 240 and 720 micrometers at the output faces 1606, 1608. Inset 1622 shows the point source generated by the optical fiber imaged onto a camera to illustrate the operation of the alignment tool 1614 in an ideal case.

[0070] [Equivalent]

[0099] While applicants' teachings have been described in connection with various embodiments, it is not intended that applicants' teachings be limited to such embodiments. Rather, applicants' teachings encompass various alternatives, modifications, and equivalents, which may be made therein without departing from the spirit and scope of the teachings, as will be appreciated by those skilled in the art.

Claims

1. a first light source that generates a first light beam that includes light occupying a first region of the optical spectrum, the first light beam being located at a first input plane; a second light source that generates a second light beam comprising light occupying a second region of the light spectrum, the second light beam located at a second input plane offset from the first input plane, the first region of the light spectrum being different from the second region of the light spectrum; an imaging-dispersive device disposed in a path of the first light beam and a path of the second light beam such that the offset between the first input plane and the second input plane introduces an aberration into the second light beam from the imaging-dispersive device, the imaging-dispersive device configured to angularly disperse wavelengths of the first and second light beams in a dispersion direction, to image the first light beam at a modulation plane to form an imaged first light beam, and to image the second light beam at the modulation plane to form an imaged second light beam; a pixelated spatial light modulator disposed on the modulation surface, the pixelated spatial light modulator comprising an array of pixels positioned to be illuminated by the angularly dispersed wavelengths of the imaged first light beam such that each column of illuminated pixels in the array of pixels is illuminated by a different spectral segment of light and the array of pixels is illuminated by the angularly dispersed wavelengths of the imaged second light beam, the aberration introduced into the second light beam from the imaging dispersion device causing a position of the imaged second light beam to be at a different position on the array of pixels than a position of the imaged first light beam; a toroidal optical system disposed in the path after the pixelated spatial light modulator, the toroidal optical system configured to collect and focus the first and second light beams onto an output surface, and to focus the angularly dispersed wavelengths of the first and second light beams such that the angularly dispersed wavelengths overlap at the output surface, the toroidal optical system projecting selected portions of the first and second light beams reflected by the pixelated spatial light modulator towards the toroidal optical system to generate an output light illumination at an output; a controller having an output electrically connected to a control input of the pixelated spatial light modulator, the controller configured to direct the pixelated spatial light modulator to reflect selected portions of the first and second light beams toward the toroidal optical system and to reflect other portions of the first and second light beams away from the toroidal optical system so as to form a desired spectral shape of the output light illumination; A spectrally shaped light source comprising:

2. 10. The spectrally shaped light source of claim 1, wherein at least one of the first and second light sources comprises a transforming optic that transforms a circular beam into a rectangular beam.

3. The spectrally shaped light source of claim 1 , wherein the first light beam forms a rectangular shape.

4. The spectrally shaped light source of claim 1 , wherein the first light beam forms a line shape.

5. The spectrally shaped light source of claim 1 , wherein the second light beam forms a point source shape.

6. 10. The spectrally shaped light source of claim 1, wherein the first region of the light spectrum is the visible region of the light spectrum and the second region of the light spectrum is the NIR region of the light spectrum.

7. The spectrally shaped light source of claim 1 , wherein the first light source and the second light source are the same light source.

8. The spectrally shaped light source of claim 7 , wherein the same light source is a broadband point source.

9. The spectrally shaped light source of claim 1 , wherein at least one of the first and second light sources comprises a laser pumped light source.

10. 2. The spectrally shaped light source of claim 1, wherein the position of the imaged second light beam is in the lower half of the array of pixels and the position of the imaged first light beam is in the upper half of the array of pixels.

Images