Abstract:
Apparatus and methods are disclosed for providing a desired spectral intensity profile from a broadband light source. The apparatus comprises separation means for separating light provided by the broadband light source into radiation having a continuum of wavelengths; a blocking element having a first side and a second side, the first side having a two-dimensional surface with a desired blocking contour configured thereon, the blocking element positioned relative to the separation means so as to receive the radiation separated into the continuum of wavelengths onto the first side thereof and allow a portion of the radiation to pass from the first side to the second side, wherein the portion of the radiation conforms to the desired blocking contour; and recombination means for recombining the portion of the radiation conforming to the desired blocking contour into the desired spectral intensity profile.

Description:
REFERENCE TO PENDING PRIOR PATENT APPLICATION 
   This patent application claims benefit of pending prior U.S. Provisional Patent Application Ser. No. 60/376,439, filed May 1, 2002 by David A. Morrison for METHOD AND APPARATUS FOR PRODUCING UNIQUE RADIATION SPECTRA, which patent application is hereby incorporated herein by reference. 

   FIELD OF THE INVENTION 
   This invention is related to optical light source apparatus and methods in general, and more particularly to apparatus and methods for providing unique radiation spectra. 
   BACKGROUND OF THE INVENTION 
   It has become apparent, particularly in the field of biological sciences, that there exists a need for radiation sources that can be customized so as to produce a spectrum possessing a set of desired characteristics. This need ranges from illuminating a sample for microscopic evaluation to producing a desired spectrum for the purpose of designed stimulation of cellular activity. 
   Although there are methods to produce bands of spectra using interference filters, or some variation of spectra separation as used in spectroscopes, these methods exhibit the common deficiency of only permitting contiguous bands of energy to reach the sample. Additionally, these methods are designed to produce discrete bands with sharp frequency cut-offs and eliminate all radiation outside of these bands. Some research or analytical applications require many of these expensive and fragile filters to conduct routine laboratory evaluations. 
   SUMMARY OF THE INVENTION 
   The fundamental concept of the invention is to use a broadband source of energy, separate it into a continuum of wavelengths, eliminate all or a portion of the radiation at any wavelength, and then recombine the remaining energy to be delivered to the sample or target, thereby creating a new spectrum possessing desired and advantageous characteristics. 
   An object of the invention is to provide apparatus for producing desired radiation spectra. 
   Another object of the present invention is to provide apparatus for producing desired radiation spectra, which are scalable to high powers. 
   And another object of the present invention is to provide apparatus for producing the desired radiation spectra in which the apparatus comprises relatively low-cost components. 
   A further object of the invention is to provide apparatus for producing desired radiation spectra used in conjunction with scientific devices for biological analysis. 
   A still further object is to provide apparatus for producing desired radiation spectra used in conjunction with devices for the entertainment industry. 
   Yet another object is to provide a method for producing desired radiation spectra. 
   Still another object is to provide a method for producing the desired radiation spectra in which low-cost components are used. 
   With the above and other objects in view, as will hereinafter appear, there is provided an apparatus for providing a desired spectral intensity profile from a broadband light source, the apparatus comprising: separation means for separating light provided by the broadband light source into radiation having a continuum of wavelengths; a blocking element having a first side and a second side, the first side having a two-dimensional surface with a desired blocking contour configured thereon, the blocking element positioned relative to the separation means so as to receive the radiation separated into the continuum of wavelengths onto the first side thereof and allow a portion of the radiation to pass within the desired blocking contour from the first side to the second side, wherein the portion of the radiation conforms to the desired blocking contour; and recombination means for recombining the portion of the radiation conforming to the desired blocking contour into the desired spectral intensity profile. 
   In accordance with a further feature of the invention there is provided a system for analysis of a specimen using a desired spectral intensity profile from a broadband source, the system comprising: apparatus for providing a desired spectral intensity profile from a broadband light source, the apparatus comprising: separation means for separating light provided by the broadband light source into radiation having a continuum of wavelengths; a blocking element having a first side and a second side, the first side having a two-dimensional surface with a desired blocking contour configured thereon, the blocking element positioned relative to the separation means so as to receive the radiation separated into the continuum of wavelengths onto the first side thereof and allow a portion of the radiation to pass within the desired blocking contour from the first side to the second side, wherein the portion of the radiation conforms to the desired blocking contour; and recombination means for recombining the portion of the radiation conforming to the desired blocking contour into the desired spectral intensity profile; and an optical illumination pathway having an input end and an output end, the input end configured to receive the radiation having the desired spectral intensity profile from the recombination means, and the output end being configured to provide the radiation having the desired spectral intensity profile to a microscope. 
   In accordance with a further feature of the invention there is provided a method for producing a desired spectral intensity profile from a broadband light source, the method comprising: separating light provided by the broadband light source into radiation having a continuum of wavelengths; blocking a portion of the radiation separated into the continuum of wavelengths so as to allow a remaining portion of the radiation to pass through a blocking element, wherein the remaining portion conforms to a desired blocking contour provided by the blocking element; and recombining the remaining portion of the radiation conforming to the desired blocking contour so as to create a desired spectral intensity profile. 
   The above and other features of the invention, including various novel details of construction and combinations of parts and method steps will now be more particularly described with reference to the accompanying drawings and pointed out in the claims. It will be understood that the particular devices and method steps embodying the invention are shown by way of illustration only and not as limitations of the invention. The principles and features of this invention may be employed in various and numerous embodiments without departing from the scope of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects and features of the present invention will be more fully disclosed or rendered obvious by the following detailed description of the preferred embodiments of the invention, which are to be considered together with the accompanying drawings wherein like numbers refer to like parts, and further wherein: 
       FIG. 1  is a schematic view of one form of a spectral profiling device, illustrative of a preferred embodiment of the invention; 
       FIG. 2  is a schematic view of another form of a spectral profiling device receiving direct radiation from a broadband light source and providing direct coupling to an optical illumination pathway; 
       FIG. 3  is a schematic view of a spectral profiling device comprising a 2D transmissive light-valve array; 
       FIG. 4  is a schematic view of a spectral profiling device for stage and studio lighting; 
       FIG. 5  is a schematic view of a selectively positionable web having a plurality of selectable blocking elements thereon; and 
       FIG. 6  is a diagrammatic illustration of a flow chart illustrating combinations of components used in preferred embodiments of the present invention; 
       FIG. 7  is a schematic view of a single element LED light source; and 
       FIG. 8  is a schematic view of a blocking element supply carousel. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring to  FIG. 1 , and in a preferred embodiment of the present invention, there is shown a spectral profiling device  5  for producing various desired spectra  10  from broadband light  15 . Spectral profiling device  5  includes a lens assembly  20 , a transmissive holographic grating  25 , a blocking element  30 , a toroidal mirror  35  arranged in series with respect to one another. Spectral profiling device  5  is configured to receive broadband light from an input fiber optic bundle  40  and to provide a desired spectral intensity profile  10  to an output fiber optic bundle  45 . In turn, output fiber optic bundle  45  is used to produce illumination for a given device. This given device may include, for example, a sample stage of a microscope (not shown). 
   In an alternative preferred embodiment of the present invention, a ruled reflective grating or a ruled transmissive grating is used in spectral profiling device  5  in place of transmissive holographic grating  25 . 
   The energy exiting fiber optic bundle  40  is collimated by lens assembly  20  and then projected onto transmissive holographic grating  25 . The energy transmitted by transmissive holographic grating  25  is then diffracted to produce a rectangularly shaped continuum of color  50  such as from red to violet, which illuminates blocking element  30 . 
   Still referring to  FIG. 1 , and in a preferred embodiment of the present invention, blocking element  30  comprises an opaque material and is configured to provide a desired contour  55 . Preferably, blocking element  30  comprises a thin metal sheet which is cut by a precision laser cutting system. A precisely placed reference detent  60  in blocking element  30  provides the correct correlation of and blocking element  30  and rectangular shaped continuum of color  50  with respect to one another. Reference detent  60  is configured to correspond with a holder (not shown). Blocking element  30  and its holder (not shown) are designed with adequate width and height to prevent any sidebands, secondary orders from the diffraction grating, or stray light to enter the optical path. 
   The energy allowed to pass blocking element  30  has a given spectral intensity profile  65 . Spectral intensity profile  65  then strikes toroidal mirror  35 . Toroidal mirror  35  acts to bring spectral intensity profile  65  to the correct scale so as to produce desired spectral intensity profile  10 . Toroidal mirror  35  also acts to reposition desired spectral intensity profile  10  into an input end of output fiber optic bundle  45 . Desired spectral intensity profile  10  is delivered through output fiber optic bundle  45  to a microscope (not shown). 
   In a preferred embodiment of the present invention, input fiber optic bundle  40 , lens assembly  20 , transmissive holographic grating  25 , toroidal mirror  35 , and output fiber optic bundle  45  are all aligned and permanently mounted with respect to one another so as to form a robust design of spectral profiling device  5 . 
   Referring still to  FIG. 1 , and in a preferred embodiment of the present invention, spectral profiling device  5  may comprise commercially available components. Fiber optic bundle  45  may be selected from components sold by Dolan-Jenner Inc. of Haverhill, Mass. Fiber optic bundle  40  is typically used to produce illumination for the sample stage of a microscope, such as those sold by Carl Zeiss of Thornwood, N.Y. Lens transmissive holographic grating  25  may also be selected from commercially available components supplied by Holographix LLC, of Hudson, Mass. Desired contour  55  of blocking element  30  may be cut by a precision laser cutting system sold by Alase Technologies of Pepperell, Mass. Toroidal mirror  35  may also be selected from commercially available components, such as those sold by ARW Optical of Wilmington, N.C. Output fiber optic bundle  45  may be selected from commercially available components, such as those sold by Edmund Scientific of Barrington, N.J. With these commercially available components, and other components fabricated at low cost, spectral profiling device  5  provides a relatively low-cost system to create desired spectral intensity profile  10 . 
   For biological cellular analysis, broadband source  15  is provided by a flexible fiber optic illuminator optically coupled onto an optical microscope. The output of the fiber optic illuminator is removed from the microscope and collimated by lens assembly  20  and then dispersed by transmissive holographic grating  25  into a pseudo-rectangular shape as required for the blocking element as previously described. 
   The energy that is passed by the blocking element is reformed by a toroidal mirror, and projected onto the input end of a fiber bundle as originally used to carry the light to the microscope. The output end of the fiber bundle is constructed to the same physical requirements as the original bundle, and therefore simply inserted as a replacement source, but now with an infinitely modifiable spectrum. 
   Referring now to  FIG. 2 , and in a preferred embodiment of the present invention, there is shown a direct radiation and direct coupling spectral profiling device  70  for producing various desired spectra from a direct radiation source  75 , which in turn is directly coupled with a beam homogenizer  78  at an input port of an optical illumination pathway  80  of a microscope (not shown). Broadband white-light source  75  is positioned in a parabolic reflector  85  so as to project a reasonably collimated beam of energy  90 . Projected collimated beam  90  passes through a toroidal transmissive holographic grating  95  so as to produce a diffracted rectangularly shaped continuum of color  100 , which is preferably from red to violet. Blocking element  30  is positioned between toroidal transmissive holographic grating  95  and optical illumination pathway  80  so as to intercept a portion of continuum of color  100 . 
   Still referring to  FIG. 2 , and in a preferred embodiment of the present invention, blocking element  30  comprises an opaque material and is configured to provide a desired contour  55 . Preferably, blocking element  30  comprises a thin metal sheet which is cut to comprise desired contour  55  by a precision laser cutting system. A precisely placed reference detent  60  in blocking element  30  provides the correct correlation of blocking element  30  and continuum  100  with respect to one another when blocking element  30  is mounted in its holder (not shown). Blocking element  30  and its holder (not shown) are designed to provide adequate width and height so as to prevent any sidebands and/or secondary orders from the diffraction grating, or any stray light from entering the optical path. 
   The energy that is allowed to pass blocking element  30  has a given spectral intensity profile  105 . The optical power of the toroidal diffraction grating  95  progressively reduces given spectral intensity profile  105  until the scale is reduced to a desired spectral intensity profile  110  so as to enter beam homogenizer  78  at the input port of the microscope&#39;s illumination optical pathway  80 . 
   Referring still to  FIG. 2 , and in a preferred embodiment of the present invention, direct radiation and direct coupling spectral profiling device  70  may comprise commercially available components. Broadband white-light source  75  and parabolic reflector  85  may be selected from those sold by Oriel Corporation of Stratford, Conn. Toroidal transmissive holographic grating  95  may also be selected from those manufactured by JobinYvon of Edison, N.J. With these commercially available components, other fabricated components at low cost, direct radiation and direct coupling spectral profiling device  70  is a relatively low-cost system to create desired spectral intensity profile  110 . 
   Referring now to  FIG. 3 , and in a preferred embodiment of the present invention, there is shown a direct radiation and fiber optic coupling spectral profiling device  115  for producing from a direct radiation source  120  various desired spectra, which are coupled through a fiber optic coupling  125  to a microscope. Broadband white-light source  120  is positioned in a parabolic reflector  130  so as to project a reasonably collimated beam of energy  135 . Projected collimated beam  135  then passes through a transmissive holographic grating  140  so as to produce a diffracted, rectangularly shaped continuum of color  145 , which preferably ranges from red to violet. The continuum  145  is then intercepted by a blocking element  150 . Blocking element  150  comprises a 2-D transmissive light-valve array  155 . 2-D transmissive light-valve array  155  comprises hundreds of addressable cells positioned in an orthogonal arrangement. By computer control, or through the operation of an array controller, pre-selected combinations of the addressable cells are selectively transmissive. This pre-selected combination of cells then creates a spectral intensity profile  160 , which passes therethrough to toroidal mirror  165 . Toroidal mirror  165  acts to bring spectral intensity profile  160  to the correct scale and to illuminate the input end of the fiber optic bundle  125 . A desired spectral intensity profile  170  is provided through fiber optic bundle  125  to a microscope (not shown). 
   Referring still to  FIG. 3 , and in a preferred embodiment of the present invention, direct radiation and fiber optic coupling spectral profiling device  115  may comprise commercially available components. Broadband white-light source  120  and parabolic reflector  130  may be selected from those sold by Oriel Corporation of Stratford, Conn. Transmissive holographic grating  140  may also be selected from those manufactured by Holographix LLC, of Hudson, Mass. Blocking element  150 , which comprises 2-D transmissive light-valve array  155  may be obtained from CRI Incorporated of Woburn, Mass. Toroidal mirror  165  may be selected from those sold by ARW Optical Company of Wilmington, N.C. Fiber optic bundle  125  may be selected from those manufactured by Edmund Scientific of Barrington, N.J. With these commercially available components and other low-cost fabricated components, direct radiation and fiber optic coupling spectral profiling device  115  is a relatively low-cost system for creating desired spectral intensity profile  170 . 
   Referring now to  FIG. 4 , and in a preferred embodiment of the present invention, there is shown a stage and studio lighting spectral profiling device  175  for producing from a direct radiation source  180  various desired spectra, which in turn are coupled to a studio lighting lens  185 . A high-power broadband white-light source  190  is positioned in a parabolic cold mirrored reflector  195  so as to project a reasonably collimated beam of energy  200 . Projected collimated beam of energy  200  then passes through transmissive holographic grating  205  so as to produce a diffracted, rectangularly shaped continuum of color  210 , which preferably ranges from red to violet. 
   Blocking element  30  is configured to intercept continuum  210 . Blocking element  30  comprises an opaque material and is configured to provide a desired contour  55 . Preferably, blocking element  30  comprises a thin sheet of metal which is cut by a precision laser cutting system to create desired contour  55 . Blocking element  30  further comprises a high reflectivity coating and is mounted at an angle with respect to the path of projected collimated beam  200  so as to reflect unwanted spectral energy into a light trap  215 . Light trap  215  provides an area where the unwanted energy can be diffused and dissipated. A precisely placed detent  60  provides the correct correlation of blocking element  30  and continuum  210  with respect to one another when blocking element  30  is mounted in its holder (not shown). 
   Energy that is allowed to pass by blocking element  30  has a desired spectral intensity profile  220 . Lens  225  directs the light of desired spectral intensity profile  220  through a light shaping diffuser  230  so as to produce slightly diffused spectra  235 . Light shaping diffuser  230  is a highly transmissive element which is configured to project slightly diffused spectra  235  project to lens  185 . Preferably, lens  185  is a long focal length lens typically used in studio lighting designs so as to project the integrated color of spectra  235  to a stage area of interest  240 . 
   Referring still to  FIG. 4  and in a preferred embodiment of the present invention stage and studio lighting spectral profiling device  175  may comprise commercially available components. High-power broadband white-light source  190  may be selected from those sold by Luxtel of Danvers, Mass. Parabolic cold mirrored reflector  195  may be selected from those sold by Opti-Forms Inc. of Temecula, Calif. Transmissive holographic grating  205  may be selected from those sold by Holographix LLC of Hudson, Mass. Blocking element  30  is preferably cut to desired contour  55  by a precision laser cutting system sold by Alase Technologies of Pepperell, Mass. Lens  185  and lens  225  may be selected from components sold by Edmund Scientific of Barrington, N.J. Light shaping diffuser  230  can be obtained from Physical Optics Corporation of Torrance, Calif. With these commercially available components, and other components fabricated at low cost, stage and studio lighting spectral profiling device  175  is a relatively low-cost system for creating slightly diffused spectra  235 . 
   Looking now at  FIG. 5 , and in a preferred embodiment of the present invention, there is shown a carrier device  250  having a supply roll  255  and a take-up roll  260  with a web of material  265  being supported therebetween for selectively providing storage and access to a plurality of blocking elements  270 A– 270 D. Preferably, carrier device  250  is used in conjunction with a protective enclosure and configured with one of the spectral profiling devices described herein, such as a spectral profiling. Preferably, material  265  comprises continuous web of opaquely coated polyester with a perforated edge  275  so as to provide transport and positioning when placed into the enclosure. A set of fiducial marks  280  placed in or on web  265 , are created at the same time as the contour on blocking elements  270 A– 270 D so as to provide accurate positioning. The transport and positioning can be manual or automatically selected. Blocking elements  270 A– 270 D are created by selectively removing the opaque material by processing, etching, or ablating to obtain the desired contours. 
   Referring to  FIG. 6 , there is shown a block diagram  285  identifies a series of steps for producing desired radiation spectra using preferred embodiments of the present invention. Block  290  identifies a preferred group of broadband energy sources. Block  295  identifies a preferred group of input optics. Block  300  identifies a group of preferred wavelength separation devices. Block  305  identifies a group of preferred blocking methods. Block  310  identifies recombining optics used in a final step. 
   In another embodiment of the present invention (not shown), for laboratory microscope illumination, a quartz tungsten halogen lamp is used as a broadband visible ‘white light’ source. The output beam of the lamp is passed through a lens to produce a reasonably collimated source of radiation. The collimated beam is then passed through an equilateral prism to produce a separation of the ‘white light’ into a continuum of color, representing the spectral content of the white light source. A second lens is used, either before or after the prism so as to shape the color spectrum into a rectangle of uniform intensity and spectrally separated energy. Preferably, the rectangle of energy comprises a wavelength axis having a greater length than the intensity axis so as to provide adequate wavelength discrimination by the blocking element used further along in the optical path. This projected rectangle of energy is then intercepted by a blocking element. The blocking element, in its simplest form, is a rectangle of thin metal, dimensionally similar to the rectangle of projected energy. The blocking element is configurable for accurate, repeatable placement. The blocking element is specifically contoured, such as required for fluorescence microscopy, to eliminate predetermined amounts of spectral intensity across the entire desired wavelength band. The contour also permits and acts to correct any intensity variations in the source. The spectral intensity allowed to pass the blocking element passes through one or more additional lenses so as to alter its cross-sectional shape prior to illumination of a microscope. Preferably, the lamp position, prism, lenses along the optical path, and the blocking element are mechanically positioned for a compact robust design. 
   A low-cost narrow band filter is assembled onto a blocking element having a known pass-band and is provided for validating the correct wavelength relationship of the blocking element and the spectrum produced by the prism. Using this arrangement, energy is only transmitted when the position of the blocking element is correctly aligned with the spectrum produced by the prism. This embodiment performs a function similar to individual interference filters at approximately 1/10 the cost. Also, due to the infinite number of contours possible, the ability to pass 100% of the incident energy at any wavelength, totally eliminate side-bands, and simultaneously provide discrete bands of separated energy from one source is possible. This embodiment is able to outperform interference filters in most design requirements. In addition, these advantages are even more valuable in the UV spectrum, where interference filters suffer from low throughput. 
   In another preferred embodiment of the present invention (not shown), a broadband source as described herein, is collimated, and then formed into a rectangle of ‘white light’, which is then used to uniformly radiate a ‘linear variable filter’ (continuous interference filter). This is a filter that provides a spectral continuum by continuously varying the internal design elements along one axis, thereby passing specific wavelengths along that axis, while blocking all other wavelengths. 
   The other axis is an axis of uniform transmittance. A blocking element as described herein is juxtapositioned in front of or behind the filter so as to provide the preferred spectral intensity modification. The transmitted energy is then optically collected and shaped into the required dimensions to become the input beam to a microscope. As above, the mechanics of construction are designed for stable and robust operation. 
   Referring now at  FIG. 7 , and in a preferred embodiment of the present invention, there is shown a broadband LED  400 , used to illuminate the input ends of a multi-fiber optical assembly  40 . Alternatively, a series of less broad LEDs are used to illuminate the input ends of a multi-fiber optical assembly. The fibers are optically mixed and formed into a bundle. The output of the bundle is then collimated and used to illuminate a prism or diffraction grating as described above. The energy is formed into a rectangle and projected onto a light valve array. As described herein above, the energy that is passed through the array is optically collected and directed to the sample or target. 
   Referring now to  FIG. 8 , and in a preferred embodiment of the present invention, there are shown mechanical blocking elements  30  configured for selective use from a storage carousel  500  or an equivalent structure. In a preferred embodiment of the present invention, a computer or controller is used for remote selection and use of mechanical blocking elements  30 . 
   Additionally, in a preferred embodiment of the present invention (not shown), mechanical blocking elements may be configured for selective use from a storage carousel or an equivalent structure. In a preferred embodiment of the present invention, a computer or controller is used for remote selection and use of the mechanical blocking elements. 
   In is further envisioned that other combinations of the above elements may be made practical for other applications throughout the UV-Visible-IR range. Additionally, portions of the spectrum may be optically magnified to produce more critical embodiments, or the lamps themselves may only output over a limited range of the spectrum. However, the fundamental concept of the invention of using a broadband source of energy, separating it into a continuum of wavelengths, eliminating, all of, or some lesser portion of, the radiation at any wavelength, and then recombining the remaining energy for delivery to the sample or target is consistent with each of the preferred embodiments of the present invention.