Abstract:
A multi field of view hyperspectral imaging device and method for using the same which can be used in many applications including short wavelength infrared (SWIR) and long-wavelength infrared (LWIR) applications are presented herein. In one embodiment, the multi field of view hyperspectral imaging device comprises multiple fore optics, multiple fold mirrors, a slit including a multiple openings, a spectrometer, and a 2-dimensional detector.

Description:
PRIORITY 
     This application claims the benefit of priority under 35 U.S.C. §119 of U.S. Provisional Application Ser. No. 61/471,393 filed on Apr. 4, 2011 the content of which is relied upon and incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present invention relates to the hyperspectral imaging field and, in particular, to a multi field of view hyperspectral imaging device and method for using the multi field of view hyperspectral imaging device. 
     BACKGROUND 
     A spectrometer is a device which receives a light signal as an input and produces as an output a light signal which is spread out in space according to the different wavelength components, or colors, of the input light signal. A detector attached to the spectrometer analyzes the output signal, called the spectrum, to quantify the amount of each wavelength component which is present in the input signal. One specific type of spectrometer is known as an Offner spectrometer which can be used to produce images of a remote object over a contiguous range of narrow spectral bands. This type of imaging is known as hyperspectral imaging and has recently emerged as an important part of the military/aerospace solution to airborne and spaceborne reconnaissance and remote sensing. Basically, the hyperspectral imaging system utilizes an Offner spectrometer and an advanced data processing technology to produce imagery with embedded spectral signature data. This signature data is useful in a wide-variety of applications such as target designation/recognition, missile plume identification and mine detection (for example). In addition, the hyperspectral imaging system can be used in a wide-variety of commercial applications such as cancer detection, environmental monitoring, agricultural monitoring and mineral exploration. An exemplary conventional hyperspectral imaging system which incorporates an Offner spectrometer is discussed below with respect to  FIGS. 1A-1B  (PRIOR ART). 
     Referring to  FIGS. 1A-1B  (PRIOR ART), there are shown two perspective views of an exemplary conventional hyperspectral imaging system  100  which incorporates an Offner spectrometer  102 . The hyperspectral imaging system  100  includes a first housing  104  which is positioned next to and attached to a second housing  106  (see  FIG. 1A ). The first housing  104  encloses and protects a single fore optic  108 , a slit  110  (with a single opening  111 ), and a 2-dimensional detector  112 . The second housing  106  encloses and protects the Offner spectrometer  102  (see  FIG. 1B ). In this example, the Offner spectrometer  102  is a one-to-one optical relay which includes an entrance opening  114  (can be same as or adjacent to slit&#39;s opening  111 ), a first mirror  116 , a diffraction grating  118 , a second mirror  120  and an exit opening  121  (positioned next to the 2-dimensional detector  112 ). It should be appreciated that for clarity the description provided about the conventional hyperspectral imaging system  100  omits certain details and components which are well known in the industry and are not necessary to explain and understand the present invention. 
     The conventional hyperspectral imaging system  100  operates to produce images of a remote object  105  over a contiguous range of narrow spectral bands when the fore optic  108  receives a beam  107  from the remote object  105  and directs the beam  107  to the slit&#39;s single opening  111  which outputs a trimmed beam  122  (slice of the image) to the Offner spectrometer  102  which diffracts the trimmed beam  122  and forwards the diffracted beam  124  to the detector  112  (see  FIGS. 1A and 1B ). In particular, the slit&#39;s single opening  111  outputs the trimmed beam  122  which passes through the entrance opening  114  (if present) and is received at the first mirror  116  (spherical mirror  116 ) which reflects the trimmed beam  122  towards the diffraction grating  118 . The diffraction grating  118  receives the trimmed beam  122  and diffracts and reflects the diffracted beam  124  to the second mirror  120  (spherical mirror  120 ). The second mirror  120  receives the diffracted beam  124  and reflects the diffracted beam  124  through the exit opening  121  to the detector  112 . The detector  112  (e.g., two dimensional focal plane array (FPA)  112 ) receives and processes the diffracted beam  124  which passed through the spectrometer&#39;s exit opening  121 . 
     This type of hyperspectral imaging system  100  generally works well in most applications however in the short wave infrared (SWIR) wavelength band (0.75-2.5 μm) and the long-wavelength infrared (LWIR) wavelength band (7-15 μm) the current commercially available detector  112  has a limited number of pixels which can be used to image when compared to the commercially available detectors associated with the visible wavelength band. In particular, the current commercially available detector  112  has a limited number of pixels that can be used to image the remote object  105  in a two dimensional focal plane which is composed of a spatial direction and a spectral direction. Thus, to improve the spatial field coverage at a particular resolution, multiple conventional hyperspectral imaging systems  100   a ,  100   b  . . .  100   n  are currently located side-by-side such that the “linear field of view” of each conventional hyperspectral imaging system  100   a ,  100   b  . . .  100   n  are aligned end-to-end with one another to image the remote object  105  (not shown) at a particular resolution as shown in  FIG. 2  (PRIOR ART). This solution is prohibitive for many applications including the SWIR and LWIR applications due to the space, weight, power constraints, and costs of the multiple detectors (which are very expensive), coolers, spectrometers etc. 
     SUMMARY 
     A multi field of view hyperspectral imaging device and a method for using the same which overcomes the shortcomings of the prior art and which can be used in many applications including the SWIR and LWIR applications are described in the independent claims of the present application. Advantageous embodiments of the multi field of view hyperspectral imaging device and the method for using the same are described in the dependent claims. 
     In one aspect, the present invention provides a multi field of view hyperspectral imaging device for imaging a remote object. The multi field of view hyperspectral imaging device comprises: (a) a first fore optic that receives a first image from a first portion of the remote object; (b) a second fore optic that receives a second image from a second portion of the remote object; (c) a first fold mirror; (d) a second fold mirror; (e) a slit including a first opening and a second opening, wherein the first fore optic is associated with the first fold mirror which receives the first image from the first fore optic and directs the first image to the first opening which outputs a trimmed first image, and wherein the second fore optic is associated with the second fold mirror which receives the second image from the second fore optic and directs the second image to the second opening which outputs a trimmed second image; (f) a spectrometer positioned to receive the trimmed first image from the first opening and output a diffracted first image and to receive the trimmed second image from the second opening and output a diffracted second image; and (g) a 2-dimensional detector positioned to receive the diffracted first image and the diffracted second image at a final focal plane from the spectrometer and then output a 2-dimensional image of the diffracted first image and the diffracted second image. 
     In another aspect, the present invention provides a method for using a multi field of view hyperspectral imaging device to image a remote object. The method comprising the steps of: (a) providing the multi field of view hyperspectral imaging device which comprises: (i) a first fore optic that receives a first image from a first portion of the remote object; (ii) a second fore optic that receives a second image from a second portion of the remote object; (iii) a first fold mirror; (iv) a second fold mirror; (v) a slit including a first opening and a second opening, wherein the first fore optic is associated with the first fold mirror which receives the first image from the first fore optic and directs the first image to the first opening which outputs a trimmed first image, and wherein the second fore optic is associated with the second fold mirror which receives the second image from the second fore optic and directs the second image to the second opening which outputs a trimmed second image; (vi) a spectrometer positioned to receive the trimmed first image from the first opening and output a diffracted first image and to receive the trimmed second image from the second opening and output a diffracted second image; and (vii) a 2-dimensional detector positioned to receive the diffracted first image and the diffracted second image at a final focal plane from the spectrometer and then output a 2-dimensional image of the diffracted first image and the diffracted second image; and (b) controlling the first fore optic and the second fore optic to obtain the 2-dimensional image of the diffracted first image and the diffracted second image. 
     Additional aspects of the invention will be set forth, in part, in the detailed description, figures and any claims which follow, and in part will be derived from the detailed description, or can be learned by practice of the invention. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as disclosed. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       A more complete understanding of the present invention may be had by reference to the following detailed description when taken in conjunction with the accompanying drawings wherein: 
         FIGS. 1A-1B  (PRIOR ART) illustrate an exemplary conventional hyperspectral imaging system for imaging a remote object at a low resolution in SWIR and LWIR applications; 
         FIG. 2  (PRIOR ART) illustrates multiple conventional hyperspectral imaging systems located side-by-side such that the “linear field of view” of each conventional hyperspectral imaging system is aligned end-to-end with one another to image a remote object at a high resolution in SWIR and LWIR application; 
         FIGS. 3A-3C  illustrate an exemplary multi field of view hyperspectral imaging system for imaging a remote object in accordance with an embodiment of the present invention; 
         FIG. 3D  illustrates an exemplary multi field of view hyperspectral imaging system similar to the one shown in  FIGS. 3A-3C  but also incorporating a shutter, a fixed pick-off mirror (associated with a first fore optic), and a moveable steering mirror (associated with a second fore optic) in accordance with an embodiment of the present invention; 
         FIGS. 4A-4E  are diagrams of an exemplary slit that can be incorporated within the multi field of view hyperspectral imaging systems shown in  FIGS. 3A-3D  in accordance with an embodiment of the present invention; 
         FIG. 5  illustrates another exemplary slit that can be incorporated within the multi field of view hyperspectral imaging systems shown in  FIGS. 3A-3D  in accordance with an embodiment of the present invention; and 
         FIG. 6  illustrates another exemplary multi field of view hyperspectral imaging system for imaging one or more remote objects in accordance with another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 3A-3C , there are shown three perspective views of an exemplary multi field of view hyperspectral imaging system  300  for imaging a remote object  305  in accordance with an embodiment of the present invention. The hyperspectral imaging system  300  includes a first housing  304  which is positioned next to and attached to a second housing  306  (see  FIG. 3A ). The first housing  304  encloses and protects a first fore optic  308 , a second fore optic  310 , a first fold mirror  312 , a second fold mirror  314 , a slit  316  (which includes a first opening  318  and a second opening  320 ), and a 2-dimensional detector  322  (see  FIGS. 3B-3C ). The second housing  306  encloses and protects a spectrometer  302  (e.g., Offner spectrometer  302  (shown), Dyson spectrometer  302 ) (see  FIGS. 3B-3C ). In this example, the spectrometer  302  is a one-to-one optical relay including an entrance opening  324  (can be same as or adjacent to slit&#39;s openings  318  and  320 ), a first mirror  326 , a diffraction grating  328 , a second mirror  330  and an exit opening  332  (positioned next to the 2-dimensional detector  322 ). The hyperspectral imaging system  300  may include a controller  323  which controls the operation of several components including the first fore optic  308 , the second fore optic  310 , and the 2-dimensional detector  322 . It should be appreciated that for clarity the description provided about the hyperspectral imaging system  300  omits certain details and components which are well known in the industry and are not necessary to explain and understand the present invention. 
     The hyperspectral imaging system  300  operates to produce images of the remote object  305  over a contiguous range of narrow spectral bands when the first fore optic  308  receives a first image  307  (e.g., first beams  307 ) associated with a first portion  309  of the remote object  305  and the second fore optic  310  receives a second image  311  (e.g., second beams  311 ) associated with a second portion  313  of the remote object  305  (see  FIG. 3A ). The first fold mirror  312  receives the first image  307  from the first fore optic  308  and directs the first image  307  to the slit&#39;s first opening  318  which outputs a trimmed first image  334  (slice of the first image) (see  FIGS. 3B-3C ). The second fold mirror  314  receives the second image  311  from the second fore optic  310  and directs the second image  311  to the slit&#39;s second opening  320  which outputs a trimmed second image  336  (slice of the second image) (see  FIGS. 3B-3C ). The first and second fold mirrors  312  and  314  would be adjusted to align the two fields of view to one another prior to directing the first and second images  307  and  311  to the slit&#39;s openings  318  and  320 . 
     The spectrometer  302  is positioned to receive the trimmed first and second images  334  and  336  from the slit&#39;s first and second openings  318  and  320  and output diffracted first and second images  338  and  340  to the 2-dimensional detector  322 . In particular, the slit&#39;s first and second openings  318  and  320  output the trimmed first and second images  334  and  336  which pass through the entrance opening  324  (if present) to the first mirror  326  (spherical mirror  326 ) which reflects the trimmed first and second images  334  and  336  towards the diffraction grating  328 . The diffraction grating  328  receives the trimmed first and second images  334  and  336  reflected from the first mirror  326  and outputs the diffracted first and second images  338  and  340  to the second mirror  330  (spherical mirror  330 ). The second mirror  330  receives the diffracted first and second images  338  and  340  from the diffraction grating  328  and reflects the diffracted first and second images  338  and  340  through the exit opening  332  to the 2-dimensional detector  322 . The 2-dimensional detector  322  (e.g., 2-dimensional FPA  322 ) is positioned to receive the diffracted first image  338  and the diffracted second image  340  at a final focal plane  341  and then output a 2-dimensional image of the diffracted first image  338  and the diffracted second image  340  (e.g., see  FIGS. 3C and 4E ). 
     In one set-up of the hyperspectral imaging system  300 , the first fore optic  308  and the second fore optic  310  have different magnifications with respect to one another. For example, the first fore optic  308  can have a wide field of view and the second fore optic  310  can have a narrow field of view both of which are imaged onto the 2-dimensional detector  322 . Plus, the first fore optic  308  may have positioned in front thereof a fixed pick-off mirror  342  and the second fore optic  310  may have positioned in front thereof a fast moveable steering mirror  344  (see  FIG. 3D ). This particular set-up can be used such that the wider field of view image “leads” in a time domain, to look for a specific spectral signature. If an area of interest is found, then the fast moveable steering mirror  344  can position the narrow field of view image to the area of interest. In an application like this, one or more shutters  346  can also be incorporated to further improve the signal-to-noise ratio in the image, by activating only one field of view at a time from either the first fore optic  308  or the second fore optic  310  (see  FIG. 3D ). In this example, one shutter  346  is shown located behind the slit  316  and moveable to cover anyone of the slit&#39;s openings  318  and  320 . The controller  323  would control the movement of the fast moveable steering mirror  344  and the shutter  346 . It should be appreciated that for clarity the description and drawing provided omit certain details about components used to support the fixed pick-off mirror  342 , the fast moveable steering mirror  344 , and the shutter  346 . 
     In another set-up of the hyperspectral imaging system  300 , the first fore optic  308  and the second fore optic  310  have the same magnifications. This particular set-up can be used such that one field of view (associated with the first fore optic  308 ) can be staggered in a time domain with respect to the other field of view (associated with the second fore optic  310 ) to implement various “scene change” applications. For example, one scene change application can involve tracking of certain vehicles 
     Referring to  FIGS. 4A-4E , there are several diagrams of an exemplary slit  316  that can be incorporated within the multi field of view hyperspectral imaging system  300  in accordance with an embodiment of the present invention. In  FIGS. 4A-4B , there are respectively shown front and back perspective views of the slit  316  which includes a substrate  402  within which there is extending there through the first opening  318  and the second opening  320 . In one example, the slit  316  is made from a diamond machinable substrate  402  (e.g., cooper, nickel, aluminum, silicon, germanium, gold, calcium fluoride) having a first side  404  which has a portion  406  removed therefrom by a diamond ball nose milling process (for example) to define the length of a slit aperture  408  (see  FIG. 4A ). The diamond machinable substrate  402  also has a second side  410  which has two portions  412  and  414  removed therefrom by a diamond fly-cutting process (for example) to form two grooves  416  and  418  which breaks through to the first side  404  to form the two openings  318  and  320  (see  FIG. 4B ). These and other machining techniques permit the manufacturing of the slit  316  in a common substrate to sub-micron tolerances. These machining techniques will also be an advantage in manufacturing the slit&#39;s openings  318  and  320  so they are precisely aligned to optimize the performance of the spectrometer  302  which requires precise alignment between the slit  316 , the diffraction grating  328 , and the 2-dimensional detector  322  (e.g., less than 1/10 of a pixel at the 2-dimensional detector  322 ).  FIGS. 4C-4D  respectively illustrate a photograph of an exemplary monolithic knife edge dual slit  316  and a diagram of a computer screen  425  illustrating a  400   x  image of a portion of the exemplary monolithic knife edge dual slit  316 . 
     The exemplary slit  316  has two openings  318  and  320  which are separated from one another by more than a diffracted field at the spectrometer&#39;s final focal plane  341  (assuming a one-to-one optical relay spectrometer  302 ) (see  FIG. 4E ). In particular, the slit&#39;s first and second openings  318  and  320  each output trimmed images  334  and  336  which are separated from one another by the spectral band of interest so that the diffracted first and second images  338  and  340  are separated from one another when imaged on the final focal plane  341  at the 2-dimensional detector  322  (see  FIG. 4E ). Furthermore, the diffraction grating  328  can be configured with a diffraction efficiency that prevents an overlap of the diffracted first image  338  and the diffracted second image  340 . In addition, the 2-dimensional detector  322  can incorporate band pass filters, order sorting filters, or other techniques to prevent the overlap of the adjacent diffracted first image  338  and the diffracted second image  340 . 
     Referring to  FIG. 5 , there is a diagram of a computer screen  500  illustrating a portion of another exemplary slit  316 ′ that can be incorporated within the multi field of view hyperspectral imaging system  300  in accordance with an embodiment of the present invention. The exemplary slit  316 ′ is the same as the aforementioned slit  316  except that the slit  316 ′ has two openings  318 ′ and  320 ′ with different widths where the first opening  318 ′ is wider than the second opening  320 ′. In this example, the first opening  318 ′ has a width  322 ′ of 40 μm and the second opening  320 ′ has a width  324 ′ of 10 μm while both openings  318 ′ and  320 ′ are 11 mm long. The exemplary slit&#39;s two openings  318 ′ and  320 ′ are separated from one another by more than a diffracted field at the spectrometer&#39;s final focal plane  341  (assuming a one-to-one optical relay spectrometer  302 ). In particular, the slit&#39;s first and second openings  318 ′ and  320 ′ each output trimmed images  334  and  336  which are separated from one another by the spectral band of interest so that the diffracted first and second images  338  and  340  are separated from one another when imaged on the final focal plane  341  at the 2-dimensional detector  322  (e.g., see  FIG. 4E ). Alternatively, the aforementioned slit&#39;s  316  and  316 ′ could have more than two openings. In this case, the multi field of view hyperspectral imaging system  300  would have more than two fore optics and more than two fold mirrors an example of which is discussed below with respect to  FIG. 6 . 
     Referring to  FIG. 6 , there is a diagram of another exemplary multi field of view hyperspectral imaging system  600  for imaging one or more remote objects (not shown) in accordance with another embodiment of the present invention. The hyperspectral imaging system  600  includes a first housing  604  which is positioned next to and attached to a second housing  606 . The first housing  604  encloses and protects a first fore optic  608 , a second fore optic  610 , a third fore optic  612 , a fourth fore optic  614  (associated with a pick-off mirror  615 ), a first fold mirror  616 , a second fold mirror  618 , a third fold mirror  620 , a fourth fold mirror  622 , a slit  624  (which includes a first opening  626 , a second opening  628 , a third opening  630 , a fourth opening  632 ), and a 2-dimensional detector  634 . The second housing  606  encloses and protects a spectrometer  602  (e.g., Offner spectrometer  602  (shown), Dyson spectrometer  602 ). In this example, the spectrometer  602  is a one-to-one optical relay including an entrance opening  636  (can be same as or adjacent to slit&#39;s openings  626 ,  628 ,  630  and  632 ), a first mirror  638 , a diffraction grating  640 , a second mirror  642 , and an exit opening  646  (positioned next to the 2-dimensional detector  634 ). The hyperspectral imaging system  600  may include a controller  648  which controls the operation of several components including the fore optics  608 ,  610 ,  612  and  614 , and the 2-dimensional detector  634 . It should be appreciated that for clarity the description and drawing provided about the hyperspectral imaging system  600  omits certain details and components which are well known in the industry and are not necessary to explain and understand the present invention. 
     The hyperspectral imaging system  600  has four fore optics  608 ,  610 ,  612  and  614  each with 90 degrees field of view to cover 360 degrees and image remote object(s) (surveillance or transient events). In operation, the hyperspectral imaging system  600  operates to produce images of the remote object(s) over a contiguous range of narrow spectral bands when the first fore optic  608  receives a first image  650  (e.g., first beams  650 ) associated with a portion of the remote object(s), the second fore optic  608  receives a second image  652  (e.g., second beams  652 ) associated with another portion of the remote object(s), the third fore optic  612  receives a third image  654  (e.g., third beams  654 ) associated with another portion of the remote object(s), and the forth fore optic  614  receives a fourth image  656  (e.g., fourth beams  656 ) from the pick-off mirror  615  associated with yet another portion of the remote object(s). The first fold mirror  616  receives the first image  650  from the first fore optic  608  and directs the first image  650  to the slit&#39;s first opening  626  which outputs a trimmed first image  658  (slice of the first image  650 ). The second fold mirror  618  receives the second image  652  from the second fore optic  610  and directs the second image  652  to the slit&#39;s second opening  628  which outputs a trimmed second image  660  (slice of the second image  652 ). The third fold mirror  620  receives the third image  654  from the third fore optic  612  and directs the third image  654  to the slit&#39;s third opening  630  which outputs a trimmed third image  662  (slice of the third image  654 ). The fourth fold mirror  622  receives the fourth image  656  from the fourth fore optic  614  and directs the fourth image  656  to the slit&#39;s fourth opening  632  which outputs a trimmed fourth image  664  (slice of the fourth image  656 ). The fold mirrors  616 ,  618 ,  620  and  622  would be adjusted to align the four fields of view to one another prior to directing the images  650 ,  652 ,  654  and  656  to the slit&#39;s openings  626 ,  628 ,  630  and  632 . 
     The spectrometer  602  is positioned to receive the trimmed images  658 ,  660 ,  662  and  664  from the slit&#39;s openings  626 ,  628 ,  630  and  632  and output diffracted images  666 ,  668 ,  670  and  672  to the 2-dimensional detector  634 . In particular, the slit&#39;s openings  626 ,  628 ,  630  and  632  output the trimmed images  658 ,  660 ,  662  and  664  which passed through the entrance opening  636  (if present) to the first mirror  638  (spherical mirror  638 ) which reflects the trimmed images  658 ,  660 ,  662  and  664  towards the diffraction grating  640 . The diffraction grating  640  receives the trimmed images  658 ,  660 ,  662  and  664  reflected from the first mirror  636  and outputs the diffracted images  666 ,  668 ,  670  and  672  to the second mirror  642  (spherical mirror  642 ). The second mirror  642  receives the diffracted images  666 ,  668 ,  670  and  672  from the diffraction grating  640  and reflects the diffracted images  666 ,  668 ,  670  and  672  through the exit opening  646  to the 2-dimensional detector  634 . The 2-dimensional detector  634  (e.g., 2-dimensional FPA  634 ) is positioned to receive the diffracted images  666 ,  668 ,  670  and  672  at a final focal plane  674  and then output a 2-dimensional image of the diffracted images  666 ,  668 ,  670  and  672 . 
     The hyperspectral imaging system  600  may incorporate fore optics  608 ,  610 ,  612  and  614  which have the same magnifications, different magnifications, or any combination of magnifications. If desired, the hyperspectral imaging system  600  may incorporate one or more fixed mirrors, fast moveable steering mirrors and shutters as described above with respect to hyperspectral imaging system  300 . Furthermore, the hyperspectral imaging system  600  incorporates the slit  624  with openings  626 ,  628 ,  630  and  632  which are each separated from one another by more than a diffracted field at the spectrometer&#39;s final focal plane  674  (assuming a one-to-one optical relay spectrometer  602 ). The slit&#39;s openings  626 ,  628 ,  630  and  632  may have the same widths, different widths, or any desired combination of widths. Furthermore, the diffraction grating  640  can be configured with a diffraction efficiency that prevents an overlap of any of the diffracted images  666 ,  668 ,  670  and  672 . In addition, the 2-dimensional detector  634  can incorporate band pass filters, order sorting filters, or other techniques to prevent the overlap of the adjacent diffracted images  666 ,  668 ,  670  and  672 . 
     From the foregoing, one skilled in the art will appreciate that the aforementioned hyperspectral imaging systems  300  and  600  can be used in many types of applications including the SWIR and LWIR applications and thus address the aforementioned shortcomings associated with the prior art. To address these shortcomings, the hyperspectral imaging systems  300  and  600  take advantage of the available detector area which is not the case with the conventional hyperspectral imaging system  100  (for example). In particular, the conventional hyperspectral imaging system  100  does not take advantage of the full detector area in the spectral dimension and in many cases less than 20% of the available detector area is active and utilized. However, the hyperspectral imaging systems  300  and  600  are configured to take advantage of the available detector space by having an innovative diffraction grating design, image splitting techniques, and multiple fore optics which cover multiple hyperspectral fields of view in a single spectrometer. In addition, the hyperspectral imaging systems  300  and  600  can leverage the optical performance of many “semi-symmetric” spectrometers such as an Offner spectrometer and a Dyson spectrometer to cover extended fields in the spectral direction, but can also be applied to other refractive and reflective designs. An exemplary Dyson spectrometer which can be used instead of the Offner spectrometer  302  is described in the following documents: (1) J. Dyson, “Unit magnification optical system without Seidel aberrations,” J. Opt. Soc. Am. 49, 713-716 (1959); (2) David W. Warren, David J. Gutierrez, and Eric R. Keim, “Dyson spectrometers for high-performance infrared applications”, Optical Engineering/Volume 47/Issue 10, published online Oct. 14, 2008; and US Patent Publication No. 2009/0237657 (the contents of these documents are incorporated by reference herein). The hyperspectral imaging systems  300  and  600  also provide a significant cost reduction in equipment (detectors, spectrometers, coolers etc.), occupy significantly less volume, and require much less power when compared to the multiple conventional hyperspectral imaging system  100   a ,  100   b  . . .  100   n  (see  FIG. 2 ). 
     Although multiple embodiments of the present invention have been illustrated in the accompanying Drawings and described in the foregoing Detailed Description, it should be understood that the invention is not limited to the disclosed embodiments, but is capable of numerous rearrangements, modifications and substitutions without departing from the invention as set forth and defined by the following claims. It should also be noted that the reference to the “present invention” or “invention” used herein relates to exemplary embodiments and not necessarily to every embodiment that is encompassed by the appended claims.