Abstract:
The Precision Hyperspectral Imaging Array with Active Photonic Excitation Targeting Capabilities (defined as “the instrument”) provides a high performance spectral imaging capability and process for exploiting detailed multispectral, hyperspectral and ultraspectral (defined together within this document as “hyperspectral”) imaging and non-imaging signature information. This is accomplished in real-time and/or near real-time in order to discriminate and identify the unique spectral characteristics of the target within its naturally occurring environment. The instrument contains one or more mechanically integrated hyperspectral sensors installed on a fixed or moveable hardware frame and co-boresighted with a similarly mounted digital camera, calibrated visible light source, calibrated thermal source and calibrated fluorescence source. The array moves across the target via mechanical means, and in doing so, simultaneously carries all necessary passive hyperspectral imaging sensors and active calibration sources to effect collection of absolute radiometrically corrected spectral data against the target at high spatial and spectral resolutions.

Description:
RELATED INVENTION  
       [0001]    This invention claims the benefit of provisional application titled, Apparatus Having Precision Hyperspectral Imaging Array With Active Photonic Excitation Targeting Capabilities And Associated Methods, U.S. Serial No. 60/260,275 filed Jan. 8, 2001, which is incorporated herein in its entirety. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates generally to a ground based self-contained hyperspectral array for providing and exploiting radiometrically calibrated hyperspectral digital imagery in real-time and near real-time and associated methods. An active excitation source is included with this array, along with calibrated white light and thermal sources to provide natural scene illumination and increase the observed signal-to-noise ratio (SNR) of the target.  
         BACKGROUND OF THE INVENTION  
         [0003]    Hyperpectral imagers or sensors provide imaging capabilities that combine three distinct photonic technologies: conventional imaging; spectroscopy; and radiometry. This unique combination of technologies enables spectral sensors to produce images that associate a spectral signature with each two-dimensional spatial resolution element (i.e., pixel). The spectral signature is a wavelength value corresponding to the light emitted, reflected, or otherwise associated with an imaged target or its background. In this sense, a spectral sensor produces data elements that can be conceptualized as a 3-dimensional “cube” image. Each cube is formed by taking the spacial plane formed by two perpendicular axes and adding a third axis perpendicular to the spacial plane. On the third axis, is measured the go corresponding spectral values of the underlying imaged target or target&#39;s background.  
           [0004]    Thus, a hyperspectral image is one that is fully three dimensional in the sense that it can be represented as a high-dimensional vector or matrix. For example, the data cube can be viewed as composed of multiple points each represented by a vector, &lt;X, Y, λ&gt;, where X and Y are spacial values measured, respectively, along the X and Y axes and λ is a spectral value corresponding to the wavelength associated with the target (e.g., emitted or refected). These data cubes are usually constructed sequentially in one of two ways. Either the cube is constructed by sequentially recording one full spatial image after another, each at a different wavelength, or the cube is constructed by sequentially recording one narrow image swath (one pixel in width and multiple pixels long) after another with the corresponding spectral signature for each pixel in the swath.  
           [0005]    Hyperspectral imaging has come to play an increasingly important role in remote sensing. Hyperspectral imaging is the use of several dozen to several hundred simultaneously collected image scenes at different incremental frequencies. Typically hyperspectral analysis is accomplished in the form of an image representing a manifestation of the frequencies of reflected or transmitted energy levels within the scene. By manipulating the resulting layers of images (i.e., the data cube), extraction of unique signature information is possible, as well as correlation to established substance spectral libraries and databases. Normally, hyperspectral imaging permits delineation of different classes of vegetative, mineral, and various organic/non-organic targets. Most remote sensing and hyperspectral imaging, however, applies to targets normally located from an airborne platform and at long ranges between target and sensor.  
         SUMMARY OF THE INVENTION  
         [0006]    With the foregoing in mind, the present invention advantageously provides an apparatus having precision spectral imaging capabilities based on close range imaging of an optimally positioned target. These imaging capabilities are further enhanced by extending the imaging across frequency boundaries using a “virtual” sensor formed of an array of co-boresighted spectral sensors each operating in distinct frequency ranges. These capabilities are complementary but distinct, in that enhanced imaging is achieved as described herein using a spectral sensor at very close range when mounted on a frame for optimally positioning a target. Exclusive of the close range advantage, a further advantage is achieved with a consolidated array of spectral sensors that enables the search and imaging of spectral phenomena occurring across the frequency boundaries of the individual spectral sensors. As described fully herein, the apparatus specifically includes a consolidated array of spectral sensors each of which operates in a distinct spectral frequency and range and which is co-boresighted with the other spectral sensors so as to extend the imaging of a target across several spectral frequency bands. As also described more fully below, the apparatus further includes both a real-time imager(e.g., video or digital camera) co-boresighted with the spectral sensosrs and a target illuminator (e.g., light source for emitting at different preselected frequencies).  
           [0007]    The invention advantageously enables previously airborne hyperspectral sensors to be made available for close-in applications in biomedical, security and industrial type applications. The invention further advantageously provides a portable hyperspectral imaging array that can gather data from target areas in their natural environment. The invention also further advantageously includes use of commercial-off-the-shelf (“COTS”)) technologies and the provision to easily upgrade those technologies within the instrument through a modular chassis for holding discrete sensor head components and common data processing resources. The invention yet further advantageously enables the collection of more hyperspectral data by moving the hyperspectral sensors over the target using a motorized drive or moving the target past the sensors.  
           [0008]    The apparatus preferably includes a ground mounted frame and along with the plurality of distinct frequency range spectral sensors mounted to the frame. In addition, the light source is mounted to the frame to illuminate the target along with the real-time imager (e.g., a video or digital camera) also mounted to the frame to provide a real time human intuitive perspective of the target. The plurality of spectral sensors, light source, and real-time imager define a consolidated instrument array. The consolidated instrument array is preferably in communication with a controller to coordinate the functioning of the consolidated instrument array. The controller is preferably a single commercial-off-the-shelf (“COTS”)) computer. The controller preferably utilizes industry standard Environment for Visualizing Images (“ENVI”)) software to exploit data under the direction of the operator.  
           [0009]    Targets are placed under, alongside, or in front of the array, and may move past the array conveyor belt style, or alternatively, the array may move by means of a motorized drive. Because many hyperspectral sensors are very limited in field-of-view, the ability to move past the target increases the amount of data that can be collected. Also, many airborne hyperspectal sensors operate as “pushbroom”) systems, requiring forward aircraft motion to operate in collecting data along the spectral axis by virtue of their basic mechanical/optical design. The use of these airborne moving sensors over a fixed platform, and moving target mechanisms with pushbroom type systems provides a cost effective conversion to ground operations and permits collection of high resolution spectral data at closer ranges.  
           [0010]    To support the vast variety of commercial applications, it is necessary to fully characterize the targets within their ambient environment. These phenomena may occur across a wide frequency range in the electromagnetic spectrum. Conventional hyperspectral sensors are typically limited in collecting to discrete ranges, such as visible/near infrared, short-wave infrared, thermal, etc. But by placing a plurality of spectral sensors, each operating in a distinct frequency range and co-boresighted with each other spectral sensors, the effective spectral coverage can be enhanced beyond the capabilities of each individual discrete sensor. Use of selected combinations of commercially available hyperspectral sensors, respectively operating in the ultraviolet, visible/near-IR, short-wave-infrared, mid-wave infrared and long-wave infrared frequency regions, enables extended coverage of spectral frequency bands as a single virtual array for the instrument.  
           [0011]    On a passive sensing basis, the instrument array is used as a high performance calibrated hyperspectral imaging system to observe, collect and analyze naturally occurring spectral absorption and emission phenomenon without interference or invasiveness to the target system. This capability can be further increased by adding active stimulation of the target in those cases where this process will add value to the information base. By analyzing fluorescence, photo-luminescence excitation (“PLE”)) and hyperspectral data together from a consolidated sensor and controlled collection platform, new levels of identifying detail are possible.  
           [0012]    By adding active imaging capability in the form of excitation energy, the instrument potential includes not only vast hyperspectral applications, but provides a new level of delineation of target information. By coupling fluorescence to highly detailed hyperspectral data, new levels of detail are extractable from the resulting data cube.  
           [0013]    The instrument is operated in combinations of passive and active modes to find and effect the best use of hyperspectral imaging frequencies and algorithms against a given class of target, such as melanomas on human skin, foreign chemical substances on materials and chemicals absorbed into human hair. The various embodiments of the apparatus lead to greater instrument capability to resolve, discriminate and identify target substance compositions for a variety of new applications. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    Some of the features, advantages, and benefits of the present invention having been stated, others will become apparent as the description proceeds when taken in conjunction with the accompanying drawings in which:  
         [0015]    [0015]FIG. 1 is a perspective environmental view of an apparatus including a frame-mounted consolidated instrument array for precision hyperspectral imaging with active photonic excitation targeting and real-time viewing capabilities according to the present invention;  
         [0016]    [0016]FIG. 2 is a perspective view of a consolidated instrument array for precision hyperspectral imaging with active photonic excitation targeting and real-time viewing capabilities according to the present invention;  
         [0017]    [0017]FIG. 3 is a schematic block diagram of a controller used to control a precision hyperspectral imaging array with active photonic excitation targeting and real-time viewing capabilities according to the present invention;  
         [0018]    [0018]FIG. 4 is a perspective view of the display screen of apparatus having a frame-mounted consolidated instrument array for precision hyperspectral imaging with active photonic excitation targeting and real-time viewing capabilities according to the present invention;  
         [0019]    [0019]FIG. 5 is a schematic flow diagram of an algorithmic-based method of detecting target anomalies based on spectral data according to the present invention;  
         [0020]    [0020]FIG. 6 is a schematic flow diagram of an algorithmic-based method of matching targets based on spectral data according to the present invention; and  
         [0021]    [0021]FIG. 7 is a schematic flow diagram of an algorithmic-based method of detecting target changes based on spectral data according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0022]    The present invention will now be described more fully hereinafter with reference to the accompanying drawings which illustrate preferred embodiments of the invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout. The prime notation, if used, indicates similar elements in alternative embodiments.  
         [0023]    As perhaps best shown in FIG. 1, the apparatus includes a ground mounted frame  27  and preferably includes at least one sensor mounted to the frame to gather data from the target  34 , a light source  41  mounted to the frame to illuminate the target  34 , and a video or digital camera  49  mounted to the frame to provide a real time human intuitive perspective of the target  34 . If the apparatus includes a plurality of sensors, the sensors along with the light source and video or digital camera collectively define a consolidated instrument array  24 . The consolidated instrument array  24  is preferably in communication with a controller  31  to coordinate the functioning of the consolidated instrument array  24 . As shown in FIG. 3, the controller  31  is preferably a computer including at least one processor  50  and memory  54  for storing instructions and data. The at least one processor  50  and memory  54 , moreover, are preferably connected via a bus  52  as will be readily understood by those skilled in the art. The bus  52  also provides a data path between the controller  31  and the consolidated instrument array  24  as illustrated in FIG. 3.  
         [0024]    As shown in FIG. 2, the plurality of sensors can range from one through n, with n being a multiple number of discrete sensors. Use of selected combinations of commercially available spectral sensors, respectively operating in the ultraviolet, visible/near-IR, short-wave-infrared, mid-wave infrared and long-wave infrared frequency regions, enables extended coverage of spectral frequency bands as a single “virtual” array for the instrument. This virtual array permits search of spectral phenomenon occurrences which may take place across the boundaries of the individual sensors. The plurality of sensors can be an ultraspectral, multispectral, or hyperspectral array of sensors (hereinafter collectively referred to as “spectral sensors”). These spectral sensors can constitute a variety of different designs such as thermal sensors  43 , short wave/infrared sensors  45 , or visible/near infrared sensors  47  and may be produced by a variety of vendors.  
         [0025]    A further characteristic of the ground mounted frame  27  is modularity and scalability such that a variety of different spectral sensors can be detachably and selectively mounted to the frame  27  so that the frame  27  and consolidated array  24  are still portable. Accordingly, the spectral sensors and the frame  27  are adapted to permit different spectral sensors to be removably positioned on the frame  27 . Thus, at different times and in accordance with each particular need, new spectral sensors can be removably positioned on the frame  27 , as others not in use or in need of replacement are removed. The ground-mounted frame  27  and frame-mounted sensors also preferably are modular and light enough so as to be deconstructed taken to locations where the material to be scanned is located, and reconstructed there.  
         [0026]    Through use of co-bore sighting or sensor alignment techniques in which the center of each sensor points to a common target point, however, the resulting image taken from the spectral sensors will be acquired on an optically consistent basis in any number of hyperspectral band combinations. This common focus permits each spectral sensor reading to be mathematically corrected so that each pixel area from the target  34  for a given spectral sensor may be “matched” with that from any of the other specteral sensors on the array. This capability is the key element in expanding the capability to that of a single “virtual” array operating across many regions of the spectrum from a variety of unmatched and unplanned hyperspectral sensors.  
         [0027]    To date, the majority of spectral applications have been in the field of hyperspectral airborne-based imaging. The instrument configuration according to the present invention, however, facilitates conversion to ground operations, opening the door for a vast variety of medical, scientific, and commercial applications at closer ranges. As already noted and described more fully below, the optimal positioning of the target and even a single spectral sensor at close range provides unique advantages and benefits not heretorfore recognized or achieved.  
         [0028]    For those sensors that operate as staring arrays (i.e., those which operate from fixed positions rather than moving positions), they may also be included inside the mounting of the instrument array. This design now permits the groundborne merging of two distinctly incompatible types of airborne systems (pushbroom and staring types), further increasing the new applications potential.  
         [0029]    As illustrated in FIG. 1, the ground mounted frame  27  for mounting the at least one sensor of a consolidated instrument array  24  can be combined with various devices to expand the target area to be read by the consolidated instrument array  24 . In one embodiment, the consolidated instrument array  24  is moved over the stationary target or targets  34  or to the side of the target or targets  34  via a motorized drive assembly mounted to the frame  27 . Specifically, the consolidated array  24  is mounted on the frame  27  so that it can be repositioned for optimal imaging. As shown in FIG. 1, the array  24  can be moved over the target  34  using, for example, a drive assembly  21 . As expressly illustrated in FIG. 1, the frame preferably includes at least one, and more preferably two, tracks  23  in addition to the drive assembly  21  connected to the frame  27  to reposition at least one of the plurality of spectral sensors by moving at least one spectral sensor along the track  23  to thereby permit the spectral sensors to be optimally positioned relative to the target  34 . Thus, as illustrated in FIG. 1, each of the plurality of spectral sensors of the array  24 , for example, can be mounted on a movable platform  26  connected to the frame  27  and drive assembly  21  such that the spectral sensors may be moved along the track  23  in at least a substantially horizontal direction H.  
         [0030]    To further permit the optimal positioning of the consolidated instrument array  24  relative to a target  34 , the frame preferably further has the capability of moving the sensors in a vertical direction V as well. For example, as illustrated in FIG. 1, the frame can include four vertically extendable posts  25  extending vertically from a base  37  of the frame  27 . Each of the posts  25  more preferably can be automatically (e.g., hydraulically) or manually adjusted to changed the vertical distance between the consolidated instrument array  24  and the target  34 . Preferably, the apparatus  10  further includes a motion encoder or other sensor to sense the presence of the target  34  and position the target  34  and consolidated instrument array  24  relative to one another so as to achieve optimal imaging of the target  34 . More preferably, the motion encoder is positioned on the drive assembly  21 .  
         [0031]    In another embodiment, the target or targets  34  are associated with a motorized drive assembly  21  that includes a conveyor  29  (e.g., endless belt) so as to be moved past the consolidated instrument array  24  in at least a substantially horizontal direction H 2 . Preferably, as shown in FIG. 1, the conveyor  29  is positioned beneath the platform  26  on which is mounted the consolidated instrument array  24 . More preferably a housing  28  overlies the platform  26  to cover the consolidated instrument array  24  seated thereon. In addition, the consolidated instrument array  24  can further include at least one auxiliary module  40  for adding to the sensing capabilities of the consolidated instrument array  24  by adding one or more additional sensors such as an x-ray, fluoroscope, ultrasound, or other sensor.  
         [0032]    Thus, the conveyor  29  is able to convey the target  34  to an optimal position relative to the at least one sensor of the consolidated instrument array  24 . Again, the apparatus  10  preferably includes a motion encoder or other sensor positioned on the drive assembly  21  to sense the presence of the target  34  and position the target  34  and consolidated instrument array  24  relative to one another so as to achieve optimal imaging of the target  34 .  
         [0033]    In a third embodiment, the ground mounted frame  27  is equipped with a scan mirror  33  assembly to acquire motion compensated data from targets  34  that are at longer ranges or not feasible to place within the confines of the instrument array. In the preferred embodiment the frame includes the scan mirror and both the movable platform  26  mounted so as to be vertically extendable on the frame  27  along with the base-mounted conveyor  29  to achieve the maximum degrees of freedom for positioning the target  34  and the consolidated instrument array  24  relative to each other.  
         [0034]    Although the consolidated instrument array of at least one spectral sensor  24  can be used to collect target data using only naturally occurring light, the light source  41  mounted to the frame can be used to obtain additional or improved data from the target  34 . The light source  41  is preferably a tunable, possibly monochromatic, light source which provides the “reservoir” of energy via direct illumination of the target at close range in its natural environment. The target absorbs this energy, then re-emits it at a shifted wavelength. Coupled with the inherent detail of precision hyperspectral imagery (on the order of one half millimeter of spatial resolution at one nanometer spectral resolution in the visible spectrum at a distance of three feet between sensor and target), fluorescence and photoluminescence excitation (“PLE”)) data add additional information to the hyperspectral data cube, in that different wavelengths of a material will result from this excitation. The tunable light source can be set to different frequencies to measure PLE in solids, liquids and gases by taking multiple Hyperspectral data cubes at two or more frequencies and/or amplitudes of illumination, and analyzing both individual images and the difference between image sets in order to extract information about the target  34 . The light source  41  can be used for constant scene illumination to greatly increase the target signal as the consolidated instrument array  24  moves over the target  34  or the target  34  moves under the consolidated instrument array  24 . This provides a constant spectroradiometric environment in which to calibrate all the data, thus permitting scene characterization simultaneously across the various spectral bands during the collection process.  
         [0035]    In the alternative, the light source  41  can be a pulsed illumination to capture hyperspectral data cubes so that luminescence can be gathered from the sample as a function of time. The light source  41  can also be a tunable and fixed frequency fluorescing light source at any frequency to cause fluorescence in solids, liquids, gases, vapors and aerosol targets  34  in order to hyperspectrally measure changes in unique spectral absorption and/or emission return signature data for precision information. Target illumination increases the close-range imaging capabilities provided by the ground-mounted, co-boresighted spectral array.  
         [0036]    Preferably, the consolidated instrument array  24  further includes a real-time imager  49  mounted to the frame to provide a real time human intuitive perspective of the target  34 . As illustrated in FIGS.  3 - 4 , the controller preferably further includes a display  56  that can display a real-time image of the target  34  generated by the real-time imager  49 . More preferably, as illustrated in FIG. 4, data cubes  60  generated by the consolidated instrument array  24  can be overlaid with the real-time image of the target  34 . This real-time view of the target coupled with the generated spectral data cube allows for increased accuracy in positioning the spectral sensors and target relative to each other.  
         [0037]    The apparatus  10  as described enables the enhanced imaging of a target when the target and at least one spectral sensor are positioned relative to each other at close range. Close range is herein understood to be preferably at least one inch (1″) but no more than fifty inches (50″). More preferably, a close range is achieved by positioning the frame-borne target  34  and the frame-mounted at least one spectral sensor relative to one another so that the distance between them is at least six inches (6″) but no more than twenty four inches (24″).  
         [0038]    Target data collected from the sensors is transmitted from the moving mount of the array to the controller  31  which as already described includes a computer having at least one processor  50  and memory  54 . The data is transmitted via flexible cable, fiber optic, or high bandwidth radio frequency link. It should be noted the hyperspectral data is very large in comparison to conventional color imagery, on the order of one hundred to one thousand times larger for a given scene. It is important that means be established to bring this raw format large volume sensor data from the source of collection to the controller  31  and that the controller  31  having processing and memory storage capabilities as already described. Once the data is stored in memory, it can be processed and manipulated to extract desired trend information. A number of commercially available software packages exist for this purpose, most notably, the Environment for Visual Images (“ENVI”)) program available from Research Systems, Inc. of Boulder, Colo.  
         [0039]    Once data has been acquired to develop and utilize appropriate algorithms, the instrument array can be used to then collect and identify unique signatures based on “templates” derived from these processes. These templates include both the unique signature data and the optimal algorithm for exploiting a given signature against a given background. Neural net, heuristic processing methods and artificial intelligence techniques can be used to analyze large scale data trends and extract information from the instrument across the resulting broadband spectral range available from the extended combination of spectral and fluorescence data acquired by the instrument. The computer can be programmed to automate this process for a given degree of certainty and false alarm rate.  
         [0040]    One example of the many algorithmic-based applications enabled by the present invention is a method  100  of using relative spectral differences for anomaly detection as illustrated in FIG. 5. Anomaly detection  100 , according to the present invention, preferably includes inputting target spectra data (BLOCK  101 ) and spectra data associated with the environment or background of the target  34  (BLOCK  102 ). A plurality of spectral sensors, each preferably operating in a distinct frequency range, is co-boresighted on a target positioned preferably at close range (BLOCK  103 ). The real-time imager  49  is co-boresighted with the plurality of spectral sensors (BLOCK  104 ). Preferably, the co-boresighted spectral sensors and real-time imager  49  are then positioned with respect to the target  34  for optimal imaging. If not, further positioning and sighting are undertaken (BLOCK  105 ). Energy in the form of light provided by the light source  41  is directed at the target  34  to illuminate the target  34  and spectral data is acquired (BLOCK  106 ). The data so acquired is then compared by the processor  50  to one or more preselected criterion values stored in memory  54  in order to compute a unique spectral difference corresponding to the data element undergoing analysis (BLOCK  107 ). If the computed difference is anomalous according to a preselected set of criteria (BLOCK  108 ), then an indication of an anomaly for the particular data element is provided (Block  109 ). To increase the available data for analysis the target  34  can be imaged by re-setting the wavelength of the light provided by the light source  41  to illuminate the target (BLOCK  110 ). The steps are repeated until each data element has been analyzed (Block  111 ).  
         [0041]    A related application also enabled by the present invention is illustrated in FIG. 6 in which acquired data is compared to that of a database stored in memory  54 . Specifically, the application provides a method of spectral matching  200  so as to match a target image from amidst a background with a preselected image or identification criterion. Again, the method  200  is initiated by inputting target spectra (BLOCK  201 ) and background spectra data (BLOCK  202 ). Also, again, a plurality of distinct frequency range spectral sensors are co-boresighted with each other (BLOCK  203 ) and with the real-time imager  49  (BLOCK  204 ). The target  34 , spectral sensors, and real-time imager  49  are positioned relative to one another so as to permit optimal imaging (BLOCK  205 )of the target  39  and background. The target is imaged as it is illuminated by light directed to the target from the light source  41  (BLOCK  206 ). Rather than computing a spectral difference as in the previously illustrated application, however, each acquired data element is sequentially compared to the individual elements of a stored database (BLOCK  207 ). If a match is made (BLOCK  208 ) against any one of the stored elements, then a match is so indicated (BLOCK  209 ). To add to the data available for analysis, the light source can be re-set to provide light at a different wavelength and new data is generated (BLOCK  210 ). The comparison is repeated until the acquired data element has been compared to each database element (BLOCK  211 ). The analysis can be performed for multiple data elements acquired by the consolidated instrument array  24  (BLOCK  212 ).  
         [0042]    A specific a use for the application is drawn from the field of criminology in which various physical features of an individual could be compared with those of a database to determine whether the suspect is a wanted fugitive or suspected criminal. Still another use is drawn from the field of medicine in which data is acquired from some target area of a patient&#39;s body and compared to stored data representing the characteristics of a healthy person to determine whether the patient&#39;s characteristics match that of a health person.  
         [0043]    Yet a third application  300  is illustrated in FIG. 6 in which the apparatus  10  is used to determine whether the characteristics at time T 1  of a target have changed since T 0 . At time T 1 ,target and background spectra data provided (BLOCKS  301  and  302 ). The plurality of distinct frequency band spectral sensors is co-boresighted (BLOCK  303 ). The real-time imager  49  is co-boresighted (BLOCK  304 ) and the target  34  is optimally positioned relative to the spectral sensors and real-time imager  49  (BLOCK  305 ). The target is illuminated with light of a selected wavelength form the light source  41  and the target  34  along with its background is imaged (BLOCK  306 ) to acquire spectra data at time T 1 . Assuming data on the target has been collected at time T 0  and stored in memory  54 , each newly acquired data element at time T 1  is compared to corresponding data element acquired at time T 0  (BLOCK  307 ) to determine whether there has been a change in the characteristics of the target during the time interval T 1 -T 0  (BLOCK  308 ). If there has been a change, the change is so indicated (BLOCK  309 ). The imaging and comparison can be repeated with the light source illuminating the target with light of a different wavelength (BLOCK  310 ). The steps are repeated until each of the newly acquired data elements has been compared to a corresponding one (BLOCK  311 ). This third application also provides tremendous advantages in the field of medicine in which a diseased target area of a patient must be monitored over time to determine changes in the diseased area.  
         [0044]    More generally, according to one method aspect of the present invention, enhanced spectral imaging of a target is achieved by positioning the target on a frame  27 , mounting at least one spectral senor on the frame  27 , and positioning the spectral sensor to provide a substantially close range spectral image of the target  34 . As noted already, a substantially close range is defined by the distance between the target and the spectral sensor, and the distance so defined is at least one inch (1″) but no more than fifty inches (50″). More preferably the distance is at least six inches (6″) but no more than 24 inches (24″). The method preferably further includes illuminating the target  34  by directing light onto the target from a light source  41 , the light source  41  preferably being capable of being set to different frequencies so as to further enhance imaging of the target by causing the target to re-emit the light at a shifted wavelength.  
         [0045]    A further method of enhanced imaging of a target  34  according to the present invention encompasses imaging the target  34  over an extended range of spectral frequency ranges. The method specifically entails positioning a plurality of spectral sensors relative to the target  34 , each of the plurality of spectral sensors operating in a different spectral frequency range from the other of the plurality of spectral sensors. Each of the plurality of spectral sensors is co-boresighted so that an imaginary straight line extends from the center of each sensor to a common point on the target. The target receives energy by being illuminated by light directed onto the target from a light source  41  that can be set to different frequencies so as to further enhance imaging of the target  34  by causing the target to re-emit the light at a shifted wavelength. Preferably, the step of illuminating the target  34  specifically includes directing light onto the target  34  so as to cause fluorescence and photoluminescence excitation.  
         [0046]    Applications for the for the present invention as an imaging system include a variety of scientific, medical, commercial, and military implementations. In the field of medicine, the present invention in particular provides significant benefits over many conventional devices. Unlike surgery, it is noninvasive. Unlike X-ray, imaging can be accomplished without subjecting a patient to harmful gamma rays. Some of the key areas of application include detection of skin anomalies, such as cancer and melanomas. Others include observation and discrimination of human sub-dermal phenomenon, observation and discrimination of blood oxygen saturation, observation and discrimination of human dermatological phenomena, assessment of the bio-state of burned human tissue and skin, assessment of bio-state of human organs pending imminent transplant into a new recipient, assessment of bio-state of internal organs in vitro (using, for example, hyperspectral endoscopy).  
         [0047]    Non medical applications include detection of drug use through skin and hair absorption of substances, discrimination of unique bio-metric parameters, water quality assessment, detection of surface residue from explosives and hazardous materials, polygraphic assessment of human psycho/physiological states through detection of surface changes corresponding to human reactions, gemology assessment, forensic crime scene analysis, counterfeit materials assessment and detection, industrial process control, health state of meats and poultry, materials stress and fractures, and genetic and transgenic materials identification.  
         [0048]    The present invention advantageously provides a single, consolidated apparatus utilizing a consolidated instrument array having at least one spectral sensor and preferably including a light source provided light of different preselected wavelength. Preferably, the consolidated instrument array also includes a real-time imager. A complementary, but entirely distinct advantage, is provided by mounting the at least one spectral sensor on a frame that permits the imaging of a preselected target at close range. The at least one spectral sensor provides close range imaging to conduct close-in high spatial/spectral resolution, collection, and analysis. Through collection of large data sample populations and analysis of optimal algorithms, a small portable system will be capable of undertaking these processes on an unattended basis in various field environments. As spectral signatures are collected and developed, the ever increasing quantity of bio-informatics data will expand the scope of applications for the basic design.  
         [0049]    In the drawings and specification, there have been disclosed a typical preferred embodiment of the invention, and although specific terms are employed, the terms are used in a descriptive sense only and not for purposes of limitation. The invention has been described in considerable detail with specific reference to these illustrated embodiments. It will be apparent, however, that various modifications and changes can be made within the spirit and scope of the invention as described in the foregoing specification and as defined in the appended claims.