Abstract:
A method is used for imaging applications so that one can simultaneously apply multiple illumination schemes and simultaneously acquire the images, each associated with one of the multiple illumination schemes. The illumination schemes can be, but not limited to, any combination of reflective illumination, transmitive illumination (backlighting), bright field illumination, dark field illumination, diffused illumination, cloudy-day illumination, and structured illumination. The radiation can be in any wavelengths, ranging from sonic waves, ultra sound, radio waves, microwaves, infrared, near infrared, visible light, ultra violet, X-rays, and gamma rays. The radiation of each of the illumination schemes used in an imaging application is modulated, that is, affixed with a unique signature. One or more imaging devices can be used to collect the radiating rays simultaneously after the rays interact with the object(s). The image signal(s) are then demodulated, separated into several images, each is associated with an illumination scheme, based on the signatures. A preferred embodiment is to use radiation wavelengths of 430 nm, 575 nm or 670 nm as the signatures.

Description:
RELATED APPLICATIONS  
       [0001]    This application claims the benefit of U.S. provisional application Ser. No. 60/173,186 filed Dec. 27, 1999. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Technical Field  
           [0003]    The present invention relates generally to image acquisition systems, and, more particularly, to an image acquisition system having multiple illumination schemes for simultaneous image acquisition.  
           [0004]    2. Description of the Related Art  
           [0005]    There are many different ways to illuminate object(s) in order to capture information about the object. The type of information that can be obtained by a specific illumination scheme depends upon the nature of the illumination scheme.  
           [0006]    In imaging applications, in which one or more imaging devices such as CCD cameras and optical scanners are used to gather object information carried by radiation, it is well known that different illumination schemes result in dramatically different images from the same object. Examples of different illumination schemes include, but are not limited to, a transmitive illumination system  10  and a reflective illumination system  12 . For instance, an object can be illuminated utilizing a transmitive illumination system  10 , as described below in FIG. 1.  
           [0007]    In transmitive illumination, an object  14  is placed between an illumination source  16 , such as a light, and an imaging device or a signal receiver, such as a camera  18 . In this arrangement, the contour boundaries of the object will be well defined while the surface details are poorly shown in the image. An image processing unit  20  is also shown.  
           [0008]    In transmitive illumination scheme  10 , the illumination source(s)  16  can be (a) conditioned or non-conditioned; (b) structured or non-structured; (c) collimated or scattered; (d) uniform or non-uniform; or (e) monochromatic or color. Different combinations of the foregoing can be used that allow the user to accomplish specific system requirements. In addition, there are any number of otherwise conventional optical components such as, but not limited to, lenses, mirrors and diffusers (not shown) that can be used in the design of transmitive illumination scheme  10  to accomplish specific system requirements.  
           [0009]    Another type of illumination is reflective illumination (FIG. 2), in which the radiation is projected on the object surface and reflected back to the imaging device. Reflective illumination allows the imaging device  18  to detect the surface characteristics of object  14 . In a reflective illumination scheme, the illumination source(s)  16  can be (a) conditioned or non-conditioned; (b) structured or non-structured; (c) collimated or scattered; (d) uniform or non-uniform; or (e) monochromatic or color. Different combinations of the foregoing can be used that allow the user to accomplish specific system requirements. In addition, there are any number of otherwise conventional optical components such as, but not limited to, lenses, mirrors and diffusers (not shown) that can be used in the design of the reflective illumination scheme to accomplish specific system requirements. The reflective illumination can be further broken down into several types such as bright field illumination, dark field illumination and cloudy-day illumination.  
           [0010]    In bright field illumination, as shown in FIG. 3, most of the radiation or at least a large portion thereof originating from the source(s)  16  strike object  14  and then is reflected to imaging device  18 . The angle of projection is deliberately selected such that the desired reflective path is established. This illumination scheme is often used to detect surface characteristics such as color patterns, marks, and/or discoloration.  
           [0011]    In dark field illumination, as shown in FIG. 4, the illumination source projects a signal  22  upon object  14  that in most instances will be reflected away (e.g., ray  24 ) from imaging device  18 . A surface anomaly  26 , such as surface sculptures, foreign objects, or contaminants, may then be imaged by imaging device  18 , due to acquisition of scattered signals  28  caused by the surface anomalies. The scattered signals  28  comprise radiation reflected by the surface anomalies towards the imaging device.  
           [0012]    In cloudy-day illumination, the illumination source (s) are arranged such that there exists no shadow of the object  14 .  
           [0013]    It is often the case that different aspects of an object or objects, such as surface anomalies and contour boundaries, are desired to be observed. For instance, it may be desired to measure the distance between two boundary lines accurately with good boundary definition using transmitive illumination as shown in FIG. 1. At the same time, it may also be desirable to detect surface anomalies using reflective illumination on the object(s) as shown in FIG. 4. In some known applications, images sequentially obtained using different illumination schemes are overlapped with an image processing operation, such as a difference operation, to extract the intended information. For instance, a dark field illuminated image and a bright field illuminated image may be overlapped to extract the surface defects on a processed semiconductor wafer.  
           [0014]    Other known approaches of applying different illumination schemes are all sequential approaches. One known approach is to have multiple imaging stations, each with a particular illumination scheme. For instance, a first station is equipped with transmitive illumination so that the dimensions of an object(s) can be detected. Then, the object(s) are moved to a second station in which surface discoloration can be detected using bright field illumination. Afterward, the object(s) are moved to a third station where surface scratch marks can be detected using dark field illumination.  
           [0015]    Another known approach is to have multiple illuminating devices in an imaging station, in which the illuminating devices can be controlled to provide different illumination schemes. The object(s) are first placed in this station. One illumination scheme, for instance, bright field, is applied on and to the objects and an image is taken. Then, another illumination scheme, for instance, a dark field illumination, is applied onto the objects and another image is taken.  
           [0016]    Still yet another known approach is to have multiple sets of imaging devices and illuminating devices in an imaging station. The object(s) are first placed in the station. One set of the imaging and illuminating devices, for example, a CCD camera and a light for dark field illumination, is applied onto the object(s), or a portion of the object(s), for taking a first image. Then, another set of the imaging and illuminating devices, for example, a CCD camera and a light for transmitive illumination, is applied onto the object(s), or the same portion of the object(s), for taking a second image.  
           [0017]    The sequential nature of conventional illumination schemes and image acquisition systems provide obstacles or limitations on how quickly image processing can take place where multiple features of the object are desired to be imaged. Additionally, where objects are moved between stations, an increased amount of damage to the object may occur, due to the increased material handling. Also, multiple stations increase cost. Finally, accuracy is impaired with respect to image overlap since different data is used to image overlap since different data is used for each object feature.  
           [0018]    U.S. Pat. No. 4,595,289 to Feldman et al. disclose a dual illumination system that uses two light sources, having two separate wavelengths, to illuminate an object. Feldman et al. further disclose that such illumination may occur simultaneously. However, the system of Feldman et al. uses distinct light signal paths, increasing the amount of optical components/cameras, and the like that is required. Every optical component is different even when the components are made to the same specifications. Therefore, different light paths and optical components will generate different image distortions, impairing the applications of the approach of Feldman et al.  
           [0019]    Accordingly, there is a need for an imaging system, or portions thereof, that minimizes or eliminates one or more of the problems set forth above.  
         SUMMARY OF THE INVENTION  
         [0020]    It is an object of the present invention to provide an imaging system that provides a solution to the above-identified problems. The invention simultaneously applies different illumination schemes to an object(s) so that different aspects of the object(s), such as the boundaries and the surface defects, can be detected simultaneously.  
           [0021]    A system according to the invention provides the following advantages:  
           [0022]    (i) Saves time by simultaneous image acquisition thereby minimizing material handling;  
           [0023]    (ii) Provides improved accuracy for image overlap by using the same datum and the same image collecting optics;  
           [0024]    (iii) Reduces damage to the object(s) by minimizing material handling; and  
           [0025]    (iv) Lowers costs by having only one mechanical station for all the imaging needs.  
           [0026]    A system for observing an object in accordance with the present invention includes first and second radiation projectors, an image acquisition device, and an controller. The radiation projectors are configured to produce first and second radiation signals, respectively, having different first and second wavelengths. The image acquisition device is arranged to have the object in a field of view and is further configured to simultaneously capture radiation signals having the first and second wavelengths to produce an image of the object. The controller is configured to cause the first and second radiation projectors to simultaneously illuminate the object with the first and second radiation signals and control the image acquisition device to produce the image of the object in timed relation therewith. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0027]    [0027]FIG. 1 is a schematic diagram view of a conventional transmitive illumination (back lighting) scheme used in an imaging application;  
         [0028]    [0028]FIG. 2 is a schematic diagram view of a conventional reflective illumination scheme used in an imaging application;  
         [0029]    [0029]FIG. 3 is a schematic diagram view of a conventional bright field illumination scheme used in an imaging application;  
         [0030]    [0030]FIG. 4 is a schematic diagram view of a conventional dark field illumination scheme used in an imaging application;  
         [0031]    [0031]FIG. 5 is a schematic diagram view of an imaging system of the present invention, illustrating N modulated signal projectors are incorporated with an imaging device for the image acquisitions.  
         [0032]    [0032]FIG. 6 is a schematic diagram view of a preferred embodiment of the present invention having radiating wavelengths as unique signatures;  
         [0033]    [0033]FIG. 7 is a schematic diagram view of another embodiment of the present invention showing two (2) illumination schemes;  
         [0034]    [0034]FIG. 8 is a schematic diagram view of yet another embodiment of the present invention showing four (4) illumination schemes;  
         [0035]    [0035]FIG. 9 is a schematic diagram view of still another embodiment of the present invention in which one of the radiation sources is used to support a plurality of projectors via a light delivering mechanism;  
         [0036]    [0036]FIG. 10 is a schematic diagram view showing a configuration for an imaging device with three (3) CCD chips for simultaneously collecting images with simultaneous illumination schemes;  
         [0037]    [0037]FIG. 11 is a schematic diagram view showing a plurality of cameras configured to simultaneously collect corresponding images with simultaneous illumination schemes; and  
         [0038]    [0038]FIG. 12 is a schematic diagram view showing still yet another embodiment having a plurality of cameras with multiple illumination schemes. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0039]    This invention is an imaging system that permits the simultaneous illumination and simultaneous image acquisition of one or more objects with two or more illumination schemes.  
         [0040]    An “imaging system” as the term is used herein means any system that is capable of receiving, and/or acquiring, and/or storing, and/or processing, and/or analyzing, and/or transmitting, and/or transferring, image data from or about, an object or objects which have been either illuminated by (a) an external radiation source or (b) is itself a self-radiating object. An imaging system in this invention includes two or more illumination sources.  
         [0041]    The invention consists of either (1) adding a unique, discernable signature (hereinafter referred to as the signature(s)) to the radiation which emanates from an object or objects and/or (2) identifying any such signature that is inherent in the radiation so that the imaging system can differentiate the radiation signals from different illumination sources based on the unique signature of each of the radiation signals. The invention allows the simultaneous illumination and simultaneous acquisition of images from one or more objects using two or more illumination schemes simultaneously.  
         [0042]    In this invention, there can be N illumination sources (hereinafter referred to as the “signal projectors”) in an imaging system, where N is an integer that is greater than or equal to 2. Each signal projector is generally part of a specific illumination scheme; that is, there can be N illumination schemes co-existing and used simultaneously in an imaging system. A signal projector can be facilitated by one radiation source. It is also possible that more than one signal projector can be facilitated by a single radiation source.  
         [0043]    Generally, each of the signal projectors is equipped with a modulation device. The modulation device blends a unique, discernible signature into the radiation signal being projected by the signal projector. The modulation device can be either an electronic device, an electrical device, a mechanical device, an optical device, an opto-mechanical device, a software device, or any combination of the above. The modulated projection signals are then used to illuminate the intended object(s). In some cases in which a signal projector inherently carries a unique signature, the modulation process is not necessary.  
         [0044]    Each of the projection signals is designed to deliver a specific illumination scheme, such as dark-field illumination, to the intended object(s). The projection signals will then interact with the intended object(s), and be modified by such interactions. After the interaction, the projection signals are collected by a signal image acquisition device (imaging device) simultaneously. The imaging device is designed such that it can simultaneously detect all the projection signals, including the modulation signatures blended in the projection signals and the modifications incurred by the interactions with the intended object(s). The imaging device is also designed such that it can discern the modulation signatures, distinguishing one from the other, and conduct a demodulation process. Such demodulation process will allow the said imaging device to extract images resulted from different illumination schemes.  
         [0045]    Referring now to the drawings wherein like reference numerals are used to identify identical components in the various views, in FIG. 5, an object  30  having a surface characteristic  32  is to be observed. It is desired to observe the boundaries of object  30  accurately. It is also desired to simultaneously observe surface characteristics  32 , such as foreign objects and discoloration, of object  30 . It is further desired to simultaneously detect the height of certain patterns on a surface  34  of object  30 . In order to satisfy all the desires, it is determined that N illumination schemes are necessary to facilitate acquisition of the required information. In the illustrated embodiment, a first projector  36  is used to provide dark field illumination so that a foreign object or the like can be detected. A second projector  38  is used to provide bright field illumination so that any surface discoloration can be detected. A third projector  40  is used to provide transmitive illumination so that the boundaries of object  30  can be accurately defined. Further projectors may be included to achieve predetermined, desired illumination characteristics. An N-th projector  42  is used to provide a structured line illumination so that the scheme of triangulation can be used to determine the wavy profile of the object surface  34 .  
         [0046]    The radiation signal projectors  36 ,  38 ,  40 , . . . ,  42  may comprise radiation sources capable of various emission types and can be sonic, electromagnetic, IR, visible light, UV, X-ray, structured or non-structured, scattered or collimated, color or monochromatic. In one embodiment, sources  36 ,  38 ,  40 , . . . ,  42  may comprise one of a metal-halide lamp, a Xenon lamp, and a halogen lamp, each a relatively broadband light source, in connection with a filter, to be described below. Lasers may be used (i.e., specific wavelength devices) and the need for a filter can be avoided. Each signal projector  36 ,  38 ,  40 , . . . ,  42  is modulated and/or selected in a specific way so that the radiation from a particular signal projector carries a unique signature and can be identified after an image acquisition device  44  collects all the radiation signals. The imaging device  44  consists of one or more radiation sensors, such as, but not limited to, sonic detectors, CCD chips, and IR imaging arrays. The radiation sensor(s) in imaging device  44  are arranged such that the radiation signals from all the radiation projectors  36 ,  38 ,  40 , . . . ,  42  can be collected simultaneously. It is necessary to demodulate the radiation signals based on the signatures so that information carried by different illumination schemes can be differentiated. The demodulation process can be performed before or after the radiation signals reach the radiation sensor(s). FIG. 5 further shows an image processing unit  46 . FIG. 5 further shows a controller  48 . Controller  48  is configured to cause the radiation projectors (or at least two or more of them) to simultaneously illuminate object  34  the respective radiation signals generated by the projectors. Further, the controller  48  is further configured to control the image acquisition device  44 / 46  to produce an image of the object in timed relation (i.e., substantially simultaneously with) with the illumination. While controller  48  is shown as separate from image process unit  46 , these functions may be merged into a single control unit, such as a general purpose digital computer suitably programmed to achieve the functions described herein.  
         [0047]    [0047]FIG. 6 shows a preferred embodiment of the invention which uses an optical modulation scheme, namely, system  50 . In this system, as shown above, a color CCD camera (with an optical lens)  52  is used as the imaging device. Camera  52  is coupled to an image process unit  54 , forming a demodulation block  56 . Also shown is a controller  57 , which operates in the same manner as described above for controller  48 . In color camera  52 , color pixels are arranged in a plenary array. Each color pixel typically consists of several, 3 or more, monochromatic pixels. There would be a color filter in front of each monochromatic pixel; this color filter determines which color, typically one of red, green, and blue, this monochromatic pixel is detecting the intensity of. With the color filters, radiation at a wavelength of 435 nm (blue light) can only be detected by the monochromatic pixels whose color filters are blue, but not other monochromatic pixels. Similarly, radiation at a wavelength of 575 nm (green light), or 670 nm (red light), can only be detected by the monochromatic pixels whose color filters are green, or red. These color filters, red, green, or blue serve as the demodulation devices on the imaging device.  
         [0048]    The image acquired by way of camera  52  can be digitized and processed by image processing unit  54 , which may comprise a computer or similar devices. In processing unit  54 , the three portions of a color image, the red image, the green image, and the blue image, can be separated. Each of the three monochromatic images carries the optical characteristics of an object  58 , resulting from different illumination schemes.  
         [0049]    There are three illumination schemes used in the embodiment of FIG. 6. The first illumination scheme is a dark field illumination, facilitated by a metal-halite light source  60  and an interference filter  62  at 575 nm (green). A metal-halite light source is a white-light light source. That is, its radiation contains multiple wavelengths. Among the radiating wavelengths of metal-halite light source  60 , there are three significant peaks, at 435 nm, 550 nm, and 575 nm, respectively. This white light radiation from source  60  is modified (modulated) by passing through filter  62 . After passing through filter  62 , the radiation from source  60  has only a single wavelength, 575 nm. This mentioned wavelength is the signature of the radiation from filter  62  that is unique and discernible in the imaging device  52 . Imaging device  52  can receive the signal from illumination source  60  in its GREEN plane of the resulting color image. This illumination is configured to detect surface anomalies, such as a foreign object  64  on a surface  66  of object  58 . If surface  66  of object  58  is free of anomalies, the radiation emanating from filter  62  will be reflected away from the imaging device  52 , into a direction of ray designated  68 . When the radiation from filter  62  strikes anomaly  64 , the radiation is scattered into the directions of rays  70 . Some of the scattered radiation can be detected by imaging device  52 .  
         [0050]    The second illumination scheme is structured illumination, facilitated by a second source comprising a laser diode  72  or the like that radiates at a wavelength of 670 nm (red), and a line generating optic  74 . The modulation is inherently built in the radiation source  72 , as laser  72  is a monochromatic laser. The wavelength of 670 nm is the signature of the radiation from laser  72  that is unique and discernible in the imaging device  52 . Imaging device  52  can receive the signal  76  from this illumination source in its RED plane of the resulting color image. This structured illumination is configured to measure the profile of surface  66  of object  52 .  
         [0051]    The third illumination scheme is transmitive illumination, facilitated by a third source comprising a metal-halite light source  78  and an interference filter  80  at 435 nm (blue). The white light radiation from source  78  is modified (modulated) by passing through filter  80 . After passing through filter  80 , the radiation from source  78  has only a single wavelength, 435 nm. This mentioned wavelength is the signature of the radiation from source  78  that is unique and discernible in the imaging device  52 . Imaging device  52  can receive the signal from this illumination source in its BLUE plane of the resulting color image. This illumination is designed to define contour boundaries  82  of object  58 . The radiation from a light source, such as source  78 , can be further modified by one or more optical components, such as an optical screen  82 . Screen  82 , in this particular embodiment, comprises a condensing lens (not shown) and a diffuser (not shown) to deliver a uniform light panel for transmitive illumination. Screen  82 , in different embodiments, can have different arrangements and components.  
         [0052]    In system  50 , the radiation rays from sources  60 ,  72  and  78  strike object  52  simultaneously. The radiation rays interact with the optical properties of object  52 . Nevertheless, the unique signatures of these radiation rays, the corresponding wavelengths, are not affected by such interactions. After the interactions, the radiation rays are collected by the imaging device  52 . In camera  52 , the radiation rays are demodulated by the color pixels. Within each color pixel, a portion is sensitive only to red light, such as the 670 nm radiation from source  72 , a portion is sensitive only to green light, such as the 575 nm radiation from source  60  (and filter  62 ), and a portion is sensitive only to blue light, such as the 435 nm radiation from source  78  (and filter  80 ).  
         [0053]    In an alternate embodiment, interference filters (not shown), instead of regular color filters, are placed in front of the monochromatic pixels. The interference filters can have selected wavelengths as desired for the imaging application. It is also possible to have less (such as 2) or more (such as 4) types of interference (or color) filters used in a color pixel.  
         [0054]    [0054]FIG. 7 illustrates an implementation with only  2  simultaneously illumination schemes, and thus only two types of interference (color) filters are needed in a color pixel.  
         [0055]    The schematic shown in FIG. 8 is an implementation with  4  illumination schemes. In this implementation, four types of interference (color) filters are needed in a color pixel. In this embodiment, a fourth source comprising a metal-halite light source  84  and an interference filter  86  at a wavelength of 550 nm are provided. Source  84  and filter  86  facilitate bright field illumination to object  58 . In this embodiment, imaging device  52  is modified. The green color filters in camera  52  are not effective in differentiating the radiation rays from source  60  (575 nm) and source  84  (550 nm). These green color filters in camera  52  must be replaced by two types of interference filters, one at 550 nm and another at 575 nm. That is, a color pixel in camera  52  has at least four monochromatic pixels, one with a red color filter, one with a blue color filter, one with a 550 nm interference filter, and one with a 575 nm interference filter.  
         [0056]    It is also possible to have one radiation source for two or more radiation projectors. In the schematic shown in FIG. 9, a light focusing device  88  is used to put the radiation from source  60 , a metal-halite light source, into a light guide  90 . Light guide  90  can be a fluid-based light guide, a periscope, an optical fiber bundle, or other devices having similar functionality. A portion of the light is delivered by light guide  90  to a projector  92  and another portion of the light is delivered by light guide  90  to a projector  94 .  
         [0057]    It is also possible to use a color camera  52 ′ that is made of multiple CCD chips  96   R ,  96   G , and  96   B  such as a 3-chip CCD camera. In this arrangement, there will be a prism  98  that separates the red, green, and blue light, and deliver the light of each color to a respective one of the CCD chips.  
         [0058]    It is possible, for those who are skilled in the art, to have an interference filter (not shown) installed in front of each CCD chip  96   R ,  96   G , and  96   B  in this configuration. It is also possible, for those who are skilled in the art, to have one or more CCD chips, with associated interference filters, installed in this configuration.  
         [0059]    In another embodiment, multiple CCD cameras  521 ,  522 ,  523  are provided in the imaging device  52 , as shown in FIG. 11. In this case, the radiation to be collected is split using beam splitters  106 ,  108  into several copies with each directed to a respective CCD camera  52   1 ,  52   2 ,  52   3 . A respective interference filter  100 ,  102 ,  104  are installed in front of each CCD camera. In the illustrated embodiment, these filters  100 ,  102  and  104  filter at 670 nm, 575 nm, and 435 nm, respectively. These cameras can be used in a synchronous mode, for grabbing images at exactly the same time, or in an asynchronous mode.  
         [0060]    In another embodiment, multiple CCD cameras in the imaging application, as shown in FIG. 12. The radiation to be collected is directed into several cameras with interference filters in front of the cameras. The cameras are positioned at the best locations with the best attitudes to accept the intended radiation signals. These cameras can be used in a synchronous mode, for grabbing images at exactly the same timing, or an asynchronous mode. FIG. 12 shows a radiation source  110 , such as a metal-halite lamp, proximate an interference filter  112 , configured at 435 nm. Light rays  114  emerging from filter  112  impinge on object  58 , producing reflected light rays  116 . A corresponding interference filter  118 , configured at 435 nm, its only light at such wavelength passing therethrough. Imaging device, such as CCD camera  120 , is disposed proximate filter  118 , and permits capture the reflected radiation. Likewise, FIG. 12 further shows another radiation source, such as a laser line generator  122 , configured to radiate at 670 nm, shown in schematic fashion as generated light ray  124 . Reflected ray  126  passes through an interference filter  128 , a 670 nm interference filter, and thence to CCD camera  130 .  
         [0061]    For instance, a semiconductor wafer inspection station can utilize the simultaneous illumination technology to conduct both the inspections facilitated by dark field illumination and bright field illumination. Furthermore, the images obtained using different illumination schemes can be accurately cross-referenced (overlapped) for better defect detection. The inspection throughput is increased because image acquisition is done simultaneously. The risk of damaging the wafers is lowered because the wafers are not moved from one station to another.  
         [0062]    In another aspect of the present invention, problems caused by ambient light are minimized or eliminated. Ambient light, such as sunlight, indoor lighting, or reflection/shadow from a person walking by the imaging site, can influence the performance of a machine vision system. According to this aspect of the present invention, the projected light from sources  36 ,  38 ,  40 , . . . ,  42 , in this alternate embodiment, are modulated. Modulation may occur, for example, by way of frequency modulation (FM) or a particular wavelength. Any ambient light can be removed through, for example, a difference operation: light (on)−light (off=ambient_light). Through the foregoing, the machine vision system can see just the projected light.  
         [0063]    The imaging system of the present invention can be used in the semiconductor industry for wafer inspection, either for inspecting non-patterned wafers or patterned wafers. The imaging system of the present invention can also be used in the semiconductor industry for the inspection of printed circuit boards used in chip packaging. The imaging system of the present invention can be used in the flat panel display industry for panel and circuit inspection. The imaging system of the present invention can be used in the printed circuit board industry for product inspection. The imaging system of the present invention can be used in the automotive industry for component inspection, such as, but not limited to, engine bearings and pistons, inspection.  
         [0064]    Those who are skilled in the art will also appreciate the fact that imaging device(s), and/or camera(s) in any formats, standard or non-standard, such as, but not limited to, RS170, CCIR, NTSC, PAL, line scan, area scan, progressive scan, digital, analog, time-delay integration, and others, can be incorporated into this invention, including the preferred embodiments herein described.