Patent Publication Number: US-2023152232-A1

Title: Active illumination-based multispectral contamination sanitation inspection system

Description:
FIELD OF THE INVENTION 
     The disclosed subject matter relates to imaging systems associated with contamination and sanitation inspections. Specifically, the subject matter described herein allows a user to capture an image of a large scene (such as a food processing line facility or food products storage areas) and identify contamination within the scene and represent the contamination on a spatially accurate map (or floorplan) so that contamination within the inspection/map area is clearly identified and recorded for subsequent treatment. 
     BACKGROUND OF THE INVENTION 
     Outbreaks of food-borne illnesses (particularly bacterial illnesses) continue to be a problem in the food service industry. In many cases, bacterial contamination of food products and food handling facilities are the cause of the problem. One potential solution is an efficient and effective contamination identification system and an effective inspection protocol. 
     Handheld inspection devices give inspectors a degree of versatility and flexibility that improves both the speed and quality of the inspection process as well as immediate mitigation. Existing scanning technology relies primarily on the use of physical filters (and similar hardware devices) on imaging systems. There is currently no digital image chip-based sensor technology (e.g., existing CCD or CMOS image chips) designed for selecting and using specific wavebands for multispectral imaging and processing. Existing chip-based digital color image sensors are predominantly used for broadband RGB color imaging (e.g., Bayer filter array) and cannot be used for narrow-band multispectral fluorescence or reflectance imaging. The inventors have previously demonstrated that multispectral imaging can be effective to detect contamination on food materials or processing equipment (e.g., chlorophyll in animal fecal matter residues on plant crops or meat, biofilms). Examples of the currently-used technology are evident in the inventor&#39;s U.S. Pat. No. 8,310,544. More recent systems that perform some to the functions identified herein include U.S. patent application Ser. No. 17/161,567 (Pub. No. US 2021/0228757). Both U.S. Pat. No. 8,310,544 and U.S. patent application Ser. No. 17/161,567 are hereby incorporated by reference. 
     Sensor chip-based multispectral imaging allows for miniaturized instrumentation compared to existing technology. The system described herein incorporates orientation/position sensing capabilities and target recognition algorithms (such as a rangefinder and scene/facial/surface recognitions) that enable non-expert technicians to conduct effective inspections. For example, instead of requiring the user to precisely position an inspection device, the user simply moves the device toward a targeted surface so that multispectral imaging is automatically triggered (pulsed illumination and multiple images acquired within a second) when the device senses the surface in a certain distance range, with incorporation of a safety feature to prevent initiation of ultraviolet (UV)-based fluorescence imaging if any faces are detected within the field of view. 
     Use of the invention described herein could significantly facilitate image-based safety/quality inspection for food/agricultural processing and production environments with user-friendly, automated multispectral image analysis/processing and data presentation. The United States Department of Agriculture (USDA) Environmental Microbial &amp; Food Safety Laboratory (EMFSL) research has developed multispectral imaging techniques for contamination and sanitation inspection in part as a response to food safety issues related to the US Food and Drug Administration&#39;s Hazard-Analysis-Critical-Control-Point regulations and Food Safety Modernization Act guidelines/requirements. The technology and techniques described herein can facilitate the detection of specific contaminants of interest by making detection quicker, easier, and more intuitive in real-world user scenarios. The rapid detection helps the inspector to initiate disinfection or risk mitigation. One way of risk mitigation is to use UV germicide illumination to deactivate pathogen and remove the treat. 
     The system described herein also allows a user/inspector to conduct contamination inspections regardless of the lighting condition of the inspected space. This capability is important for conducting consistent and standardized inspections under a wide variety of ambient light environments. If contamination is present in the inspected space, the product of the inspection is an image of the inspected area showing the position of a fluorescent image of the contamination on a floor plan/map of the inspected space. 
     The need exists for an effective multispectral imaging system that allows a human inspector to capture an image of a large scene (such as a food processing line, facility, or food products storage areas) and identify contamination within the scene and represent the contamination on a user interface including on a spatially accurate map (or floorplan) so that contamination including invisible and poorly visible contaminations within the area including the map area is clearly identified and recorded for subsequent treatment and remediation. The digital report can be created to proof the cleanliness above human visual inspection capabilities. The current invention comprises a hand-held contamination sanitation inspection system (hereinafter, a “CSIS”) that enables an operator to quickly conduct and document sanitation inspections of a designated facility regardless of the lighting conditions in the inspected area. 
     SUMMARY OF THE INVENTION 
     This disclosure is directed to a handheld contamination sanitation inspection system (CSIS). The CSIS comprises at least one active illumination light (preferably an LED light) and at least one multispectral camera. In the preferred embodiment, the multispectral camera comprises a chip-based multispectral camera. The CSIS further comprises a processor that controls the active illumination light and the multispectral camera. 
     In operation, the CSIS is structured so that as a user directs the CSIS toward a target inspection area in ambient light, the processor directs the CSIS multispectral camera to acquire a multispectral image of the inspection area in ambient light. Immediately thereafter, the processor pulses at least one active illumination light and simultaneously acquires an illuminated multispectral image of the inspection area. The processor then subtracts the ambient light multispectral image from the illuminated multispectral image to produce a multispectral fluorescence image of any contamination in the inspection area. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The patent or application file associated with this disclosure contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee. 
         FIG.  1    is a perspective view of a user/operator-facing first side  30  of an exemplary embodiment of a CSIS  20 . The user-facing first side  30  of the CSIS  20  faces toward the user during CSIS  20  operation. In the preferred embodiment, the user-facing first side  30  includes (among other things) a user interface screen  32 . 
         FIG.  2    is a perspective view of an inspection area-facing second side  50  of an exemplary embodiment of a CSIS  20 . The inspection area-facing second side  50  is opposite the user-facing first side  30 . The inspection area-facing second side  50  of the CSIS faces away from the operator and toward the inspection area during CSIS  20  operation. In the preferred embodiment, the inspection area-facing second side  50  includes (among other things) light emitting diode (LED) lights  56 , and a multispectral imaging primary camera  52 , and a designated UV camera  54 . In the preferred embodiment, the multispectral imaging primary camera  52  comprises a chip-based multispectral camera. In alternative embodiments, the multispectral imaging primary camera  52  may comprise a conventional RGB camera with a multiband pass filter configured to produce a multispectral image. 
         FIG.  3    shows a color elevational schematic view of a multispectral filtering chip  60  comprising an array of bandpass filters  64  positioned to filter incident light  66  reaching a photosensor  62 . 
         FIG.  4    is a graphical representation showing three exemplary selected wavebands that may comprise the wavebands selected to produce a multispectral image. 
         FIG.  5    is an exemplary flowchart of an inspection protocol. 
         FIG.  6    shows a CSIS supplemental module  100  that can be added to a mobile device, such as a smart phone, to create an enhanced cell phone  102  with at least some CSIS capabilities. Note that it may be possible to modify other multifunctional electronic devices that have (or can be modified to have) a camera to perform some CSIS  20  functions. 
         FIG.  7    shows the enhanced cell phone  102  with the CSIS supplemental module  100  installed. 
     
    
    
     Note that assemblies/systems in some of the FIGs. may contain multiple examples of essentially the same component. For simplicity and clarity, only a small number of the example components may be identified with a reference number. Unless otherwise specified, other non-referenced components with essentially the same structure as the exemplary component should be considered to be identified by the same reference number as the exemplary component. 
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     System Description 
     As generally shown in  FIGS.  1  and  2   , the system  20  described herein comprises a contamination sanitation inspection system (hereinafter, a “CSIS”)  20 . The CSIS  20  enables the rapid detection of saliva, respiratory droplets, bacteria, fungi, or other organic residues that may be present in kitchens, dining areas, and food processing facilities, and other areas where food is present. The system  20  processes and records the detection data and thereby provides immediate documentation of contaminants on inspected surfaces. The CSIS  20  incorporates the technology to wirelessly communicate the inspection process, which allows remotely located personnel to provide oversight and respond to inspection issues in real time. 
       FIG.  1    shows an exemplary embodiment of a user-facing first side  30  of the CSIS system  20 . As shown in  FIG.  1   , the user-facing first side  30  includes an operator interface screen  32  that, in combination with the various function activation/selection control means (i.e. buttons, switches, levers, dials, rheostats, knobs, etc.)  38 , enables the user to control and communicate with the system  20 . In operation, a user holds the CSIS  20  by at least one of the handles  34  and directs the main body  36  of the system  20  toward an inspection area. 
     The CSIS  20  is specifically designed as a hand-held device. For the purposes of this disclosure, a “handheld device” is a device fully operable and useable by a single operator. A handheld device is sized so that the handheld device is compact and light enough to be carried and maneuvered by hand by a single operator via one or more handles  34 . In the preferred embodiment, the “hand grip(s)”  34  comprises an “ear” type configuration with two essentially symmetric handles. In alternative embodiments, the hand grip(s)  34  feature may comprise a single pistol-type grip or another configuration that enables a user to easily operate the system  20  with one or two hands. 
     The CSIS  20  may further include onscreen “touch screen” menus, or a remotely controlled wireless system for controlling the functions of the system  20  remotely. A data processor  40  is generally housed within the lower portion of the main body  36  of the CSIS  20 . Various storage, communication, and utility devices may be connected to the processor  40  through access ports  42  included on the CSIS  20  main body  36 . A chargeable battery module  44  is attached to the base of the system&#39;s  20  main body  36  to power the system  20 . In alternative embodiments, the CSIS  20  may send and receive data to/from a remote processor  40  that is not housed within the body  36  of the CSIS. 
       FIG.  2    shows an inspection area-facing second side  50  of an exemplary embodiment of a CSIS  20 . The inspection area-facing second side  50  is opposite the user-facing first side  30 . The inspection area-facing second side  50  of the CSIS  20  faces away from the user and toward the inspection area during CSIS  20  operation. The inspection area-facing second side  50  includes a multispectral primary camera  52 . In the preferred embodiment, the multispectral primary camera  52  comprises a “chip-based multispectral camera”. 
     For the purposes of this disclosure, a “chip-based multispectral camera” comprises a camera wherein incident light  66  passing through a camera lens is directed to a multispectral imaging chip  60  comprising a photosensor  62  covered by a matrix of narrow band pass filters  64 —as best shown in  FIG.  3   . Although the exemplary embodiment shown in  FIG.  3    depicts a relatively small bandpass filter  64  matrix, in operation, the filter  64  matrix may comprise hundreds or thousands of narrow bandpass filters  64 , the number of filters  64  being proportional to the resolution of the chip-based multispectral camera. The photosensor  62  receives the filtered light and generates a “multispectral image” which is then directed to the processor  40 . 
     For the purposes of this disclosure, a “multispectral image” is an electronic image comprising two or three selected/targeted light wavebands so that all other light wavebands are filtered out, as best shown in  FIG.  4   . The light wavebands that comprise a “multispectral image” are selected to generate a fluorescent response from contamination within an illuminated area. As shown in  FIG.  4   , in the exemplary embodiment shown in  FIG.  3   , the three target light wavebands comprise about 420-440 nm, 520-540 nm, and 690-710 nm. In alternative embodiments, different specific wavebands may be targeted. The targeted wavebands may have a span of about 10-30 nm. Preferably the targeted wavebands have a span of about 20 nm each. 
     In alternative embodiments, the multispectral primary camera  52  may comprise a conventional RGB camera with supplemental/separate multiple bandpass filter hardware configured to produce a multispectral image. For the purposes of this disclosure, an “RGB camera” is defined as a visible light camera with standard broadband filters through which colored images are acquired specifically to replicate human color vision perception. As discussed supra, the CSIS  20  may also include a designated UV camera  54  with multiple band pass filters. The cameras  52 ,  54  are at least partially surrounded by an array of active illumination LED lights  56 . In further alternative embodiments, the system may comprise more than one RGB or chip-based cameras. In any case, all cameras/imaging systems are controlled by the processor  40 . 
     In the preferred embodiment, the multispectral imaging chip  60  is paired with an active illumination system and specialized software to enable the CSIS  20  to detect and identify contamination regardless of ambient light conditions. As shown in  FIG.  2   , active illumination is provided by one or more of the of the LED lights  56  on the inspection area side  50  of the CSIS  20 . The LED lights  56  may comprise any lights (or combination of lights) in the electromagnetic spectrum including ultra-violet (UV) lights, near-infrared (NIR) lights, and infrared (IR) lights. 
     At least one pulsed light source  56  is used to provide synced/gated active illumination for multispectral imaging. Pulsed and synced/gated illumination enables automated multispectral fluorescence image acquisition and processing to be conducted in non-dark environments (i.e., outdoors in daylight or indoors with bright artificial lighting, as well as under darkened conditions) due to rapid processing of images. 
     For the purposes of this disclosure, an “Ambient light image” is a multispectral image acquired in the ambient light present in an inspection space without the presence of active illumination from the light source  56  present on the CSIS  20 . 
     Further, for the purposes of this disclosure, an “Illuminated image” comprises a multispectral image acquired in the ambient light present in an inspection space and with the presence of active illumination from the light source  56  present on the CSIS  20 . 
     System Operation 
     Pulsed and synced/gated illumination enables processing for immediate, nearly instantaneous fluorescence-based feature detection for real-time inspection of the scene being examined by a user. In the preferred embodiment, real-time highlighting of detection results can be captured “live” on the CSIS screen  32 . Alternatively, the detection results can be captured in still images as selected by the user. The results of the inspection can be viewed, processed, and recorded as a continuous video stream, or as a series of still images. In either case, detected contamination is preferably depicted as an image of fluorescence. The inspection data can be communicated via any wireless (BLUETOOTH, wifi, etc.) or wired communication format/means. 
     Essentially, in accordance with the image acquisition protocol, the CSIS  20  takes two multispectral images under two conditions: the first image (an “Illuminated image”) is taken with the selected LED lights  56  pulsed “on” in ambient light conditions; and, the second image (an “Ambient light image”) is taken with the LED lights  56  pulsed “off” in ambient light conditions. 
     The multispectral fluorescence response of objects within the field of view of the camera is acquired through the following equation: 
       Multispectral fluorescent image=Illuminated image−Ambient light image
 
     For example, a single multispectral image acquisition protocol (a “single shot” image acquisition cycle triggered by the user) comprises the steps of:
         1. Pulse the LED light source  56  ON, (fluorescence excitation) and the CSIS  20  acquires an illuminated image at the two or three filtered targeted wavebands (as shown in  FIG.  4   ).   2. Pulse the light source  56  OFF, and the CSIS  20  simultaneously acquires an ambient light image at the same two or three targeted wavebands under ambient light (background conditions).   3. The CSIS processor  40  software automatically processes the acquired images to subtract the ambient light image from the illuminated image to acquire a multispectral fluorescence image of the inspection area.   4. The CSIS processor  40  software automatically highlights contamination targets within the inspection area and displays the multispectral fluorescence image onscreen  32  for the user, including: (1) image registration to correct slight mismatch of images resulting from any movement of device between the ON and OFF pulsing of the light source  56 ; (2) background removal; and, (3) band ratios; and (4) multispectral image processing algorithms.       

     In operation, the “single shot” protocol described in steps 1-4 is repeated continuously until the inspection is complete. 
     Data Analysis 
     The image data generated by CSIS  20  can be analyzed using computer vision classification algorithms. The detection algorithm continuously adapts to changing fluorescence and background intensity levels. While imaging with a fixed-mount camera can allow simple conventional thresholding (e.g., Otsu method) and supervised learning, constantly moving the camera across different scenes is more complex. To address this complexity, the inventors adopted adaptive thresholding to change the threshold dynamically over each frame. Whenever intensities between an object&#39;s fluorescence and the image background are significant, but their exact magnitude or location in the image is unknown, segmentation is possible by threshold optimization through the image intensity histogram. Alternatively, the image data can be analyzed using deep learning approach to provide semantic segmentation for the precise detection and segmentation of contaminated areas. Over the past ten years, there have been significant contributions to semantic segmentation systems by neural network systems including ALEXNET, GOOGLENET, and RESNET by MICROSOFT. Semantic segmentation assigns classification values at the pixel level in an image. 
     The CSIS  20  can be also connected to a cloud data base with a distributed learning paradigm (e.g. Federated Learning) that can learn a global or personalized model from decentralized datasets on edge devices (including CSIS). This is highly desirable for the users who do not share a complete data set with the main cloud system due to privacy concerns, while the data analytics (e.g. image classification, image segmentation, and object detection) is highly needed to improve the contamination detection and segmentation learner. 
     Inspection Protocol 
       FIG.  5    generally describes the data gathering and processing protocol  70 . In accordance with the protocol  70 , a user holds and points the CSIS  20  in the direction of an inspection area and takes a color image of the whole scene using the primary multispectral camera  52 . As the inspection progresses, the user systematically acquires multispectral images of the entire inspection area ( FIG.  5    reference numbers/steps  72 - 84 ). 
     As further described in  FIG.  5    reference numbers/steps  86 - 90 , once the area/sub area inspection is complete, the CSIS processor  40  processes all fluorescence and reflectance images to identify any contamination or anomalies and a virtual montage of the inspection area is created and the data is presented as an overlay of the inspection area to allow a user to take remedial action if required. Alternatively, the CSIS processor  40  may process the multispectral images in real time, based on the capability of the processor and/or the needs of the inspector. 
     Mapping 
     In the preferred embodiment, the CSIS  20  is equipped with position/orientation sensing hardware (e.g., GPS, accelerometer, motion/rotation sensor, rangefinder, light detecting and ranging (LiDAR) technology, etc.) to create feature maps and to precisely identify features of interest imaged at close range within a larger scene image. In the case of a facility inspection, the location of any detected contamination can be mapped onto a representational map or floorplan (that may also be preloaded). Mapping the position of detected contamination relative to localized reference features within a larger scene provides precise reference data that can make remediation/decontamination more efficient and reliable. The inclusion and mapping of reference features means that users/inspectors no longer have to rely on human observation and memory or descriptive note-taking. 
     Specific Alternative Embodiments 
     Although multiple alternative embodiments of the current system  20  are identified in this disclosure, the current section of the disclosure further discusses some specific embodiments. This section is not intended to be a complete list of possible embodiments or to limit the number and type of embodiments in any way. 
     In one alternative embodiment, the CSIS  20  may incorporate a disinfection means, so that the composite system comprises a sanitation inspection and disinfection system (hereinafter a “CSI-D”). In the CSI-D embodiment, the inspection area-facing side of the CSIS specifically further includes excitation lights  56  comprising UV-B or UV-C active illumination lights, or the excitation lights  56  may comprise other types of electromagnetic radiation or laser lights having disinfecting/sanitizing capabilities. The CSI-D embodiment enables a user to effectively sanitize an inspected surface after the inspection process identifies a contaminating material on the inspected surface. 
     The CSI-D embodiment also enables a process of multispectral fluorescence inspection and decontamination of live plants in a plant production area/facility such as a farmer&#39;s field, a greenhouse, a hydroponics production facility, or any other area where plants are produced. In a plant production environment, the CSI-D is used to detect either (1) the presence/location of plant disease agents such as mildew, fungal spores and mycelia, bacterial/viral infection points, or (2) the symptoms of such diseases, both of which would be detected in fluorescence images of the plant tissues. Inspection with real-time image processing to highlight the contaminant locations or plant symptoms can then be followed immediately by UVB/UVC treatment to (1) deactivate plant disease agents or mitigate the severity of their effects, or (2) strengthen the plant by inducing an increase in UV light-sensitive defenses and by gene activation to stimulate biological defense responses to aid the plant&#39;s resistance to or recovery from the disease agents. 
     In a further alternative embodiment, mobile or portable devices such as smartphones, tablets, laptops, or other devices that may include a camera and/or data processing capabilities may be augmented or modified to perform some of the functions described herein. 
     As shown in  FIGS.  6  and  7   , a supplemental camera/active illumination module  100  can be added to a cell phone to create an enhanced cell phone  102  with at least some CSIS-type capabilities. The CSIS supplemental module  100  comprises a camera with a narrow band pass multispectral filter  104  and a user-selectable light source  106 . As shown in  FIG.  7   , the necessary structural modifications to the existing cell phone are relatively minor. Software modifications will be also be required to modify a conventional cell phone to operate with the enhanced CSIS capabilities. 
     For the foregoing reasons, it is clear that the subject matter described herein provides a compact and innovative multispectral imaging system  20  to be used for surface inspection and contamination identification under a wide range of ambient light conditions. The current system  20  may be modified in multiple ways and applied in various technological applications. For example, the system  20  may be modified to include a decontamination capability. The system  20  may also take the form of a modified cell phone  102  or other modified electronic device. The disclosed method and apparatus may be modified and customized as required by a specific operation or application, and the individual components may be modified and defined, as required, to achieve the desired result. 
     Although the materials of construction are not described, they may include a variety of compositions consistent with the function described herein. Such variations are not to be regarded as a departure from the spirit and scope of this disclosure, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims. 
     The amounts, percentages and ranges disclosed in this specification are not meant to be limiting, and increments between the recited amounts, percentages and ranges are specifically envisioned as part of the invention. All ranges and parameters disclosed herein are understood to encompass any and all sub-ranges subsumed therein, and every number between the endpoints. For example, a stated range of “1 to 10” should be considered to include any and all sub-ranges between (and inclusive of) the minimum value of 1 and the maximum value of 10 including all integer values and decimal values; that is, all sub-ranges beginning with a minimum value of 1 or more, (e.g., 1 to 6.1), and ending with a maximum value of 10 or less, (e.g. 2.3 to 9.4, 3 to 8, 4 to 7), and finally to each number 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 contained within the range. 
     Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as molecular weight, reaction conditions, and so forth as used in the specification and claims are to be understood as being modified in all instances by the implied term “about.” If the (stated or implied) term “about” precedes a numerically quantifiable measurement, that measurement is assumed to vary by as much as 10%. Essentially, as used herein, the term “about” refers to a quantity, level, value, or amount that varies by as much 10% to a reference quantity, level, value, or amount. Accordingly, unless otherwise indicated, the numerical properties set forth in the following specification and claims are approximations that may vary depending on the desired properties sought to be obtained in embodiments of the present invention. 
     Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods and materials are now described. 
     The term “consisting essentially of” or excludes additional method (or process) steps or composition components that substantially interfere with the intended activity of the method (or process) or composition, and can be readily determined by those skilled in the art (for example, from a consideration of this specification or practice of the invention disclosed herein). The invention illustratively disclosed herein suitably may be practiced in the absence of any element which is not specifically disclosed herein. The term “an effective amount” as applied to a component or a function excludes trace amounts of the component, or the presence of a component or a function in a form or a way that one of ordinary skill would consider not to have a material effect on an associated product or process.