Abstract:
A fiber end-surface inspection device and method illuminates the fiber end-surface from at least 2 different illumination angles, taking observations at the different angles, for detection of fiber end-surface imperfections, scratches or the like.

Description:
BACKGROUND 
     This disclosure relates to testing of fiber optic communication lines, and more particularly to the inspection of the end surfaces of fiber optic cables. 
     Current fiber inspection probes (or cameras) in the market use one fixed light (for example, a LED or light bulb) that shines light through a prism onto the fiber end-surface for inspection. The detection of defects on fiber end-surface can be dependent on the angle of the single light source provided with a typical fiber inspection tool. With a typical single light source tool, in a particular case it may be that a scratch cannot be detected from first inspection, but, upon a user manually rotating or otherwise maneuvering the fiber to get different angles of light falling on the fiber end, scratches that might not be visible at first, may come into view. 
     To inspect dirt or chirp of fiber connector-end, a small fiber scope (or probe) is typically used. In machine vision systems, light source is one of the key factors. Some of the big scope stations use fiber ring light sources and other small scopes use a LED light next to the scope. If the light shades from center or perimeter like fiber ring light source, some of the defects (dirt, chirp, or scratch) are difficult to find because defects can be obscured by shadows. On the other hand, if the light is from side, the other half of the fiber-end becomes dark because the fiber-end is not a straight plane but instead has curvature. Thus, some experienced technicians rotate the fiber to inspect the other side of the fiber end. However, this method does not work with angled connectors and with automated fiber-end inspection system using machine vision. Also, requiring such manual movement to accomplish testing adds a factor of operator skill to the reliability of the test results, which is undesirable. 
     SUMMARY 
     In accordance with the disclosure, a fiber end-surface inspection tool provides dual (or multiple) light sources for inspection, and can toggle the application of light from the different sources, providing improved scratch detection. 
     Accordingly, it is an advantage of the present disclosure to provide an improved fiber end-surface inspection tool. 
     It is a further advantage of the present disclosure to provide an improved method for inspecting fiber optic communication line fiber end-surfaces. 
     It is yet another advantage of the present disclosure to provide an improved system for inspecting the end-surfaces of fiber optic cables. 
     The subject matter of the present technology is particularly pointed out and distinctly claimed in the concluding portion of this specification. However, both the organization and method of operation, together with further advantages and embodiments thereof, may best be understood by reference to the following description taken in connection with accompanying drawings wherein like reference characters refer to like elements. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of a device in accordance with the present disclosure; and 
         FIG. 2  is a flow chart of the operational steps of performing tests with the device of  FIG. 1 ; 
         FIG. 3  is a view of an implementation of the light sources and camera; 
         FIG. 4  is a view of an alternative implementation of the light source and camera, using a variable angle mirror; 
         FIG. 5  is a view of the system of  FIG. 4  with the mirror at a first angle; 
         FIG. 6  is a view of the system of  FIG. 4  with the mirror at a second angle; and 
         FIG. 7  is a flowchart of the operational steps with a pivoting mirror configuration. 
     
    
    
     DETAILED DESCRIPTION 
     The system according to a preferred embodiment of the present disclosure comprises a device that uses two (or more) LEDs positioned at locations to provide different angles of application of the light source. In operation, first, one LED is turned on, and an image of the fiber end-surface is taken. Then, that first LED is turned off and the second LED is turned on, and another image is taken, providing multiple angles of applied light automatically, without requiring the operator to manually rotate, or maneuver the fiber or the light source. 
     Referring to  FIG. 1  a block diagram of a test device  10  in accordance with the disclosure, the device includes a test chamber  12  (which may comprise an open air space), having first and second light sources  14 ,  16 , suitably LEDs in a particular embodiment, with the 2 LEDs positioned at alternated sides of a camera  18 . The camera and LEDs are controlled by/communicate with a processor  20 . Camera  18  observes viewing position  22  which is positioned at or receives therein a fiber optic cable end  24  therein, for inspection. 
     A display  26  for displaying results, images and providing a control interface (in conjunction with user interface  28  (e.g., keys or touch screen functionality) also interfaces with the processor. Power supply  30 , which can be battery or AC mains supply, provides power to operate the device. 
     Referring now to  FIG. 2 , a flow chart of the operational steps of testing a fiber end-surface, first, the fiber is positioned (step  32 ) at an inspection site (for example, viewing position  22 ), whereupon the first light (assuming a 2 light system) is turned on (step  34 ) and an image of the fiber end-surface is captured (step  36 ), and provided to the processor or otherwise stored. Next, the first light is turned off (step  38 ) and the second light is turned on (step  40 ), providing illumination of the fiber surface from a different light angle. An image is captured (step  42 ) and stored or otherwise held for further use, and the second light is turned off (step  44 ). The resulting images may be superimposed (step  45 ), employing the images taken in different directions to get a complete image that contains defects observed in every directions. The resulting combined image, that contains all the defects as observed from the multiple angles of illumination, may be processed (step  47 ) by image processing algorithm to detect defects automatically. 
     The resulting images may be displayed also for visual inspection by an operator of the device, thereby providing detection of defects, scratches, etc. 
     The operation may be automated by processor  20 , in conjunction with the camera to automatically detect when a fiber is present, or can be performed under direction of a user. 
       FIG. 3  is an illustration of a two light source illumination system wherein camera  18 ′ observes the fiber under test  24 ′ through first and second coated prisms which are positioned in line with one another, with their reflection direction oriented towards the fiber under test. First prism  46  is closest to camera  18 ′, and receives and reflects light from light source  50  at orientation  52 . Second prism  48  is spaced between the first prism and the fiber under test, with its reflective surface directed to reflect towards the fiber under test. Light source  54  is positioned to provide light to the prism  48 , which is reflected towards the fiber under test at orientation  56 . The prisms are positioned such that orientations  52  and  56  provide light to the fiber under test at different angles. As is known in the art, the prisms reflect part (typically half) of light from the light sources, and part of the light reflected from the surface of the fiber under test is transmitted to camera  18 ′ which observes the reflected light  58  from the fiber under test as passed through the prisms. The illumination of lights sources  50 ,  54  may be accomplished in accordance with the steps of  FIG. 2 , wherein the light sources are alternately illuminated. 
       FIG. 4  illustrates an alternate embodiment employing a single light source and an alternating angled mirror to provide different angles of light injection to the fiber under test. Partial mirror  60  is positioned between camera  18 ′ and fiber under test  24 ′, with the mirror adapted to be pivoted about axis  62  as illustrated by arc  64 . Two possible positions of the mirror are illustrated in  FIG. 4 , a left-most and right-most position (when considered from the top of the mirror in  FIG. 4 ) Light source  66  shines light  68  to the reflective surface of the mirror, causing reflected light  70 ,  72  to be transmitted to the fiber under test, reflected light  72  coming from the mirror when in the right-most tilt position and reflected light  70  coming from the mirror when in the left-most tilt position. Camera  18 ′ then observes the reflected light from the fiber under test. 
       FIG. 5  is representative of the setup with the mirror in a first, left-most position, and illustrates the transmission  70  and reflection  74 ′ of light with the mirror at a first angle, while  FIG. 6  illustrates the transmission, and reflection of light with the mirror at a second angle. The fiber under test is thus illustrated with light from two different angles. Configurations may be employed that alter the mirror angle to more than 2 different angles. 
       FIG. 7  is a flowchart of the operational steps with a pivoting mirror configuration, wherein the fiber is positioned for inspection at step  32 ′, the light source  66  is illuminated and the mirror  60  is moved to a first position, step  76 . An image is then captured at step  78  and suitably stored for future use and processing. Next, a decision is made as to whether sufficient images have been captured. Ideally 2 or more different mirror position images would be taken. If a sufficient number have not been taken, then in block  82  is entered to reposition the mirror to a different angle then previously employed, and the process loops back to block  78  to capture another image. If a sufficient or desired number of images have been captured at block  80 , then the light source is turned off at step  84 , the images taken and stored may be superimposed (step  85 ) to provide a single image having all the defects as detected from various angles of illumination, and analysis may be performed on the combined image (step  87 ) and the process is complete. 
     An alternative embodiment employs multiple light sources, for example more than 2 total, with the light sources positioned spatially in different locations to provide additional angles of light illumination of the fiber under test, or, as noted above, by angling of mirror  60  to more than 2 different angles relative to the fiber under test. 
     Still further, a single light source may be employed, with direction of the light through a splitter or other method so as to provide illumination of the fiber end-surface from more than one angle. 
     The test device may be implemented as a hand held/portable device, or a bench top test unit, for example. 
     Accordingly, an improved method and device for inspecting fiber end-surfaces is provided. 
     While a preferred embodiment of the technology has been shown and described, it will be apparent to those skilled in the art that many changes and modifications may be made without departing from the broader aspects. The appended claims are therefore intended to cover all such changes and modifications as fall within the true spirit and scope of the technology.