Patent Publication Number: US-2009232458-A1

Title: Optical Waveguide Splice Apparatus and Method for Performing a Splice of at Least Two Optical Fibers

Description:
RELATED APPLICATIONS 
     This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application Ser. No. 60/998,983, filed Oct. 15, 2007, which is incorporated by reference herein. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an optical waveguide splice apparatus and to a method for performing a splice of at least two optical waveguides. 
     2. Technical Background 
     A fusion splicer is commonly used to splice a pair of optical waveguides or fibers by thermally heating the ends of the optical fibers. Generally speaking, a fusion splicer aligns the fibers and then applies heat to fusion splice the ends of the two optical waveguides together to form a continuous optical waveguide. 
     SUMMARY 
     A fusion splicer of the disclosure is useful for splicing optical waveguides or fibers by thermally heating the ends of the optical fibers. The fusion splicer may comprise a camera for recording an image of the ends of the optical fibers. During a splice process, the recorded image is displayed on screen of the fusion splicer, thereby allowing a user to monitor the splice process. 
     An optical waveguide splice apparatus according to an embodiment comprises a camera adapted to record an image of at least two optical waveguides, a screen, a control unit coupled to the screen to generate a display representation to be displayed on the screen, wherein the display representation comprises a first region comprising a first portion of the recorded image and a second region comprising a second portion of the recorded image, a semitransparent layer and information about a splice process. 
     In the embodiment, the recorded image and information about the splice process generated by the control unit of the optical waveguide splice apparatus may be displayed on the screen at the same time. The semitransparent layer provides a visual contrast with respect to the information about the splice process. Thereby, the readability of the information about the splice process is enhanced. Furthermore, an image of ends of optical fibers recorded by the camera and superimposed by the semitransparent layer is visible. 
     The provision of the semitransparent layer produces the visual impression, that the semitransparent layer is superimposed over the second portion of the recorded image, and that the portion of the recorded image is at least partially visible. This means, that the basic information of the recorded image is maintained in spite of the semitransparent layer. 
     A semitransparent layer as used herein refers to a layer which is neither fully opaque nor fully transparent. Furthermore, a fully transparent layer has a transparency value of 1 and a fully opaque layer has a transparency of 0. Accordingly, a semitransparent layer has a transparency value of between 0 and 1. 
     It is to be understood that both the foregoing general description and the following detailed description present embodiments of the invention, and are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed. The accompanying drawings are included to provide a further understanding of the invention, and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments of the invention, and together with the description serve to explain the principals and operation of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is explained in detail below using exemplary embodiments with reference to the accompanying drawings, in which: 
         FIG. 1  shows an optical waveguide splice apparatus according to an embodiment; 
         FIG. 2  illustrates a schematic view of the optical waveguide splice apparatus shown in  FIG. 1 ; 
         FIG. 3  shows a schematic representation of a screen of an optical waveguide splice apparatus according to an embodiment, on which a display representation composed of an image recorded by a camera and of splice information is displayed; 
         FIG. 4  shows a schematic representation of a screen of an optical waveguide splice apparatus according to an embodiment, on which a display representation composed of an image recorded by a camera and of splice information is displayed; 
         FIG. 5  shows a screen of an optical waveguide splice apparatus according to an embodiment, on which a display representation of an image recorded by a camera is displayed; 
         FIG. 6  shows a schematic representation of a screen of an optical waveguide splice apparatus according to an embodiment, on which a display representation comprising splice information, is displayed; 
         FIGS. 7A ,  7 B,  7 C illustrate the determination of a color value of a pixel of the display; 
         FIG. 8  shows a schematic representation of a screen of an optical waveguide splice apparatus according to an embodiment, on which a display representation composed of an image recorded by a camera and of splice information is displayed. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Whenever possible, like reference numbers will be used to refer to like components or parts. 
       FIG. 1  shows an optical waveguide splice apparatus  1  for splicing optical waveguides such as optical fibers according to an embodiment. The fusion splicer  1  comprises a removable cover  100 , under which elements of the fusion splicer  1  are disposed. 
     After splicing ends of optical fibers, the splice region is typically protected from mechanical damage. For protecting the splice region, a shrinking hose may be pulled over the splice region and heated using for example the shrink oven  300 . The heating results in a contraction of the shrinking hose wherein the position of the shrinking hose is fixed around the splice. 
     Control elements  6  such as buttons, allow a user to control the operations of the splicer  1 . Operator control may include inputting certain commands and parameters which are processed by a control unit (not shown in  FIG. 1 ). The fusion splicer  1  further comprises a screen  2  for displaying computer software application, for example, a graphical user interface of software for controlling the fusion splicer  1 . 
     After the fusion splicer is switched on by pressing for example the button  6   f , a main menu of the splicing software is displayed on the display  2 . The main menu may comprise a list of sub menus. By means of the buttons  6   d ,  6   e ,  6   b  and  6   c , a user can navigate through the different menus. The main menu comprises a sub menu for selecting a specific splice program, a sub menu for controlling the shrink oven  300 , a sub menu for changing settings of the fusion splicer and a sub menu for performing maintenance of the fusion splice and so forth. 
     The cover  200  may be closed when the fusion splicer  1  is not in use, for example, during transporting the fusion splicer  1 , to protect the control elements  6  and the screen  2  from being mechanically damaged. 
       FIG. 2  illustrates a schematic view of an optical waveguide splice apparatus  1  according to the embodiment shown in  FIG. 1 . The fusion splicer  1  is used to connect an end  5   a  of a first optical fiber  4   a  and an end  5   b  of a second optical fiber  4   b  by means of a splice process. 
     Positioning units  14   a ,  14   b  are provided for aligning the ends of the fibers to be spliced. Each of the positioning units  14   a ,  14   b  may comprise one or more V-shaped grooves  15  extending along a Z-direction, in which the optical fibers  4  are placed. The positioning units  14   a ,  14   b  may comprise 12 of these grooves  15  to receive a plurality of optical fibers  4  contained for example in a ribbon. The first and the second optical fibers  4   a ,  4   b  are placed in respective grooves  15   a ,  15   b  of the positioning units  14   a ,  14   b  such that faces  31   a ,  31   b  of the ends  5   a ,  5   b  of the first and the second optical fibers  4   a ,  4   b  substantially face each other. 
     The screen  2  is coupled to a control unit  9  and adapted to display a graphical user interface of the application software and the data. The screen  2  may be an LCD screen or a TFT screen. In an embodiment, the screen  2  is configured as a touch screen, wherein the control unit  9  detects when a specific portion  50  of the display  2  is touched by user. In response to the touching of the specific portion  50 , the control unit  9  performs a dedicated function of the splice process, for example aligning the ends of the optical fibers or splicing the ends of the optical fibers. 
     The screen  2  comprises a plurality of pixels arranged in a matrix, which may comprise 640×480 pixels. Each of the pixels of the matrix is individually controlled by the control unit  9 . A color of each of the pixels is set by assigning each of the pixels a plurality of color values representing an intensity of a respective color. For example, based on the RGB-color model, a first color value R representing the intensity of the color red, a second color value G representing the intensity of the color green and a third color value B representing the intensity of the color blue may be assigned to each of the pixels. Alternatively, a plurality of color values may be assigned to each of the pixels based on the CMYK-, or the HSV-color model. 
     The fusion splicer  1  further comprises a camera  7 ,  8  coupled to the control unit  9  for recording an image of an area between a first electrode  12  and a second electrode  13 . The first and the second electrode  12 ,  13  are coupled to the control unit  9  for generating an arc and thereby heating the ends of the optical fibers. 
     In the embodiment shown in  FIG. 2 , the fusion splicer  1  comprises a first camera  7  for recording an image from a first angle and a second camera  8  for recording an image from a second angle. However, by providing a suitable optical system, only one camera may be used to record alternately or simultaneously images from the first and second angle. As depicted, the first camera  7  records an image along the X-direction and the second camera  8  records an image along the Y-direction. Furthermore, light sources  10  and  11  are provided to illuminate the area between the first and the second electrode  12 ,  13 . 
     After placing the optical fibers  4  in the positioning units  14   a ,  14   b  the splice process for connecting the respective ends  5   a ,  5   b  of the optical fibers  4   a ,  4   b  can be performed. A splice process may comprise the steps of aligning the ends  5  of the optical fibers  4 , analyzing properties of the ends  5  of the optical fibers, splicing the ends  5  of the optical fibers and evaluating the splice result. 
     The fusion splicer  1  is adapted to allow a user to perform the individual steps of the splice process either manually or automatically using software for controlling the splice process. A storage device  32  coupled to the control unit  9  is provided for storing data and application software, for example, the software for controlling the splice process, and for retrieving the application software and the data. 
     During the aligning step, the faces  31   a ,  31   b  of the optical fibers  4   a ,  4   b  are aligned with respect to each other and with respect to the first and the second electrode  12 ,  13  by moving at least one of the positioning units  14   a ,  14   b  using the position control unit  20  which is controlled by the control unit  9 . The position control unit  20  may comprise a motor or piezoelectric element to move at least one of the positioning units along the Z-direction. In addition, the position control unit may be adapted to move at least one of the positioning units along the X-direction and/or along the Y-direction. 
     The cameras  7 ,  8  are used to record images of the ends  5  of the optical fibers during the splice process. The images of the optical fibers recorded along the X-direction and along the Y-direction may be processed by the control unit  9  to determine the position of the ends  5   a ,  5   b  of the optical fibers  4   a ,  4   b . Based on the determined positions, the control unit  9  may calculate an offset along the X-, the Y- and the Z-direction between the ends of a pair of optical fibers and display a warning on the display, if the offset is greater than a predetermined value. In an embodiment, the aligning of the faces  31   a ,  31   b  may be based on the calculated offset. Furthermore, the control unit  9  may be adapted to determine the quality of the ends of the optical fibers and to display a warning on the display if the quality does not fulfill certain predetermined requirements. Evaluating the quality of the ends of the optical may include determining if dust or particles are disposed on an optical fiber and if a cleave angle of an end of an optical fiber is greater than a predetermined value. 
     The image recorded by the camera  7 ,  8  comprises a plurality of pixels, wherein a color of a pixel is determined by at least one color value representing intensity or a saturation of specific colors assigned to the pixel. In an embodiment, a color value of a grayscale table may be assigned to each pixel. In an other embodiment, three color values may be assigned to each pixel, wherein a first color value represents an intensity of the color red, a second color value represents an intensity of the color green and a third color value represents an intensity of the color blue. Alternatively, a plurality of color values may be assigned to each of the pixels based on the CMYK-, or on the HSV-color model. 
     The control unit  9  processes the image recorded by the camera  7 ,  8  and displays the processed image on the screen  2 . In an embodiment, the control unit  9  may comprise a first processor for performing numerical calculations and general control of the fusion splicer  1  and a second processor, for example a graphic processor, for displaying an image on the screen. 
     Processing the recorded image as used herein includes a number of manipulations of the pixels of the recorded image, for example selecting a portion of the recorded image and enlarging or diminishing the selected portion as well as changing a contrast or a color saturation of the recorded image. 
     In particular, the control unit  9  generates a display representation to be displayed on the screen  2  by assigning each pixel of the screen respective color values based on respective color values assigned to one or more of the pixels of the recorded image. 
       FIG. 3  illustrates a schematic representation of a view of the display being shown on the screen  2  of the splice apparatus. The display is generated by the control unit of the splice apparatus. The display schematically shows an image recorded by a camera of the splice apparatus. To identify the particular camera the display also shows an icon S 4  in its upper left corner. The icon with a marked character “X” indicates that the camera arranged in the x-direction has recorded the underlying image showing the position of the optical fibers  5  and  4 . So the user is able to identify the direction from which the picture was taken. 
     Furthermore, information S 2  about the splice process is shown together with a first icon S 1  and a battery icon S 3  in an upper portion P 1  of the display. In addition, a semitransparent layer T 1  is provided in the portion P 1 , such that the portion of R 1  of the underlying recorded image is still visible. Consequently, the portion with the splice information S 2 , S 1  and S 3  is shown simultaneously with the underlying portion of the recorded image. 
     In a second portion P 3  in region R 3  of screen  2 , the recorded image is shown, without any additional splice information. The display also comprises a third portion P 4  at the lower region R 4  of screen  2  providing further splice information. 
     In this embodiment, the splice information requests an action by the user. Particularly, the splice information in the second portion P 4  comprises some characters S 5  asking the user whether to start the actual splice process. Two words S 6  and S 7  having different characters and color are arranged in the lower corners of portion P 4 . Portion P 4  also comprises a semitransparent layer T 4  with a color represented by hatching, such that the underlying portion of the recorded image showing various optical fibers is still visible. 
     The display representation shown on the screen  2  allows simultaneously displaying a splice information image, camera position information and the recorded image. The splice information image comprises the splice information and a semitransparent layer. The splice information image is laid over the recorded image so that the recorded image is still visible. Due to the semitransparent layer in the regions P 1 , P 2  and P 4  the information of the underlying recorded image is still visible. 
     In an embodiment, the semitransparent layers T 1 , T 2 , T 4  in portions P 1 , P 2 , P 4  are superimposed on the respective parts of the recorded image. Furthermore, the splice information S 1  . . . S 7  is superimposed over the semitransparent layers T 1 , T 2  and T 4 . The semitransparent layers T 1 , T 2 , T 4  serve to provide a contrast with respect to the splice information S 1 , . . . , S 7  and thereby enhancing the readability of the splice information S 1 , . . . , S 7 . In addition, the portions of the image of the optical fibers superimposed by the respective foregrounds are still visible. 
     During operation of the splice apparatus, a user is able to see all information about the splice process and the recorded image of, for example, an optical fiber alignment without switching the display representation. Additional and important information in various colors can be superimposed on a recorded image, providing the user with additional information. Particularly, information about the underlying recorded image can be displayed simultaneously on the screen. 
     Thus, a user can be provided with all available information on the screen  2  without switching a display representation between any splice information being displayed or not and the recorded image. 
     In situations in which the user requires both hands to operate the splice apparatus, for example to prepare optical fibers for a subsequent splice process, the user is able to see his working results without interrupting his work to switch the display. Real-time operation including checking the results of actual process becomes possible. Accordingly, the handling of the fusion splicer is improved and time can be saved during the splice process. 
       FIG. 4  shows a further embodiment of a schematic representation of a display shown on a screen  2  combined of a recorded image and one or more splice information images. As in the previous exemplary display, the upper portion P 1 ′ in region R 1 ′ of screen  2  comprises a superimposed image of a portion of the recorded image and the splicing information image. The latter comprises the same information as in the previous example according to  FIG. 3 . 
     Further, the user is requested to choose whether to continue the splice process. For this purpose, the lower regions R 5 ′, R 6 ′ and R 7 ′ of the display representation shows information S 9  representing a result from a previous measurement. In this case, the user is informed about a fiber offset which is in the particular embodiment &gt;7.5 μm. 
     In region R 6 ′ showing portion P 6 ′, the user can request further details of the previous fiber alignment. This is indicated by characters S 10  and S 11 . In addition, the user may choose in the portion P 7 ′ shown in region R 7 ′ of screen  2  whether to continue the splice process indicated by the characters S 7  or to cancel the splice process indicated by characters S 6 . Finally, in screen region R 3 ′ no additional splice information is displayed and only the recorded image is visible. 
     Again, the splice information in several portions as well as the underlying recorded image portions is simultaneously displayed. The semitransparent layers T 2 ′ in portion P 5 ′ of the display may comprise a different color compared to the semitransparent layer T 3 ′ in portion P 6 ′. For example, the colors chosen for the foreground T 2 ′, T 4 ′ and T 1 ′ can be set to a different colors compared to semitransparent layer T 3 ′. 
     The different colors for the semitransparent layers may indicate special functions, which can be requested by the user in order to receive additional information about the splice process. For instance, if the user requests more details by, for example, pressing a button assigned to the character S 11  or pressing the appropriate position on the screen, additional information about the splice process may be displayed in portion P 5 ′. Since at least portions P 1 ′, P 5 ′, p 6 ′ and P 7 ′ comprise a semitransparent layer, the underlying recorded image is simultaneously visible to a user. In such an embodiment the user can request various information about the splice process, for example the fiber offset while simultaneously controlling the splicing result visually. 
     In an embodiment, the control unit of the splice apparatus may generate in a first step a splice information image composed of the respective splice information and corresponding semitransparent layers. In a second step, the control unit may generate a combined display representation to be displayed as a display on screen  2  composed of the splice information image and the recorded image. 
     In another embodiment, the control unit may generate in a first step a plurality of splice information images, wherein each of the splice information images is composed of one of or more splice information and one or more corresponding semitransparent layers. In a second step, the control unit generates a plurality of combined display representations to be displayed on a screen, wherein each combined display representation is composed of a splice information image and a portion of the recorded image. 
     For this image processing, the control unit may comprise specific circuitry, for instance a graphic processor coupled to the control unit, or a sub-circuits implemented in a main processor. Processing a recorded image as used herein includes a number of manipulations of pixels of the recorded image, for example selecting a portion of the recorded image and enlarging or diminishing the selected portion as well as changing a contrast or color saturation of the recorded image. 
     In particular, the control unit or a graphic processor may generate an image to be displayed on the screen by assigning each pixel of the image respective color values based on respective color values assigned to one or more of the pixels of the recorded image and the splice information image. 
     With reference to  FIGS. 5 to 7  the generation of such combined image comprising a splice information image superimposed on a recorded image is explained in greater detail. 
       FIG. 3  shows a schematic representation of an image  42  recorded by a camera during the splice process, illustrating the ends  5  of a plurality of optical fibers  4 . The size of the image  42  equals the size of the screen, so the recorded image  42  can be displayed on the screen  2  completely. The image  42  comprises a plurality of pixel arranged in rows and columns. Each pixel comprises a value for one or more color values. Depending on a chosen color model, such as RGB, CMYK, HSV or others, a pixel may comprise a single value for different colors. Superposition of the values results in a combined color value of that pixel. Alternately, each pixel can be assigned a value representing a shade of gray, in case only black-white images can be displayed on the screen. 
     In  FIG. 5 , the references P 1 ′ to P 7 ′ corresponding to the portions of the combined image and corresponding regions of the screen in the embodiment of  FIG. 4  are indicated for convenience purposes. 
       FIG. 4  shows the splice information image also comprising a plurality of pixels arranged in rows and columns. The size of the splice information image equals the size of screen  2  and the size of the recorded image. The splice information image comprises the splice information S 2 , S 3  and S 6  to S 10  displayed on some colored background. The background color in portion T 3 ″ differs from the background color T 2 ″ and T 1 ″. In a portion, which is later shown in region R 3 ′ of the screen, no information is displayed. 
     In the present splice information image  4 , the user is informed about the specific splice program being in use and with the symbol S 3  about the charge status of a battery of the fusion splicer. Further, information about the results of an alignment step is provided, indicating that an offset between a pair of optical fibers to be spliced is greater than 7.5 μm. The splice information image also comprises a warning represented by the symbol S 8  displayed in the upper portion P 1 ′ of the splice information image and by the text “fiber offset &gt;7.5 μm” S 9  displayed in portion P 5 ′ of the splice information image. The splice information further comprises the terms “details” S 10 , “cancel” S 6 , “OK” S 7  displayed on the portions P 6 ′ and P 7 ′. In response to the warning being displayed, the user may touch corresponding region of the screen  2 , in case screen  2  is a touch-screen which respective information is displayed for affecting the control unit to execute a respective function. For example, if the user touches the region R 6 ′ in the embodiment of  FIG. 4 , an information about the offsets of each of the pairs of optical fibers is displayed. Furthermore, the user may touch the part the region R 7 ′ of the screen  2  on which the text “cancel” is displayed, to cancel or abort the current splice process. However, the user may also ignore the warning and touch the on which the text “OK” is displayed to continue with the splice process despite the warning. 
     The control unit or a graphic processor may generate a combined image composed of the recorded image and the splice information image. Such combined image considered as a display representation may then be display as a display on the screen. 
     Generating the combined display representation includes assigning a pixel of the combined image a combined color value derived from a respective color value of at least one pixel of the recorded image and from a respective color value of a at least one pixel of the splice information image. In an exemplary case of an RGB color model, the combined color values R, G, B are determined by adding the respective color value R1, G1, B1 of the pixels of the recorded image multiplied by an opacity value a and the respective color value R2, G2, B2 of the pixel of the splice information image multiplied by a transparency value. 
     For example, the intensity of the colors red R, green G and blue B of a pixel of the combined image to be display on the screen is calculated using the following formulas: 
         R=R 1 *α+R 2*(1−α)  (1) 
         G=G 1*α+ G 2*(1−α)  (2) 
         B=B 1*α+ B 2*(1−α)  (3) 
     wherein 0≦α≦1. In the present case, the factor (1−α) can be considered and defined a transparency value. Accordingly a transparency value of 0 indicated full opacity, while a transparency value of 1 represents full transparency. 
     Due to the fact that different portions of the splice information image comprise different information, different opacity values are used. For example, colour values R2, G2, B2 of pixel which show parts of the splice information, for instance a portion of a character, may be multiplied with a first transparency value (1−α), while pixels including only portions of the layers T 2 ″, T 3 ″ are multiplied with a different transparency value (1−α2). Accordingly, the corresponding opacity values are different as well. Depending on the chosen values, the background color becomes semitransparent. The first and the second opacity values α1, α2 may be set by a user by means of the splice software. In one embodiment, the first opacity value α1 is 1 and the second opacity value is 0.5. In such case, only the characters and symbols overlap the underlying recorded image, while the remaining portions of the splice information image, including the background portions are semitransparent. 
       FIGS. 7A ,  7 B and  7 C illustrate the determination of a colour value of a pixel of the display derived from a colour value of a pixel of the recorded image and a colour value of a pixel of the splice information image. In particular, the pixel of the splice information image comprises a portion of the splice information.  FIG. 7A  shows a pixel PX 1  of the recorded image having a colour value R1 representing the intensity of the colour red, a colour value G 1  representing the intensity of the colour green and a colour value B1 representing the intensity of the colour blue. The pixel PX 2  of the image comprising the splice information has a colour value R2 representing the intensity of the colour red, a colour value G2 representing the intensity of the colour green and a colour value B2 representing the intensity of the colour blue. The colour values R, B, G of the pixel PX 3  are determined using the above recited formulas (1), (2) and (3), wherein a is set to 0.5. As depicted, the pixel PX 3  has a colour combined from the colors of the pixels PX 1  and PX 2 . 
     After all pixels of the combined image are calculated by assigning each of the pixels of the display respective colour values R, G, B using the above mentioned formula the combined image is displayed on the screen. 
     Referring back to  FIG. 4 , the Figure illustrates the result of such superimposition of the images according to  FIGS. 5 and 6  using and different transparency and opacity values. 
     By adjusting the opacity value a and the transparency value (1−α), a user can individually select the best display representation. 
     The image  41  comprises a first portion P 1 ′ displayed in the first region R 1 ′ of the screen  2 , a second portion P 3 ′ displayed in the second region R 2 ′ and further portions P 5 ′ to P 7 ′ displayed in the third respective regions. 
     The colour values of each pixel of the portion P 3 ′ are determined by a first opacity value α1. In the embodiment shown in  FIG. 4 , α1 equals 0. Accordingly, the optical fibers are fully visible. 
     The portions P 5 ′ to P 7 ′ of the combined image  41  are composed of the corresponding portions of the recorded image  42  and of the splice information image  42 . Accordingly, colour values of pixels of the portions P 5 ′ to P 7 ′ derived from a pixel comprising a portion of the splice information S 6 , s 7  or S 9  are determined by a second opacity value α2. In the embodiment shown in  FIG. 7 , α2 equals 1. Therefore, the pixels of the second region R 2  of the display  2 , which comprise a portion of the splice information, are opaque. 
     The colour values of the remaining pixels of the portions P 5 ′ to P 7 ′ are determined by the corresponding pixels of the splice information image multiplied by a third opacity value a 3 . In the embodiment shown in  FIG. 4 , α3=0.5. However, other values for U 3  may be used, for example α3 may be between 0.3 and 0.7. 
     Finally, the portion P 1 ′ of image  41  is composed of the respective portion of the recorded image and of the image  4 . The colour values R, G, B of those pixels derived from a pixel comprising the splice information S 2 , S 3  and S 8  are determined by the second opacity value α2 or the third opacity value α3, wherein in the exemplary embodiment shown in  FIG. 2  α2 equals 1. Accordingly, thee pixels are opaque. 
     The colour values R, G, B of the remaining pixels of portion P 1 ′ are determined by the third opacity value a 3 . In the embodiment shown in  FIG. 5 , α3=0.5. However, other values for α3 may be used, for example α3 may be between 0.3 and 0.7. 
     By using suitable values for α2 and α3 for determining the color values of the pixels of P 1 ′, P 5  to P 7 ′, the opaque layers of the corresponding portions shown in  FIG. 6  is transformed into a semitransparent layer. 
     Accordingly, the combined image comprises parts with portions of the recorded image  42 , a semitransparent layer T 1 ′ to T 4 ′ superimposed over those portions of the recorded image and some splice information S 2  to S 8  superimposed over the semitransparent foreground  36 . 
     By selecting opacity values α2 and α3 suitably, the optical fibers comprised in the second portion P 2  and the third portion P 3  of the recorded image  40  are visible while the splice information is simultaneously displayed. 
     A further embodiment is shown in  FIG. 8 . In this representation, the combined image displayed on screen shows a recorded image of a plurality of spliced optical fibers  500   b  to  500 D on which on the right side quality parameters of the optical fibers are presented. Particularly, the attenuations determined in the previous measurement are displayed onto a semitransparent portion in region R 9  of the screen  2 . Each attenuation result is assigned to a corresponding optical fiber. A user is now able to check the optical fibers visually, for example to determine why a specific optical fiber comprises a very high or a very low attenuation. 
     For instance, very high attenuation of greater than 1 dB illustrated in character S 12 A in a different color is assigned to the first optical fiber in the upper part of a display representation. A user may now study the recorded image, particularly the optical fiber, to possibly determine the error causing the higher attenuation. Such study can be performed without changing the display. The different color for character S 12 A also indicate to the user a critical attenuation for the corresponding optical fiber. 
     In the lower right and left edges of the display representation in region R 10  two further icons S 13  and S 14  are displayed having a semitransparent foreground. By choosing one of the icons, for instance touching the screen at the appropriate position or selecting the icons by pressing a specific button, a user may repeat the previous measurement, continue the splicing process or cancel the whole process. 
     As a result the simultaneous representation of information about the splice process and an image of a splice to be or already performed provides a high flexibility and improvement. A user does not have to switch between the splice information being displayed or not by pressing a dedicated button. In particular in situations, in which the user uses both hands, for example to prepare optical fibers for a following splice process, the user does not have to interrupt his work to perform the switching. 
     Although the present invention has been illustrated and described herein with reference to preferred embodiments and specific examples thereof, it will be readily apparent to those of ordinary skill in the art that other embodiments and examples can perform similar functions and/or achieve like results. All such equivalent embodiments and examples are within the spirit and scope of the present invention and are intended to be covered by the appended claims. It will also be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit and scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.