Modern computing systems typically include several computing, storage and networking components. These components communicate with one another via communication cables which carry, for example, electrical or optical signals between the components. Increasing the number of components in a system leads to corresponding increases in the number of required communication cables.
It may be necessary to trace the path of a particular communication cable during maintenance and/or repair of a computing system. Tracing the path of a particular cable amongst dozens or hundreds of adjacent and intertwined cables, particularly in a data center environment, is time-consuming and inefficient. Some systems attempt to address this issue by providing a light source at each end of a cable. These systems facilitate identification of cable ends, but do not address the identification of other portions of the cable. Such systems would not improve a technician's ability to, for example, find a cable among a large bundle of cables laying in a data center cable tray.
Systems are desired to efficiently assist in the tracing of communication cables.
The following description is provided to enable any person in the art to make and use the described embodiments. Various modifications, however, will remain readily-apparent to those in the art.
Generally, some embodiments provide a system to selectively illuminate a communication cable. A cable according to some embodiments includes a first cladding covering at least a portion of the cable and a second cladding covering at least a portion of the first cladding. The first cladding is composed of a first material having a first index of refraction, and the second cladding is composed of a second material having a second index of refraction greater than the first index of refraction. This arrangement allows selective illumination of the cable according to some embodiments.
For example, upon injecting light into the second cladding at an appropriate angle, the light travels through the second cladding and illuminates the second cladding. The second cladding may include imperfections, reflective material, phosphorescent material, or other material which facilitates perception of the light from outside the second cladding. The light may be selectively injected into the second cladding of a selected cable using a light injection apparatus as will be described below. Accordingly, embodiments may provide an efficient system to “light up” a selected cable so that the cable may be efficiently traced and, if needed, serviced. Moreover, as will also be described below, a cable may be selectively illuminated without disconnecting the cable from the components it connects.
Injection of the light causes cable 210 to illuminate along at least a portion of its length as illustrated. In some embodiments, the outer cladding includes elements to disperse some of the internally-reflected light away from cable 210 (i.e., toward an observer). Examples of these elements include imperfections within the outer cladding and small synthetic beads. The outer cladding may include phosphorescent elements which glow in response to received light.
Accordingly, a technician may selectively illuminate cable 210 using injection apparatus 240.
Cladding 320 is composed of a first material and cladding 310 is composed of a second material. The refractive index of the first material of cladding 320 is lower than the refractive index of the second material of cladding 310. According to some embodiments, cladding 320 and cladding 310 are composed of polymers, where the polymer of cladding 320 exhibits a lower index of refraction than the polymer of cladding 310. For example, cladding 320 may be composed of polyethylene, having an index of refraction of 1.53, and cladding 310 may be composed of polyferrocenylsilanes, having an index of refraction of 1.7.
By virtue of the foregoing arrangement, light entering cladding 310 within a certain range of entry angles will be totally reflected at interface 315 between cladding 310 and cladding 320. The range of entry angles may be determined using Snell's law, which calculates the critical angle as θc=sin−1(n320/n310), as depicted in
Cladding 310 includes small elements embedded therein. These elements may scatter some of the internally-reflected light out from cladding 310 as shown in
According to the illustrated implementation, to which embodiments are not limited, apparatus 400 includes housing 402 consisting of upper portion 402a and lower portion 402b. Latch 410 secures upper portion 402a to lower portion 402b, securing internal surfaces of apparatus 400 to cladding 310 and creating seam 405.
In this regard, upper portion 402a of housing 402 may comprise a material having a lower index of refraction than the material of which light pipe 425 is composed. In some embodiments, light pipe 425 exhibits a similar or identical index of refraction as cladding 310, and may be composed of the same material as cladding 310. Upper portion 402a of housing may be composed of the same material as cladding 320. In a case that the index of refraction of light pipe 425 is substantially similar to the index of refraction of cladding 310, light 430 may pass through interface 432 between light pipe 425 and cladding 310 with minimal reflection or refraction. As illustrated, and due to the lower index of refraction of upper portion 402a and the higher index of refraction of cladding 310, light 430 experiences total internal reflection at interface 436 between cladding 310 and upper portion 402a.
Hinge 440 may couple upper portion 402a to lower portion 402b. According to some embodiments, an operator “opens” apparatus 400 by rotating upper portion 402a and lower portion 402b away from one another, with hinge 440 being the pivot point for this rotation. Upper portion 402a and lower portion 402b are placed around cladding 310 as shown and latched together using latch 410.
In some embodiments, optical epoxy or grease may be applied to interface 432 prior to attachment of apparatus 400 to cladding 310. This application may improve optical continuity between light pipe 425 and cladding 310. Optical continuity may also benefit from precise machining of light pipe 425 and upper portion 420a to match the profile of cladding 310. Similarly, light pipe 425 and upper portion 420a may be configured to firmly mate with light source 420, to assist optical continuity between light source 420 and light pipe 425. Embodiments are not limited to the arrangement of
Light source 420 may be controlled and powered by any suitable circuitry. In some embodiments, light source 420 is powered by a battery and activated by a switch in any suitable configuration. For example, the securing of latch 410 may engage the switch, while opening of latch 410 may disengage the switch.
In particular, cladding 720 is composed of a first material and cladding 710 is composed of a second material. The refractive index of the first material of cladding 720 is lower than the refractive index of the second material of cladding 710. Accordingly, light entering cladding 710 within a certain range of entry angles (e.g., using an apparatus such as apparatus 400) will be totally reflected at interface 715 between cladding 710 and cladding 720, and also at the interface between cladding 710 and ambient air. Cladding 710 includes embedded elements which scatter or otherwise transmit the light, or light generated therefrom, out toward an observer.
For example, cladding 820 is composed of a first material having a first refractive index and cladding 810 is composed of a second material having a second refractive index which is greater than the first refractive index. Light entering cladding 810 within a certain range of entry angles (e.g., using an apparatus such as apparatus 400) will be totally reflected at interface 815 between cladding 810 and cladding 820, and also at the interface between cladding 810 and ambient air. Like claddings 310 and 710 described above, cladding 810 may include embedded elements which scatter or otherwise transmit the light, or light generated therefrom, out toward an observer.
Initially, a data cable is acquired at S910. The data cable may comprise any type of cable for carrying one or more communication signals between electrical components. Next, at S920, at least a portion of the data cable is covered with a first material having a firs index of refraction. At S930, at least a portion of the second material is covered with a second material. The second material has a second index of refraction which is greater than the first index of refraction.
S940 may occur a good deal of time after S910, S920 and S930. S940 may occur during testing of the cable and/or after deployment of the cable in a computing system. Light is injected into the second material at S940. The light is injected at an angle which causes total internal reflection at an interface between the second material and the first material. The light may be injected at S940 using an apparatus such as apparatus 400 described above, but embodiments are not limited thereto.
Embodiments described herein are solely for the purpose of illustration. Those in the art will recognize other embodiments may be practiced with modifications and alterations to that described above.