Tech Tip: OPT2040 Fiber Optic Cables Quick Start

AutomationDirect offers a huge variety of fiber optic cables for the OPT series sensors. Let’s see if we can break it down so you can figure out which cable you need. First decide which type you need: Through Beam or Reflex. Through beam is when you have a separate heads. One transmits light the other receives it. When the object passes between the fiber optic heads it breaks the ‘continuity’ of the light. In this case the sensor normally expects to see the light and when the light goes away it triggers the output. We call that Dark On. We triggered the output when the light went dark. The through beam OPT series optic cables - when used in the OPT series amplifiers – can be used out to about 19 inches. Some of the cables have a smaller diameter fiber core which gives you a tighter bending radius, but also sorter detection distance capability because it collects less light. This piece of plastic is just to make the diameter of the black jacket thick enough to fit in the sensor. Just slide it down the cable to the length you need and then cut the fiber with the included cutting tool. The thicker plastic fibers you just cut normally with the cutting tool. The cutting tool is included with the fiber optic cable. There are several different head sizes to choose from. Panel mount in M3 and M4 sized, these long bayonet style probes which you can bend, these straight barrel types in straight and sidewise for applications where you don’t need threads. Flat mounted cables so you can bolt them right to a panel that shoots a beam right out the end or sidewise, and a panel mount right angle. The reflex cables have both transmit and receive cables in the same head. One shoots the light out, the other receives the light reflected back. Some folks break that up into retro-reflective and diffuse. Retro reflective works like a through beam. The amplifier expects to see light from the reflector and when an object breaks that beam the light goes away and triggers the sensor. So we also call that “Dark-On” because the output gets triggered when the object blocks the beam. Diffuse is the same setup, but now we wait for an object to pass by and reflect light back to the senor. So since the object is reflecting light back to the sensor to trigger the output, we call that “Light-On.” The Reflex cables also have lots options: Bulkhead mount, the longer bayonet style, smooth shaft with both straight and sidewise looking, long rods you can bend to get into tight spaces with both straight and sidewise beams, flat heads for mounting on the surface of a panel again both in straight and sidewise configurations, and a right angle bulk head mount version. There are two types of cable configurations in the optic cable heads. Parallel and Coaxial. In parallel the fibers are aligned in the head side by side. If I hold the other end of the cable up to an LED you can see the fiber bundles are side by side or parallel. This is one side, this is the other. In a coaxial cable the receive fibers are arranged concentrically around the transmit fibers. Let’s hold it up to the LED and as I switch fibers you can see the pattern of fibers in the head. Here is the transmit fiber and here is the receive fiber. This coaxial arrangement of the fibers make this cable ideal for detecting very small objects. The narrow transmit beam pinpoints the small item you want to detect, while the large ring of receive fibers gathers the reflected light from that small item and returns it to the amplifier. When using the coaxial fiber you need to be sure you get the right fiber in the right hole of the amplifier. On this one there is a little arrow on the plastic to remind you how the fibers should be oriented. There is also a note on the bag it comes in. And of course you can always see on the sensor which hole is transmitting light. With the parallel fibers, it doesn’t matter which hole you plug them into. There’s also a variety glass fiber optic cables in both through beam and reflex style cables. These are ideal for harsh environments because of the steel jacket and because the glass fibers are not as susceptible to corrosive environments as the plastic fibers are. Glass fibers can also handle higher temperature environments, although plastic are a little better at the low end. If you have any questions, please contact AutomationDirect’s free award winning tech support team during regular business hours. They will be happy to help. And don’t forget the forums. There are lots of folks there that love to share their years of experience. Just don’t post any questions directed at AutomationDirect’s support staff there. They don’t monitor the forums on a regular basis.