Using fiber-optic technology for custom sensoring

        The advantage of the fiber optic technology is that the light in the form of a small diameter beam can be easily manipulated. Each time the beam is interrupted from an object (product, probe, etc.), then a signal activates the proper function. The cost of high tech sensors is larger than the cost of a fiber optic system (cable, diffuse and amplifier), and also the fiber optic cable is very robust with small bending radius, it can be cut to its length easily and instantly with a simple cutting tool, and it can be mounted very easy as well.

        There two main types of fiber-optic cables, the through-beam and the diffuse fiber-optic cables (reflective). The first type uses two cables one coaxial facing the other and the light beam is driven from the core material of the first to the core material of the second. When something interrupts the light beam, the sensor activates the control system. The diffuse fiber-optic cable is made also from two cable mounted side by side. The diffuse end is placed near a passing object, and the light beam is reflected on the object surface. The reflected beam is detected from the other cable of the sensor and the control system is activated.
The diffuse type has a smaller sensing distance than the through-beam type. If an object with transparent or bright white surfaces interrupts the light beam of a diffuse type sensor, then the reflective light may not be strong enough to activate the control system. Two major advantages of the fiber optic technology are that sensors are activated instantly through the light and that are best for sensing objects made from plastic material (cannot use induction technology). The diameter of the light beam is very small and permits control of objects with small dimensions or very close the one with the other.
The fiber optic equipment could be mounted directly or indirectly with the custom mounting parts. Extra care should be taken on the mounting parts during design. Mounting holes, Pg threads, locking sleeves and through threads can be used to clamp the end of the optic cable. This is necessary because the fiber optic cable can be easily pooled out due to its small size. The diffuse type (threaded tube) can be secured with nuts due to its end or by a set screw in socket hole. Due to the fact that the through beam type should not be clamped from the cable (the core will be damaged), what is usually needed is a custom adaptor. The easiest way to make this, is to modify a small set screw in order to fit the fiber-optic cable inside. When there is not enough space to fit the cable to the adaptor, a special sleeve with a slit can be used to clamp the cable.