Tri-Tronics Sensing Solutions

Bifurcated fiber-optics with a lens

Challenge:

Photoelectric sensors are often used with fiber-optic cables.  The advantages are the ability to install the sensing tip of the fiber-optic into tight, space-constrained areas, keeping the sensor itself from direct exposure to heat, water, or physical harm from the machinery itself, and experience a difference in optical performance that the sensor itself may not provide without a fiber-optic being used (as in the case of a fixed lens on a the sensor itself).  Of course, using a fiber-optic allows the sensor to be remote from the point of sensing, and allow physical adjustment of the sensor parameters as needed for the application.

One of the most popular fiber-optic cables in industry is the glass core, bifurcated, used for proximity/prox mode sensing.  A Tri-Tronics glass-core bifurcated fiber-optic, one that sends and received in the same package, will exhibit a performance inversely proportional to distance from the fiber’s sensing face; i.e, the closer to the fiber face, the stronger will be the return signal for a given target, and vice-versa.  It is important to note that the highest sensitivity to any target or accumulation of dust, etc…… is the actual sensing face of the glass bifurcated fiber-optic.  This behavior is a “sitting duck” in a dusty, dirty, wet environment.  With Tri-Tronics glass fiber-optics, the beam distribution inherently fans out in typically a +/- 10-degree cone with increased distance.  The sensing face of the Tri-Tronics bifurcated fiber, having sender and receiver strands randomly oriented with one another, makes the sensing face very sensitive to accumulation of dust, dirt, water droplets, etc….., that may build up on it.  The sensing distance of such a bifurcated fiber-optic is well defined by Tri-Tronics for a given sensor and its selection of LED light source.  For the sensing distance aspect, the best analogy of such an application is like a garden hose without a nozzle on the end of it.  The water comes out in a less controlled manner and has limited range for a given pressure in the line.

The challenge is that for applications that may require or benefit from using a fiber-optic, to include longer range, narrower beam, or some immunity to accumulation on the sensing face, the fiber-optic alone is limited.

Solution:

Tri-Tronics offers glass fiber-optic cables with threaded sensing tips (at the sensing face end), typically for ease of mounting using jamb nuts. However, those same threads, when specified accordingly, can accept a number of different Tri-Tronics lens options that can be threaded onto the sensing face end of the fiber.  There are distinct advantages/tradeoffs when such a lens is used correctly.  Specifically, the addition of a lens will generally increase the overall sensing distance, reduce the spread of the distributed beam (reduction to small, projected spot sizes are possible), and will create a focal point for maximum response to a given target at that focal point.  The focal point produced is not the face of the lens itself, but rather at some distance out in space, away from the lens.  Accumulation that occurs on the face of the lens is NOT occurring at the focal point and is therefore not occurring at the point of maximum response.  Using a lens on a Tri-Tronics glass core bifurcated fiber-optic significantly reduces its sensitivity to detection of such accumulation.  Tri-Tronics offers lenses for producing either a 1-inch, or a 2-inch, focal point.  Excluding the focal point behavior with a lens, the analogy of using a Tri-Tronics bifurcated fiber-optic with a lens is like using a garden hose with a nozzle on its end to achieve a narrower beam, and to a greater distance, in a more controlled manner.

Net Value to our Customers:

Whether you have an easy, or more challenging type application, give us a call.  Chances are we may have either the sensor and/or the experience to solve it.  Excel Automation, and Eagle Sensors & Controls, have years of experience, and are application-oriented Authorized Distributors of numerous products for Industrial Automation, and LED Lighting.