FTI Tech


Developing Custom Solutions for Fiber Optics—It’s All About Relationship Building

By: Peter Brown


Figure 1: A custom fiber optic cable developed by Fiberoptics Technology. Source: Fiberoptics Technology, Inc.

When it comes to fiber optic technology, standard products can only go so far to meet the needs of engineers and designers who typically require specific lengths or configurations not offered by off-the-shelf fiber optics.

Standard fiber optic products can be formed into a ring, a line, a bundle or even a multi-legged bundle. These do the job if a designer doesn’t know very much about the technology or if a design already has a specific size that will fit a mold. Oftentimes, engineers use standard products as a launching point to see what’s feasible; this helps frame the groundwork for a discussion regarding a more technical or custom part.

For custom designs, much of the work begins at the brainstorming phase, mostly because designers can’t or don’t think of everything that goes along with developing specific fiber optic products. This time investment is important because it not only gives designers a better understanding about what they are asking for, but it also allows the developer to best understand the application, and to hash out solutions to problems the customer hasn’t even thought of.

Typically, custom work in fiber optics begins with submitting a  sketch or drawing of what is needed including tolerance of mechanical parts, optical properties, numerical aperture, fiber type, output configuration, and required length. This information frames a basic configuration for the custom design.

Then a fiber optic developer, such as Fiberoptics Technology Inc., begins a dialog to determine or confirm  whether or not the provided design characteristics will fit the needs of the application.

While suppliers want to honor and accomplish all of the requests they are given, customer engineers often have an idea they think is feasible and will reach out to see if the idea can work, or if they are unintentionally violating the laws of physics.

Fiberoptics Technology believes the role of the developer goes beyond designing… and includes the effort to confirm the design will work for the intended purpose. Without this time investment and consultation effort, a design could be created that matches the customer’s drawing, but … does not suit the intended purpose.

Finally, even if a design is lucid, complete, and functional, it may not be cost-efficient. Fiberoptics Technology’s consultative style includes a sharp focus on cost, helping customers produce efficient, cost-effective components optimized for performance. This strategy is not solely for the customer’s benefit; it makes little sense to work on a project with slim chances for commercial success… here is where the customer and fiber optic supplier are tied closely together… the customer must be successful before the fiber optic manufacturer can be successful.

This resulting effort and time investment establishes a bond of trust which naturally forms a partnership. Most often, if the customer is successful marketing his product, the mutually beneficial relationship between customer and fiber optic developer can last for decades.

Mitigating Customer Risk With Process Validation

By: Peter Brown

Navigating an increasing best practice for quality management service.

About 25 years ago, customers’ requirements for parts included wanting a good part, on time and at fair price.

But in today’s world, that just isn’t good enough anymore.

Increasingly, more companies are taking a risk-based approach to running their business — wanting to ensure a part process is in control, what the yields are and if the part will act the same way if different or other components are switched out of a system.

More and more, this type of risk mitigation as part of quality management services is taking the form of process validation, a method of best practice that has become critical in the delivery of quality parts.

Process validation is a collection and evaluation of data from the process design stage through the production stage, which provides evidence that a process is capable of consistently delivering quality parts.

For Fiberoptics Technology, this process validation includes how the company draws the fiber to the correct size, the assembly for specific products, how rod and tapers are drawn, how laser engraving is accomplished and many more validations depending on the parts.

This is important because internally Fiberoptics knows that its process yields good results every time — otherwise it is a waste of time, resources, material and human effort. If the company finds that the process is producing large amounts of scrap and waste, then the process is not validated for producing a good part every time.

Externally, this is important because companies see that Fiberoptics evaluates risk to reduce the risk they take in trusting the company to produce a quality product.

By providing further proof of the process and further risk mitigation that the parts are validated, this reduces the risk of making a bad part. And in the aerospace, medical and military markets, risk management and process validation are of paramount importance.

In fact, process validation is quickly becoming a standard in numerous industries including aerospace, military and medical even though regulatory requirements per standards don’t require it to a certain extent.

As recently as two years ago, Fiberoptics rarely heard the phrase process validation in any of its audits from medical and military customers. However, nowadays every audit has questions regarding the company’s process validation.

As a result, Fiberoptics Technology has taken this growing intensity for process validation and applied it to its best practices in order to ensure quality parts to customers and mitigate any risk concerns.

Optical Fiber’s Utility Expands In Complex Instrumentation

The benign nature and unique advantages of light transmission through optical fiber have led to some unusual applications, fr om sensing methane gas to flow cytometry.

Because fiber doesn’t use or conduct electricity, optical fiber is already widely used “as a conduit for temperature sensors based on infrared (IR) light.”
1 These pyrometers, typically utilized in high-temperature applications, use a fiber extension to pick the emitted IR fr om a heated body so that the sensitive electronics can be kept at a safe distance. This is particularly important wh ere there are high levels of electromagnetic or radio-frequency interference, such as on a factory floor with larger motors or welders.

Of course, much depends upon the fiber’s own operating temperature range and it may need special protection, such as water cooling, if ambient temperatures rise above 900˚F.

Once inside an electrical system, the characteristics of fiber are again useful. It can weave its way in and around electrical components and systems without risking dielectric breakdown. Also, because fiber is non-conductive, there’s no risk of arcing or associated sparks from worn or broken wires. As such, through the use of fiber, the risk of fire or explosions caused by electrical cable faults/shorts is significantly reduced.

Optical fiber is widely used for conveying sensor data, as well as functioning as a sensor for pressure or strain. Additionally, fiber can be used to convey modulated or altered properties of light, such as specific wavelength(s) or polarized light. Still, researchers continue to discover new ways of applying fiber to develop new types of sensing and sensors.

In one such example, optical fiber is being used as a means of detecting methane by measuring the amount of laser light absorbed by the methane. Methane has its own absorption signature, so if there is methane present, the reflected light will contain the signature. The detector can be in a single, portable instrument. Alternatively, a gas monitoring system can use laser light distributed over multiple fibers together to detect gas leaks at multiple points in service tunnels, utility ducts, mines, and unconventional gas operations.

Using optical fiber as the backbone for sensing applications in off-shore oil or gas rigs also plays into the use of fiber for safe, heat- and electricity-free area and equipment lighting.

Medical instrumentation

We recently spoke of the many areas [LINK TO PREVIOUS BLOG HERE] in which fiber is being applied that even the manufacturers of fiber would not have thought of; many are at the cutting-edge of bio-medical research.

The use of fiber for spectroscopy, wh ere light absorption and reflection is used to identify elements in solids and liquids is well advanced. But many may not be as familiar with flow cytometry. Here, single cells from complex solutions are detected, quantified, and analyzed in a reagent stimulated by lasers. The detector may be a photomultiplier tube (PMT) or a charge-coupled device (CCD), but before the resulting fluorescence or side-scatter light gets to the detector, it must first be gathered with a collection lens, and then routed to the detector, typically using fiber (Figure 1).

Due to its flexibility, fiber has a big advantage here as it allows the lens to be placed anywhere within the instrument for optimum collection, then small, flexible, reliable fiber can serve as a conduit, this time to the cytometer’s detector. Note that for better coupling, an optical gel is often used as the interface between the lens and the fiber.


Figure 1: The scattered light from the interrogation point is gathered by the collection lens (there may be many such lenses), collimated and conveyed to the detector. Fiber can be used as the conveyor. (Image source:

As fiber becomes even more integrated, its flexibility, non-electrical-conductive and lightweight nature will continue to play a role in helping designers advance state-of-the-art instrumentation size, cost and portability.

While fiber’s applications vary widely, they can be quite simple too, such as basic absence/presence detection, Here, when used in conjunction with an emitter/receiver sensor, fiber optimizes the ability to detect discrete samples during processing, which assures non-stop analysis and accurate, fool-proof organization of results; yet another good example of optical fiber’s simplicity and utility.

Glass Fiber vs. Plastic Fiber in fiber optic applications

Glass Fiber vs. Plastic Fiber in fiber optic applications

The question concerning glass versus plastic optical fiber is fundamental, but it comes up more often than you’d think, so it’s worth a few words here, just for the record.

We’ll not get into the structure of the actual fiber itself, as it follows the same basic principles of differing refractive indexes between the core and the cladding that leads to total internal reflection and light propagation. Instead, we’ll look directly at the materials and performance.

Typical end emitting plastic optical fibers (POFs) are made fr om polymethyl methacrylate (PMMA), commonly known as acrylic or polystyrene. They function well for illumination, sensing, and many home, transportation, and industrial applications where weight and vibration may be factors. They’re also easier to work with in that they can be sliced and reconnected in the field (for data transmission applications). They are available in several fixed diameters, (.25mm - 3mm) and 2 numerical apertures, and exhibit good transmission efficiency between 400 and 700nanometers. Even the 3mm diameter will have a reasonable bend radius. They have the same chemical resistance as acrylic.

Glass and synthetically fused silica (quartz) fibers are more stable under temperature extremes, with good resistance in excess of 400° C versus 70° C for PMMA.

Glass fibers can be made in a wide variety of diameters and different numerical apertures, with good transmission efficiency from 200-2200 nanometers. Glass fibers stop bending (they will deflect, but will not bend to form a circle for practical applications) when the diameters increase beyond .4mm.  Silica fibers will exhibit better bending capability (mostly because of the buffer)… but their bend radius is also limited… more to do with NA and power loss through tight bends, than actual physical bending property.

Chemical resistance is very good (for glass)… and OK for silica (due to a typical polyimide buffer requirement).

The decision to use glass or plastic fibers, as in so many cases, defaults to application requirement(s).  While there are a multitude of applications wh ere either type can be used, some clear limitations (and preferences) make a fiber choice straight forward.

Heat is a major differentiating factor. While there are protective measures that can be put in place to make POF more stable, temperature intolerance will remain a fundamental limitation; any part of the light guide exposed to temperatures over 70C will destroy the light guide prematurely.

Vibration favors plastic; it’s more capable of withstanding a dynamic environment than glass.

Because larger fiber diameters are still flexible, plastic fibers should be considered when the light guide diameter matches a plastic fiber diameter; a single plastic fiber will transmit more power than a bundle of glass fibers… the only losses in a single fiber are Fresnel and wavelength attenuation over length.

Material cost favors plastic, and it could cost is less to build a single plastic fiber light guide. However, because plastic fiber is manufactured and collected on a spool, multi-fiber plastic light guides could cost more than glass… (the labor content to form the bundle is higher than the same light guide made from glass) but never more than silica fiber, which is by far the most expensive of the three types.

If you need a wider, or more narrow, Numerical Aperture, plastic is limited to .48 or .63. Flint glass range is .25 – 1. Silica range is typically .22 .37 and .5.

If the coupled power is high, Plastic will solarize much faster than glass. Silica has even better resistance. (None of these fibers will withstand nuclear radiation).

As always, if you have any questions on your next design and you’re not sure which way to go, plastic or glass,
just call us.

Multi-port light sources are no bargin!

When I started working the fiber optics field I was meeting with Microscope dealers to learn the market and get first-hand feedback. Several dealers really wanted us to develop a multiport light source...they thought it could help them more-than-double their sale of units. Their argument made sense to me, so I brought the idea back to the President of FOSTEC, my employer at the time. Rolf listened intently, then began a review of the technology. Here's the synopsis:

    Putting a number of light sources in a common enclosure offers no gain in input power efficiency... the same total power is still required, as is the same physical footprint for the power suppl(ies)*, ports, dimmers. controllers, etc.... the more power needed, the larger the power supply required. And there is more risk.... If multiple power supplies are included in one box, a failure of one power supply could destroy good supplies and/or shut down most or all lamps.

    There is no change in the amount of heat management required....  air movement or other heat management strategies would still be required, commensurate with total heat generated.

   Manufacturing cost would be higher... Some part volumes would be cut in half. Testing and review for safety would not change (cost or labor), and furthermore, it's possible that the effort/technology required to control EMI would be more difficult.

   While the project could be undertaken...I would not recommend it.... The cost would most likely be more than purchasing 2 stand-alone units.

    *Note: it’s possible to reduce the overall footprint to some degree, perhaps as much as 8%- this is the only real advantage I could envision....but as you could surmise from above, the added cost and risk are probably not worth it.

Need it Good, Quick, AND Cheap? ….Get it printed!

Sorry, I know this isn't a question, but it's great information and a very cool new piece of technology!

In March 2014, we added high-definition additive machining to our capability.  The machine (3D Systems Pro Jet 3000HD Plus) is capable of holding tolerance to +/-.001, more than good enough to create high quality housing and fixturing designs.

The printed material is rigid, dry, non greasy, non-powdery,  ABS-like polymer, which is hardened under a UV lamp. The wax support material is easy to remove and clean off. The resulting surface finish is smooth; the output looks like a molded/machined part.

We’ve calibrated the equipment and our engineering approach to negate material shrinkage and warping.

Lead time from engineering model to finished parts is (currently) 24 hrs. If you’re really in a hurry and need a working proof of concept, or short run output, this technology is more than good enough to accommodate your needs. If you need it, we can turn around the approved design in a week (fiber and all). Of course, if you only want the printed model, it’s no problem.

In addition to the time-saving aspect, the cost for the service can be less than a traditional machining effort, particularly when the requirement is for one piece…and if you intend to use molded components in your serial production design, this technology will save $1000’s of dollars and weeks of time proving out the design.

We have been working with several customers using this resource; they love it, and no longer want to use machined housings.

Of course, the technology is not optimal for every application; if the parts require repetitive dry fitting prior to assembly, if the application is high temp or corrosive, or exposed to high torque fixturing, metal is still best.  

Additionally, volume efficiency is size dependent… and unlike traditional machining, there is very little economy of scale saving… so as the quantity goes up, the cost saving (compared to machining) goes down.

This technology is very impressive... I'm sure it could be a useful and cost efficient part of your next product development effort.

Can I use fber optic lighting for plant illumination?

We get more calls and e-mails on this topic, more often than one would think…

In general, the principle of using fiber optic components (with or without halogen light sources) as an illumination source to grow plants (or funnel sunlight into dark spaces for the same purpose) has some technical merit, but offers zero potential from a cost perspective.

The spectral content of the Halogen lamp is OK (plants need blue light for vegetative growth (although not too much blue light in Halogen lamps), and red light for flowering (lots of red light is available). Even more appealing is the technique of filtering out IR radiation (lamp or sun) using a filter… and you can be really efficient using the light coming from the fiber, because you can aim it.

However, the aforementioned positives are neutralized by several factors. First, there's inefficient light transmission; about 35% of photonic energy striking the face of a fiber bundle never makes it into the fiber. Of the 65% that is collected, at least 4% more never makes it out. If you need a deeper understanding, see the technical section on Transmission loss in our website (

Furthermore, unless you use a focused lamp or special collection optics, the amount of energy striking the fiber (and thus transmitted) is very small relative to what is available. (i.e. a 12 x 24 basement window offers 288sq.in... a .5" fiber bundle only provides .196sq. in. of surface area! (.06%)

BTW, focusing optics have been tried several times... in conjunction with parabolic collectors on the roof. They have proven to work..... but you need to get a price quote to realize the ROI (it is not quick or even worth considering unless your environmental concern overrides the financial considerations.)...and you still need to deal with weather (or night time) raining on your parade... (OK, some pun intended)

After adding up the cost of equipment to overcome the performance inefficiency, and adding in the cost of fiber optic light guides,  most budding entrepreneurs give up on the idea….and we agree. In the vast majority of applications, windows, flood lamps or “grow lights” are still the most efficient, and by far, the most economical means to provide light for growing indoors.

Will leaded glass fiber fall under restriction from use guidelines in the RoHS directive?

We have received more than a few calls over the past several months inquiring about RoHS compliance.

We have published a new webpage on our site to help educate and inform the market in general.

Most of the recent RoHS confusion has been generated by a competitor’s marketing push to sell a new proprietary fiber. While this fiber may have some (unconfirmed) performance characteristics (which may (or may not) have value in some applications), most of the buzz is being generated by their claim of RoHS compliance, (because the new fiber has no lead content), inferring the remaining market offers non-conforming fiber.

In general the RoHS directive was intended to apply to the electronics industry; glass containing lead was an unfortunate "victim" of the directive's interpretation. If you look at the EU directive for RoHS, you’ll find an exemption covering white glass for optical components in section 13A on page 103. We publish a copy of the compete directive on our site for your convenience and review.  As a general practice, FTI works diligently to maintain compliance with all quality and environmental mandates, and the RoHS directive is no exception. All of our products, and all of our competitors glass fiber products meet the requirement of RoHS. In July 2014, the directive committee will convene to discuss removal of optical glass entirely from the list, as the directive was never intended to cover lead in the manufacture of glass.

With regard to technical differences of the fiber, the potential performance improvement is more than offset by the premium cost. We believe the cost difference can be 2-4x more than the current market price for the raw fiber, and perhaps as much as 10x more as a component in a light guide.  You should get pricing directly from potential sources and make your own value judgments.

We encourage you to discuss your application with your supplier to be sure they provide what will work best for your instrument, customer, and shareholders.

Can I use a fiber to focus light?

Contrary to what some folks believe, fiber optic glass strands have no ability to focus light. Many times designers and engineers believe that using fiber with a small numerical aperture (N.A) will collimate (or focus) light.

While it’s true that the light output cone will emit at full angle commensurate with N.A., a small N.A. will also restrict light collection. If the application measures output power in the center area, on axis with the fiber and within the cone of the small NA fiber, the light power projected from a small NA fiber will have the same value as light power projected from a larger NA fiber  (but smaller NA fiber almost always costs more!).

Where it counts

If the application uses a wide angle source, and the designer includes focusing optics (even simple focusing optics) at the launch end of the fiber, the amount of power delivered by a .66NA fiber (above) could be (as much as) a factor of 3 greater than the same light focused and delivered by the .22 fiber at the same point. The reason for the difference is the focusing optic…it collects higher angle light emitted by the higher NA fiber and focuses the light (redirects it) within the field of interest.

In the world of fiber optic lighting, more efficient fibers can be less efficient

Silica fiber is more efficient (lower attenuating loss) than leaded glass fiber. The statement is particularly true in communication applications wh ere the source is wavelength specific laser energy (very narrow launch angle power).

However, silica fiber is less efficient (collecting light energy) than leaded glass fiber when the source emits high angle, broad band (White light), particularly over shorter runs.  Almost all non-telecom applications use this type of source. Once again, the main reason is NA. Most leaded glass fibers have a NA between .44 and .66 (Some go as high as .87) Most Silica fibers have NA between .22 and .37 (Some go as high as .48). Silica fibers will not collect as much light from these sources as the leaded glass types.

From a design and cost perspective, unless the fiber run is very long or the wavelength of interest is outside the visible spectrum, it’s quite possible the design would benefit more from using leaded glass rather than silica!


As you work through design parameters, keep the light source output characteristic in mind, along with required light characteristics to optimize your fiber selection.

Question: I am looking for a low-cost Fiberscope solution for imaging inspection, do you have a product that may help?

FTI offers a number of fiber optic imaging guides, or Fiberscopes, for almost any application.  Unlike other fiber optic light guide solutions that only transfer light, Fiberscopes can carry an image over most working lengths.  FTI can work with you to design a solution specific for your application; this includes offering Fiberscopes with a C-Mount or CS-Mount direct threaded eyepiece, to accommodate nearly all CCD imaging cameras.  The custom or standard Fiberscopes are a rugged, and durable quality, are manufactured right here in Connecticut, utilize a high quality fused-quartz fiber optic imaging bundle, are made with patent pending Duraflex technology, and most importantly, the cost is more than competitive for the quality of the product and service provided by our qualified sales engineers!

For application, design and pricing questions, contact Sales Engineer Zach Morin

Question: I am looking for an inexpensive fiber optic lighting solution for a star ceiling in my son’s room. Can you help?

Answer:  We currently offer a wide variety of solutions for fiber optic star ceiling lighting.  We offer small area LED star ceiling kits for areas up to 24, 48, 72, and 96 square feet!  These kits were specifically designed to be a cost-effective fiber optic lighting solution for a small area star ceiling, and are normally in-stock, ready to ship!  These kits are manufactured at our main facility in Pomfret, CT USA!

We also offer a selection of standard kits with different numbers of fibers.  These kits are not typically stocked, so there will be a little lead time, but they are an equally cost-effective fiber optic lighting solution as the LED small area star ceiling kits.  Please contact Zach Morin for exact pricing and project application details so that the proper materials are ordered.

Question: Can I use a credit card as payment for my order?

Answer:  We accept Visa, Mastercard, American Express, as well as USA Government Paycards for payment for all of our products; whether for fiber optic light guides, or even star ceiling systems.  Unless otherwise specified by the Sales Representative (usually due to a larger order), we will charge the credit card when we ship materials from the order, whether we ship the full order, or make a partial shipment.  

We will issue, whenever possible to all credit card users, an authorization form for the person to fill out, sign and email of fax back to us.  For the user’s security, we only ask for the last 4 digits of the card on the form so that all sensitive data is not transmitted in one place.  With this in mind, we ask that users call in with the remaining digits of the card for us to file.  All credit card data used by FTI to charge for an order and/or shipment is stored securely in accordance with the Payment Card Industry Data Security Standard (PCI-DSS).


Since we started our business in 1977, we've answered more than a few questions related to Fiber optics applications, machine vision products and applications, star ceilings and fiber optic characteristics..... Over that time, we  also noted that a group of questions gets repeated with some regularity. To help researchers and engineers become acquainted with this information, we decided to create a blog that addresses them, in addition to the all of the resources currently offered on the site. While we'll post here regularly with questions and answers, you may have a question we haven't yet addressed. Take a minute to add a comment..we'll answer for sure, and consider publishing the response as well!