Specifications of our Fiber and Cable

End Emitting or Endpoint Fiber (POF): Made for many uses in many applications such as: Interior or exterior signage, scale models, floral displays, hobbyists and underwater spectacles in aquariums.


End-Point Fiber Specs:
Plastic optical fiber is a total reflective type which has a concentric double structure consisting of a core of transparent polymethylmethcrylate (PMMA) of a high refractive index, covered with a thin layer of special transparent cladding material of a low refractive index. The light entering from one end is transmitted, repeating the total reflection and then is discharged from the other end.
Endpoint fiber optic PMMA (polymethylmethcrylate) Acrylic Fiber Optics come in many size diameters from .25mm up to 3mm. The Attenuation is measured with a 1mm fiber at 650 nm-collimated light. Here are its specifications:

Refractive Index Core: 1.492

Reflective Index Clad: 1.402

Numerical Aperture: 0.51

Temperature Range: -55� C ~ 70� C

Maximum Attenuation: 0.2 dB/m (0.18 dB/m Typical)

Applications: Signs, illumination, sensors, lamps, data link (short distance)



Sideglow Cable Specs:

As an alternative to neon, solid core Sideglow optic cable can be used to decorate buildings, highlight architectural features and exterior signage. It can be used in such applications as underwater lighting in swimming pools and spas, backlighting of signage, glass block lighting, cove lighting and landscape lighting.

Sideglow fiber optic cable is a single large diameter Solid optical gel core made from optically pure cast acrylic monomers, including MMA, to ensure flexibility, and superior light transmission. It can transmit light over reasonable long distances. Light is transmitted over the entire length of the solid core cable without electrical danger, or heat. The light source such as a halogen light box is used as an illuminator, which is place at one or both ends of the fiber. A color wheel can be added to the illuminator to change the color of the fiber to as many as eight colors. Its bend radius is less than 6 X its diameter.
Utilizing a recently perfected production process called continuous casting, Sideglow solid cable can now give off brilliant color clarity and a continuous bright light transmission that was not possible in earlier solid core fibers. A crystal clear Teflon sleeve gives high intensity brightness along the entire length of the optic cable. The distance of light carried is only for 100' or less before needing to add another illuminator or loop back to the light source.
The optic fiber is energy efficient, flexible, and requires virtually no maintenance. It is available in 5.5mm (1/5"), 7mm (1/4") 9mm (3/8") and 12.7mm (1/2") diameters. Spool lengths are 260 continuous feet of Cable.

Sideglow cable Specs:

Temperature Stability:
Core to 120 deg. C. (248 deg.F) Cladding to 390 deg. C. (734 deg.F)
Operating Temp. Range:
Minimum: minus 40 deg.C (-104 deg.F) Maximum:plus120 deg C (248 deg.F)
Moisture Absorption: Core composition is hydroscopic. Optics ends must be sealed to avoid absorption.
Chemical resistance: Teflon cladding is chemically resistant and impervious to solvents. The core is affected by strong solvents.
Storage: Dark/dry location where temperature is within specifications.

Spectral Range: 370 to 690 nm�visible wavelength range

Acceptance Angle: 45 deg.

Numerical Aperture: 0.65

Glass Transition Temp: 53.8 deg. C

Attenuation: Less than 1.6% per foot (5.3% per meter)

As with any type of illumination, lighting via optical fiber requires the answers to a few questions before a successful installation can be executed. Fiber optics can distribute and project high quality illumination that can supplement traditional methods, often to an advantage. Additionally, fiber optics can perform dazzling tricks that no other form of lighting can touch. They are often used purely for their unique aesthetic, often referred to as "flexible neon".

Generally, the first question to answer is "How much light is required?" For task and area lighting, various groups and agencies have established light levels as standards and guidelines. Or, experience dictates what is appropriate for a given application. In either case, the need will be to project light into an area via fiber optics and knowing what needs to come out will determine what needs to go in. For the "flexible neon" or, what is referred to as "side-illuminated" effects, it is still necessary to determine how bright the glow will need to be to provide the desired effect. In many cases, particularly for side-illuminated fiber, experimentation may be the only way to determine what looks best. At first blush, it would seem that to evaluate fiber optics for the purposes of illumination, it would be good to start with photometric measurements. These might be a foot-candle (lux) measurement for task lighting; a lumen measurement for raw output; and in the case of edge-illuminated fiber, a foot-lambert (nit) for "brightness".

But unless you already have the fiber, the light source, luminaries (for end-light), tracking (for sidelight), and all the various other bits, you will not be able to make these measurements. And neither can any of the manufacturers of optical fiber. There are just too many variables in installations that affect these three measurements for any manufacturer to be able to reasonably duplicate them all. When it comes to optical fiber, any raw output data for fiber optic illumination are meaningless... period. A fiber optic illumination system is a little different. When the light source and fiber (at set lengths), along with all the other accessories are evaluated together, then manufacturers and suppliers can provide useful photometric data. But you must still be careful to follow the installation instructions very closely.

Optical fiber is a passive conductor of light; the measure of ultimate "brightness" will be largely a function of the light source powering the fiber. Most Tec's consider loss or attenuation to be the most important evaluation parameter. All fibers exhibit attenuation that will prevent 100% transmission. The amount of loss will depend on many factors; the type of media used in the fiber core, the surface geometry of the core/clad interface, mechanical stresses imposed on the fiber, and the finish quality on the input and output ends of the fibers, among others.

The second most important criteria are numerical aperture, which affects the light gathering ability of the fiber.

And the third, unique to side-illuminated fiber, is the evenness of the glow effect. Scattering effects within the fiber core and cladding force light to be directed out of the fiber, something typically avoided with most optical fiber.

ATTENUATION

All fiber experiences losses, and this shows up as two distinct but related forms. The gross attenuation of a fiber is concerned with broad band losses that affect the transmission of light. This figure of merit for a fiber is the loss or attenuation value presented in manufacturer's literature. It is most often given as "%/foot", "%/meter", "dB/foot", or dB/meter". The other form of attenuation is often the most important however. Fiber losses will affect certain portions of the visible spectrum more than others. Color shifting results from the selective transmission and attenuation of various wavelengths of light passing through the fiber. These losses are minimized by using extremely pure base materials, by designing polymers that are will better carry the visible wavelengths, and by incorporating high-finesse fiber geometry. FOP takes advantage of all three of these to produce the best fiber available with the least amount of spectral attenuation (color shifting).

It is important when evaluating fiber (ours or anyone else�s) on the basis of loss and color shift to make sure the same "white balance" is used, or that the data has been "normalized". This means that the data are adjusted in reference to the spectral content of the light source to eliminate fluctuations in the source colors. The light source has a dramatic affect on the measurement of fiber performance. Two sources rated identically in terms of wattage can yield vastly different results. Even if both units were rated the same in terms of optical power, there can be huge differences if the white balance is not the same or the data not normalized.

MEASURING LOSSES

This is how most manufacturers measure gross loss in a fiber: A relatively long sample of fiber is illuminated and the output is measured. A pre-determined section of the fiber is then removed from the output end, and another measurement is taken. The same length section is then again removed from the output end of the fiber, and another measurement taken. This continues until the remaining sample can no longer be cut back by the same amount. From these measurements, it is possible to calculate a loss factor. This is known as the "cut-back" method.

LOGARITHMIC SCALE

As mentioned above, loss factors are presented as a logarithmic value such as a percentage of loss per unit length such as "%/foot", or in decibels as "dB/meter", or "dB/ft". The use of decibels (dB) to measure light may be confusing at first, but in this case, "decibel" simply refers to the logarithmic nature of loss in the fiber, exactly as the term relates to loss or attenuation in sound and radio signals. Coincidentally, logarithmic values are also appropriate for measuring light and sound because of the way our senses work. In order to deal with the huge variation in energy levels we encounter in nature, both the eye and the ear exhibit the same logarithmic sensitivity to their respective stimuli. Understanding the logarithmic nature of light is extremely important when evaluating the visual performance of fiber optics prior to installation, because it is the one figure that relates to subjective brightness.

The logarithmic sensitivity of our eyes requires a doubling of optical power to perceive an increase in "brightness". This doubling requires a 3dB gain. Conversely, a drop of 3dB would bring perceived brightness down to the next perceptible level. Our hearing is the same (as any car-stereo installer will tell you!). Double the power of an amplifier, and you get just a bit more sound. In both cases, this logarithmic nature allows us to safely observe variations in light and sound over a 10,000:1 ratio. (When verifying this fact by experiment, it is necessary to maintain a constant spectral content as power is being reduced, a difficult task in practice when producing both aural or visual stimuli. While insensitive to gross power differences, the eye and the ear are both highly sensitive to changes in spectral balance.) All things being equal (and that is saying a lot), a length of fiber with an attenuation factor of .2 dB/ft. will have dropped to the next level of perceived brightness after 15 feet. (.2 x 15= 3dB).



LIGHT "QUALITY" AND COLOR BALANCE

Many factors such as contrast ratio, color, viewing angle, and ambient light conditions will affect the observed quality of light from either type fiber. When using end-illuminated fiber for task and/or area lighting, be prepared to adjust the spectral content of the output to match standard illumination sources. Very typically, for polymer based fibers, there will be a shift towards the green or yellow-green part of the spectrum after several feet. Correction filters used in photography to correct the color temperature of various lights may or may not work, depending on the light source spectral content, and the length of fiber used. Ideally, the proper correction filter would display the inverse (or "opposite") function of the fiber spectral attenuation curve. This would "balance" the various hues in exact proportion to each other by filtering out those portions of the spectrum shifting the color away from white light. Most manufacturers supply data concerning the spectral attenuation of their fiber products, and these can give you a good idea of what to expect in the field.

NUMERICAL APERATURE, F#, AND ACCEPTANCE ANGLES

After attenuation, the numerical aperture is the next important consideration. Bear in mind that higher or lower NA�s (wider or narrower acceptance angles) does not make a fiber "better" or "worse". In some applications, there may be an advantage to the wider spread of light possible from larger NA fibers, but there are practical trade-offs that may cancel out any gains. Similarly, the narrow angles of low NA fiber can improve light source coupling, but may impose other constraints, such as higher cost. It should be noted that currently, there are no manufacturers of large core (6mm and up), polymer fiber manufacturing small NA fiber, though there are some smaller diameter fibers. (We consider NA�s under .45 to be small, those over .45 to be large.)

The way fiber optics work (dictated by physics) imposes limits on the angles through which light can enter the fiber. This limit is called the Numerical Aperture (NA) of the fiber, and has the same affect as the aperture in a camera lens. That effect is to limit the angles of light rays passing into the system. Both can be evaluated in terms of F#, NA, or acceptance angles. Like camera apertures, the "faster" the fiber, the more light it can collect. A camera lens of F#1.0 is considered very fast. A fiber at F#1.0 is about average. This is equivalent to a numerical aperture of .50; an acceptance angle of 45 degrees (full angle).

Here is the relationship:

F#= distance to target/ diameter of spot at target

NA= 0.5/F#

Acceptance angle (full) = 2 x sin e-1 [NA]

Just how the NA affects performance can be illustrated in the following: Imagine yourself in a dark room with a window that has been painted over so as to be opaque. You want to look outside, so you start to scratch the paint off the window but make the smallest of holes so your activity won�t be noticed. You have to bring your eye right up to the hole in order to see out and you really can�t look around because to hole is too small to see much more than straight ahead. So you open the hole a little more (at great risk of being caught!) and look again. Now that the hole is larger, you can see over a wider range of angles. By increasing the whole diameter- the aperture, you allow light rays from more angles to pass into your eye. Not only that, but the room gets brighter as the hole becomes larger. The aperture for optical fiber is a little different in terms of how it is formed, but the effect is exactly the same. The larger the aperture, the more light you can "couple" into the fiber. But rather than being a simple hole in a surface, the aperture of a fiber is formed by what is called the "critical angle".

Fiber Optic Products fiber has a NA of .66 which calculates to an acceptance angle of 82.59 degrees, and an F# of .33. What is actually useful though, is usually somewhat less. Practical limits on the perfection of fiber geometry and chemical composition, as well as installation-specific effects, all work to decrease the useful angle. So most designers don�t feel the need to run light out to the maximum acceptance angle. The half power points in the angle vs. throughput graph are often used to set what we call the "working acceptance angle". Additionally, finding light sources that efficiently operate at the extreme wide angles is also difficult... try going to a light source designer and tell them you want a light cone converging at F#=.33 and watch them squirm!



CRITICAL ANGLES

Contrary to popular belief, fiber optics are almost never "silvered on the inside", or hollow, though some exotic fibers are either or both. The vast majority of optical fiber relies on the phenomenon of total internal reflection, to conduct light from end to end. In the same manner as the sky is reflected from hot pavement, light traveling through a fiber is re-directed back into the core whenever it begins to wander out. And just like a hot pavement mirage, the effect only works at certain angles. Exceed the critical angle and you see pavement and not the reflection of the sky. Or, in the case of fiber, the light passes through the side instead of getting a nudge back into the core.

What determines this critical angle is the relationship between the fiber core (equivalent to the relatively cool air several inches above the pavement), and the fiber cladding (equivalent to the layer of hot air hugging the road surface). It is this relative difference in "optical density" (better known as "refractive index") between the hot and cold air over the pavement, and the core and cladding of the fiber that provides the mechanism for reflection. Light travels faster in denser mediums. When a ray of light encounters the "interface"- the boundary between more dense and less dense media. The laws governing the conservation of energy dictate that the energy present in the ray will have to undergo a transformation if it is to pass through into a different density medium- a process that cannot occur without loss. Re-direction incurs less of a loss penalty than transmission. And like so many things in nature, light will tend to follow the path of least resistance, and that path is back into the core of the fiber, the lowest energy-loss option.



MODES

Up to a point then, larger NA�s mean the fiber can gather light from wider angles. But past a NA of about .60, equivalent to an acceptance angle of around 70 degrees, there isn�t much useful light available. "Mode stripping" in the fiber removes much of the light at the extremes of the acceptance angle. In discussing or reading about optical fiber, the term "mode" often comes up. "Single-mode" and "multimode" are used to describe two basic classes of fiber optics. A mode is simply a path that a ray of light can take through an optical conductor. Thus, "single-mode" refers to an optical conductor that allows only one path for the light ray to follow. In order for this to happen, the optical conductor must be very small... generally on the order of 50 microns, or about 1/2000 of an inch. But the advantages gained for applications like high speed data transmission are so significant, that use of such tiny structures are routine and relatively simple to use.

For the job of illumination however, much larger fibers are more efficient. These are "multimode" fibers; countless modes in the case of the very large fiber we manufacture. But the "order" of the modes, which (in a serious over simplification) refers to the relative number of "bounces" the light ray takes as it passes through the fiber, has limits. On the low end, the lowest order mode possible would be a straight path right down the fiber with no bounces. On the other end of the scale, the highest order mode is the ray following a path right at the critical angle. So long as it doesn�t exceed this angle, a light ray following this high-order mode will travel from end to end.

But like a driver careening down a one-lane mountain road with no shoulder, these highest order modes are prone to being lost "over the edge" if there something goes wrong. Because they are so close to the critical angle, these rays are the first to be lost or "stripped" if something causes them to exceed the critical angle. There are many things that can cause this to happen. Microscopic deviations from a smooth surface, scattering effects, too tight of bend radii or clamps tightened too tight can all have this affect. The point here is that the highest order modes is lost pretty quickly. There are no perfectly smooth, flat, transparent materials and so some mode stripping is always going to occur. This is why again, contrary to popular belief, output angles are not the same as input angles.

EVEN OUTPUT

For side illuminated applications, the evenness of the light spread along the length of the fiber is as important as overall clarity. By taking advantage of controlled molecular-scattering phenomena, we have tailored our side-illuminating fiber to achieve a high degree of evenness along lengths up to 260-ft. (80m). Evenness is also highly dependent upon the illuminator and "launch" conditions. Projecting the light from the lamp into the fiber at narrower-than- normal angles can improve the evenness of light over longer lengths. But there is no agreed upon method for gauging "evenness" or even an agreement on just what should be measured. Reputation and testing a sample on a subjective level is often the only way to get an idea of what to expect.

Manufacturing quality is also an important factor affecting the evenness of the glow-effect. Material purity and consistency, and the quality of the core/clad interface will contribute significantly to the quality of the glow. The installation will also affect glow quality. Tight bend radii, tight clamping or tracking, excessive bending and kinking prior to installation will produce deleterious affects.

After the optical considerations have been addressed, the mechanical aspects of installing fiber need to be looked at. Some of these will affect what is practically possible, particularly heat.

An ideal light source for fiber illumination would contain no invisible radiation- no infrared and no ultraviolet. But aside from lasers (which are monochromatic or quasi-chromatic at best) no such source exists. But even if there was such a source, the contribution of visible light to the heat load on a fiber can be considerable, with varying results depending on the fiber material. Why? Because no medium is loss-less and virtually all fibers will have "absorbency" losses. This is where atomic and molecular structures resonate with photons of various wavelengths of light and convert them to heat (seeing also the section on spectral attenuation, above). So as the visible radiant energy applied to the end of a plastic optical fiber increases, so too heat increases. Additionally, because it is impossible (or nearly so) to produce enough visible light to be useful without producing infrared energy, there is further heat load contribution to the system by the effects of the infrared light.

THERMAL RADIATION

Heat will cause a polymer fiber to burn if it is too high for too long. Far more common however, are changes in the optical and mechanical properties of the fiber that occur well before burning. The extra heat can further "polymerize" the core materials and affect the way they transmit light and the stiffness of the fiber. As it works out, the more flexible a fiber is, the poorer it�s transmissive qualities. The plastisizers used to make the fiber flexible absorb a certain amount of light. These along with several other factors, many which are mutually exclusive, dictate a balancing act for the chemist formulating the fiber polymer. A choice has to be made: either sacrifice clarity for flexibility, or sacrifice flexibility for clarity. Fiber Optic Products fiber is formulated to favor clarity over flexibility. The penalty is not severe, the fiber is flexible when installed, but becomes stiffer with photo/thermal-activity. Fiber clarity is improved and color shifting reduced over time by the same activity.

But in spite of using some heat to advantage, service temperatures that are too high will degrade the fiber over time. Illuminator design can become very complex for this reason. Illuminator designers have opted for safer, lower wattage halogen lamps, or using lamps such as the metal halide light variety which have inherently less infrared energy. Always follow the light source manufacturers� instructions for both using the illuminator and connecting the fibers to it. An interesting note: we have had customers report the sensation of heat accompanying the light from the end of some fibers. This isn�t infrared energy being transmitted through the fiber, but rather the visible light being converted to heat by the skin and underlying tissues and blood supply.

"UV" EXPOSURE

At the other end of the visible spectrum is ultraviolet. When it comes to polymers, "ultra-violence" is more like it! (A nod to Anthony Burgess, author of "A Clockwork Orange") Ultraviolet light wreaks havoc on polymers by breaking chemical bonds within the molecular structure of the material. The result is varied depending on the polymer in question. Nearly all polymers used in optical fiber will turn yellow, brown, or dark red when exposed to UV over time. Even the very best fiber will eventually turn color after just a few months of spring/summer exposure if exposed to the sun without protection (we know, we make it and we test it). So outdoor installations simply have to be protected from UV exposure, there is no way around it. No one, not even us will warrantee their product for unprotected outdoor use. UV from daylight is not the only source of these problematic wavelengths. Nearly every available light source used for lighting fiber will produce some UV energy. This is even true of quartz-halogen lamps, and especially true of metal-halide lamps. It is crucial that the illuminator manufacturer provide means for reducing UV to negligible levels before the light is launched into the fiber. And one more point- UV light is scattered all over the sky and can still be a problem even if the fiber is shielded from direct sunlight. UV light also is strongly reflected by water, so pools and spas need more than a simple overhang to effectively protect the fiber.

BEND RADIUS LIMITATIONS

Bending too tight (8 times the fiber diameter is the limit!), kinking, repeated tight radii flexing, stepping on, placing heavy (20lbs+) objects on, and localized heating of the fiber can destroy the core clad interface quality and so reduce transmission. Our fiber is durable, it will take a lot of punishment of certain kinds, but as with everything,, care and attention must be paid for proper results. Firm yet gentle fixturing and tracking is the rule, use sweeping elbows in conduit runs, don�t run the fiber over hot water pipes without insulation, and make sure that the uncoiling is done carefully.

Source:www.fiberopticproducts.com/Specs.htm