Laser Wire® White Paper

Abstract

This paper describes the composition of Laser Wire® cable and how its properties are achieved. In this paper, Laser Wire® cable is described by the technical term Light Diffusing Fiber (LDF). Generally speaking, LDF is achieved by direct exposure of a photo-curable material to a light source, or reflected light from a source. The light source can be LED or laser based. Brightness is achieved from focused light through lensing, reflectors, and prisms. Light Diffusing Fiber is an optical fiber intentionally designed so that when light is input into the core on one end, light disperses out the sides throughout the length. This process is referred to as “Lossy.”

Introduction: How LDF Differs from Standard Fiber

In data communications, optical fibers transmit light from one point to another, sometimes over very long distances. A good data fiber will have >99% of its light transmission sent from one end to the other, making the fiber a vessel that transmits light energy across distance. This makes standard optical fiber a poor choice when the light is intended to be seen throughout the cable length.

Laser Wire® embraces the “lossy” nature of the fiber, and has the light bounce back and forth along the fiber length. The goal is to have <10% of the light energy pass through the end of the fiber at its given diffusion length, dispersing the rest throughout the line.

This loss of light — called “decay” — is not necessarily linear. Each wavelength of light has a slightly different rate of decay. The rate of decay in LDF is exponentially longer than in Plastic Optical Fiber (POF), which has been prevalent in the lighting industry for decades. POF has an extremely high decay rate and is typically suitable only for low-cost, short-run applications like children’s toys that do not require even illumination.

LDF Profiles

LDF is made in various profiles that bend light or decay at different rates, causing different results based on light intensity and the location of the light source. The Laser Wire® profiles are Super Pop, Pop, Accent, and Ice.

Operation: The Three Critical Factors

It is important to know the precise nature of the fiber. Three major factors are required for even, efficient illumination: Connector, Light Source / Lensing, and Polishing.

Connectors

LDF can have a multitude of connectorization options. However, the precise nature of light transmission requires specialty connectors. Connectors are only critically important if the fiber is intended to be removed from the light source, which is typically the case in wearable applications.

Light Source and Lensing

The light required to illuminate LDF properly is extremely precise. Lensing is extremely important to achieve the most efficient and effective light source. The terms Light Source and Lensing are commonly related and will be referenced together.

Light Emitting Diodes (LED) can be a suitable choice for installations, but the nature of LEDs creates inherent challenges. Because LEDs generally want to shine outward, they require a great deal of lensing to give enough light output needed for normal operation. They also require more power than laser light sources — generally 10–100x more. This is why laser light sources are recommended for illuminating LDF.

Laser light is more focused by nature, which makes it easier to collimate the light and direct enough focused energy onto the fiber. Selecting the right light source and lensing combination is the most important component of LDF system design.

Polishing

The core of the fiber is 170μm (0.17mm) and must be polished to a perfect round circle. When the fiber is not polished perfectly, light loss or uneven illumination throughout the wire can occur. A high-grade connector capable of precision placement, a light and lensing system with proper focus length, and optically polished fiber — these three components together ensure a bright, even illuminated fiber.

Advanced: Dual Light Source Operation

LDF can be driven from a single light source or from multiple sources. Gradients in light are typically not possible in thinly illuminated devices, but LDF enables a light source to be placed on each end of the fiber. This allows even more light possibilities including gradients, unlocked colors, and impressive effects not seen in any other lighting device.

With two modules active simultaneously, the intensities of the wire are increased, as there is roughly 2x the amount of light energy passing through the cable at any given point. If a brightness increase is desired from a particular profile, adding another light source is the primary option.

Color Blending with DualDrive

If two different-colored modules are used, the bending properties of each color mix with one another throughout the line, giving a perceived gradient across the fiber length. Notice that intensity diminishes the farther from each original light source it becomes.

The gradient rate can be manipulated based on the LDF profile chosen. Using two different colors on the three various profiles will produce different results of the same length. Super Pop will have the largest defined color gradient. Pop will have a softer transition. Accent will produce the most gradual sweep.

By increasing the run length past the intended profile length, a larger color gradient can be achieved. For instance, Pop profile disperses 90% of its light energy over 5M, leaving 10% at that distance. If the length is increased to 8M, approximately 2% of the light energy remains at the far end. Adding a different color at the other end would show a gradient of approximately 98% of one color transitioning to approximately 98% of the opposite color.

Perceived Brightness and Viewing Angle

Perceived brightness is complex because each color wavelength has different properties when interacting with the fiber. Typically, Green (~520nm) is the easiest color for the human eye to perceive, followed by Blue (~450nm), then Red (~638nm). When two different light sources are used, the higher perceived brightness color may overpower the LDF and cause a slightly unbalanced effect. This can be mitigated by using external controls to turn down the brightness of the higher-visibility color.

Viewing angle is similar to perceived brightness but can be used differently. Depending on where the viewer is located, different color intensities are accentuated. More defined light is seen with the light source pointed toward the viewer. In the opposite direction, the other color source is more perceived. In reality, this shift is more subtle than theoretical models suggest.