Fiber Optics

Light Guide

A cord of many glass optical fibers bundled together for the purpose of transmitting light is known as a light guide.
Sumita accepts not only standard light guide described on our website, but also customized light guide which is optimum for customer's request.
Ratio of Customization Exceeds 90% !

light guide

Variations and Properties

Fiber optic numerical aperture and aperture angle is calculated by the following formula in refractive index of core material and clad material.


Sumita manufactures various fiber optics in various numerical aperture with making use of this features.

List of Fiber Type

Wavelength Fiber Type Numerical Aperture(NA) Aperture Angle(2θ)
Visibility SOG-120S 0.87 120°
SOG-100 0.77 100°
SOG-70S 0.57 70°
SOG-35 0.29 35°
SOG-15 0.13 15°
Visible, Near Infrared SON-60 0.50 60°
SON-30 0.28 33°
Near Infrared SOG-70IRA 0.57 70°

Optical Fiber is…

Composition and Principle

Optical fiber applied for light guide has dual structure such as drawing 1. The internal side is composed of optical glass with superior core. The external side is composed of glass with superior weather resistance as clad.

By this composition, the incoming light from one side is being transmitted to the other side with repeating total reflection in core interface.

  • * Total reflection means that light completely reflects in a certain angle (critical angle) on a border of two kinds of light-transparent material substances(dielectric) which have different refractive index as shown on figure 2.
Figure 1:composition
Figure 2:principle

Transmittance in Each L Dimensions


transmittance in each L dimensions
Measurement condition
Light guide of fiber diameter Φ5(strand diameter : 50μ) is applied.
(Occupancy rate of core is about 70%.)

Transmittance in Each Fiber

Two Meter Products Each

transmittance in each fiber
Measurement Condition
Light guide of fiber diameter Φ5(strand diameter : 50μ) is applied.
(Occupancy rate of core is about 70%.)

Delivery Froms

We are not only develop glass materials for fibers, but also draw fibers in house.
We control every stage of production process in fibers to keep high quality and we can control the number of fibers by count. Fibers are offered three forms based on customer needs.

delivery forms
Contact us for information and questions
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