Light Guide Data

Mechanical/Environmental Characteristics

Mechanical Characteristics

Minimum Bend radius

The minimum bend radius of optical fiber light guides is mainly determined by the tube bend radius, but is also affected by factors such as the optical fiber bundle diameter and optical fiber bundle length. Excessive bending of an optical fiber light guide can cause wavelength loss or break of the optical fiber, etc., which may result in a drop in the transmitted light intensity, leading to poor performance.

Note that optical fibers with the random arrangement specification will have a larger minimum bend radius than standard optical fiber bundles.

Repeated Bend Resistance

Repeatedly bending optical fiber light guides can cause fiber twisting, friction between fibers, and friction between fibers and the tube (the optical fiber bundle covering). This can result to optical fiber breaks or deterioration, causing a drop in the transmitted light intensity and performance.

An optical fiber light guide's ability to withstand repeated bending varies by fiber type. Multicomponent glass fibers generally have less repeated bend resistance than plastic fibers. Note that optical fibers with the random arrangement specification will have less repeated bend resistance than standard optical fiber bundles.

If you require high durability, use a bend-resistant light guide (available by special order) with a customized internal structure and special coating.

Environmental Characteristics

Heat Resistance

The heat resistance of bare optical fibers varies by material, with a value of 70°C for plastic, 430°C for multicomponent glass (excluding the lubricant), and over 1000°C for quartz (excluding the covering). The maximum heat resistance temperature of light guide end faces will be determined by the heat resistance of the adhesive, optical fiber protective coating and covering in use. The value is 70°C for plastic, 200°C for multicomponent glass, and 200°C for quartz. For applications requiring high end face heat resistance, use a heat-resistant light guide (multicomponent glass or quartz types heat resistant up to 300 °C are available by special order).

Quartz models heat resistant up to 500°C are available for applications requiring even higher heat resistance. The life of bare optical fibers will vary depending on the operating temperature, and the existence, degree and duration of any temperature variations present. If you intend to use the product in a nonstandard environment, inquire for details before purchase.

Heat Resistance Temperatures
Optical Fiber Type Heat Resistance Temperature of a Bare Fiber only (℃) End Face Heat Resistance Temperature of Standard Types (℃) End Face Heat Resistance Temperature of Heat-Resistant Types (℃)
Plastic 70 70
Multicomponent glass 430 (excluding lubricant) 200 300
Quartz Over 1,000 (excluding covering) 200 300, 500

Humidity Resistance, Eater Resistance

Optical fibers do not have very good humidity or water resistance. For applications requiring humidity- or water resistance, use a special-type light guide (available by special order; multicomponent glass fiber only).

The diagram on the right shows the result of an autoclave test. (A single test cycle consisted of 20 minutes at a temperature of 132°C, humidity of 100%, and pressure of 2 kg/cm2, followed by a reduction in temperature, humidity and pressure to the ambient conditions.)

Transmissivity/Luminous Intensity Distribution Characteristics

Bare Optical Fiber Data

Material Multicomponent Glass Plastic Quartz
Fiber Diameter 50 µm 250 µm 500 µm 750 µm
1,000 µm 2,000 µm
208 µm (and several other values)
Core Diameter 45 µm (3 to 5 µm less than fiber diameter) 200 µm
Aperture Angle Approx. 70° Approx. 60° Approx. 25°
End Face
Heat Resistance Temperature*1
Standard type 200℃ Standard type 70℃ Standard type 200℃
Special-order type 300℃ Special-order type 500℃
Bending Resistance Δ ×
Heat Resistance ×
(Visible light; short distance)
Price ×

Distribution Characteristic for Light Guide with Halogen Light Source

Relationship between Light Guide Length and Transmissivity

Luminous intensity characteristic for ring light guide (example)

Luminous intensity characteristic for line light guide (example)

Light guide spectral transmissivity

Characteristics of Quartz Fibers for UV/Visible Range

Fiber filament specifications

Numerical Aperture (NA) and Structural Dimensions NA 0.22 ± 0.02
Diameter Core (µm) 200 ± 3
Cladding (µm) 208 ± 3
Primary Covering (µm) 240 ± 10
Minimum bend radius 20
Material Core Pure SiO2
Cladding SiO2 with fluorine

Caution: Fiber diameters (core/cladding) may change without prior notice.


Application Examples

Wavelength Loss Characteristic

Wavelength Transmissivity Characteristic (per meter; excluding Fresnel reflection loss)