When choosing a suitable optical fiber for a fiber optic spectrometer, several key factors need to be considered to ensure the accuracy and reliability of spectral measurements. The following are some of the main selection points:
1. Fiber Parameters
● Fiber core diameter (core diameter)
The core diameter determines the ability of the optical fiber to receive light signals. Common core diameter specifications include 5μm, 50μm, 105μm, 200μm, 400μm, 600μm, etc., and even thicker up to 1mm or more.
Increasing the core diameter can increase the energy received by the front end of the optical fiber, but due to the receiving capacity of the spectrometer (limited by the front slit width and the height of the photosensitive surface of the back detector),the core diameter is not the thicker the better. Users should choose the appropriate core diameter according to actual needs.
● Working band and material
Users should select appropriate fiber materials according to the working band of the spectrometer to ensure effective transmission of optical signals.
The material of the fiber determines its wavelength transmittance. For example, high hydroxyl fiber is suitable for the ultraviolet/visible light band (UV/VIS), while low hydroxyl fiber is more suitable for the near infrared (NIR) band. For the UV band, special UV-resistant fiber should also be considered.
● Numerical Aperture (NA) Value
Numerical aperture describes the ability of optical fiber to receive light and is an important optical parameter. A higher numerical aperture means that more light source signals can be captured, but it may also lead to a higher light source background. Fiber optic spectrometer manufacturers usually consider matching the NA value of the optical fiber when designing the spectrometer to ensure that energy is received as much as possible. Users should choose the appropriate optical fiber according to the NA value requirements of the spectrometer.
2. Optical Fiber Type and Interface
● Fiber Type
Choose single-mode fiber or multi-mode fiber according to actual needs. Single-mode fiber is suitable for long-distance, high-speed optical signal transmission, while multi-mode fiber is suitable for short-distance, high-capacity optical signal transmission.
● Interface compatibility
Most fiber optic spectrometers use SMA905 fiber optic interface, but some applications require FC/PC or other non-standard interfaces. Users should ensure the compatibility of the selected fiber optic and spectrometer interface to avoid connection problems.
3. Fiber Performance and Environmental Factors
● Flexural and tensile properties
In actual applications, optical fibers may experience stresses such as bending and stretching. Users should choose optical fibers with good bending and stretching properties to ensure stable transmission of optical signals.
● External covering and sheath
The outer coating and sheath of the optical fiber should take into account environmental factors such as temperature, humidity, and mechanical properties. In an environment with corrosive gases or high temperatures, an optical fiber sheath with corrosion resistance and high temperature performance should be selected.
4. Other matters needing attention
● Fiber Length
The longer the fiber length, the easier it is to lay out, but it will also bring greater loss. Therefore, users should choose the appropriate fiber length according to actual needs to balance the relationship between transmission distance and loss.
● Customization requirements
If standard optical fiber cannot meet specific needs, users can consider customizing optical fiber. Customized optical fiber can adjust core diameter, NA value, working band and other parameters according to actual needs to meet the needs of special application scenarios.
Therefore, choosing the right optical fiber is crucial to the performance and measurement results of the fiber optic spectrometer. Users should make comprehensive considerations and choices based on actual needs, spectrometer parameters, working environment and other factors.
Post time: Aug-01-2024