Why is the core diameter 200µm for this Shelyak calibration fiber?
The 200µm core diameter is specifically chosen to match the requirements of calibration units used with spectrographs like the Shelyak eShel. It provides a broad, even illumination of the spectrograph slit, which is critical for accurate flat-fielding and wavelength calibration.
Will the 20-meter length of this fiber reduce my calibration signal strength?
No. The fiber itself has a transmission rate close to 100%, and the total attenuation is rated at less than 0.5dB. This low level of loss is independent of the fiber's length up to 20 meters, so you will not see a noticeable drop in signal compared to a shorter fiber.
What systems is the Shelyak 200µm fiber compatible with?
This fiber is primarily designed for Shelyak Instruments' own fiber-fed spectrographs, such as the eShel and Whoppshel systems. It uses standard FC-FC connectors, making it potentially compatible with other astronomical or laboratory equipment that uses the same interface.
I am setting up an eShel spectrograph in my observatory. Is this 20-meter fiber the correct one for connecting the calibration unit to the FIGU?
Yes, this is the correct fiber for that purpose. The 200µm core is designed to carry the light from the calibration module to the Fiber Injection & Guiding Unit (FIGU) of the eShel. The 20-meter length offers ample flexibility for routing the cable between your telescope and the spectrograph.
What are FC-FC connectors and why are they used on this calibration fiber?
FC (Ferrule Connector) connectors are a type of fiber optic connector known for their secure, screw-on coupling mechanism. They provide excellent mechanical stability and repeatable alignment, which is critical in spectroscopy to prevent signal fluctuations. The FC-FC designation means the cable has this type of connector on both ends.
My calibration lamp seems dim when using the 20-meter fiber with my Whoppshel system. Is the fiber causing the light loss?
It is unlikely the fiber itself is the cause, as its attenuation is less than 0.5dB. The most common source of signal loss in a fiber optic system is at the connection points. Ensure both FC-FC connectors are perfectly clean (free of dust) and securely tightened to minimize junction loss and maximize signal throughput.
