loss of signal by a factor of 4 compared to my last observation. Dramatic!
I noticed this problem immediately by measuring the intensity of the ThAr lines and quickly confirmed by stars observations
The explanation is simple and classic: the presence of dust at the entrance of the 50 microns core fiber. I disassembled
the fiber all night (which is not great
) and despite careful handling, clean is a potential probem.I quickly identified the problem by carefully cleaning the input of
the fiber entrance with a very soft lens paper. Must rub very gently,
in the direction of the paper fiber.
The resulting was spectacular. I found my original signal (and even better!).
As you can be seen, the cleanliness of the fiber can be a source (sometimes) of efficiency lost.
Christian B