Dear all, We performed some additional tests in order to assess the current state of our confocal microscope. We would greatly appreciate receiving your feedback on the observations that I will describe below. The first thing we did was to thoroughly clean the tip of the optical fibre that goes from the three-laser unit to the scanning head (referred to as the “optical-fibre cable for excitation light” in the microscope manual). We carried out the cleaning with propanol-2 and lens cleaning paper. I am sending you four different pictures that show how the output of the aforementioned optical fibre looked like before and after the cleaning. Two of the pictures show the beam profile of a 488-nm laser, while the remaining two pictures show the beam profile of a 405-nm laser. I am also attaching two images of a rhodamine B film that show a somewhat inhomogeneous illumination pattern. The images were recorded using 488- and 405-nm lasers as excitation sources. Could you please tell us if the beam profile shown in the pictures significantly differs from the profile that would be expected for this kind of optical fibre? In other words, is it a cause for concern? We would like to be sure that a visit from a technician is really needed before requesting one. We thank you in advance and look forward to your reply. Kind regards, XXXX.