Pigtail style collimator for 850nm with an f=2.61mm C-lens in a 2.5mm OD housing (short version), with -40dB return loss, with a 1 meter long, 900µm OD cabled, 5/125µm singlemode fiber, terminated with an angled FC/APC connector. The predicted collimated beam diameter will be around 0.5mm at the 1/e^2 level.
