The 77646 Focusing and Imaging Beam Probe focuses the output of our Fused Silica Fiber Bundles. The fiber bundle is placed one focal length from Lens 1, to produce a collimated beam. This collimated beam is focused one focal length from Lens 2 (not included). The working distance is 7 mm less than the focal length of Lens 2. Lens 1 is a 19 mm focal length, F/1.7 fused silica lens, and is included with the probe. Choose lens 2 from the Lens Ordering Information Table, based on the image magnification and working distance required. The nominal magnification is defined as the ratio of the focal lengths of Lens 2 to Lens 1. The Imaging Beam probe images the output from Oriel® Glass Fiber Bundles. It uses a complex lens (Lens 1) to collect the light, and a second lens, Lens 2, to re-image the end of the fiber bundle one focal length away. You can re-image at 1:1, 2 mm from the end of the probe, with the 40230 Lens. Or, form a larger image at greater distances. At 100 mm from the probe, the magnification is 12.5 and you can clearly see the individual fibers.