Microscopic level and maintaining it exactly about the CD's tracks: Goal lens - High quality focusing lens, very similar to a fantastic microscope aim having a numerical aperture (N.A.) of 0.forty five and focal length of 4 mm. (In the event you care, the N.A. is outlined given that the http://claytonetgpz.blogvivi.com/2482276/rumored-buzz-on-sewing-machine-repair-boulder