Non-Contact Air-Gap Tester also named Lens surface positioner(or Scanner)，it is based on the technique of low coherence interferometry to precisely locate the lens surfaces, thus achieve the precise measurements of lens thickness and air gap. Compared with the traditional one-by-one mechanical contact testing, all the lens thickness and air spacing could be measured at the same time in one scan, and the software could show the results directly. It could combine with the Lens eccentricity tester(such LensCT-DAF or LensCT-AF) to realize one-stop measurement of tilt, offset, and air-gap for all the material with transparent or semitransparent. The measurement is non-contacting, higher precision and efficiency