A thin transparent media adapter is used when scanning transparent media on a contact image sensor or reduction optics scanner. The adapter uses illumination from a light guide assembly to illuminate a diffuser and the media. A lens assembly is used to focus the light from the media to create an intermediate image between the adapter and the scanner platen glass. The adapter is an optical assembly that forms an intermediate image of the transparent media in the object side focal plane of existing scanner optics. The existing scanner optics can then capture and focus the light from the intermediate image onto the scanner's existing sensor array. The adapter magnetically couples to the scan system to allow the lens array to follow movement of the optical system of the scanner.