Manual wavefront holoscopy for inspection and visualization of engraved marks in progressive addition lenses

Manual wavefront holoscopy, or simply manual w-holoscopy, is presented as a simplification of our recently reported concept of wavefront holoscope [B. Perucho and V. Mico, J Biomed Opt. 19(1):16017 (2014)]. The w-holoscope introduces an extremely simple visualization and inspection system for permanent marks in progressive addition lenses (PALs) as an application of digital in-line holography, the digital version allowing visualization (recognition and identification) and characterization (quantitative measurement) of the engravings in PALs. Here, we present a further simplification of such concept by avoiding digital elements in the setup. The layout is extremely simple and defines a new concept of marking reader for visualization and identification of engraved marks in PALs. Experimental results are reported using different PALs.