title: Topographic optical profilometry by absorption in liquids.
abstract: Optical absorbance within a liquid is used as a photometric probe to measure the topography of optical surfaces relative to a reference. The liquid fills the gap between the reference surface and the measuring surface. By comparing two transmission images at different wavelengths we can profile the height distribution in a simple and reliable way. The presented method handles steep surface slopes (<90°) without difficulty. It adapts well to any field of view and height range (peak to valley). A height resolution in the order of the nanometer may be achieved and the height range can be tailored by adapting the concentration of water soluble dyes. It is especially appropriate for 3D profiling of transparent complex optical surfaces, like those found in micro-optic arrays and for Fresnel, aspheric or free-form lenses, which are very difficult to measure by other optical methods. We show some experimental results to validate its capabilities as a metrological tool and handling of steep surface slopes.
authors.affiliation: Departamento de Óptica, Escuela Universitaria de Óptica, Universidad Complutense de Madrid, C/. Arcos de Jalón 118, 28037, Madrid, Spain. jcmartin@fis.ucm.es
authors.forename: Juan Carlos Martinez
authors.initials: JC
authors.lastname: Antón
authors.forename: Jose
authors.initials: J
authors.lastname: Alonso
authors.forename: Jose Antonio Gómez
authors.initials: JA
authors.lastname: Pedrero
authors.forename: Juan Antonio
authors.initials: JA
authors.lastname: Quiroga
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D008027:Light; D009391:Nephelometry and Turbidimetry / Q000379:methods*; D012031:Refractometry / Q000379:methods*; D012542:Scattering, Radiation; D012996:Solutions / Q000737:chemistry*
chemical_list: D012996:Solutions