title: On-line metrology with conoscopic holography: beyond triangulation.
abstract: On-line non-contact surface inspection with high precision is still an open problem. Laser triangulation techniques are the most common solution for this kind of systems, but there exist fundamental limitations to their applicability when high precisions, long standoffs or large apertures are needed, and when there are difficult operating conditions. Other methods are, in general, not applicable in hostile environments or inadequate for on-line measurement. In this paper we review the latest research in Conoscopic Holography, an interferometric technique that has been applied successfully in this kind of applications, ranging from submicrometric roughness measurements, to long standoff sensors for surface defect detection in steel at high temperatures.
authors.affiliation: University of Oviedo, Dept. Electrical Engineering. Campus de Viesques s/n, 33204 Gijón, Spain; E-Mails:  ialvarez@isa.uniovi.es  (I.A.);  mfrade@isa.uniovi.es  (M.F.);  gojea@isa.uniovi.es  (G.O.).
authors.forename: Ignacio
authors.initials: I
authors.lastname: Alvarez
authors.forename: Jose M
authors.initials: JM
authors.lastname: Enguita
authors.forename: María
authors.initials: M
authors.lastname: Frade
authors.forename: Jorge
authors.initials: J
authors.lastname: Marina
authors.forename: Guillermo
authors.initials: G
authors.lastname: Ojea