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Beam blocking method for optical characterization of surfaces
Author(s) -
Cywiak Moisés,
Murakowski Janusz,
Wade Glen
Publication year - 2000
Publication title -
international journal of imaging systems and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.359
H-Index - 47
eISSN - 1098-1098
pISSN - 0899-9457
DOI - 10.1002/1098-1098(2000)11:3<164::aid-ima1001>3.0.co;2-n
Subject(s) - optics , photodiode , beam (structure) , perpendicular , signal (programming language) , physics , enhanced data rates for gsm evolution , laser , materials science , computer science , geometry , mathematics , telecommunications , programming language
A new method for measuring local topography of optical surfaces gives excellent lateral resolution. To obtain one‐dimensional image information, the surface is mechanically scanned at a slow rate and vibrated sinusoidally in the direction of the scan. The motion lies in a plane perpendicular to an incident, focused, probing laser beam. The reflected laser beam, angularly modulated by the moving variations in the vibrating surface, is gathered by a lens and directed toward a knife‐edge and photodiode combination. One half of the beam is blocked by the knife‐edge, the orientation of which is at a right angle with respect to the angular motion of the beam. The detected signal from the photodiode is proportional to the derivative of the local slope convolved with a spread function stemming from the surface vibration and the beam profile. The operational characteristics of the proposed method are superior compared with available methods. © 2001 John Wiley & Sons, Inc. Int J Imaging Syst Technol 11, 164–169, 2000