Determination of surface contour by temporal analysis of shadow moiré fringes

✍ Scribed by C Quan; Y Fu; C.J Tay

• Publisher: Elsevier Science
• Year: 2004
• Tongue: English
• Weight: 610 KB
• Volume: 230
• Category: Article
• ISSN: 0030-4018
• DOI: 10.1016/j.optcom.2003.11.035

✦ Synopsis

A simple temporal analysis algorithm (phase scanning method) is proposed for 3-D surface profile measurement of a vibrating object based on shadow moir e e technique. A grating is positioned close to a low-frequency vibrating object and its shadow is observed through the grating. The moir e e fringe patterns, generated by the interference of grating lines and shadow lines, are captured by a high-speed CCD camera with a telecentric gauging lens. Phase values are evaluated point by point using phase scanning method. From the phase values of each point on the object, the high-quality surface profile of the specimen at different instants of vibration can be retrieved. In this application, two specimens are tested to demonstrate the validity of the method, one is a spherical cap with height of 4 mm, the other is a small coin with unevenness of less than 0.2 mm. The experimental results are compared with test results using mechanical stylus method.