Shadow Moire measuring system for automatic compensation of contrast of fringe pattern

• Main Authors: ZENG GUOHUA, WANG HONGXIA, LIU QIANG, SUN GUOXING, ZHANG WEI, REN AIHUA, WANG HUAN
• Format: Patent
• Language: English
• Published: 20.05.2015
• Subjects: MEASURING; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS; MEASURING LENGTH, THICKNESS OR SIMILAR LINEARDIMENSIONS; PHYSICS; TESTING

The invention relates to a Shadow Moire measuring system for automatic compensation of contrast of a fringe pattern. The measuring system is characterized in that a to-be-tested object is arranged on an object carrying table, and a sinusoidal grating is arranged above the to-be-tested object; an adjustable light source is used for projecting parallel light through a lens collimating system, the parallel light is irradiated to the sinusoidal grating which is parallel with the object carrying table, the sinusoidal grating is overlapped with a shadow grating which is modulated by the surface shape of the to-be-tested object to form a moire fringe pattern, and a generated moire deformation fringe pattern is collected, processed and transmitted by a CCD (charge coupled device) camera; the pitch of the sinusoidal grating is P, and P is 0.08mm or 0.1mm or 0.25mm; the adjustable light source is used for projecting the parallel light through the lens collimating system, the parallel light is irradiated to the sinusoidal grating and form an incident angle alpha with the sinusoidal grating, the CCD camera is used for collecting the moire fringe at an angle beta with the sinusoidal grating, and a servo motor is arranged under the object carrying table. The measuring system has the advantages that by obtaining the change rule of the gray level of any point on the fringe pattern, the change of fringe contrast of the fringe pattern is compensated by automatically adjusting the light intensity, so the fringe pattern is collected, and the basic uniform contrast is maintained; the measuring reliability and measuring accuracy are improved, and the measuring system is suitable for the surface non-contact three-dimensional optical measurement.