Differential heterodyne interferometer for measuring thickness of glass panels.
Differential heterodyne interferometer is applied for measuring spatial thickness variations across glass panels of liquid-crystal displays. This system uses the Zeeman laser as a source of two-frequency shifted orthogonally linearly polarized probe waves, passing through the glass in two spatially separated points. These waves are then recombined in a single beam to produce the intermediate frequency signal with the phase proportional to the thickness gradient of a glass sample. The phase of the intermediate signal is measured against the laser reference by means of a lock-in amplifier, and finally real-time integration provides the thickness variation. Since spatial separation of the probe beams is only 1.35 mm good approximation for the thickness gradient is achieved. Detailed design of the interferometer and experimental results on real samples are presented.
Samsung Electronics, Mechatronics Center, 416 Maetan-3Dong, Yeongtong-Gu, Suwon-City, Gyeonggi-Do 442-600, South Korea. proto.vladimir@samsung.com
Vladimir
V
Protopopov
Sunghoon
S
Cho
Kwangso
K
Kim
Sukwon
S
Lee
Hyuk
H
Kim
D004867:Equipment Design; D019544:Equipment Failure Analysis; D005898:Glass / Q000737:chemistry*; D007368:Interferometry / Q000295:instrumentation*; D008422:Materials Testing / Q000295:instrumentation*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity