David W. Abraham, C.C. Williams, et al.
Journal of Microscopy
Absolute optical ranging has been demonstrated by wavelength-multiplexed interferometry with a range resolution of 200 nm, well below the single-wavelength ambiguity. Two current- and temperature-tunable GaAlAs laser diodes (850 nm) provide an equivalent wavelength below 100 μm and a resolution of less than 200 nm. The achievement of such resolution provides the means for combining single- and multiple-wavelength interferometric measurements to achieve unambiguous distance measurement with nanometer resolution. The ranging system is also used to profile unambiguously an integrated circuit structure with a 2.5-μm surface topography. © 1989 Optical Society of America.
David W. Abraham, C.C. Williams, et al.
Journal of Microscopy
C.C. Williams, H.K. Wickramasinghe
SPIE OE/LASE 1988
A.P. Ghosh, D.B. Dove, et al.
Microlithography 1992
R.S. Shenoy, K. Gopalakrishnan, et al.
VLSI Technology 2006