Abstract
We have developed a new photodisplacement microscope system for practical use that achieves high-sensitivity simultaneous real-time imaging of surface and subsurface structures from a single space-frequency multiplexed interferogram. In this system a linear region of photothermal displacement is excited on the sample surface for subsurface imaging by a line-focused intensity-modulated laser beam. Surface information such as reflectivity and topography along with the displacement is detected with a charge-coupled device sensor-based parallel heterodyne interferometer. Surface and subsurface information components are space-frequency multiplexed into the sensor signal as orthogonal functions based on a frequency-optimized undersampling scheme, allowing each to be discretely reproduced by using a real-time Fourier analysis technique. Preliminary experiments demonstrate that this system is effective, simultaneously imaging reflectivity, topography, and photodisplacement for the detection of subsurface lattice defects in silicon, at a remarkable speed of only pixel area. This new microscope is promising for nondestructive hybrid surface and subsurface inspection and other applications.
© 2006 Optical Society of America
Full Article | PDF ArticleMore Like This
Toshihiko Nakata and Takanori Ninomiya
Appl. Opt. 44(27) 5809-5817 (2005)
Toshihiko Nakata and Takanori Ninomiya
Appl. Opt. 43(16) 3287-3296 (2004)
Toshihiko Nakata and Takanori Ninomiya
Appl. Opt. 45(29) 7579-7589 (2006)