Demonstration of a no-moving-parts axial scanning confocal microscope using liquid crystal optics

For the first time, to the best of authors' knowledge, a no-moving-parts axial scanning confocal microscope (ASCM) system is designed and demonstrated using a combination of a large diameter liquid crystal (LC) lens and a classical microscope objective lens. By electrically controlling the 5 mm. diameter LC lens, the 633 nm wavelength focal spot is moved continuously over a 48 mu m range with a measured 3-dB axial resolution of 3.1 mu m using a 0.65 numerical aperture (NA) micro-objective lens. The ASCM is successfully used to image an Indium Phosphide (InP) twin square optical waveguide sample with a 10.2 mu m waveguide pitch and 2.3 mu m height and width. Using fine analog electrical control of the LC lens, a super-fine sub-wavelength axial resolution of 270 nm is demonstrated. The proposed ASCM can be useful in various precision three-dimensional (313) imaging and profiling applications. (c) 2006 Elsevier B.V. All rights reserved.