Scan-less confocal phase imaging based on dual-comb microscopy

Published on 2018-05-16T13:53:37Z (GMT) by
Confocal laser microscopy is a powerful tool in life science research and industrial inspection because it offers two-dimensional optical-sectioning or three-dimensional imaging capability with micrometer depth selectivity. However, the objects to be measured must be reflective, absorptive, scattering, or fluorescent because the image contrast is given by the optical intensity. If a new image contrast can be provided by the optical phase, confocal laser microscopy can be further applied for transparent non-fluorescent objects or reflective objects with nanometer unevenness by providing information on refractive index, optical thickness, or geometrical shape. Here, we report scan-less confocal dual-comb microscopy offering a phase image in addition to an amplitude image with depth selectivity by using an optical frequency comb as an optical carrier of amplitude and phase with discrete ultra-multichannels. Our technique encodes confocal amplitude and phase images of a sample onto a series of discrete modes in the optical frequency comb with well-defined amplitude and phase to establish a one-to-one correspondence between image pixels and comb modes. The technique then decodes these images from comb modes with amplitude and phase. We demonstrate confocal phase imaging with milliradian phase resolution under micrometre depth selectivity on the millisecond timescale, showing the potential to seamlessly combine confocal imaging with phase imaging by further improving the system. As a proof of concept, we demonstrate the surface topography of nanometer-scale step structures. Our technique for confocal phase imaging will find applications in nanometer-to-micrometer-to-millimeter surface topography of semiconductor objects and three-dimensional visualization of stacked living cells in culture.

Cite this collection

Hase, Eiji; Minamikawa, Takeo; Mizuno, Takahiko; Miyamoto, Shuji; ichikawa, ryuji; HSIEH, YI-DA; Shibuya, Kyuki; Sato, Katsuya; Nakajima, Yoshiaki; Asahara, Akifumi (2018): Scan-less confocal phase imaging based on dual-comb microscopy. The Optical Society. Collection.