Title : Aberration-insensitive interferometric microscopy
Abstract:
Imaging techniques based on optical correlation measurements and using spatially incoherent illumination have been shown to be able to reduce the effect of optical aberrations. One of such techniques is classical ghost imaging based on spatial intensity correlations in two optical beams of which one is transmitted through the object. The image can be obtained from the correlation measurements even though the object beam is analyzed with a bucket detector. Another imaging technique using spatially incoherent illumination is full-field optical coherence tomography that is based on optical interference instead of intensity correlations for three-dimensional imaging of back-scattering objects. This technique, utilizing light with short coherence time, is insensitive to aberrations if the wavefront shifts are smaller than the longitudinal coherence length of the field.
In this presentation, a novel interferometric ghost-like imaging microscopy that is insensitive to severe optical aberrations will be discussed. The aberration insensitivity stems from a large longitudinal coherence length of the applied spatially incoherent illumination. The approach makes use of a Mach-Zehnder interferometer for transmissive objects or a Michelson interferometer for reflective and back-scattering objects. The technique yields sharp and non-deformed microscope images even if the objects are screened by an optical diffuser that destroys the intensity image completely. Furthermore, not only amplitude, but also phase objects can be imaged with high resolution in the presence of strong aberrations. The resolution is given by the size of the aberration-free diffraction-limited point-spread function no matter if the aberrations are deterministic or random. The approach may find applications in optical microscopy and interferometry.
