Towards Mixed-State Coded Diffraction Imaging

Benjamin Attal, Matthew O'Toole

Abstract:

Coherent diffraction imaging (CDI) is a computational technique for reconstructing a complex-valued optical feld from an
intensity measurement. The approach is to illuminate an object with a coherent beam of light to form a diffraction pattern, and use a
phase retrieval algorithm to reconstruct the object’s complex transmittance from the measurement. However, as the name implies,
conventional CDI assumes highly coherent illumination. Recent works therefore extend CDI to account for partial coherence and
imperfect detection, by modeling light as an incoherent mixture of multiple felds (e.g., multiple wavelengths) and recovering each feld
simultaneously. In this work, we make strides towards the practical implementation and usage of multi-wavelength diffraction imaging.
In particular, we provide novel analysis of the noise characteristics of multi-wavelength diffraction imaging, and show that it is
preferable to coherent diffraction imaging under high signal-independent noise. Additionally, we present a compact coded diffraction
imaging system and corresponding phase retrieval algorithms to robustly and simultaneously recover complex felds representing
multiple wavelengths. Using a novel mixed-norm color prior, our prototype system reconstructs a larger number of multi-wavelength
felds from fewer measurements than existing methods, and supports applications such as micron-scale optical path difference
measurement via synthetic wavelength holography