Phase retrieval with extended field of view based on continuous phase modulation

Highlights: • Single-shot phase retrieval algorithm was proposed based on weak scattering modulator, rather than binary random phase modulator with strong scattering ability. • Higher resolution is possible due to the absent of constraint in the focus plane and the employment of the weak scattering modulator. • Extended field of view of phase retrieval is realized in a noniterative manner. • The random speckle noise introduced by a coherent light could be restrained obviously, as well as the signal-to-noise ratio compared with ptychography. -- Abstract: In order to address two main obstacles that affect the practical application of coherent modulation imaging (CMI)i.e., the low signal-to-noise ratio (SNR) and limited field of view (FOV), a new algorithm providing extended FOV based on CMI is proposed. A weak scattering modulator was used instead of a binary random phase modulator with strong scattering ability, to improve the final resolution of CMI combined with probe scanning. An unlimited FOV was achieved in a noniterative manner, resulting in a superior SNR compared with ptychography. Compared with the original CMI with a binary random phase modulator, the errors decreased obviously when continuous phase plate was utilized based on simulation and experimental results. Moreover, the random speckles that are associated with coherent diffractive imaging could be effectively eliminated. The proposed algorithm facilitates single-shot or extended FOV phase imaging with a high SNR and high resolution.