Resolution enhancement and edge ringing suppression in digital holography using speckle illumination

Abstract Digital Holography (DH) enables high-accuracy quantitative phase imaging but is limited by reduced lateral resolution and coherent artifacts, such as diffraction noise, unwanted interference due to reflections and edge ringing. This work introduces Speckle Illumination Digital Holography (SIDH) for reflective surface samples, integrating DH with multiple decorrelated speckle illuminations to combine the phase sensitivity of DH with the resolution enhancement and noise suppression of incoherent imaging. An on-axis phase-shifting DH setup uses a holographic diffuser on a motorized stage to generate uncorrelated speckle fields, followed by object field reconstruction via calibration and averaging. Experiments on a USAF 1951 test target, supported by numerical simulations, demonstrate that SIDH enhances lateral phase resolution and significantly reduces edge ringing compared to plane-wave illumination. However, instrument transfer function (ITF) analysis reveals that contrast transfer decreases at higher spatial frequencies, limiting quantitative phase accuracy and preventing the full realization of theoretical resolution gains. These results highlight SIDH’s potential and limits.