A single shot multi-wavelength phase retrieval method is proposed by combining common coherent modulation imaging (CMI) and a low rank mixed-state algorithm together. A radiation beam consisting of multi-wavelength is illuminated on the sample to be observed, and the exiting field is incident on a random phase plate to form speckle patterns, which is the incoherent superposition of diffraction patterns of each wavelength. The exiting complex amplitude of the sample including both the modulus and phase of each wavelength can be reconstructed simultaneously from the recorded diffraction intensity using a low rank mixed-state algorithm. The feasibility of this proposed method was verified with visible light experimentally. This proposed method not only makes CMI realizable with partially coherent illumination but also can extend its application to various traditionally unrelated fields, where several wavelengths should be considered simultaneously.

We propose a simple single-shot spatiotemporal measurement technique called coherent modulation imaging for the spatio-spectrum (CMISS), which reconstructs the full three-dimensional high-resolution characteristics of ultrashort pulses based on frequency-space division and coherent modulation imaging. We demonstrated it experimentally by measuring the spatiotemporal amplitude and phase of a single pulse with a spatial resolution of 44 µm and a phase accuracy of 0.04 rad. CMISS has good potential for high-power ultrashort-pulse laser facilities and can measure even spatiotemporally complicated pulses with important applications.

Accurate measurements of the transmittance of large optical elements are essential to improve the energy density in inertial confinement fusion (ICF). The required complex transmittance of such optical elements used in ICF is obtained by computing the phase difference between the illuminating and transmitting fields using modulation coherent imaging (MCI). A phase plate designed as a modulator has a known transmission function in this technique. It presents a simple and quick method to measure the transmittance of large optical elements with irregular surface profiles by retrieving it from only two diffraction patterns recorded by a CCD camera. The complex transmittance of a continuous phase plate (CPP) with a large aperture used in ICF is measured experimentally, and the results are found to agree with the designed value.

The wavefront-sensing-based autofocus method can precisely determine the focal plane only with few captured images; however, the required phase retrieval, numerical wavefront propagation, and in-focus determination are often time consuming, inevitably limiting its high-speed applications. To accelerate its processing speed, the pixel-reduced wavefront-sensing-based autofocus (PRWSA) method is proposed: with field of interest selection as pixel reduction in the spatial domain and image compression as pixel reduction in the frequency domain, the wavefront with fewer pixels can be used for autofocusing, significantly decreasing the processing time. With simulations, pixel reduction criteria in both the spatial and frequency domains are first determined and tested; next certificated by experiments, the PRWSA method is proved to be well implemented for different specimens. Considering it can precisely locate the focal plane with simple setup, and accelerate the processing speed, this PRWSA method can be a potential tool for high-speed autofocusing.

Single-shot ultrafast multidimensional optical imaging (UMOI) combines ultrahigh temporal resolution with multidimensional imaging capabilities in a snapshot, making it an essential tool for real-time detection and analysis of ultrafast scenes. However, current single-shot UMOI techniques cannot simultaneously capture the spatial-temporal-spectral complex amplitude information, hampering it from complete analyses of ultrafast scenes. To address this issue, we propose a single-shot spatial-temporal-spectral complex amplitude imaging (STS-CAI) technique using wavelength and time multiplexing. By employing precise modulation of a broadband pulse via an encoding plate in coherent diffraction imaging and spatial-temporal shearing through a wide-open-slit streak camera, dual-mode multiplexing image reconstruction of wavelength and time is achieved, which significantly enhances the efficiency of information acquisition. Experimentally, a custom-built STS-CAI apparatus precisely measures the spatiotemporal characteristics of picosecond spatiotemporally chirped and spatial vortex pulses, respectively. STS-CAI demonstrates both ultrahigh temporal resolution and robust phase sensitivity. Prospectively, this technique is valuable for spatiotemporal coupling measurements of large-aperture ultrashort pulses and offers promising applications in both fundamental research and applied sciences.

In ptychographical imaging with X-ray or electron beam, the recorded speckle intensity pattern of far field diffraction was often saturated by the presence of strong zeroth-order which was undesirable. A beam-stop was widely used to block the area of strong central diffraction in the pattern. The image was then reconstructed by disregarding the diffraction constraints within that area where inaccuracies exists due to saturation or blocking of the beam. Though reconstructions were obtained in this way by omitting saturation regions, the rationale behind this method was not discussed in detail and its effect on the final image quality was not studied. The physics of this method was analyzed theoretically and experimentally in this study. The convolution effect between illumination and object functions was able to retrieve and bring back the information lost in the blocked or saturated area from its neighborhood. This was possible while the saturated or blocked area was not wider than the spectral width of illumination, and once it exceeds this minimum, the quality of reconstruction would degrade seriously. The theoretical model was verified by numerical simulations and experiments.