Experimental observation of differential self-mixing interference signals using a randomly polarized laser: a differential self-mixing interferometry.

Differential measurement has strong anti-interference ability. We report the first, to the best of our knowledge, experimental demonstration of differential self-mixing interference signals using a randomly polarized laser for differential self-mixing interferometry (SMI). In the differential SMI system, the detection light can be divided into interference signals of $p$p-polarized and $s$s-polarized light with identical intensity and pi-shift phase difference. By exploiting such a new experimental phenomenon, we propose a noise-robust and low-cost self-mixing interferometer. Experiments show that the proposed approach can effectively suppress both periodic and aperiodic noise. Thus, the reported phenomenon and approach has a good application prospect in self-mixing interferometers.

Reflection light-field microscope with a digitally tunable aperture by single-pixel imaging.

Reflected light microscope is a tool for imaging opaque specimens. However, most of the existing reflected light microscopes can only obtain the two-dimensional image of the specimen. Here we demonstrate that with the help of single-pixel imaging, we can develop a reflection light-field microscopy for volumetric imaging. Importantly, using single-pixel imaging, we can digitally adjust the size of the aperture diaphragm of the proposed reflection light-field microscope for changing the depth of field and for achieving three-dimensional differential phase-contrast imaging in an arbitrary direction, without a hardware change. Our approach may benefit various reflective specimens with wide depth information in the semiconductor industry and material science.

Micro-tomography via single-pixel imaging.

Tomographic imaging allows for the cross-sectional imaging of specimen, whereas single-pixel imaging can produce image only with a spatial non-resolved detector. Here we propose a compact tomographic imaging system combining single-pixel imaging. This approach uses a digital micromirror device (DMD) to encode the spatial information of specimen and employs an array of single-pixel detectors to record the light signals from different directions. For each single-pixel detector, we can retrieve an image of the specimen from a unique perspective angle. Based on the retrieved images, we can realize tomographic imaging, such as intensity images refocusing and three-dimensional (3D) differential-phase-contrast imaging, without mechanically scanning the specimen. Experimental results also demonstrate that the micro-tomographic images with 384×384 pixels can be simultaneously realized only with an array of 5×6 single-pixel detectors. Furthermore, due to the broad operational spectrum of the single-pixel detector, the proposed method is a good candidate to realize tomographic imaging with the non-visible light wavebands, such as terahertz and x-ray, thus it would open up opportunities in many life science and engineering fields.