Computational imaging-based single-lens imaging systems and performance evaluation.

The minimalist optical system has a simple structure, small size, and lightweight, but the low optical complexity will produce optical aberration. Addressing the significant aberration degradation in minimalist systems, we propose a high-quality computational optical framework. This framework integrates a global point spread function (PSF) change imaging model with a transformer-based U-Net deep learning algorithm to achieve high-quality imaging in minimalist systems.

Low-cost and simple optical system based on wavefront coding and deep learning.

With the development of computational imaging, the integration of optical system design and digital algorithms has made more imaging tasks easier to perform. Wavefront coding (WFC) is a typical computational imaging technique that is used to address the constraints of optical aperture and depth of field. In this paper, we demonstrated a low-cost and simple optical system based on WFC and deep learning.

Complex amplitude field recovery of a scattering media obstructed object with multi-captured images.

An iterative-based method for recovering the complex amplitude field behind scattering media is presented in this Letter. This method compensates the random phase modulation of scattering media by using multiple captured scattered light fields. Complex amplitude reconstruction with local iterative averaging of scattered light fields, and double weighted feedback is efficiently applied.

Single-shot imaging through scattering media under strong ambient light interference.

Speckle correlation imaging (SCI) has found tremendous versatility compared with other scattering imaging approaches due to its single-shot data acquisition strategy, relatively simple optical setup, and high-fidelity reconstruction performance. However, this simplicity requires SCI experiments to be performed strictly in a darkroom condition. As background noise increases, the speckle contrast rapidly decreases, making precise interpretation of the data extremely difficult.

Measurement of full polarization states with hybrid holography based on geometric phase.

We propose a method for measuring the full polarization states of a light field by using hybrid polarization-angular multiplexing digital holography based on geometric phase. Through acquiring the geometric phase distribution of the whole light field by only recording a composite hologram, and according to quantitative relationship between the geometric phase and polarization state, the Stokes parameters of a light field can be calculated. Compared with other methods, this method can be used to obtain the complex amplitude information of the light field simultaneously without requiring other complex devices or elements to be adjusted, thus enabling dynamic polarization state measurement.

Measurement of thermal effect in laser pumped silicon employing infrared digital holographic interferometry.

We present a short-coherence infrared digital holographic interferometry (IRDHI) to quantitatively measure the weak thermal effect in silicon wafer under visible laser pumping. In IRDHI, a superluminescent diode and a narrow-band filter are introduced to eliminate the self-interference fringes and suppress the noise. The effect of coherence length of the detection light source is analyzed and the optimal coherence length range in the proposed configuration is given.

Measurement of ultrafast combustion process of premixed ethylene/oxygen flames in narrow channel with digital holographic interferometry.

The premixed ethylene and oxygen flame that is burning in a narrow channel is investigated with digital holographic interferometry (DHI). Combustion in either a narrow tube or channel is quite different. This is caused by the significant effects of the boundary layer.

Integrated digital holographic microscopy based on surface plasmon resonance.

We propose a novel digital holographic microscopy (DHM) by integrating surface plasmon holographic microscopy (SPHM) with reflection DHM based on the angular and polarization multiplexing techniques. Taking advantages of the high sensitivity of surface plasmon resonance (SPR) and the high reflectivity of gold film, the tiny variations of specimen's refractive index (RI) can be measured by using SPHM, and meanwhile, the thickness changes of the specimen can be determined by means of reflection DHM. We experimentally monitor the volatilization process of an alcohol-water mixture droplet to verify the validity of the integrated DHM.

Wavelength-multiplexing surface plasmon holographic microscopy.

Surface plasmon holographic microscopy (SPHM), which combines surface plasmon microscopy with digital holographic microscopy, can be applied for amplitude- and phase-contrast surface plasmon resonance (SPR) imaging. In this paper, we propose an improved SPHM with the wavelength multiplexing technique based on two laser sources and a common-path hologram recording configuration. Through recording and reconstructing the SPR images at two wavelengths simultaneously employing the improved SPHM, tiny variation of dielectric refractive index in near field is quantitatively monitored with an extended measurement range while maintaining the high sensitivity.

Quantitative phase microscopy for cellular dynamics based on transport of intensity equation.

We demonstrate a simple method for quantitative phase imaging of tiny transparent objects such as living cells based on the transport of intensity equation. The experiments are performed using an inverted bright field microscope upgraded with a flipping imaging module, which enables to simultaneously create two laterally separated images with unequal defocus distances. This add-on module does not include any lenses or gratings and is cost-effective and easy-to-alignment.

Lateral shearing common-path digital holographic microscopy based on a slightly trapezoid Sagnac interferometer.

We propose a compact and easy-to-align lateral shearing common-path digital holographic microscopy, which is based on a slightly trapezoid Sagnac interferometer to create two laterally sheared beams and form off-axis geometry. In this interferometer, the two beams pass through a set of identical optical elements in opposite directions and have nearly the same optical path difference. Without any vibration isolation, the temporal stability of the setup is found to be around 0.

Phase-shifting infrared digital holographic microscopy based on an all-fiber variable phase shifter.

Phase-shifting infrared digital holographic microscopy based on a homemade all-fiber variable phase shifter is presented to quantitatively obtain the phase distribution of an object wave carrying the information of a transparent specimen in the infrared band. The all-fiber variable phase shifter, which consists of a tubular piezoelectric transducer (PZT) and a single-mode fiber, can accurately produce any phase shift between 0 and 2π by modulating the driving voltage of the tubular PZT. Taking measurements of different staircase structures on a silicon wafer as samples, two configurations are presented based on different phase-shifting implementations: one is a slight off-axis two-step phase shift and the other is an in-line four-step phase shift.

Simultaneous measurement of refractive index distribution and topography by integrated transmission and reflection digital holographic microscopy.

We propose a method for simultaneously measuring dynamic changes of the refractive index distribution and surface topography, which integrates the transmission and reflection digital holographic microscopy based on polarization and angular multiplexing techniques. The complex amplitudes of the transmitted and reflected object waves can be simultaneously retrieved. The phase information of the reflected object wave is directly used to determine the topography of the specimen which corresponds to its physical thickness.

Dual-wavelength common-path digital holographic microscopy for quantitative phase imaging based on lateral shearing interferometry.

A dual-wavelength common-path digital holographic microscopy based on a single parallel glass plate is presented to achieve quantitative phase imaging, which combines the dual-wavelength technique with lateral shearing interferometry. Two illumination laser beams with different wavelengths (λ=532  nm and λ=632.8  nm) are reflected by the front and back surfaces of the parallel glass plate to create the lateral shear and form the digital hologram, and then the hologram is reconstructed to obtain the phase distribution with a synthetic wavelength Λ=3339.

Transmission and total internal reflection integrated digital holographic microscopy.

We develop a transmission and total internal reflection (TIR) integrated digital holographic microscopy (DHM) by introducing a home-made Dove prism with a polished short side. With the help of angular and polarization multiplexing techniques, the 2D refractive index distribution of a specimen adhered on the prism surface is determined using TIR-DHM. Meanwhile, the thickness profile is unambiguously calculated from the phase information using transmission DHM.

Dynamical measurement of refractive index distribution using digital holographic interferometry based on total internal reflection.

We present a method for dynamically measuring the refractive index distribution in a large range based on the combination of digital holographic interferometry and total internal reflection. A series of holograms, carrying the index information of mixed liquids adhered on a total reflection prism surface, are recorded with CCD during the diffusion process. Phase shift differences of the reflected light are reconstructed exploiting the principle of double-exposure holographic interferometry.

Harmonic mode locking of bound-state solitons fiber laser based on MoS(2) saturable absorber.

We present a kind of harmonic mode locking of bound-state solitons in a fiber laser based on molybdenum disulfide (MoS(2)) saturable absorber (SA). The mode locker is fabricated by depositing MoS(2) nanosheets on a D-shaped fiber (DF). In the fiber laser, two solitons form the bound-state pulses with a temporal separation of 3.