Lensless diffuser camera is a novel and flexible approach to capture object’s images. Here, we propose a compact spectral and polarization diffuser camera (SPDC) enabled by a diffuser and a complementary metal oxide semiconductor (COMS) sensor. We demonstrated SPDC to reconstruct images with spectral and polarization by simulations. It can be highly integrated with lightweight, and lower cost, compared with traditional multi-dimensional imaging systems. SPDC has great potential in many applications, such as compact bioimaging systems, portable optical sensing, and consumer applications.
Miniature spectrometers are in high demand for portable optical sensing, on-chip systems, and other consumer applications, due to their small size and light weight. Recently, on-chip spectrometers, which are based on simple hardware systems, and recover unknown spectra by reconstruction algorithms, have become one of the most important research trends. Such on-chip computational spectrometers typically employ random spectral filters such as quantum dot arrays, photonic crystal arrays, and so on. However, these random spectral filters generally need expensive materials or complex preparation processes. So, the low-cost and easy-to-prepare spectral filters are pursued in developing computational spectrometers. Here we report the on-chip spectrometer using polarization-responsive filters, which are directly placed on top of a CMOS sensor. These spectral filters contain birefringent material and two polarizers and generate different transmittance spectra by the complex optical interference of them with different polarization angles. We verified the validity of this approach by simulation. This spectrometer only uses polarizers, micas, and a CMOS sensor, and has the advantages of low cost, simple preparation, and small footprint.
KEYWORDS: Super resolution, Upconversion, Near infrared, Light sources and illumination, Nanoparticles, Biological imaging, Multiplexing, Microscopy, Super resolution microscopy, Deep tissue imaging
Super-resolution microscopy provides a high spatial resolution that is beyond the diffraction barrier and can visualize nano-sized structures and interactions in biological and material study. In recent years, lanthanide-doped upconversion nanoparticles (UCNPs) that can upconvert the near-infrared (NIR) excitation photons to visible emission photons, have been developing as a kind of novel nanoprobes for bioimaging. Here we report the recently developed NIR superresolution imaging techniques by exploring the nonlinear fluorescence responses in UCNPs. Upconversion Nonlinear Structured Illumination Microscopy (U-NSIM) employes nonlinear fluorescence, along with NIR excitation and emission light, to deliver rapid frame rates and high-resolution capabilities, enabling in-depth super-resolution imaging. The tunability of lifetime in UCNPs is also introduced to develop the multiplexed super-resolution imaging with lifetime-engineered nanoprobes. By detecting two emission channels with different nonlinear fluorescence responses, a single doughnut illumination beam is used to scan the sample to generate a Gaussian-like emission point spread function (PSF) and a doughnut-emission PSF simultaneously, which can be fused by algorithms to an optimized super-resolution nanoscopy. These upconversion super-resolution imaging techniques provide new strategies to develop deep-tissue and multiplexed super-resolution imaging and also help to achieve it in a simple optical scheme.
Upconversion nanoparticles (UCNPs) is a series of lanthanoid ions doped nanocrystals that are of great interest for biomedical applications, including nanoscale optical sensing and imaging, benefiting from its bright, stable, multicolour emission. Each of the nanoparticles contains thousands of Lanthanide ions, which works as both sensitizers and activators to absorb the near-infrared photons and transfer the energy from sensitizers to activators through nonlinear energy transferring process for an upconverting emission. A few new super-resolution imaging methods have been developed recently based on UCNPs’ unique nonlinear energy transferring process. Most recently, upon these advances, we have found that the thousands of Lanthanide ions provide a strong dielectric resonance effect in a single UCNP. In this work, we will review using the nonlinear response of lanthanoid ions to improve super-resolution nanoscopy. We will also report the ion resonance effect in UCNPs could substantially increase the permittivity and polarizability of nanocrystals, leading to an enhanced optical force on a single 23.3 nm radius UCNP, more than 30 times stronger than the reported value for gold nanoparticles with the same size. The enhanced optical force also provides a way to bypass the optical trapping requirement of “refractive index mismatch”. We further report that the resonance effect could engineer the Rayleigh scattering of UCNPs. These applications suggest a new potential of UCNPs as force probe, scattering probe and fluorescence probe simultaneously for multiplexed imaging.
Dual beam fiber traps are potentially useful for integrated trapping devices aimed at studying aerosols, and offer opportunities for cavity-enhanced traps. The alignment of such traps is typically seen to be critical. Here we explore the impact of the angular alignment of the optical fibers, and assess trapping viability as a function of misalignment and how particle dynamics change when interacting with displaced fibers. We find that good trapping capability for dual fibers tilted at the same angle, while more complex aerosol dynamics become apparent at higher single fiber tilt angles.
We propose and demonstrate a new correlation imaging method using a periodic light source array. The image of the object is reconstructed by exploiting the correlation between the total intensity of the beam interacting with the object and the precomputed intensity distribution patterns of the light source. The implementation of this experiment is quite simple and low-cost without the need for a beam splitter or spatial light modulator. Due to its single-pixel detection configuration, it should have great potential in many imaging applications.
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