Search

By encoding object information (object phase, surface height, spectrum) into the polarization state, we can use polarization cameras to image other dimensions of the light field while viewing dynamic scenes. We discuss three recent examples of such video polarization encoding, allowing for quantitative imaging of transparent micro-organisms, for measurement of dynamic surface shape, and for compact spectral imaging. [ABSTRACT FROM AUTHOR]

Nanocelluloses and their different designs, such as films and nanopapers, have gained considerable interest in many application areas due to their unique properties. For many purposes, such as packaging and electronics, the thermal stability and optical properties of nanocellulose materials are crucial characteristics. In this study, the effects of heat treatment (100 ºC, 150 ºC and 200 ºC) on the optical and mechanical properties of 2,2,6,6-tetramethylpiperidinyl-1-oxy radical-oxidised cellulose nanofibre (TO-CNF) films were investigated, especially the alteration of the colour, complex refractive index and birefringence. Exposing TO-CNF films to high temperatures (> 150 ºC) induced permanent transformations in the CNF structure, leading to an increase in the refractive index, decreases in the birefringence and crystallinity index, colour darkening and significant deterioration of the mechanical properties. [ABSTRACT FROM AUTHOR]

We demonstrate a single-shot uniaxial 3D profilometry system that illuminates a sample with a structured polarization pattern and measures the reflected full-Stokes polarimetric image. Some non-contact 3D measurements require evaluating samples located in a protected environment. For example, this may be a sample under the lid of an acrylic Petri dish, a sample that has a protective film overlay, or products housed inside a plastic container. To deal with these cases, we adapt our measurement system to capture the complete polarization state using a single-shot full-Stokes imaging system consisting of two polarization cameras. This system cannot only measure the dynamic 3D shape at video rate, but can also compensate for any birefringent layers between the illumination arm and the sample under measurement. We present the measurement principles of the system and show the results of a real-time 3D profilometry experiment in which a sample was measured under the lid of an acrylic Petri dish. [ABSTRACT FROM AUTHOR]

The presence of native oxide layers on aluminum mirrors can be a nuisance for precision optical design. As the native oxide thickness varies from mirror to mirror, its effect cannot be completely canceled even in the conventional crossed fold mirror geometry. We show how this effect arises and how it can be mitigated, and provide an experimental demonstration in which the residual linear retardance and linear diattenuation are reduced to <0.14° and <0.001, respectively, over the visible and near-infra-red spectral range. [ABSTRACT FROM AUTHOR]

This study measured the polarised light reflected from the surface of thermally modified Scots pine (Pinus sylvestris L.) wood using a Stokes imaging polarimeter. The data were analysed using the Mueller matrix method. The Scots pine boards were heat treated in an oven at temperatures of 160 ºC, 200 ºC and 220 ºC, with a heat treatment time of 3 h at the maximum temperature. The results indicated that the chemical composition of the thermally modified wood underwent a permanent transformation, leading to a change in the degree of polarisation of the reflected light. The presented method provides useful information for inspecting the quality of thermally modified wood products. [ABSTRACT FROM AUTHOR]

Optically driven actuators do not require contact and thus can be used to generate movement remotely. In this paper, we propose a method for optically driving a magnetic levitation system that consists of a diamagnetic material as the moving object, a neodymium magnet, and a temperature-sensitive ferrite for varying the potential energy of the diamagnetic object. The diamagnetic object is levitated by the magnetic force between it and the neodymium magnet. Laser irradiation of the temperature-sensitive ferrite reduces its magnetic susceptibility due to the photothermal effect. In this study, the conditions for levitation are derived using a numerical approach. The results reveal that movement can be controlled in a three-dimensional region. [ABSTRACT FROM AUTHOR]

We propose a complete Mueller matrix polarimeter using dual photoelastic modulators and rotating half wave plates. The complete Mueller matrix of a sample is obtained by combining four partial Mueller matrices (nine elements each), by rotating the half wave plates in four different orientations. By considering the effect of retardance errors of the wave plates, a more general calibration method is developed. We demonstrate the accuracy of the system by measuring a Babinet-Soleil compensator and the scattering coefficient of an intralipid sample, whereas the depolarization characteristics is shown for different column density of intralipid. Simultaneous determination of optical rotation and depolarization is verified by conducting studies on glucose concentrations ranging from 0 to 400 mg/dl mixed with 2% v/V intralipid. [ABSTRACT FROM AUTHOR]

We review the generation of the determined vectorial vortex beams in the terahertz (THz) beams at frequencies of 0.16 and 0.36 THz, and intense middle infrared pulsed beam at 10.6 µm by use of an achromatic axially symmetric waveplate. It is possible for the method to decide the polarization states of incident beam with arbitrary polarization, and to determine the angular variant polarization after converting into vectorial vortex beams, instantaneously. This approach could apply to not only obtain the polarization states of the beams in the broadband spectral regions from ultraviolet to THz but also generate the determined vectorial vortex beams. [ABSTRACT FROM AUTHOR]

An ultra-high resolution spectral domain optical coherence tomography (SD-OCT) was developed using a cost-effective supercontinuum laser. A spectral filter consists of a dispersive prism, a cylindrical lens and a right-angle prism was built to transmit the wavelengths in range 680-940 nm to the OCT system. The SD-OCT has achieved 1.9 μm axial resolution and the sensitivity was estimated to be 91.5 dB. A zero-crossing fringes matching method which maps the wavelengths to the pixel indices of the spectrometer was proposed for the OCT spectral calibration. A double sided foam tape as a static sample and the tip of a middle finger as a biological sample were measured by the OCT. The adhesive and the internal structure of the foam of the tape were successfully visualized in three dimensions. Sweat ducts was clearly observed in the OCT images at very high resolution. To the best of our knowledge, this is the first demonstration of ultra-high resolution visualization of sweat duct by OCT. [ABSTRACT FROM AUTHOR]