We have developed ultraviolet (UV)- and visible-light one-shot spectral domain (SD) optical coherence tomography (OCT) that enables in situ imaging of human skin with an arbitrary wavelength in the UV–visible-light region (370–800 nm). We alleviated the computational burden for each color OCT image by physically dispersing the irradiating light with a color filter. The system consists of SD-OCT with multicylindrical lenses; thus, mechanical scanning of the mirror or stage is unnecessary to obtain an OCT image. Therefore, only a few dozens of milliseconds are necessary to obtain single-image data. We acquired OCT images of one subject’s skin in vivo and of a skin excision ex vivo for red (R, 650±20 nm), green (G, 550±20 nm), blue (B, 450±20 nm), and UV (397±5 nm) light. In the visible-light spectrum, R light penetrated the skin and was reflected at a lower depth than G or B light. On the skin excision, we demonstrated that UV light reached the dermal layer. We anticipated that basic knowledge about the spectral properties of human skin in the depth direction could be acquired with this system.
High-sensitivity low-coherence dynamic light scattering (LC-DLS) is a powerful technique for measuring particle sizes in dense suspensions without the need for dilution. We have developed an LC-DLS system with a single-mode (SM)- fiber probe system and small container that can be used to hold samples of 10μL in volume. The system can be applied to lysozyme of a few nm in diameter. We have developed an angle-resolved SM-fiber probe system that is able to identify particle motion type and we verified our design by identifying the diffusion modes of particles in a polystyrene suspension.
High-sensitivity low-coherence DLS apply to measurement of particle size distribution of pigments suspended in a ink. This method can be apply to extremely dense and turbid media without dilution. We show the temporal variation of particle size distribution of thixotropy and sedimentary pigments due to aggregation, agglomerate, and sedimentation. Moreover, we demonstrate the influence of dilution of ink to particle size distribution.
We have developed a high-sensitivity, low-coherence dynamic light scattering system for the measurement of particles a
few tens of nanometers in size. A Mach-Zehnder interferometer and a confocal optical system were adopted for
improved sensitivity to scattered light intensity. The developed system can detect scattered light 3000 times weaker than
that detectable by a previous system. We applied the newly developed system to measure the particle size distribution of
10 vol.% polystyrene particles with an average diameter of 13 nm. The obtained particle size distribution agreed quite
well with a distribution determined by transmission electron microscopy.
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