Time-lapsed, three-dimensional multiphoton microscopy showed that application of air-drying and glycerol to animal
tissue induced a well-expressed optical clearing. The effect was dynamic, reversible process, and can be used to enhance
capabilities of nonlinear imaging.
Collagen, the main structural protein in vertebrates, possesses different structural organization that is responsible for
specific functions of the tissues. Polarization dependence of the second harmonic generation (SHG) signal on spatial
orientation of optically nonlinear materials, such as collagen, provides information on characteristic organization and
architecture not available from intensity measurements alone. Here we describe a simple approach for determining
both the azimuth and elevation angles of collagen fiber orientation in biological tissues. Azimuth angle of the fiber
orientation is determined as an orthogonal angle to the laser polarization direction, when laser-induced total SHG
signal is minimal, whereas the elevation angle is estimated from the ratio of the minimal SHG intensity to the
intensity when laser polarization and fiber directions are parallel to each other. Using this approach pixel-resolved
mapping of the spatial orientation of collagen fibers in tendon and cornea is demonstrated. The new approach may be
used for analyzing of biological tissues in vivo. Spatial orientation mapping method provides additional information
concerning fiber organization, and may be incorporated into nonlinear optical imaging systems.
A compact fiber optic scanner for biomedical applications such as optical coherent tomography has been designed,
fabricated and tested. The scanner is designed as an in vivo device and composed of an optical fiber coated with nickel-powder
loaded paint for external magnetic actuation. The compactness of the imaging device makes it suitable for
applications where size, precision and low power consumption is critical. We have previously demonstrated the
principles utilizing magnetic actuation for the fiber scanner coated with magnetic gel. This work focused on verification
and optimization of the scanner operation. The magnetic properties of the nickel particle mixed with paint were
characterized using an alternating gradient magnetometer. The optical scanner is externally actuated by an
electromagnet and so it does not require a voltage or current supply in the probe itself. The displacements of the scanner
were recorded using a position sensitive detector. The result showed a 0.8-mm displacement under the influence of a
static magnetic field of 17.6 KA/m in a fiber with a moveable length of 4.2cm. Dynamic analysis showed a
displacement of 0.83mm with an input current amplitude of 41mA and a magnetic field of 2.4 KA/m. The
measurements are in good agreement with the theoretical lumped-element calculations. Finite-element analysis was
performed and the results agree with the theoretical and experimental results. The static and dynamic displacements of
the fiber optic scanner depend on the thickness and length of the magnetic coating. Thus, scanners for different
displacements and operating frequencies can be designed by varying the coating thickness and length.
To meet the performance requirements for some applications, including small sizes, precise optics, low power consumption and non-electrical control in the devices, an optical fiber scanner using electromagnetic actuation has been developed. This paper acquaints a compact external magnetic field actuated fiber optic scanner, in which the main structure is an optical fiber coated with nickel magnetic gel. The advantages of device architecture are: (1) the scanner dimensions are in the same scales of an optical fiber diameter, (2) optical properties and information are well preserved in the fiber, and (3) the actuation control is external and requires no electrical wiring in scanner design and zero power consumption. In this work, magnetic properties of the nickel based ferromagnetic gel were measured in order to carry out the theoretical calculations of static response and resonant frequencies. With the dynamic waveforms of input and output signals from the position sensing device at both modes of resonant frequencies, we conclude that it is significant to operate at the resonant frequencies so that the scanner requires less power to reach large displacement and the oscillating motion of the scanner is purely sinusoidal. A simple and versatile rotary gel coating technique, static and dynamic performance characterization and potential applications of the fiber scanner will be discussed. Moreover, we will also discuss the practical issues in operation and possible waveform distortion that affects imaging and display quality.
Optical second-order nonlinear thin film was developed by doping dye organic molecules in a UV curing epoxy host polymer system and followed by an electric field poling step. The nonlinear optical polymeric thin film fabrication will be described. Results from a systematic evaluation of the film physical and optical properties using AFM, ellipsometer and Maker Fringe will be presented. The film absorption spectrum shows a promising advantage for frequency doubling in the blue color window. Optical nonlinear constants extraction from the Maker Fringe raw data will also be discussed.
Electromagnetic actuation shows promising suitability for constructing actuators and sensors with an optical fiber in terms of speeds, device dimensions, and power consumption. In this work we invented a fiber scanner which is composed of an optical fiber coated with nickel powder based ferromagnetic gel. The optical scanner, in which the optical fiber is mechanically steered with external electromagnetic fields, satisfies the applications that require small
sizes, precise optics, low power consumption and prefers non-electrical control in the device. The device architecture makes the scanner dimensions in the same scales of an optical fiber diameter and the optics is well preserved in the fiber. In addition, the external actuation eliminates the needs of voltage or current in the scanner. Magnetization hysteresis curve of the nickel based ferromagnetic gel, which gives relevant magnetic material properties, is characterized in order to carry out the calculation of static and dynamic responses. A rotary gel coating technique is used to construct fiber optical scanners. The material preparation and fabrication method is described in this paper. We characterized the scanner in two modes. The static scanning results showed a 0.5 mm displacement under the influence of static magnetic field of 14.5 KA/m. At the first peak of resonant frequency in dynamic scanning, a linear displacement of 0.75 mm with a magnetic field amplitude of 6.69 KA/m was demonstrated. In this paper, we discussed the fabrication procedures and performance characterization of the fiber scanner as well as some of the potential applications.
Electro-optical channel waveguide is fabricated using an optical nonlinear polymer developed by doping dye organic molecules in a host polymer system and followed by an electric field poling step. A single-mode polymeric electrooptical channel waveguide is modeled using the <i>BeamProp</i>. Photolithography followed by wet chemical etching is used to fabricate the polymeric channel waveguide. A fabrication process is described. Results from a systematic evaluation of the film and waveguide physical and optical properties using AFM, profilometer, ellipsometer and the Maker Fringe technique is presented.