Macroporous EH-PEG hydrogels fabricated by porogen-leaching method are characterized by optical coherence
tomography (OCT). High-resolution OCT visualizes the microstructures of the engineered tissue scaffolds in threedimensions.
It also enables subsequent image processing to investigate several key morphological design parameters for
macroporous scaffolds. Image processing algorithms are then presented to automatically quantify the pore size, porosity,
and pore interconnectivity. The results indicated that those parameters highly depend on the porogen size. Further,
fluorescence imaging was conducted to monitor the population of labeled human mesenchymal stem cells (hMSCs)
loaded on the surface of the scaffolds. The results revealed the hMSCs' viability as well as their infiltration into the
scaffold. The effect of infiltration is more profound in the scaffold of larger pore sizes, in accordance with the result
suggested by image analysis.
A video-rate laser scanning microscope was developed as an imaging engine to integrate with other photonic building
blocks to fulfill various microscopic imaging applications. The system is quipped with diode laser source, resonant
scanner, galvo scanner, control electronic and computer loaded with data acquisition boards and imaging software.
Based on an open frame design, the system can be combined with varies optics to perform the functions of fluorescence
confocal microscopy, multi-photon microscopy and backscattering confocal microscopy. Mounted to the camera port, it
allows a traditional microscope to obtain confocal images at video rate. In this paper, we will describe the design
principle and demonstrate examples of applications.
A new type of the normal incidence scanning reflectometer has been designed and constructed. In the system design, instead of using a reference reflective sample or adjusting the optical path as did in the traditional design, we use a fixed M-type fused quartz prism to split the incidence light source beam into two ones by a total internal reflection configuration. Therefore, these two light beam have the same spot sizes, intensities and spectral response. One beam goes directly to the detector and is used as the incidence reference beam. The second sampling beam goes to the sample first, and then is reflected by the sample with the beam intensity measured finally by the same detector. A metal disk with three holes is driven precisely by a stepping motor and is used to control the reference beam, reflection beam and background signals to be measured in sequence. Afterwards, the absolute reflectivity of the sample at the certain wavelength can be determined immediately by the computer through calculating those three signals. The system is controlled automatically by the computer and worked in a wavelength range from 400 to 800 nm under a 5-degree nearly normal incidence angle condition. In the paper, the details of the system design, optical element configuration and error reduction are given and discussed. The measured reflective spectral results for testing samples are also given and shown in good agreement with those measured by other optical method. The system designed in this work, however, is simpler and more reliable to be used in many optical measurements of the sample.
An improved type of scanning and analyzer rotating magneto-optic spectroscopy has been designed and constructed. By adding an achromatic quart-wavelength retarder to the system and using Fourier transformation, the complete magneto-optic parameters, both polar Kerr rotation angle 6kand ellipticity k' have been measured in the 1.5-5-eV photon energy range and at a near normal incident angle of less than 2 degrees. A fine step motor with 1000 steps per revolution and a hollow shaft, on which the analyzer is directly mounted, is used to control precisely the analyzer azimuthal angle. The magnetic field, spectral scanning, and retarder position, as well as data processing are totally controlled by a microcomputer. The magneto-optic spectral results of the system is illustrated for FeTeCo film samples.