High-resolution colposcopic optical coherence tomography (OCT) provides key anatomical measures, such as thickness and minor traumatic injury of vaginal epithelium, of the female reproductive tract noninvasively. This information can be helpful in both fundamental investigations in animal models and disease screenings in humans. We present a fiber-based visible-light OCT and two probe designs for colposcopic application. One probe conducts circular scanning using a DC motor, and the other probe is capable of three-dimensional imaging over a 4.6×4.6-mm2 area using a pair of galvo scanners. Using this colposcopic vis-OCT with both probes, we acquired high-resolution images from whole isolated macaque vaginal samples and identified biopsy lesions.
Spectrally encoded endoscopy (SEE) is a minimally invasive optical imaging modality capable of fast confocal imaging of internal tissue structures. Modern SEE systems use coherent sources to image deep within the tissue and data are processed similar to optical coherence tomography (OCT); however, standard processing of SEE data via the Fast Fourier Transform (FFT) leads to degradation of the axial resolution as the bandwidth of the source shrinks, resulting in a well-known trade-off between speed and axial resolution. Recognizing the limitation of FFT as a general spectral estimation algorithm to only take into account samples collected by the detector, in this work we investigate alternative high-resolution spectral estimation algorithms that exploit information such as sparsity and the general region position of the bulk sample to improve the axial resolution of processed SEE data. We validate the performance of these algorithms using bothMATLAB simulations and analysis of experimental results generated from a home-built OCT system to simulate an SEE system with variable scan rates. Our results open a new door towards using non-FFT algorithms to generate higher quality (i.e., higher resolution) SEE images at correspondingly fast scan rates, resulting in systems that are more accurate and more comfortable for patients due to the reduced image time.
Speckle noise is one of the dominant factors that degrade image quality in optical coherence tomography (OCT). Here, we propose a new strategy, interleaved OCT (iOCT), for spatial compounding and angular compounding. We demonstrate the efficiency of compounding with iOCT to restrain speckle noise without compromising imaging speed in phantoms and tissue samples.
A polarization sensitive optical coherence tomography based automated algorithm for segmentation of the chorio-scleral
interface is presented. The algorithm employs a two-step segmentation approach. At first, local birefringence based
segmentation with low precision is performed to roughly distinguish the choroid and sclera. Successively, a depth
oriented slope fitting to phase retardation is applied in both the choroid and sclera. The interface is determined as the
cross-point of the two phase retardation slope lines. The algorithm shows potential for functional, objective, and
volumetric choroid thickness measurement.
We present a new method of glucose concentration detection with a differential absorption
optical low-coherent interferometry (DAOCI) technique. In our system, we uses two OCI signals
recorded by turns in one period with the same detector. Two different light sources are selected
corresponding to the different absorption coefficient of the glucose absorption band. The ratio of the
two intensities depends on the concentration of the glucose in samples. With the known difference in
the absorption cross section or experimental data, it is possible to calculate the mean glucose
concentration of samples. In our experiment, we measured a series of glucose solution in a cuvette, and
the systemic resolution we got is 16.14mg/dL which achieves the required accuracy(20mg/dL) for
practical application. The results prove the feasibility of this method to be used for no-invasive
detection of glucose in the aqueous humor.
A novel but brief method is developed for spectral domain optical coherence tomography(SD-OCT). This method
is based on two mirror locales in both sample arm and reference arm, independent of a mercury argon calibration
source, and then get the exact spectral distribution on the line array charge coupled device (CCD) through
fitting and interpolation. The rescaling parameters is determined by a short time Fourier transformation(STFT) and
a series of calculation. A SD-OCT system is set up. The signal-noise-ratio(SNR) of this system is experimentally
found to be 51dB. Axial resolution is 8.5μm. Improved 3D image of human retain based on the proposed
method is demonstrated.
For stable and efficienct organic light-emitting diodes, it is essential to find molecules with
high photoluminescent efficiency, little self-quenching and balanced charge transporting properties.
Recently, we've designed and synthesized some highly emissive naphtho[2,3-c][1,2,5]thiadiazole
(NTD) derivatives and naphtho[2,3-c][1,2,5]selenadiazole (NSeD) derivatives with unusual
ambipolar transporting properties.
The ambipolar transporting properties of the NTDs were explained by Marcus theory with
carrier reorganization energies and charge-transfer integrals. We obtained high quality single
crystals of 4,9-di(biphenyl-4-yl)-naphtho[2,3<i>-c</i>][1,2,5]thiadiazole (NTD02) and
4,9-bis(4-(2,2-diphenylvinyl)phenyl)-naphtho[2,3<i>-c</i>][1,2,5]thiadiazole (NTD05). They have
disordered NTD rings' orientation with the opposite directions in the center of the molecule
because of NTD's planar configuration and the single-bond connection with the phenyl
substituents. The packing structure of NTD02 shows the planar arrangement of NTD rings,
forming a "charge transporting channel". Quantum calculation also confirms that the π-π stacking
interaction in NTD derivatives benefits the charge transporting via intermolecular hopping on
NTD rings. The hole and electron mobilities of NTD05 are 7.16×10<sup>-4</sup> cm2/V·s and 6.19×10<sup>-4</sup>
cm<sup>2</sup>/V•s at an electronic field E = 2.0×10<sup>5</sup> V/cm, respectively. The hole mobility of NTD05 is
close to that of <i>N,N'</i>-diphenyl-<i>N,N'</i>-bis(1-naphthyl)(1,1'-biphenyl)-4,4'-diamine (NPB) and the
electron mobility of NTD05 is two orders-of-magnitude higher than that of
tris(8-hydroxyquinoline) aluminum (Alq<sub>3</sub>). For the NTD derivatives, NTD05 also shows the best
performance in non-doped OLEDs. CIE coordinates of (0.65, 0.35) and a peak efficiency of 2.4%
are achieved for a double layer OLED with NPB as the hole transporting layer and NTD05 as the
emitting layer. Moreover, we get ultimate red emission with CIE coordinates of (0.71, 0.29) for
some of the NSeD based non-doped OLEDs.