Congenital Heart Disease (CHD) is the most common congenital malformation in newborns in the US. Although
knowledge of CHD is limited, altered hemodynamic conditions are suspected as the factor that stimulates cardiovascular
cell response, resulting in the heart morphology remodeling that ultimately causes CHDs. Therefore, one of recent efforts
in CHD study is to develop high-speed imaging tools to correlate the rapidly changing hemodynamic condition and the
morphological adaptations of an embryonic heart in vivo. We have developed a high-speed streak mode OCT that works
at the center wavelength of 830 nm and is capable of providing images (292x220 μm<sup>2</sup>) of the outflow tract of an
embryonic chick heart at the rate of 1000 Hz. The modality can provide a voxel resolution in the range of 10 μm<sup>3</sup>, and
the spectral resolution allows a depth range of 1.63 mm. In the study reported here, each of the 4D images of an outflow
tract was recorded for 2 seconds. The recording was conducted every 2 hours (HH17 to HH18), 3 hours (HH14 to HH17),
and 4 hours (HH18 to HH19). Because of the fast scan speed, there is no need for postacquisition processing such as use
of gating techniques to provide a fine 3D structure. In addition, more details of the outflow tract are preserved in the
recorded images. The 4D images can be used in the future to determine the role of blood flow in CHD development.
Doppler Fourier domain optical coherence tomography is able to be used for in vivo blood flow measurement. In
conventional methods, the highest velocity that can be measured is limited to the range the phase shift between two
successively recorded depth profiles at the same probe-beam location, which cannot exceed (-π, π), otherwise phase
wrapping will occur. This phase-wrapping limit is determined by the time interval between two consecutive A-scans. We
present a novel approach to shorten the time interval between two consecutive A-scans and thus increase the phase-wrapping
limit by using an area scan camera to record the interference spectrum in a streak mode. To demonstrate the
effectiveness of this method, the blood flows in HH18 and HH19 chick hearts were imaged and phase wrapping free
Doppler images were obtained.
Recently, we developed the streak-mode Fourier domain optical coherence tomography (OCT) technique in which an
area-scan camera is used in a streak-mode to record the OCT spectrum. Here we report the application of this technique
to in ovo imaging HH18 embryonic chick hearts with an ultrahigh speed of 1,016,000 axial scans per second. The high-scan
rate enables the acquisition of high temporal resolution 2D datasets (1,000 frames per second or 1 ms between
frames) and 3D datasets (10 volumes per second), without use of prospective or retrospective gating technique. This
marks the first time that the embryonic animal heart has been 4D imaged using a megahertz OCT.
Here we present an ultrahigh-speed Fourier-domain optical coherence tomography (OCT) that records the OCT spectrum in streak mode with a high-speed area scan camera, which allows higher OCT imaging speed than can be achieved with a line-scan camera. Unlike parallel OCT techniques that also use area scan cameras, the conventional single-mode fiber-based point-scanning mechanism is retained to provide a confocal gate that rejects multiply scattered photons from the sample. When using a 1000 Hz resonant scanner as the streak scanner, 1,016,000 A-scans have been obtained in 1 s. This method's effectiveness has been demonstrated by recording in vivo OCT-image sequences of embryonic chick hearts at 1000 frames/s. In addition, 2-megahertz OCT data have been obtained with another high speed camera.
We report a technique, which uses an area-scan camera to record the interference spectrum. Traditional point-scanning is
remained in this streak-mode FDOCT so that the small aperture of the single-mode fiber functions as a confocal gate and
screens multiply scattered photons very well. While the sample beam is scanning the specimen laterally, the interference
spectrum is physically scanned on the area scan camera using a streak scanner. Therefore, pixels of the camera are
illuminated by the spectrum of OCT signal row by row, corresponding to each A-scan at different lateral position. A
unidirectional B-scan of 700 lines is obtained in 1 ms; thus, an A-scan time of 1.4 μs is achieved. A Day 4 chick embryo
sampled is imaged using this method. This technique is highly potential for multi-Megahertz OCT imaging.
A rotational microelectromechanical(MEMS) motor based common-path Fourier-domain OCT for endoscopic imaging,
which uses the interface between the index-match oil and distal-end surface of the fiber as a self-aligned reference
mirror, is reported. The reference intensity is easy to be tuned by altering the index of the match oil to optimize the signal
to noise ratio of the system. An external Michelson interferometer is used to compensate for the optical path difference
and dispersion mismatch to the index-match oil and the GRIN lens. Due to this common-path design, the OCT signal is
immune to bending or stretching of the endoscopic catheter. The outer diameter of the probe is 3 mm, and 22
circumferential-scans and 50,000 lines A-scans are obtained in one second.
A common-path Fourier-domain OCT for endoscopic imaging, which uses the distal-end surface of the fiber as a selfaligned
reference mirror, is reported. A miniaturized probe is designed for this OCT system. A reference Michelson
interferometer is used to compensate for the optical path difference and mismatch of dispersion and polarization states
due to the miniaturized probe. This configuration allows arbitrary probe fiber length and provides sufficient working
space for imaging optics and their package, and thus is suitable for OCT imaging of lumens of various sizes.
Additionally, the reference intensity is able to be tuned by index match oil to optimize the signal to noise ratio of the
system. Due to this common-path configuration, the OCT signal is immune to the bending or handling of the fiber
connecting with the probe.
In this paper, we developed a full-field OCT system using thermal light as the low-coherence light source. A well-known
Linnik interferometer configuration was used. Broad spectral width of the thermal light 450-650nm was used to achieve
high axial resolution of 1.1&mgr;m in biological sample for OCT imaging. Two water immersion objectives of 0.5N.A were
used to balance the dispersion and a transverse resolution of 0.7μm was obtained. With a fast machine-coding algorithm,
system sensitivity of more than 80dB and imaging rate as high as 18frame/s with 500x500 pixels per frame could be
achieved. Mouse embryos were imaged in vivo with full-field OCT at different depth for the developmental study. Useful
information for pre-implementation genetic diagnosis (PGD) was obtained by image analysis and segmentation. As far as
known, for the fist time, 3D images of mammalian embryos were obtained with full-field OCT without the need of dye
It is the trend of Coordinate Measuring Machine (CMM) measurement technology that creates measurement plan automatically. Based on Pro/CMM module of Pro/E software, the idea for automatic generation of the main DMIS (Dimensional Measuring Interface Standard) file of measurement plan is described. To satisfy the special measurement requirements of different customers conveniently, a method of variant design of DMIS file based on SML (Tabular Layouts of Article Characteristics) and the main DMIS file is proposed.
We developed a full-field OCT system using thermal light as the low-coherence light source. The whole system is
combined with a commercial fluorescent microscope. A compact Linnik interferometnc adapter is designed as
reference arm. Due to the broad spectral width of the thermal light, a sub micrometer axial resolution can be achieved
for OCT imaging. As the acquisition rate of CCD is fast enough, real time OCT imaging can be achieved. The whole
system is compact and robust, very suitable for biomedical applications.
It is essential to prolong the lifetime of wireless sensor networks (WSN) via effective cooperation of its sensor nodes. Here, a dynamic clustering algorithm, named DCA, is presented to optimally and dynamically select the micro-sensor nodes to construct a dynamic sensor cluster at each time based on the integrated performance index including information acquirement and energy consumption. In distributed target tracking with WSN, the DCA can avoid the problem of "too frequent cluster head (CH) switches", save more than 80% energy and remain almost same tracking accuracy, compared with the information-driven sensor querying (IDSQ).