A two-frequency laser scanning confocal fluorescence microscope (TF-LSCFM) based on intensity modulated fluorescence signal detection was proposed. The specimen-induced spherical aberration and scattering effect were suppressed intrinsically, and high image contrast was presented due to heterodyne interference. An improved axial point spread function in a TF-LSCFM compared with a conventional laser scanning confocal fluorescence microscope was demonstrated and discussed.
A biodosimeter based on thermal-induced elastic shear wave (TIESW) in silicone acellular porcine dermis (SAPD) at thermal steady state has been proposed and demonstrated. A square slab SAPD treated with ionizing radiation was tested. The SAPD becomes a continuous homogeneous and isotropic viscoelastic medium due to the generation of randomly coiled collagen fibers formed from their bundle-like structure in the dermis. A harmonic TIESW then propagates on the surface of the SAPD as measured by a nanometer-scaled strain-stress response under thermal equilibrium conditions at room temperature. TIESW oscillation frequency was noninvasively measured in real time by monitoring the transverse displacement of the TIESW on the SAPD surface. Because the elastic shear modulus is highly sensitive to absorbed doses of ionizing radiation, this proposed biodosimeter can become a highly sensitive and noninvasive method for quantitatively determining tissue-absorbed dosage in terms of TIESW’s oscillation frequency. Detection sensitivity at 1 cGy and dynamic ranges covering 1 to 40 cGy and 80 to 500 cGy were demonstrated.
The surface effect close to the boundary of a small light-scattering object in a highly scattering medium is experimentally demonstrated. This is the first attempt to measure the surface effect of a small spherical scattering object in 1% intralipid solution by use of developed diffuse photon-pairs density wave (DPPDW) in terms of the amplitude and phase detection. Theoretically, the surface effect of a small scattering object in turbid media is localized close to the boundary according to the perturbation theory, concerning an inhomogeneous distribution of the diffusion coefficient in the frequency-domain diffusion equation. Hence, an improvement of the spatial resolution of the image via an inverse algorithm, which relates to detection sensitivity of localization to the boundary of the image object in a multiple scattering medium, is anticipated. In this study, we demonstrate that DPPDW is able to sense the surface effect of a 2-mm spherical scattering object in 1% intralipid solution, with high sensitivity. Subsequently, an improvement of spatial resolution of imaging in turbid media by using DPPDW in comparison with conventional diffuse photon density wave (DPDW) using inverse algorithm is discussed.
A two-frequency heterodyne confocal laser scanning fluorescence microscope (TF-CLSFM) is setup where a harmonic intensity modulated fluorescence signal is detected coherently. Due to the ability of reduction on refractive index mismatched spherical aberration in TF-CLSFM, it clearly shows that the performance of TF-CLSFM on axial response is better than conventional confocal laser scanning fluorescence microscope (CLSFM) according to the experimental results.
A novel two-frequency dynamic light scattering system (TF-DLS) and differential heterodyne en face laser Doppler velocimeter (LDV) are proposed and setup. The power spectrum of the heterodyne beat signal is detected whereas the width of power spectrum and shift of central frequency are measured simultaneously. These are able to provide the particle sizing and its tangential velocity in suspension. Finally, the localization ability of TF-DLS/LDV system on en face velocity measurement was discussed.
Biomedical imaging and sensing, a major part of biophotonics, are now a research focus not just in academics, but also in industry. This research aims to develop novel technologies for interrogating molecular events in living objects, to understand molecular phenomena in diseases such as cancer, cardiovascular diseases, and neurology diseases, and to accelerate much-needed new discoveries in biology and medicine. With a strong industry in electronics and photonics, development of the advanced biomedical imaging and sensing technology will strengthen future industry development toward health care and biomedical technologies.
KEYWORDS: Proteins, Fluorescent proteins, Fluorescence resonance energy transfer, In vivo imaging, Signal detection, Resonance energy transfer, Infrared radiation, Near infrared, Tumors, Tissues
Bacteriophytochrome infrared fluorescent protein (IFP) has a long emission wavelength that is appropriate for detecting pathophysiological effects via near-infrared (NIR) based imaging. However, the brightness and photostability of IFP are suboptimal, although an exogenous supply of biliverdin (BV) IXα is able to enhance these properties. In this study, we fused a far red mPlum fluorescent protein to IFP 1.4 via a linker deoxyribonucleic acid (DNA) sequence encoding eight amino acids. The brightness of mPlum-IFP 1.4 fusion protein at the IFP emission channel was comparable to that of native IFP 1.4 protein when fusion protein and IFP 1.4 were excited by 543 and 633 nm using confocal microscopy, respectively. Visualization of IFP 1.4 fluorescence by excitation of mPlum in mPlum-IFP 1.4 fusion protein is likely to be associated with Förster resonance energy transfer (FRET). The FRET phenomenon was also predicted by acceptor photobleaching using confocal microscopy. Furthermore, the expression of mPlum-IFP 1.4 fusion protein could be detected in cell culture and in xenograft tumors in the absence of BV using in vivo imaging system, although the BV was still essential for detecting native IFP 1.4. Therefore, this innovativefluorescent fusion protein would be useful for NIR-based imaging in vitro and in vivo.
In renal transplant patients, immunosuppressive therapy may result in the reactivation of polyomavirus BK (BKV), leading to polyomavirus-associated nephropathy (PVAN), which inevitably causes allograft failure. Since the treatment outcomes of PVAN remain unsatisfactory, early identification and continuous monitoring of BKV reactivation and reduction of immunosuppressants are essential to prevent PVAN development. The present study demonstrated that the developed dual-channel heterodyne-based surface plasmon resonance (SPR) biosensor is applicable for the rapid detection of urinary BKV. The use of a symmetrical reference channel integrated with the poly(ethylene glycol)-based low-fouling self-assembled monolayer to reduce the environmental variations and the nonspecific noise was proven to enhance the sensitivity in urinary BKV detection. Experimentally, the detection limit of the biosensor for BKV detection was estimated to be around 8500 copies/mL . In addition, urine samples from five renal transplant patients were tested to rapidly distinguish PVAN-positive and PVAN-negative renal transplant patients. By virtue of its simplicity, rapidity, and applicability, the SPR biosensor is a remarkable potential to be used for continuous clinical monitoring of BKV reactivation.
The actin-depolymerizing factor (ADF)/cofilin protein family has been reported to be associated with ischemia-induced renal disorders. We examine whether cofilin-1 is associated with acute kidney injury (AKI) using human urine samples. We exploited a 96-well based high-throughput biosensor that uses gold nanoparticles and a sandwich immunoassay to detect the urine cofilin-1 level of AKI patients. The mean urine cofilin-1 level of the AKI patients (n=37 from 47 cases analyzed) was twofold higher than that of healthy adults (n=21 from 29 cases analyzed). The receiver operating characteristic (ROC) curve showed that cofilin-1 was acceptable for discriminating AKI patients from healthy adults. However, an increase of the sample size is required to conclude the importance of urine cofilin-1 on AKI diagnosis, and the high-throughput ultrasensitive biosensor used in this study would greatly accelerate the measurement of urine cofilin-1 in an increased sample size.
Viscoelastic shear waves (VESW) propagation in soft matters such as gelatin under thermal steady state was studied. VESW in a slab of gelatin causes the transverse displacement of the surface in a harmonic wave. The harmonic oscillation frequency of the transverse displacement of gelatin surface was then measured in real time in order to measure the modulus of rigidity of gelatin in terms of the measured oscillation frequency. A polarized heterodyne interferometer (PHI) was setup in this experiment which enables to precisely measure the transverse displacement of surface in real time at 0.3 nm resolution. This results in the proposed VESW method able to characterize gelatin soft material in real time. From the experimental demonstration, the properties of VESW propagation in soft material at thermal steady state potentially can become a novel nano-scale non-intrusion strain-stress sensor able to characterize the modulus rigidity of soft material.
The actin depolymerizing factor (ADF)/cofilin protein family has been reported to be associated with ischemia induced renal disorders. Here we examine if cofilin-1 is associated with acute kidney injury (AKI). We exploited a 96-well based fiber-optic biosensor that uses conjugated gold nanoparticles and a sandwich immunoassay to detect the urine cofilin-1 level of AKI patients. The mean urine cofilin-1 level of the AKI patients was two-fold higher than that of healthy adults. The receiver operating characteristic (ROC) curve showed that cofilin-1 is a potential biomarker for discriminating AKI patients from healthy adults for intensive care patients.
Degree of coherence (DOC) of a paired surface plasma waves (PSPWs) in the paired surface plasma waves biosensor (PSPWB) is proposed and discussed in which a paired of surface plasma waves are excited by using a pair of highly spatial and temporal correlated P-polarized waves in a SPR device of the Kretschmann configuration. The heterodyne signal from reflected paired P-polarized laser beam is generated where the visibility of the signal is proportional to DOC of PSPWs in term of the ratio of AC and DC components of the signal. The experimental result shows that the DOC of PSPWs versus incident angle of laser beam which relates to intrinsic phonon distribution in metal film becomes much sensitive than conventional amplitude or intensity sensitive surface plasmon resonance (SPR) biosensor. Finally, the dynamic range of protein-protein interaction at ultralow concentrations is discussed.
Based on the equivalence theorem of a unitary optical system. We proposed an analytical approach to characterize the
cell parameters of a twisted nematic liquid crystal device (TNLCD) with full field resolution. The spatial distribution of
three characteristic parameters of a TNLCD were measured by using a polarizer-sample-analyzer imaging ellipsometer,
thus the untwisted phase retardation, cell thickness and twisted angle of a TNLCD can be directly calculated through the
explicit expressions as a function of its characteristic parameters. The measured results are very close to the design
values provided by TNLCD manufacture. This method shows that both the system setup and parameters calculating
process are quite simple. It would be more helpful to characterize a TNLCD in the manufacturing process.
Diffuse scattering measurements to determine the changes of glucose concentration in a highly scattering medium are
conducted by using an optical heterodyne technique. The heterodyne technique can increase the signal-to-noise ratio
(SNR) of the detection amplitude and phase by coherence gating and narrow detection bandwidth. The experimental results showed that a good sensitivity of 0.1% scattering change per mM is observed.
KEYWORDS: Heterodyning, Polarization, Modulation, Signal detection, Digital signal processing, Signal processing, Oscilloscopes, Silicon films, Silica, Thin films
In this research, a novel linear polarization modulation heterodyne ellipsometer (LPMHE) integrated with a digital
signal processor is able to measure ellipsometric parameters of a specimen was developed. In this setup, a pair of
orthogonally circularly polarized lights with slightly different frequency of the laser beam is used which behaves like a
linear polarization rotator at high speed. By integrating with a digital storage oscilloscope, LPMHE is able to real-time
measure ellipsometric parameters precisely. When the incident angles of laser beam are set at 60° and 70° in LPMHE, an
accuracy of less than 0.7% on ellipsometric parameters measurement of the SiO2 thin film deposited on silicon substrate
was demonstrated.
An equivalence theory based on a unitary optical system of a generalized elliptical phase retarder was derived.
Whereas the elliptical phase retarder can be treated as the combination of a linear phase retarder and a polarization
rotator equivalently. Three fundamental parameters, including the elliptical phase retardation, the azimuth angle and the
ellipticity angle of the fast elliptical eigen-polarization state were derived. All parameters of a generalized elliptical
phase retarder can be determined from the analytical solution of the characteristic parameters of the optical components:
linear phase retardation and fast axis angle of the equivalently linear phase retarder respectively, and polarization
rotation angle of an equivalent polarization rotator. In this study, the experimental verification was demonstrated by
testing a twisted nematic liquid crystal device (TNLCD) treated as a generalized elliptical phase retarder. A dual-frequency
heterodyne ellipsometer was setup and the experimental result demonstrates the capability of the equivalent
theory on elliptical birefringence measurement at high sensitivity by using heterodyne technique.
We present and develop an approach using optical interference and heterodyne technology to investigate the light
migration in highly scattering media. The theoretical model is based on diffusion approximation in steady-state
frequency domain. The model incorporates pair-photon dipole source in order to satisfy the emulsion boundary condition
and is suitable for either refractive index matched or mismatched surface. The experimental results showed that the
diffusion theory applies in this study. Under the appropriate boundary and interference condition, the study accurately
estimates the optical parameters of the medium.
In this study, we describe a novel method for analyzing protein-protein binding kinetics at ultra-low concentration
(1 pg/mL) using a localized surface plasmon coupled fluorescence fiber-optic biosensor (LSPCF-FOB). The association
and dissociation rate constants, ka and kd, respectively, for the binding kinetics of the mouse IgG/ anti-mouse IgG
interaction have been calculated to be ka = (5.9928±3.1540)x106 M-1s-1 and kd = (1.0587±0.5572)x10-3 s-1. The
theoretical basis of this analytical approach is a rapid-mixing model integrated with a two-compartment model; has been
experimentally verified in this study as well. The LSPCF-FOB provides a potentially alternative option for characterizing
the interaction of biomolecules at ultra-low concentrations.
In order to enhance the sensitivity of conventional rapid test technique for the detection of swine-origin influenza A
(H1N1) viruses (S-OIVs), we used a paired surface plasma waves biosensor (PSPWB) based on SPR in conjunction with an optical heterodyne technique. Experimentally, PSPWB showed a 125-fold improvement at least in the S-OIV detection as compared to conventional enzyme linked immunosorbent assay. Moreover, the detection limit of the PSPWB for the S-OIV detection was enhanced 250-fold in buffer at least in comparison with that of conventional rapid influenza diagnostic test.
We present a novel approach to measure the surface effect of a small scattering object in a highly scattering medium by using the amplitude and phase signal of diffuse photon-pairs density wave (DPPDW). The results demonstrate that DPPDW has high sensitivity for resolving the surface effect of a small object. Imaging in highly scattering media with the developed DPPDW method can potentially increase the spatial resolution of small scattering inclusions.
This study demonstrates a novel phase-sensitive surface plasman resonance biosensor (PS-SPRB) which is able to
convert the phase modulation into amplitude modulation analytically via a differential amplifier. PS-SPRB is able to
measure biomolecule interactions at ultra-low concentration relying on the properties of phase sensitive detection at
shot-noise detection in a real-time. The common-phase noise-rejection mode is provided in PS-SPRB to be able to
immune the background phase noise efficiently. The experimental results confirm the detection sensitivity of 0.00001 wt
% concentration of sucrose solution and 10 fg/ml mouse IgG interaction with anti IgG in real time.
Alpha-fetoprotein (AFP) detection by using a localized surface plasmon coupled fluorescence (LSPCF) fiber-optic biosensor is setup and experimentally demonstrated. It is based on gold nanoparticle (GNP) and coupled with localized surface plasmon wave on the surface of GNP. In this experiment, the fluorophores are labeled on anti-AFP which are bound to protein A conjugated GNP. Thus, LSPCF is excited with high efficiency in the near field of localized surface plasmon wave. Therefore, not only the sensitivity of LSPCF biosensor is enhanced but also the specific selectivity of AFP is improved. Experimentally, the ability of real time measurement in the range of AFP concentration from 0.1ng/ml to 100ng/ml was detected. To compare with conventional methods such as enzyme-linked immunosorbent assay (ELISA) or radioimmunoassay (RIA), the LSPCF fiber-optic biosensor performs higher or comparable detection sensitivity, respectively.
KEYWORDS: Multiple scattering, Signal detection, Modulation, Heterodyning, Scattering, Photon polarization, Diffuse photon density waves, Absorption, Phase shift keying, Signal to noise ratio
Conventionally, the detection and characterization of an optical inhomogeneity embedded in turbid media is dependent
on the perturbation of diffuse photon density wave (DPDW) and its noise level, which is defined as the signal-to-noise
ratio (SNR). In this study, we calculate the limitation of detection and characterization by using diffuse photon-pairs
density wave (DPPDW) which is a novel method in studying turbid media. DPPDW is produced by linear polarized
photon-pairs (LPPPs) laser beam which experience multiple-scattering events in turbid media. Meanwhile, the fractional
amplitude and phase noise in detecting heterodyne signal determine the detection and characterization of DPPDW in a
multiple scattering medium. The amplitude attenuation and phase change of heterodyne signal of DPPDW and their
SNR analysis are demonstrated and discussed. As a result, we anticipate that the properties of DPPDW depending upon
the degree of spatial coherence (DOC) and the degree of polarization (DOP) of LPPPs in turbid media can result in an
improvement on detection and then the perturbation of DPPDW produced by an inhomogeneity embedded in a multiple scattering medium is able to be measured.
Refractive-index mismatch in conventional confocal microscopy produces severe degradation on axial resolution of
sectioning image because the spherical aberration is generated in specimen. In this study, we propose a polarized
photon-pairs confocal laser scanning microscope (PCLSM) in which a two-frequency linear polarized photon-pairs
(LPPPs) laser beam is produced. The common-path propagation of LPPPs integrated with optical heterodyne technique
not only can reduce the spherical aberration but also decreases scattering effect in specimen at same time. Therefore, the
better axial and lateral resolutions of the sectioning image are produced simultaneously. In the experiment, a verification
and comparison between PCLSM and conventional confocal laser scanning microscope (CLSM) on the ability of
cancellation of spherical aberration induced by cover glass are demonstrated experimentally. Finally, the ability of
PCLSM which can decrease the spherical aberration based on the common-path propagation of LPPPs associated with
polarization gating, spatial coherence gating and spatial filtering gating is discussed.
We developed a novel differential-phase optical coherence reflectometer (DP-OCR) by using a low-coherence light
source and integrated with differential phase detection technique on surface profile measurement. In this setup, 2Å on
detection of axial displacement was demonstrated. Thus, a localized surface profile was measured precisely by
scanning an optical grating surface in this measurement. Moreover, the requirement on equal amplitude of the reference
and signal beams of this novel reflectometer is discussed.
Application of a fiber optic biosensor (FOB) to the real-time investigation of the interaction kinetics between FITC-conjugated monoclonal sheep anti-human C-reactive protein (CRP) antibody and CRP isoforms on the surface of optical fiber is described. Recently, both the native pentameric CRP (pCRP), an acute phase protein belonging to pentraxin family, and an isoform of pCRP, modified CRP (mCRP), have been suggested to have proinflammation effects on vascular cells in acute myocardial infarction (AMI). In current studies, we generate mCRP from pCRP, and use several methods including fluorescence spectral properties, circular dichroism, analytical ultracentrifuge, and Western blotting to demonstrate their differences in physical and chemical properties as well as the purity of pCRP and mCRP. In addition, we design and implement an FOB to study the real-time qualitative and quantitative biomolecular recognition of CRP isoforms. Specifically, the association and dissociation rate constants of the reaction between FITC-conjugated monoclonal sheep anti-human CRP antibody and the pCRP and mCRP are determined. The feasibility of our current approach to measure the association and dissociation rate constants of the reaction between tested CRP isoforms was successfully demonstrated.
Previous work with amplitude-sensitive paired surface plasma waves biosensor (PSPWB) demonstrated that the
detection sensitivity of PSPWB is able to experimentally detect 0.001% sucrose-water solution and biomolecular
interaction of 10pg/ml mouse IgG interacting with immobilized anti-mouse IgG successfully.
Further development of the detection sensitivity of PSPWB has been conducted by using 20nm in diameter colloid gold
nanoparticles conjugated with target molecules that can result in a higher mass coverage and a larger resonant angle
change of plasmon resonance, thereby its detection sensitivity is further enhanced significantly. Bare gold nanoparticles,
which is randomly suspended in solution, is adopted to differentiate biospecific binding induced further signal
enhancement. Experimentally, the sensitivity at 330fg/ml of Au-nanoparticle conjugated protein A (PA-Au) interacting
with mouse IgG which is immobilized on a CM5 sensor chip was detected successfully. By this arrangement, 6-fold
signal amplification is demonstrated compared with the same concentration of PA without conjugated gold nanoparticles.
We proposed and developed a novel fiber-optic biosensor based on localized surface plasmon coupled emission (LSPCE)
which consists of sandwich format of immuno-complex. It is immobilized on the
surface of optical fiber where is a fluorescence probe produced by mixing Cy5 labeled antibody
and protein A conjugated gold nanoparticles (Au-PA). The fluorophores are excited by localized surface plasmon (LSP)
on gold nanoparticle (GNP) surface where the evanescent field is applied near the core surface of unclad optical fiber.
Meanwhile, the fluorescence signal is detected by a photomultiplier tube being set beside the unclad optical fiber with
high collection efficiency. In the experiment, this novel LSPCE biosensor demonstrates the minimum detectable
concentration of mouse immunoglobulin G (IgG) at 1pg/ml (7fM) in the biomolecular interaction with anti-mouse IgG.
From the experimental result, it verifies that LSPCE biosensor is a very high sensitive biosensor which is capable of
measuring biomolecular interaction at very low concentration.
We study the scattering of diffused photon pair density wave (DPPDW) from a spherical and cylindrical inhomogeneity embedded in a homogeneous multiple scattering medium. In this study, DPPDW is composed of correlated polarized photon pairs at different temporal frequencies and parallel linear polarized states in a multiple scattering medium where two linear polarized photons are common-path propagating in the scattering medium. The heterodyne signal is then generated by a photomultiplier tube. By measuring the amplitude attenuation and the phase delay of heterodyne signal at different position of the scattering medium, the diffracted amplitude and phase wavefront of DPPDW are obtained precisely and simultaneously. In this experiment, the distorted phase wavefront and amplitude wavefront by a perfect spherical or cylindrical absorber in a multiple scattering medium is investigated. Because the feature of common-path propagation of polarized pair photons in a multiple scattering medium and the polarization gating and the spatial coherence gating working simultaneously, the sensitivity of the amplitude and phase detection of DPPDW are then enhanced significantly. The ability of detecting a smaller size of optical inhomogeneity in a multiple scattering medium is discussed and the experimental results consistent with the theoretical expectation are demonstrated.
Atherosclerosis is unquestionably the leading cause of morbidity and mortality in developed countries. In the mean time, the worldwide importance of acute vascular syndromes is increasing. Because collagen fiber is a critical component of atherosclerotic lesions; it constitutes up to 60% of the total atherosclerotic plaque protein. The uncontrolled collagen accumulation leads to arterial stenosis, whereas excessive collagen breakdown weakens plaques thereby making them prone to rupture finally. Thus, in this study, we present the first application, to our knowledge, of using polarization-sensitive optical coherence tomography (PS-OCT) in human atherosclerosis. We demonstrate this technique for imaging of intensity, birefringence, and fast-axis orientation simultaneously in atherosclerotic plaques. This in vitro study suggests that the birefringence change in plaque is due to the prominent deposition of collagen according to the correlation of PS-OCT images with histological counterpart. Moreover, we can acquire quantitative criteria based on the change of polarization of incident beam to estimate whether the collagen synthesized is "too much" or "not enough". Thus by combining of high resolution intensity imaging and birefringence detection makes PS-OCT could be a potentially powerful tool for early assessment of atherosclerosis appearance and the prediction of plaque rupture in clinic.
The proposed optical fiber biosensor is used to study the qualitative and quantitative aspects of biomolecular recognition in real time. This approach is able to apply for measuring the association and dissociation rate constants of the reaction between biomolecules.
A photon pair density wave (PPDW) is initiated and compared with the conventional defused photon density wave (DPDW) to verify its optical properties generated by correlated parallel polarized pair photons propagating in a scattering medium. An optical heterodyne signal is generated by the scattered correlated pair photons in the scattering
medium. However, the phase delay of the signal depends upon the beat frequency and the distance between source and detector. This is similar to DPDW at the lower modulated frequency of laser source in frequency domain. Spherical wave fronts of constant attenuated intensity and the phase delay of PPDW are observed in a homogenous
scattering medium by using a lock-in amplifier. The assumption that polarized photon pairs propagating as photon density wave in a multiple scattering medium is verified experimentally. Optical properties of PPDW in the scattering medium are demonstrated successfully.
A novel optical heterodyne surface plasmon resonance (SPR) biosensor using Zeeman laser is proposed. There are two surface plasma waves (SPWs) being excited by two correlated P polarized waves in an SPR device of Kretschmann configuration. The two reflected P waves are optically heterodyned so that the amplitude of the heterodyned signal is proportional to the multiplication of two attenuated reflected P waves. The detection sensitivity and the dynamical range based on this amplitude sensitive method are enhanced. In the experiment, the kinetics between mouse IgG and anti-mouse IgG is obtained according to the sensograms of different concentrations of anti-mouse IgG. The detection sensitivity corresponding to 0.2 nM is achieved. In addition, a concentration of 5 ng/ml of protein G interacting with mouse IgG is measured successfully.
The angular distribution of the photon pairs of a Zeeman laser scanning confocal microscope (ZLSCM) is measured in turbid media. By scanning the pinhole at different locations on a focal plane, the angular distribution of the snake photon pairs that is contributed by the object plane in the scattering medium is measured. The narrower width of the angular distribution of the snake photon pairs implies the better performance of the depth resolution of ZLSCM in turbid media. In this study, the dependence between depth resolutions of ZLSCM with respect to different vol. % concentrations of the scattering medium is observed. In addition, the correlation between angular distribution and depth resolution in different concentrations is also demonstrated and discussed.
Measurement of tissue radiation damage quantitatively in radiation therapy is very important to optimize the therapeutic treatment. Ionized radiation induces homogenization of the extracellular matrix which is synthesized by fibroblast and the randomization of the orientation of the collagen fibers in dermis. If the dermis is exposed by ionized radiation, a thermal acoustic shear wave which propagates in dermis becomes harmonic wave. Otherwise, an inharmonic wave is expected because of inhomogeneous and the anisotropic properties of dermis. A polarized optical heterodyne interferometer was setup in order to measure the transverse displacement of the shear wave in order to analyze the propagation mode of the shear wave in dermis. The detection sensitivity of the displacement was 1nm and the dynamic range was 300 nm in this arrangement. The lowest does that can be detected by the exposure of 4 MeV radiation on porcine dermis was 1cGy.
An amplitude sensitive optical heterodyne polarimeter was setup in order to monitor noninvasively the aqueous glucose concentration in rabbit's eye. A range of the blood glucose from 35 mg/dl to 135 mg/dl was measured in vivo by biological glucose assay (BGA), while the optional rotation of the aqueous glucose was measured by a polarimeter simultaneously. The experimental results showed the consistence between these two independent measurements. There was no time delay between the blood glucose and the aqueous glucose when the blood glucose was descending after the insulin was injected. It was in contract to a 10 minutes time delay when the blood glucose was ascending. The detection sensitivity of the polarimeter was 4 mg/dl in the measurement.
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