Autofocusing is widely used in microscopy since it provides sample details with high resolution and contrast. However, massive image recording along optical axis is often indispensable in classical autofocusing tactics, obviously decreasing autofocusing speed. To increase processing efficiency, we propose numerical wavefront propagation based autofocusing with high speed and large effective range. Firstly, quantitative sample phase is retrieved from multi-focal images according to transport of intensity equation with Gerchberg-Saxton algorithm. Then, various intensities along optical axis are numerically computed via wavefront propagation, thus focal position can be determined according to in-focus criterion. Finally, in-focus image is recorded via sample stage shifting. Since the proposed autofocusing approach can be easily integrated into commercial microscopes, additionally, it considerably reduces image captures as well as time consuming, we believe it can be adopted for rapid autofocusing in microscope.
Massive image acquisition is required along the optical axis in the classical image-analysis-based autofocus method, which significantly decreases autofocus efficiency. A wavefront-sensing-based autofocus technique is proposed to increase the speed of autofocusing and obtain high localization accuracy. Intensities at different planes along the optical axis can be computed numerically after extracting the wavefront at defocus position with the help of the transport-of-intensity equation method. According to the focus criterion, the focal plane can then be determined, and after sample shifting to this plane, the in-focus image can be recorded. The proposed approach allows for fast, precise focus detection with fewer image acquisitions compared to classical image-analysis-based autofocus techniques, and it can be applied in commercial microscopes only with an extra illumination filter.
We study on the joint training mode of optical engineering (OE) master in the ways of teaching, scientific research and practice cooperation. Our goal is to enhance the abilities and research level of OE graduate students by establishing the joint training cooperation with the domestic or foreign high level universities, the top research institutes and the famous enterprises, and to let more and more graduate students enter the high level universities and companies. In addition, we want to create the training quality evaluation index and evaluation system of the OE master students to evaluate this joint training mode.
The image quality in off-axis digital holography (DH) is often degraded by inaccuracies in the reference wave used for reconstruction and the spatial filtering adopted to avoid twin images and zeroth order diffraction. To enhance the image quality in such cases, coherent diffraction imaging is combined with a DH technique to iteratively reconstruct the hologram. By using a small aperture on the sample plane as a spatial constraint and the recorded diffraction pattern as an intensity constraint, a higher spatial resolution than usual is obtained with the proposed method.
We investigate the use of first derivative intrinsic fluorescence spectroscopy as an adjunctive tool for early diagnosis or
screening on gynecological tumors. The first derivative intrinsic fluorescence spectra from limosis morning urine of
gynecologic cancerous patient and the healthy group are measured. And Combining the first order derivative spectra
method and clinic diagnosis standard to cluster analysis the information, we obtained that the diagnostic sensitivity and
specificity are 81% and 75% based on the judgment of setting γ=300, respectively. It may be applied to early diagnose
gynecological tumors using intrinsic urine fluorescence spectra.
Ovarian cancer has the highest mortality rate among the gynecologic cancers, and it goes undetected because adequate
technology does not exist to detect preinvasive or early stage disease. Fluorescence spectroscopy of urine may provide a
cost-effective tool to improve precancer detection. This study describes initial investigation of the potential of intrinsic
urine fluorescence spectra for detecting early ovarian cancer.
Using the Xenon arc lamp to irradiate the urine from ovarian cancer, cervical carcinoma groups and healthy donors, we
obtained fluorescence emission spectra. The three groups of samples show different emission spectra peak and
fluorescence intensity. Ovarian cancer group has the largest displacement of maximum spectra peak at 380-400nm
excitation wavelength. And the fluorescence intensity from ovarian cancer group is significantly higher with the healthy
donors and cervical carcinoma group in comparison at the short wave excitation region of 320-360nm, while cervical
carcinoma group has higher fluorescence intensity than ovarian cancer group at 380-500nm excitation. Characteristic
fluorescence mechanism was studied through comparison of fluorescence spectra and software fitting image.
Fluorescence spectra at 440nm excitation is found to be perfectly lorentzian fitted by three characteristic fluorescence
peaks, which are originated form coproporphyrin, riboflavin and p-hydroxyphenol derivatives existing in the urine.
It is known that plasma is very important in the diagnosis and therapy of disease so that more and more scientific workers attach importance to the plasma storage life or storage environment. We research plasma disintegration with the increases of storage time based on the fluorescence spectroscopy. Based on the experimental researches and theoretical analysis, we find that their plasma fluorescence intensity is increasing within about 10 hours, and but is decreasing gradually and is nearly a straight line after this. It is indicated that plasma proteins have begun to disintegrate so as to make the fluorescence quenching after storage time beyond 10 hours. And the disintegration speed of plasma in the case of different concentration is different, the concentration is higher and the speed is lower in them, and but they are almost same after about 35 hours. Therefore, we think that plasma under higher concentration is deposited easier.
These research consequences may order a theoretical and experimental reference to know the changes of plasma in structure in different disintegration time. It may make sense for understand the plasma disintegrative mechanism and distinguishing the fine plasma with faulty.
The ultraviolet light-excitated fluorescence spectra from healthy human blood in vitro have been measured by FLS920 Spectrometer, made in Edinburgh Instruments, exciting light from Xe900 - 450W steady state xenon lamp. The relation between exciting light wavelength and the fluorescence spectral characteristics of blood in the case of certain concentration is provided in this paper. Ultraviolet light excitated healthy human blood fluorescence spectra profiles change in peak intensity and position with exciting light. It may be due to the abruption of large numbers of anisomerous C-C bonds or C-N bonds that absorb the energy by non-resonance on membrane of blood cells, bringing lone-pairs of electrons, forming the new fluorophores and emit fluorescence in the case of later ultraviolet light excitation. It may be why ultraviolet light is able to kill and wound cells. In addition, the fluorescence spectra distributing range is very wide. It is due to contributions of the many fluorophores with large numbers of vibrational energy levels on the ground level in the blood cells. Our understanding of the different wavelength light-induced blood cells fluorescence spectra characteristics may be useful to development of low level laser therapy in vivo and in vitro.
Acetic acid solution can emit visible fluorescence when induced by UV-light. With emitting spectrum profiles dissimilar on the whole, the fluorescent intensity changes too when the excited light alters from 230nm to 300nm. There are two spectral bands on the whole, one central wavelength is located at 307nm and the other is at 400nm. The relationship between the fluorescence relative intensity and the excited-light wavelength is described in polynomial fit. The optimal excited light is obtained both by the experiment data and the polynomial fit of the data. Investigation on the intrinsic fluorescence spectrum of acetic acid solution and its characteristics will contribute to the study of the fluorescence spectra when acetic acid serves as a solute and hydrolysis catalyst. Especially, this study will also help to offer the experiment basic for the theoretic research of the interaction of acetic acid and water molecule.
The fluorescent spectra of human blood with different concentration induced by different wavelength LED light are reported in this paper. The phenomenon that fluorescence peaks are apparently red-shifted with the increase of blood concentration is analyzed and the mechanism is given a reasonable explanation. The results indicate that the peak is shifted following the rule of e-exponent with the increase of the blood concentration. The mechanism of different energy transfer with different fluorescent areas is analyzed from the theory of energy transfer. The resonance energy transfer is the primary reason of the fluorescent spectra peaks. The concept of the idea fluorescence and the inner fluorescence is also brought forward in this paper. The research will give refer intrinsic fluorescence diagnostic techniques of organic tissue.
Autofluorescence spectra from whole blood of laboratory rat are measured in this paper. The excitation lights are light emitting diode (LED), Ar+ laser, and He-Ne laser with the wavelength located at 457nm, 457.9nm, and 632.8nm respectively. The three spectral profiles are found to be substantially different, each displaying its own characteristic fluorescence bands. Ar+ laser-induced spectrum has very rich and sharp peaks. The LED-induced one has the strongest and widest fluorescence bands. And the intensity of the spectrum induced by He-Ne laser is much lower than the former two. Comparisons of those three fluorescence spectra indicate that Ar+ laser induced spectrum can show partly fine structure of blood cells. Based on the theoretical analysis, it is presented that the absorption of the fluorophores in blood cells to the wavelength of exciting light has definite selectivity, which depend on energy level structure and state of the fluorophores.
Laser-blood cells interaction was studied by Ar+ laser-induced animal (mouse) blood fluorescence spectra in vitro. The fluorescence spectra of the blood under various irradiated powers of Ar+ laser excitation are shown that there are very rich and sharp spectral peaks from 600 nm to 860 nm. These peaks are located at 616 nm, 666 nm, 708 nm, 739 nm, 752 nm, 766 nm, 800 nm, 812 nm and 844 nm. This may be due to the fact that there are various fluorophores in the blood and the ground electronic state of the fluorophores containing a large number of vibrational levels. In addition, 666 nm peak among them is the most prominent and is a larger change in the intensity under different power of Ar+ lasers excitation. It foretell that laser near a wavelength of 666 nm may be more effective to low lever laser therapy (LLLT). Furthermore, these experiments indicate that when the laser irradiated power density reaches to 30 mW/cm2 the blood cells are still not destroyed. The results may be significative for the choice of irrediation-wavelength in LLLT.
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