Browsing by Subject "Microscopic examination"

Now showing 1 - 9 of 9

Open Access
Detection of Calcium-induced morphological changes on RBCs by digital holographic microscopy and blinking optical tweezers
(IEEE, 2016) Rad, V. F.; Tavakkoli, R.; Moradi, Ali-Reza; Anand, A.; Javidi, B.
Ca+2 level in the circulating red blood cells (RBCs) takes part not only in controlling biophysical properties, but also affects the membrane composition, and its morphological and rheological properties. Excessive accumulation of Ca2+ within the cells is associated with a number of important pathological diseases. In this paper, by the use of digital holographic microscopy (DHM), we quantitatively analyzed the volumetric behavior of RBC membrane under influence of excess Calcium ions. DHM in a transmission mode is an effective tool for quantitative visualization of phase objects. By deriving the associated phase changes 3D information on the morphology variation of the cells at arbitrary time scales is obtained. Individual cells are immobilized by the use of optical tweezers and are monitored live with DHM system, while the concentration of Ca2+ ions in the buffer is changed simultaneously. We utilized blinking optical tweezers, by inserting an optical chopper to modulate intensity of the trapping laser beam. Blinking optical tweezers, while keeping the cell trapped during the experiments, ensures of minimizing the photo-damage of trapping laser beam on the cell. Our experimental results are in agreement with previous biological studies and predictions, and experimental observations of living RBCs under Ca2+ influence.
Open Access
Generation of long-living entanglement between two separate three-level atoms
(The American Physical Society, 2005) Çakir, Ö.; Dung, H. T.; Knöll, L.; Welsch, Dirk- Gunnar
A scheme for nonconditional generation of long-living maximally entangled states between two spatially well separated atoms is proposed. In the scheme, A-type atoms pass a resonatorlike equipment of dispersing and absorbing macroscopic bodies giving rise to body-assisted electromagnetic field resonances of well-defined heights and widths. Strong atom-field coupling is combined with weak atom-field coupling to realize entanglement transfer from the dipole-allowed transitions to the dipole-forbidden transitions, whereby the entanglement is preserved when the atoms depart from the bodies and from each other. The theory is applied to the case of atoms passing by a microsphere.
Open Access
Hybridization of fano and vibrational resonances in surface-enhanced infrared absorption spectroscopy of streptavidin monolayers on metamaterial substrates
(2014) Alici, K. B.
We present spectral hybridization of organic and inorganic resonant materials and related bio-sensing mechanism. We utilized a bound protein (streptavidin) and a Fano-resonant metasurface to illustrate the concept. The technique allows us to investigate the vibrational modes of the streptavidin and how they couple to the underlying metasurface. This optical, label-free, nonperturbative technique is supported by a coupled mode-theory analysis that provides information on the structure and orientation of bound proteins. We can also simultaneously monitor the binding of analytes to the surface through monitoring the shift of the metasurface resonance. All of this data opens up interesting opportunities for applications in biosensing, molecular electronics and proteomics. © 2014 IEEE.
Open Access
A Lamb Wave Lens for Acoustic Microscopy
(1992) Atalar, Abdullah; Köymen, Hayrettin; Değertekin, F. Levent
In a conventional scanning acoustic microscope the excited leaky modes contributes significantly to the high contrast obtained in the images. However, all such modes exist simultaneously, and the interpretation of the images is not straightforward, especially in layered media. A new lens geometry is proposed that can be used with acoustic microscopes to image layered solid structures. This new lens can focus the acoustic waves in only one of the Lamb wave modes of the layered solid with a high efficiency. V(Z) curves obtained from this lens are more sensitive to material properties compared to that obtained from conventional lens. Measuring the return signal as a function of frequency results in another characteristic curve, V(f). The Lamb wave lens and the associated characterization methods for the layered structures are described. The results presented show that the Lamb wave lens is at least an order of magnitude more sensitive than the conventional lens and can differentiate between a good bond and a disbond in a layered structure easily. © 1992 IEEE
Open Access
Microsphere-Assisted Super-Resolved Mirau Digital Holographic Microscopy for Cell Identification
(OSA - The Optical Society, 2017) Aakhte, M.; Abbasian, V.; Akhlaghi, E. A.; Moradi, A. R.; Anand, A.; Javidi, B.
In this paper, we use a glass microsphere incorporated into a digital holographic microscope to increase the effective resolution of the system, aiming at precise cell identification. A Mirau interferometric objective is employed in the experiments, which can be used for a common-path digital holographic microscopy (DHMicroscopy) arrangement. High-magnification Mirau objectives are expensive and suffer from low working distances, yet the commonly used low-magnification Mirau objectives do not have high lateral resolutions. We show that by placing a glass microsphere within the working distance of a low-magnification Mirau objective, its effective numerical aperture can be increased, leading to super-resolved three-dimensional images. The improvement in the lateral resolution depends on the size and vertical position of microsphere, and by varying these parameters, the lateral resolution and magnification may be adjusted. We used the information from the super-resolution DHMicroscopy to identify thalassemia minor red blood cells (tRBCs). Identification is done by comparing the volumetric measurements with those of healthy RBCs. Our results show that microsphere-assisted super-resolved Mirau DHMicroscopy, being common path and off-axis in nature, has the potential to serve as a benchtop device for cell identification and biomedical measurements.
Open Access
Novel integrated optical displacement sensor for scanning force microscopies
(IEEE, 2003) Aydınlı, Atilla; Kıyat, İsa; Kocabaş, Coşkun
A novel displacement sensor for scanning force microscoples using an integrated optical micro-ring resonator is described. Device operates by monitoring the changes in transmission spectrum of micro-ring resonator. This design provides sensitivities about ∼10-4 Å-1.
Open Access
Optical reconstruction of transparent objects with phase-only SLMs
(Optical Society of American (OSA), 2013) Stoykova, E.; Yaraş F.; Yontem, A.Ö.; Kang H.; Onural L.; Hamel P.; Delacrétaz, Y.; Bergoënd I.; Arfire, C.; Depeursinge, C.
Three approaches for visualization of transparent micro-objects from holographic data using phase-only SLMs are described. The objects are silicon micro-lenses captured in the near infrared by means of digital holographic microscopy and a simulated weakly refracting 3D object with size in the micrometer range. In the first method, profilometric/tomographic data are retrieved from captured holograms and converted into a 3D point cloud which allows for computer generation of multi-view phase holograms using Rayleigh-Sommerfeld formulation. In the second method, the microlens is computationally placed in front of a textured object to simulate the image of the textured data as seen through the lens. In the third method, direct optical reconstruction of the micrometer object through a digital lens by modifying the phase with the Gerchberg-Saxton algorithm is achieved. © 2013 Optical Society of America.
Open Access
Room temperature scanning Hall probe microscopy using GaAs/AlGaAs and Bi micro-hall probes
(Elsevier Science B.V., 2002) Sandhu, A.; Masuda, H.; Oral, A.; Yamada, A.; Konagai, M.
A room temperature scanning Hall probe microscope system utilizing GaAs/AlGaAs and bismuth micro-Hall probes was used for magnetic imaging of ferromagnetic domain structures on the surfaces of crystalline thin film garnets and permanent magnets. The Bi micro-Hall probes had dimensions ranging between 0.25 and 2.8μm2 and were fabricated using a combination of optical lithography and focused ion beam milling. The use of bismuth was found to overcome surface depletion effects associated with semiconducting micro-Hall probes. Our experiments demonstrated that Bi is a practical choice of material for fabricating sub-micron sized Hall sensors.
Open Access
RT-SHPM imaging of permalloy microstructures and garnet films using new high performance INSB sensors
(IEEE, 2002) Oral, Ahmet; Kaval, Murat; Dede, Münir; Sandhu, A.
The room temperature scanning Hall probe microscopy (RT-SHPM) imaging of permalloy microstructures and garnet films was discussed. The high performance InSb Hall sensors were used for this purpose. It was shown that the InSb Hall probes were highly sensitive and low noise alternatives to GaAs sensors for RT-SHPM.