Differential Interference Contrast (DIC) microscopy is a label-free technique crucial for visualizing transparent biological specimens. In this study, we introduce a novel DIC interferometry imaging technique based on calcite beam displacer (CBD), significantly enhancing resolution and contrast. Our system, requires only two polarizers and a calcite beam displacer, offers a practical and straightforward implementation on standard microscopes. We demonstrate its efficacy by imaging human red blood cells (RBCs) and bacteria, retrieving differential phase information, and recording the dynamics of U2OS cells over an hour at 15 frames per second (fps). This advancement in DIC microscopy holds promise for broader applications in high-resolution imaging of transparent specimens in cell biology research.
Quantitative phase microscope (QPM) is used for the quantitative information and dynamic phase imaging of biological specimen, which provides wide application in biomedical sciences. High temporal phase stability of the QPM system is the primary requirement for accurate phase measurement. We have developed a common-path QPM geometry based on beam displacer and pinhole unit to achieve high temporal stability. The convenient adjustment of reference and object beams makes optical system compact and low-cost. The membrane fluctuations and qualitative phase are measured to demonstrate the capability and applicability of the system.
Coulomb coupling has been applied for imaging of bulk and guided acoustic waves propagating in a 0.5 mm thick, z cut
Lithium Niobate single-crystal. The excitation and detection of acoustic waves was performed by localized electrical
field probes. The developed scheme has been applied to imaging of the transport properties of skimming longitudinal and
guided acoustic waves. A short pulse of 20 ns has been used for the excitation of acoustic waves. Broadband coupling is
achieved since neither mechanical nor electrical resonances are involved. The attenuation of acoustic waves in piezoelectric
crystals is studied by this method. A thin film of conductive silver paint was deposited on the surface of the
crystal acting as an acoustic attenuator inducing also mass loading effects and shortening of electrical fields. The group
velocities of the propagating acoustic waves for both conditions, with and without the conductive silver paint film, are
determined from the propagation of the acoustic wave fronts.
Acoustic bulk waves were excited by local electric field probe in an anisotropic piezo-electric crystal Lithium Niobate
(X-cut). A narrow pulse with a width of 25 ns was used for excitation to obtain wide frequency content in the Fourier
domain. A wide spectrum ensures metamorphosis of bulk waves into Lamb waves for scan lengths comparable to the
involved wavelengths. The low frequency content experiences multiple reflections from the two surfaces of the plate and
disperses along the propagation direction. Acoustic bulk wave's evolution and transformation to Lamb waves are
illustrated and explained with the aid of the Lamb wave dispersion phenomenon. The holographic images in the Fourier
domain exemplify the metamorphosis of waves during propagation following the excitation at an approximate point
source.
Excitation and detection of acoustic waves in piezoelectric materials relies on a gradient in the piezoelectric properties
respectively a gradient in the electric field. The relatively weak coupling is usually enhanced for established practical
applications by mechanical, geometrical and electrical resonances. The geometrical resonances, as present for the
commonly used inter digital transducer (IDT), lead to limitations concerning the spatial and temporal resolution that can
be achieved with such devices. Concentration of the electric field by geometrical means and point like conversion at the surface of piezoelectric materials is the basis for the novel scheme presented here. The principles of the developed method together with instrumental details are discussed. Applications involving two dimensional imaging with time resolved recording for each pixel of the image for phase and magnitude of the transfer and echo signals are presented.
Coulomb excitation and detection of ultrasonic waves in piezoelectric crystals by spherical electrical probes is discussed
in view of the opening angle of the cone of longitudinal waves coupling to such a probe. The electric field distribution in
the piezoelectric crystal under the probe is modeled by means of finite elements in order to determine the effective size
of the probe normalized to the sphere radius. The dynamic impedance of the probe is estimated, and it is shown that a
probe of a size appropriate to illuminate or detect from the piezoelectric half space has a frequency-independent
impedance of about 3 k&OHgr; under idealizing assumptions. Measurements of the directionality of ultrasound emission and
detection at a frequency of about 100 MHz are presented for three probes with different tip radii, varying from about
30 &mgr;m to 2.5 mm. As expected, larger probes yield a higher directionality. A relatively large forward contribution is
observed even for small spheres.
Electric surface excitation of ultrasound in the Coulomb field of scanned electrically conductive spherical local probes and similar detection has been employed for imaging of the transport properties of acoustic waves in piezoelectric materials including singlecrystalline wafers. The employed Coulomb scheme leads to a fully predictable and almost ideal point excitation and detection. In combination with two-channel quadrature transient detection it allows high precision spatially and temporally resolved holographic imaging. Via modeling of the excitation and propagation properties, the effective elastic tensor and the piezoelectric properties of the observed materials can be determined with high resolution from a single measurement. The generation and detection scheme as well as the theoretical background are demonstrated and applications are exemplified.
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