We study the feasibility of polarization-entangled photon pairs to be applied for probing the density of living microorganisms in a microfluidic chamber. We investigate the polarization response of scattering samples via quantum state change and relate this to different density levels of microorganisms on example of yeast cells in water solution.
In this paper, we analyse the capabilities of the digital holographic approach for evaluation of the refractive index distribution appearing in semiconductor materials due to external optical excitation. The study is based on a modified transmission Mach-Zehnder holographic microscope operating in the near-infrared spectral range. Practical considerations for holographic characterization of semiconductor samples are discussed. Experimentally measured data are compared with simulations as well as approaches to interpretation of the retrieved data are covered.
In this paper we report on practical investigations aimed at failure detection of the integrated optical circuits (IOC) on Silicon substrate during the control measurements of the items in use. Experiments are performed with a near-infrared (1064 nm) digital holographic microscope (≈90×magnification) in transmission mode. The instrument provides non-destructive and fast (<380 ms reconstruction time for 4112×3008 pixels images) data analysis at the diffraction-limited accuracy (lateral resolution of 760 nm). High quality of the instrument performance is shown on example of topography reconstruction of a standard glass-substrate test target. Practical applicability of the approach was proven on example of diffractive input elements of the IOCs designed for sensing purposes.
In this paper we discuss a near real time digital holographic imaging algorithm achieving ∼4 fps operation speed on a common central processing unit. The hologram recording is performed in the off-axis geometry in the transmission mode. The algorithm follows a standard angular spectrum method routine and utilizes experimental calibration of the optical instrument for aberration correction. The main limiting factor is related to the size of the initial hologram and its Fourier transform (∼57% of the total execution duration). The performance of the approach is tested on different transparent and semi-transparent samples for reconstruction of sample topography and object in-depth allocation.
In this paper, we propose a direct-view digital holographic camera system consisting mostly of customer-oriented components. The camera system is based on standard photographic units such as camera sensor and objective and is adapted to operate under off-axis external white-light illumination. The common-path geometry of the holographic module of the system ensures direct-view operation. The system can operate in both self-reference and self-interference modes. As a proof of system operability, we present reconstructed amplitude and phase information of a test sample.
In this paper, we introduce a digital holographic camera objective based on conventional customer-oriented components for off-axis external white light illumination. The interferometric module based on a modified common-path point diffraction interferometer provides a direct view of the system and admits self-reference and self-interference operation modes. The proposed system is designed for self-emitting and reflective samples. Its modular assemblage provides easy scalability and up-grade possibilities. The operability of the suggested camera system has been proven for both coherent and low-coherent broadband sources, and reconstructed amplitude and phase information of test samples under white light illumination is presented.
Within this work we propose a new technique for diagnostics of dispersed media using the shock waves generated with continuous laser radiation of moderate power. Within this technique it is possible to determine geometrical sizes of the dispersed particles as well as the absorption coefficient of the disperse medium. Under long-term influence of the optical field of power less than 100 mW observable disperse medium is not destroyed which can be applied in the micro- and nanotechnologies and in biomedicine.
Focusing the continuous laser radiation on the water with absorbing particles results in the emergence of shock waves and medium blooming periodic in time. The illuminating beam diameter growth at the constant laser power results in the decrease of the signals’ modulation frequency, improving their stability and increasing their amplitudes. The decrease of signal’s modulation frequency is caused by the growth of time, which is needed for heating the medium to the critical temperature. Improving the stability and the increase of optical and acoustic signals’ amplitudes take place due to the growth of the number of particles participating in cavitation.
Water suspension of absorbing nano-sized particles is an example of a medium in which non-linear effects are present at moderate light intensities, which is applicable to optical treatment of biological objects. The experiment was dedicated to the phenomena emerging in a thin layer of such a medium under the action of inhomogeneous light field formed due to the Pearcey diffraction pattern near a microlens focus. In this high-gradient field, the light energy absorbed by the particles induces inhomogeneous distribution of the medium refraction index, which results in observable self-diffraction of the falling light, depending strongly on the medium position with respect to the focus.
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