International Journal of

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Recently atomic magnetometers are one of the best tools in biomagnetic measurement such as magnetic field of brain and heart. In this paper, the technology of optically pumped atomic magnetometer based on circularly polarized light absorption pumping is described. We have been investigated a new method for measuring polarization effect in an alkali vapor based on polarized light transmission. In addition several magnetometers’ response factors such as cell temperature, laser’s intensity are introduced and reviewed. Our results show that the difference between absorption of circular and linear light not only depends on polarization, but also in number of polarized atoms.

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Atomic magnetometers have found widespread applications in precise measurement of the Earth’s magnetic field due to their high sensitivity. In these measurements, various methods have been utilized to compensate the Earth’s magnetic field in an unshielded environment. In this paper, we have proposed a method based on finding the minimum resonance frequency (corresponding to minimum magnetic field) by producing the opposite magnetic field through three pairs of Helmholtz coils. The exact value of the Earth’s magnetic field vector is obtained as 35.132 μT with an accuracy of 2 nT by using this method.

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In this article, the optical properties of silver cubic-shape nanostructures (SCNs) were analyzed by employing the discrete dipole approximation (DDA) in aqueous media. The absorption, dispersion and extinction cross-sections of these nanostructures were calculated based on the wavelength change of the incident light in the visible and near infrared region. Moreover, the height change, wavelength and full width at half maximum (FWHM) of extinction cross-section peaks (from plasmon resonances) based on the size of nanoparticles and the environment dielectric constant were surveyed. The results showed that only two peak modes, named dipole peak and quadrupole peak, exist in this spectrum, such as spherical particles.

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The measurement of magnetic field generated by heart activity is crucial for the diagnosis and treatment of heart diseases and failures. Atomic magnetometers are an excellent choice for detecting bio-magnetic fields due to their comparable sensitivity to superconducting quantum interference devices, lower manufacturing costs, and lack of requirement for low temperatures. These magnetometers detect the magnetic field resulting from heart activity by measuring the Zeeman energy splitting and changes in laser light intensity as it passes through an alkali metal vapor cell. To improve the sensitivity of the measurements, this study presents a gradiometer design that utilizes two atomic magnetometers to eliminate environmental magnetic noise. By using a derivative technique, the homogeneous noises in both magnetometer channels are effectively eliminated. The gradiometer is capable of detecting the magnetic field produced by a frog's heart with a sensitivity of 860 fT/√Hz even without magnetic shielding and in the presence of the Earth's field. This gradiometer design can be expanded to include multiple channels for mapping the heart's magnetic field.

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Cataracts, along with presbyopia, is a common age-related vision problem that can indeed make it challenging to achieve clear vision. Multifocal intraocular lenses (IOLs) have emerged as a promising treatment option to improve vision in individuals with cataracts and presbyopia. With their unique design, these lenses provide adequate vision at multiple distances and reduce the dependency on glasses. In this study, we utilized the Liou-Brennan model in Zemax software to simulate a healthy eye and then introduced cataracts with presbyopia to the model. Subsequently, we applied treatment in the form of multifocal intraocular lenses. The improvements in the patient's vision were indicated using spot diagrams and modulation transfer function for three different viewing distances: far, intermediate, and near at three different entrance pupil diameters.