Showing 4 results for Khalkhali
Ms. Samaneh Birzhandi, Ms. Malihe Ranjbaran, Dr. Seyed Mohammad Hosein Khalkhali, Dr. Seyedeh Mehri Hamidi, Prof. Mohammad Mehdi Tehranchi,
Volume 7, Issue 2 (International Journal of Optics and Photonics (IJOP) Vol 7, No 2, Summer-Fall 2013)
Abstract
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.
Seyed Mohammad Hosein Khalkhali, Dr. Mohammad Mehdi Tehranchi, Dr. Seyedeh Mehri Hamidi,
Volume 10, Issue 1 (International Journal of Optics and Photonics (IJOP) Vol 10, No 1, Winter-Spring 2016)
Abstract
We examine the photo-assisted polarization loop in a BiFeO3 thin film under UV light illumination. BiFeO3 thin film prepared by pulsed laser deposition method onto the BaTiO3 thin film and the polarization behavior has been measured under poling voltage. Our results show the engineered polarization due to controllable schottky barrier under inverse poling voltage. This control on schottky barrier height and then polarization of thin film can be opened the new insight in the ferroelectric devices.
Amin Zamani, Maliheh Ranjbaran, Mohammad Mehdi Tehranchi, Seyed Mohammad Hossein Khalkhali, Seyedeh Mehri Hamidi,
Volume 14, Issue 1 (Winter-Spring 2020)
Abstract
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.
Maliheh Ranjbaran, Reza Sedeyan, Amin Zamani, Mohammad Mehdi Tehranchi, Seyed Mohammad Hosein Khalkhali, Seyedeh Mehri Hamidi,
Volume 17, Issue 2 (Summer-Fall 2023)
Abstract
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.
