Bessel beam

About: Bessel beam is a research topic. Over the lifetime, 1946 publications have been published within this topic receiving 42264 citations.

Cell sorting in a static optical potential landscape

Abstract: Microscopic particles with varying optical properties may be induced to move in different ways when placed on a sculpted optical potential due to differences in shape, size or polarisability. The separation of red blood cells (erythrocytes) and white blood cells (lymphocytes) is achieved in a non-invasive manner and in the absence of any microfluidic systems using a 'non-diffracting' circularly symmetric Bessel beam. The Bessel beam, which consists of a series of concentric rings, each of equal power and of 3.2μm thickness with a spacing of 2μm around a central maximum of 5μm diameter (and is akin to a rod of light as its propagation distance is 3mm), is directed upward into a sample chamber containing blood. Fluctuations in Brownian motion cause cells to escape from individual rings of the Bessel beam and travel towards the beam centre, where the intensity of the rings increases. However, these cells must be able to overcome the potential barrier of each ring which gets larger toward the central maximum. Lymphocytes - spherical in shape and 7μm in diameter (therefore overlapping two rings) - are transported, due to the gradient force of the optical field, to the beam centre where they are guided upwards and form a vertical stack, whereas erythrocytes re-align on their sides in the outer rings and are then guided upwards, because once aligned they cannot escape the potential barrier and 'lock-in' to that ring. The optical power required for optimal sorting in this static sorter which requires no fluid flow is investigated.

Ka-Band Quasi-Nondiffraction Beam Generation Through a Broadband Bessel Lens Antenna

Abstract: A broadband Bessel lens antenna with stable quasi-nondiffraction range and considerable broadband characteristics is designed and fabricated. The theoretical basis and operating principles for the broadband near-field quasi-nondiffraction antenna are introduced. Then, design procedure for the structure of the Bessel lens is discussed in detail. Considering the influence of oblique incidence waves, phase shifts of the lens elements with different incident angles are simulated, and interpolation analysis method is applied for the lens modeling to minimize phase error. The proposed lens antenna can be used as a Bessel beam launcher operating at 26–32 GHz. The lens structure is fabricated using 3D-printing and fed by a dual-mode conical horn. Measured results agree well with the simulation.

Exponential non-linear micro-axis conical mirror array device for generating Bessel-beam like lattice array

Abstract: The invention discloses an exponential non-linear micro-axis conical mirror array device for generating a Bessel-beam like lattice array. The device is formed by arraying medium micro-axis conical mirrors with an exponential height change rate. After incident light vertically enters and passes through the bottom surface of the exponential type nonlinear micro-axis conical mirror array device, a Bessel-like light field with a long working distance and stable intensity distribution is formed near the front end of the device; and after arraying, a Bessel-like lattice light sheet array can be formed. To be specific, a Bessel-like light beam generated by a nonlinear micro-axis conical mirror array has the more stable intensity change and large working area by being compared with a Bessel beam near the emergent plane of the device. Biological cells are attached to the surface of the device for development and propagation; and after the device is used for exciting fluorescence information ofthe whole sample, the dynamic development process of living organisms can be captured. The Bessel beam from the non-linear micro-axis conical mirror array has the great potential in aspects of microscopic light sheet illumination and biological fluorescence imaging.

STED super-resolution microscope and adjusting method based on a first-order Bessel beam

Abstract: “A stimulated-emission-depletion (STED) super-resolution microscope includes an excitation light source, a depletion light source , an excitation light expanded beam alignment system, a spiral-shaped phase plate, a Bessel beam generating system, a depletion light focus lens, a beam combination system , an objective lens, a piezoelectric scanning system, a filter, a signal collection system, and a single-photon detector The depletion light can be a first-order Bessel beam The depletion light has anti-scattering and self-healing characteristics, and is capable of keeping the spot shape at a deeper position of a sample, thereby improving image resolution in the deep region of the sample Compared to conventional STED super resolution microscope of deep-layer imaging using an adjustable correction collar, the present invention is simpler in experimental operations and does not require active adjustments Compared to adaptive optical systems, the present experimental apparatus is simpler and less expensive

Multiple Phase Anomalies in Bessel Beam

Abstract: The non-diverging feature of the Bessel-kind beam leads to multiple phase anomalies along the optical axis in contrary to the focused Gaussian beam. Here, we analyze the phase distributions using in a longitudinal-differential phase mode of a high-resolution interference microscope. The measured data are compared with rigorous simulations, showing an excellent agreement.