Bessel beam

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

Ultrahigh resolution optical coherence elastography using a Bessel beam for extended depth of field

Abstract: Visualizing stiffness within the local tissue environment at the cellular and sub-cellular level promises to provide insight into the genesis and progression of disease. In this paper, we propose ultrahigh-resolution optical coherence elastography, and demonstrate three-dimensional imaging of local axial strain of tissues undergoing compressive loading. The technique employs a dual-arm extended focus optical coherence microscope to measure tissue displacement under compression. The system uses a broad bandwidth supercontinuum source for ultrahigh axial resolution, Bessel beam illumination and Gaussian beam detection, maintaining sub-2 μm transverse resolution over nearly 100 μm depth of field, and spectral-domain detection allowing high displacement sensitivity. The system produces strain elastograms with a record resolution (x,y,z) of 2×2×15 μm. We benchmark the advances in terms of resolution and strain sensitivity by imaging a suitable inclusion phantom. We also demonstrate this performance on freshly excised mouse aorta and reveal the mechanical heterogeneity of vascular smooth muscle cells and elastin sheets, otherwise unresolved in a typical, lower resolution optical coherence elastography system.

Method and apparatus of processing brittle material with laser pin beam and optical system for the same

Abstract: The present invention relates to an apparatus for processing brittle materials by using laser pin beams. According to the present invention, the laser processing apparatus includes: a first optical system converting an ultra-short pulse laser beam transmitted from a laser generation unit while having Gaussian energy distribution to a Bessel beam distributing energy on multiple concentric circles around an optical shaft and the optical shaft with reference to a cross-section perpendicular to the progressing direction of the ultra-short pulse laser beam; a second optical system concentrating the Bessel beam or beams scattered from the Bessel beam to generate a pin beam concentrating energy on spots on the optical shaft with reference to the cross-section perpendicular to the progressing direction; and a third optical system concentrating the pin beam or beams scattered from the pin beam onto the inside of the brittle material. The present invention enables ultra-high concentration of the ultra-short pulse laser beam around the optical shaft to generate the pin beam with little variation in the beam diameter in the beam progressing direction and process the brittle material with the laser pin beam to cut a mirror surface without any melting, breaking, or cracking.

The role of propagation invariant light modes in single and multi-photon imaging

Abstract: Propagation invariant, ‘non-diffracting’ beams have found numerous applications in areas as diverse as filamentation, trapping, and photoporation. However, the prominent transverse structure of Bessel beams prevents localized illumination, thus hampering its use for high resolution imaging with an extended focus. We investigate the relationship between axial resolution, contrast, and propagation invariance for single and two-photon fluorescence light sheet microscopy.

Elongated focus optoacoustic microscopy with matched Bessel beam illumination and ultra-broadband axicon detection

Abstract: Current optoacoustic microscopy configurations often have narrow focal ranges that limit their use for fast volumetric imaging applications. Here, the focal range of optoacoustic microscopes is extended by matching the elongated optical illumination profile of a Bessel beam with the pencil beam acoustic sensitivity profile of a broadband axicon detector. An inverted optoacoustic microscope was developed with interchangeable optical illumination and acoustic detection units to assess the imaging depths and resolutions retained with several combinations of illumination and detection profiles. Matching Bessel illumination with axicon detection extends the depth-of-focus 17-fold over traditional configurations. Imaging a tilted mouse ear with the matched Bessel-axicon configuration revealed vasculature over an imaging depth exceeding 4.2 mm with optical resolution, while affording a 6-fold increase in imaging volume over the same scanning duration compared to configurations employing standard Gaussian illumination, demonstrating this approach's promise for increasing applications for optoacoustic microscopy in preclinical research.