Optical vortex closes itself in a laser beam after passing through a Gaussian lens

1999 ◽  
Author(s):  
Lyubov V. Kreminskaya ◽  
R. Amezquita ◽  
Vladimir B. Markov ◽  
Freddy A. Monroy ◽  
G. Arenas ◽  
...  
Keyword(s):  
Laser Beam ◽  
Optical Vortex

scholarly journals Laser Beam Positioning by Using a Broken-Down Optical Vortex Marker

2021 ◽  
Vol 11 (16) ◽  
pp. 7677
Author(s):  
Ewa Frączek ◽  
Wojciech Frączek ◽  
Agnieszka Popiołek-Masajada
Keyword(s):  
Laser Beam ◽  
Open Space ◽  
Optical Vortex ◽  
Center Of Gravity ◽  
High Order ◽  
Optical Vortices

We propose the use of high-order optical vortices as markers in the positioning of a laser beam. The broken optical vortices are arranged in constellations. The center of gravity of these constellations makes it possible to position the beam carrying information encoded in the optical vortices. This paper describes three positioning methods using both intensity and phase maps. The methods described were tested in experiments performed in a laboratory and an open space.

scholarly journals Gaussian laser beam transformation into an optical vortex beam by helical lens

2015 ◽  
Vol 63 (2) ◽  
pp. 164-176 ◽  
Author(s):  
Ljiljana Janicijevic ◽  
Suzana Topuzoski
Keyword(s):  
Laser Beam ◽  
Optical Vortex ◽  
Vortex Beam ◽  
Gaussian Laser Beam

scholarly journals Off-Axis Vortex Beam Propagation through Classical Optical System in Terms of Kummer Confluent Hypergeometric Function

Photonics ◽  
2020 ◽  
Vol 7 (3) ◽  
pp. 60
Author(s):  
Ireneusz Augustyniak ◽  
Weronika Lamperska ◽  
Jan Masajada ◽  
Łukasz Płociniczak ◽  
Agnieszka Popiołek-Masajada
Keyword(s):  
Laser Beam ◽  
Gaussian Beam ◽  
Image Plane ◽  
Optical Vortex ◽  
Confluent Hypergeometric Function ◽  
Higher Order ◽  
Phase Plate ◽  
Axis Position ◽  
Spiral Phase Plate ◽  
Spiral Phase

The analytical solution for the propagation of the laser beam with optical vortex through the system of lenses is presented. The optical vortex is introduced into the laser beam (described as Gaussian beam) by spiral phase plate. The solution is general as it holds for the optical vortex of any integer topological charge, the off-axis position of the spiral phase plate and any number of lenses. Some intriguing conclusions are discussed. The higher order vortices are unstable and split under small phase or amplitude disturbance. Nevertheless, we have shown that off-axis higher order vortices are stable during the propagation through the set of lenses described in paraxial approximation, which is untypical behavior. The vortex trajectory registered at image plane due to spiral phase plate shift behaves like a rigid body. We have introduced a new factor which in our beam plays the same role as Gouy phase in pure Gaussian beam.

Two-photon excitation microscopy in cellular biophysics

1995 ◽  
Vol 53 ◽  
pp. 62-63
Author(s):  
David W. Piston ◽  
Brian D. Bennett ◽  
Robert G. Summers
Keyword(s):  
Confocal Microscopy ◽  
Laser Beam ◽  
Duty Cycle ◽  
Excited Electronic State ◽  
Input Power ◽  
Two Photon ◽  
Simultaneous Absorption ◽  
Photon Excitation ◽  
Very High ◽  
Two Photon Excitation

Two-photon excitation microscopy (TPEM) provides attractive advantages over confocal microscopy for three-dimensionally resolved fluorescence imaging and photochemistry. Two-photon excitation arises from the simultaneous absorption of two photons in a single quantitized event whose probability is proportional to the square of the instantaneous intensity. For example, two red photons can cause the transition to an excited electronic state normally reached by absorption in the ultraviolet. In practice, two-photon excitation is made possible by the very high local instantaneous intensity provided by a combination of diffraction-limited focusing of a single laser beam in the microscope and the temporal concentration of 100 femtosecond pulses generated by a mode-locked laser. Resultant peak excitation intensities are 106 times greater than the CW intensities used in confocal microscopy, but the pulse duty cycle of 10-5 maintains the average input power on the order of 10 mW, only slightly greater than the power normally used in confocal microscopy.

The atomic-force microscope and its future in biology

1993 ◽  
Vol 51 ◽  
pp. 704-705
Author(s):  
Jean-Paul Revel
Keyword(s):  
Silicon Nitride ◽  
Laser Beam ◽  
Atomic Force Microscope ◽  
Scanning Tunneling Microscope ◽  
Point Of View ◽  
Scanning Tunneling ◽  
Close Relative ◽  
Tunneling Microscope ◽  
Atomic Force ◽  
Sharp Point

The last few years have been marked by a series of remarkable developments in microscopy. Perhaps the most amazing of these is the growth of microscopies which use devices where the place of the lens has been taken by probes, which record information about the sample and display it in a spatial from the point of view of the context. From the point of view of the biologist one of the most promising of these microscopies without lenses is the scanned force microscope, aka atomic force microscope.This instrument was invented by Binnig, Quate and Gerber and is a close relative of the scanning tunneling microscope. Today's AFMs consist of a cantilever which bears a sharp point at its end. Often this is a silicon nitride pyramid, but there are many variations, the object of which is to make the tip sharper. A laser beam is directed at the back of the cantilever and is reflected into a split, or quadrant photodiode.

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