Formation of a quasi-regular interference pattern in a speckle-modulated laser beam reflected from a transparent optically nonuniform layer

2002 ◽  
Vol 47 (4) ◽  
pp. 444-447
Author(s):  
V. P. Ryabukho ◽  
S. S. Ul’yanov ◽  
I. F. Minenkova
Keyword(s):  
Laser Beam ◽  
Interference Pattern ◽  
Nonuniform Layer

Approach to diameter measurement of optical fibres: Forward near-axis far-field interference

2001 ◽  
Vol 215 (4) ◽  
pp. 385-388 ◽  
Author(s):  
J Wu
Keyword(s):  
Laser Beam ◽  
Interference Pattern ◽  
Optical Fibre ◽  
Optical Fibres ◽  
Far Field ◽  
Diameter Measurement ◽  
Non Destructive

A new, simple, fast, accurate and non-destructive method is presented for determining the diameter of optical fibres. The technique is based on the analysis of the forward near-axis far-field interference pattern from an optical fibre illuminated by a laser beam perpendicular to its axis.

Surface quality inspection using a laser beam with a regular dynamic interference pattern

1993 ◽  
Author(s):  
Vladimir P. Ryabukho ◽  
Yuri A. Avetisyan ◽  
Andrey E. Grinevich ◽  
Dmitry A. Zimnyakov ◽  
Boris V. Feduleev ◽  
...  
Keyword(s):  
Laser Beam ◽  
Surface Quality ◽  
Interference Pattern ◽  
Quality Inspection ◽  
Dynamic Interference

Computer analysis of side-band holography in STEM

1991 ◽  
Vol 49 ◽  
pp. 684-685
Author(s):  
M.A. Gribelyuk ◽  
J.M. Cowley
Keyword(s):  
Interference Pattern ◽  
Computer Analysis ◽  
Side Band ◽  
Diffraction Plane ◽  
Illumination System ◽  
Probe Size

Recently the use of a biprism in a STEM instrument has been suggested for recording of a hologram. A biprism is inserted in the illumination system and creates two coherent focussed beams at the specimen level with a probe size d= 5-10Å. If one beam passes through an object and another one passes in vacuum, an interference pattern, i.e. a hologram can be observed in diffraction plane (Fig.1).

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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