Direct Measurement of Coherence Lengths and Analysis of Spectra of Light Sources by Using a Michelson Interferometer

2013 ◽  
Vol 63 (6) ◽  
pp. 638-642
Author(s):  
Choong Hwan LEE ◽  
Hee Joo CHOI ◽  
Byoung Joo KIM ◽  
Myoungsik CHA*
Keyword(s):  
Direct Measurement ◽  
Michelson Interferometer ◽  
Light Sources ◽  
Coherence Lengths

Temporal coherence properties of laser modules used in headlamps determined by a Michelson interferometer

2020 ◽  
Vol 9 (6) ◽  
pp. 375-383
Author(s):  
Valerie Popp ◽  
Philipp Ansorg ◽  
Burkhard Fleck ◽  
Cornelius Neumann
Keyword(s):  
White Light ◽  
Michelson Interferometer ◽  
Temporal Coherence ◽  
Experimental Setup ◽  
Light Sources ◽  
Coherence Lengths

AbstractIn this work, an investigation of the temporal coherence properties of radiation which is emitted by laser modules integrated in headlamps is presented. The motivation for these measurements was difficulties concerning the field of classification for laser products which function as conventional headlamps. Based on an experimental setup including a Michelson interferometer, a goniophotometer and a spectrometer, coherence lengths of 92.5 and 147.0 μm are obtained for two different laser modules. The results show that the temporal coherence of the examined radiation is appreciably higher than the temporal coherence of conventionally produced white light. Therefore, at this point in time, laser modules used in headlamps cannot be considered as customary white light sources.

Polariton Devices

2017 ◽  
Author(s):  
Alexey V. Kavokin ◽  
Jeremy J. Baumberg ◽  
Guillaume Malpuech ◽  
Fabrice P. Laussy
Keyword(s):  
Semiconductor Devices ◽  
Logic Gates ◽  
Light Sources ◽  
Coherent Light ◽  
Final State ◽  
Spintronic Devices ◽  
Exciton Polaritons ◽  
Terahertz Lasers ◽  
Coherence Lengths ◽  
Stimulation Of

Polariton devices offer multiple advantages compared to conventional semiconductor devices. The bosonic nature of exciton polaritons offers opportunity of realisation of polariton lasers: coherent light sources based on bosonic condensates of polaritons. The final state stimulation of any transition feeding a polariton condensate has been used in many proposals such as for terahertz lasers based on polariton lasers. Furthermore, large coherence lengths of exciton-polaritons in microcavities open the way to realisation of polariton transport devices including transistors and logic gates. Being bosonic spin carriers, exciton-polaritons may be used in spintronic devices and polarisation switches. This chapter offers an overview on the existing proposals for polariton devices.

scholarly journals Direct measurement of group dispersion of optical components using white-light spectral interferometry

2007 ◽  
Vol 15 (3) ◽  
Author(s):  
R. Chlebus ◽  
P. Hlubina ◽  
D. Ciprian
Keyword(s):  
Direct Measurement ◽  
White Light ◽  
Path Length ◽  
Michelson Interferometer ◽  
Optical Components ◽  
Interferometric Technique ◽  
Wide Wavelength Range ◽  
Path Length Difference ◽  
Group Refractive Index ◽  
Resolution Spectrometer

AbstractWe present a simple white-light spectral interferometric technique employing a low-resolution spectrometer for a direct measurement of the group dispersion of optical components over a wide wavelength range. The technique utilizes an unbalanced Mach-Zehnder interferometer with a component under test inserted in one arm and the other arm with adjustable path length. We record a series of spectral interferograms to measure the equalization wavelength as a function of the path length difference. We measure the absolute group refractive index as a function of wavelength for a quartz crystal of known thickness and the relative one for optical fiber. In the latter case we use a microscope objective in front and a lens behind the fiber and subtract their group dispersion, which is measured by a technique of tandem interferometry including also a Michelson interferometer.

Spatially Resolved Photoelectron Spectroscopy: Recent Progress and Future Plans

1990 ◽  
Vol 48 (2) ◽  
pp. 388-389
Author(s):  
A. M. Bradshaw
Keyword(s):  
Photoelectron Spectroscopy ◽  
Chemical Reactivity ◽  
Target Material ◽  
Orbital Energy ◽  
Light Sources ◽  
Analytical Technique ◽  
Hartree Fock ◽  
Spatially Resolved ◽  
Koopmans Theorem ◽  
Surface Analytical Technique

X-ray photoelectron spectroscopy (XPS or ESCA) was not developed by Siegbahn and co-workers as a surface analytical technique, but rather as a general probe of electronic structure and chemical reactivity. The method is based on the phenomenon of photoionisation: The absorption of monochromatic radiation in the target material (free atoms, molecules, solids or liquids) causes electrons to be injected into the vacuum continuum. Pseudo-monochromatic laboratory light sources (e.g. AlKα) have mostly been used hitherto for this excitation; in recent years synchrotron radiation has become increasingly important. A kinetic energy analysis of the so-called photoelectrons gives rise to a spectrum which consists of a series of lines corresponding to each discrete core and valence level of the system. The measured binding energy, EB, given by EB = hv−EK, where EK is the kineticenergy relative to the vacuum level, may be equated with the orbital energy derived from a Hartree-Fock SCF calculation of the system under consideration (Koopmans theorem).

Tandem scanning confocal light microscopy as compared with x-ray diffraction for characterizing the behavior of clays in fluid-saturated petroleum reservoir rock

1989 ◽  
Vol 47 ◽  
pp. 148-149
Author(s):  
C.J. Stuart ◽  
B.E. Viani ◽  
J. Walker ◽  
T.H. Levesque
Keyword(s):  
Light Microscopy ◽  
Image Plane ◽  
Reservoir Rock ◽  
Depth Of Field ◽  
Objective Lens ◽  
Scanning System ◽  
Light Sources ◽  
Petroleum Reservoir ◽  
Image Recording ◽  
Scan Speed

Many techniques of imaging used to characterize petroleum reservoir rocks are applied to dehydrated specimens. In order to directly study behavior of fines in reservoir rock at conditions similar to those found in-situ these materials need to be characterized in a fluid saturated state.Standard light microscopy can be used on wet specimens but depth of field and focus cannot be obtained; by using the Tandem Scanning Confocal Microscope (TSM) images can be produced from thin focused layers with high contrast and resolution. Optical sectioning and extended focus images are then produced with the microscope. The TSM uses reflected light, bulk specimens, and wet samples as opposed to thin section analysis used in standard light microscopy. The TSM also has additional advantages: the high scan speed, the ability to use a variety of light sources to produce real color images, and the simple, small size scanning system. The TSM has frame rates in excess of normal TV rates with many more lines of resolution. This is accomplished by incorporating a method of parallel image scanning and detection. The parallel scanning in the TSM is accomplished by means of multiple apertures in a disk which is positioned in the intermediate image plane of the objective lens. Thousands of apertures are distributed in an annulus, so that as the disk is spun, the specimen is illuminated simultaneously by a large number of scanning beams with uniform illumination. The high frame speeds greatly simplify the task of image recording since any of the normally used devices such as photographic cameras, normal or low light TV cameras, VCR or optical disks can be used without modification. Any frame store device compatible with a standard TV camera may be used to digitize TSM images.

Direct Measurement of the Listening of Hearing-Impaired Children

1970 ◽  
Vol 13 (1) ◽  
pp. 65-73 ◽  
Author(s):  
Mary Mira
Keyword(s):  
Direct Measurement ◽  
Continuous Measurement ◽  
Hearing Impaired ◽  
Reinforcement System ◽  
School Aged Children ◽  
Conjugate Reinforcement ◽  
Impaired Children ◽  
Hearing Impaired Children

Listening, a significant dimension of the behavior of hearing-impaired children, may be measured directly by recording childrens' responses to obtain audio narrations programmed via a conjugate reinforcement system. Twelve hearing-impaired, school-aged children responded in varying ways to the opportunity to listen. Direct and continuous measurement of listening has relevance for evaluation of remediation methods and for discovery of variables potentially related to listening.

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