1,228,486 research outputs found
Ray transfer matrix for a spiral phase plate
We present a ray transfer matrix for a spiral phase plate. Using this matrix,
we determine the stability of an optical resonator made of two spiral phase
plates, and trace stable ray orbits in the resonator. Our results should be
relevant to laser physics, optical micromanipulation, quantum information and
optomechanics.Comment: 5 pages, 3 figure
The Nature of the Chemical Process. 1. Symmetry Evolution - Revised Information Theory, Similarity Principle and Ugly Symmetry
Three laws of information theory have been proposed. Labeling by introducing
nonsymmetry and formatting by introducing symmetry are defined. The function L
(L=lnw, w is the number of microstates, or the sum of entropy and information,
L=S+I) of the universe is a constant (the first law of information theory). The
entropy S of the universe tends toward a maximum (the second law law of
information theory). For a perfect symmetric static structure, the information
is zero and the static entropy is the maximum (the third law law of information
theory). Based on the Gibbs inequality and the second law of the revised
information theory we have proved the similarity principle (a continuous higher
similarity-higher entropy relation after the rejection of the Gibbs paradox)
and proved the Curie-Rosen symmetry principle (a higher symmetry-higher
stability relation) as a special case of the similarity principle. Some
examples in chemical physics have been given. Spontaneous processes of all
kinds of molecular interaction, phase separation and phase transition,
including symmetry breaking and the densest molecular packing and
crystallization, are all driven by information minimization or symmetry
maximization. The evolution of the universe in general and evolution of life in
particular can be quantitatively considered as a series of symmetry breaking
processes. The two empirical rules - similarity rule and complementarity rule -
have been given a theoretical foundation. All kinds of periodicity in space and
time are symmetries and contribute to the stability. Symmetry is beautiful
because it renders stability. However, symmetry is in principle ugly because it
is associated with information loss.Comment: 29 pages, 14 figure
A Demonstration of LISA Laser Communication
Over the past few years questions have been raised concerning the use of
laser communications links between sciencecraft to transmit phase information
crucial to the reduction of laser frequency noise in the LISA science
measurement. The concern is that applying medium frequency phase modulations to
the laser carrier could compromise the phase stability of the LISA fringe
signal. We have modified the table-top interferometer presented in a previous
article by applying phase modulations to the laser beams in order to evaluate
the effects of such modulations on the LISA science fringe signal. We have
demonstrated that the phase resolution of the science signal is not degraded by
the presence of medium frequency phase modulations.Comment: minor corrections found in the CQG versio
Low dose and fast grating-based x-ray phase-contrast imaging using the integrating-bucket phase modulation technique
X-ray phase-contrast imaging has experienced rapid development over the last
few decades, and in this technology, the phase modulation strategy of
phase-stepping is used most widely to measure the sample's phase signal.
However, because of its discontinuous nature, phase-stepping has the defects of
worse mechanical stability and high exposure dose, which greatly hinder its
wide application in dynamic phase measurement and potential clinical
applications. In this manuscript, we demonstrate preliminary research on the
use of integrating-bucket phase modulation method to retrieve the phase
information in grating-based X-ray phase-contrast imaging. Experimental results
showed that our proposed method can be well employed to extract the
differential phase-contrast image, compared with the current mostly used
phase-stepping strategy, advantage of integrating-bucket phase modulation
technique is that fast measurement and low dose are promising.Comment: 14 pages, 6 figure
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