Applied optics
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Zoom lenses with a fixed distance between focal points are analyzed. Formulas are derived for the primary design of basic parameters of a four-component zoom lens. It is also demonstrated that a three-component zoom lens can be analyzed using derived formulas. Zoom lenses with such a design can be used in a 4-f system with variable magnification or as a part of a double side telecentric lenses with variable magnification.
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The scientific productivity of laser guide star adaptive optics systems strongly depends on the sky coverage, which describes the probability of finding natural guide stars for the tip/tilt wavefront sensor(s) to achieve a certain performance. Knowledge of the sky coverage is also important for astronomers planning their observations. In this paper, we present an efficient method to compute the sky coverage for the laser guide star multiconjugate adaptive optics system, the Narrow Field Infrared Adaptive Optics System (NFIRAOS), being designed for the Thirty Meter Telescope project. We show that NFIRAOS can achieve more than 70% sky coverage over most of the accessible sky with the requirement of 191 nm total rms wavefront.
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This is a feature issue devoted to optical phenomena that can be observed in nature, primarily with the naked eye. Many of the papers published in this feature issue are based on presentations given at the "Light & Color in Nature" conference held in June 2010 at St. Mary's College of Maryland.
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We derive an analytic formula using the Mueller matrix formalism that parameterizes the nonidealities of a half-wave plate (HWP) made from dielectric antireflection-coated birefringent slabs. This model accounts for frequency-dependent effects at normal incidence, including effects driven by the reflections at dielectric boundaries. ⋯ We discuss the coupling of a HWP to different source spectra, and the potential impact of that effect on foreground removal for the SPIDER cosmic microwave background experiment. We also describe a way to use this model in a mapmaking algorithm that fully corrects for HWP nonidealities.
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Minimally invasive functional near infrared spectroscopy (fNIRs) technology was utilized to assess the effects of mannitol and hypertonic saline (HS) in treating traumatic brain edema (TBE). Rats with TBE models were given mannitol or HS in different dosages for different groups. The reduced scattering coefficient (μ(s)') of the local cortex of rats was simultaneously monitored and recorded in vivo and real time by the minimally invasive fNIRs system. ⋯ Results implied that μ(s)' of the local cortex in rats is a good indicator for assessing effects of treatment of TBE. By recording changes in the value of μ(s)', the following conclusions were obtained: HS is more effective than mannitol in reducing cerebral edema. The effect of dehydration of HS is only related to osmotic gradient and has no correlation with concentration.