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When using the general Sweatt model for ray tracing diffractive optical elements(binary optics, holographic optical elements, etc.), lens designers must choose an index of refraction that is sufficiently high to avoid significant ...
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When using the general Sweatt model for ray tracing diffractive optical elements(binary optics, holographic optical elements, etc.), lens designers must choose an index of refraction that is sufficiently high to avoid significant errors in the ray trace. We derived two new criteria for a sufficiently high index of refraction. To avoid significant errors, the index must satisfy these two new criteria in addition to Sweatt's originally suggested criterion. In almost all cases the new criteria require a higher index than Sweatt's original criterion.... Sweatt model, Ray tracing, Binary optics.
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A descriptive climatology of atmospheric refractivity in the Caribbean Basin, prepared from USAFETAC'S upper-air climatic database. Climatologies are provided by season and by hour. Actual climatologies (in an appendix) are preced...
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A descriptive climatology of atmospheric refractivity in the Caribbean Basin, prepared from USAFETAC'S upper-air climatic database. Climatologies are provided by season and by hour. Actual climatologies (in an appendix) are preceded by a review of refractivity theory, a discussion of the meteorology of anomalous propagation, an explanation of the presentation scheme, and a summary of the climatologies.
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Optical fibers may have applications including fluorosensors which sense the concentration of an analyte. Like communication fibers, these fluorosensors are modeled using a weakly guiding approximation which is only effective when...
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Optical fibers may have applications including fluorosensors which sense the concentration of an analyte. Like communication fibers, these fluorosensors are modeled using a weakly guiding approximation which is only effective when the difference between the respective refractive indices of the fiber core and surrounding cladding are minimal. An optical fiber fluorosensor is provided having a portion of a fiber core which is surrounded by an active cladding which is permeable by the analyte to be sensed and containing substances which emit light waves upon excitation. A remaining portion of the fiber core is surrounded by a guide cladding which guides these light waves to a sensor which detects the intensity of waves, which is a function of the analyte concentration. Contrary to conventional weakly guiding principles, the difference between the respective indices of refraction of the fiber core is surrounded by an active cladding which is thin enough such that its index of refraction is effectively that of the surrounding atmosphere, thereby the atmosphere guides the injective indices of the fiber core and the cladding results in an unexpected increase in the power efficiency of the fiber core.
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This report describles the theory and use of the USAFETAC ray trace model RAYTRA. In this model atmopheric refraction is calculated using geometric optics and a single atmospheric profile. This program allows the user to define an...
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This report describles the theory and use of the USAFETAC ray trace model RAYTRA. In this model atmopheric refraction is calculated using geometric optics and a single atmospheric profile. This program allows the user to define an arbitarary path geometry in the atmosphere anywhere from the Earth's surface to space. In its present form ionospheric effects are ignored. Its use is restricted to frequencies between 30KHz(wavelength 10 km) and 1500 Hz (wavelength 0.2 m). For frequencies between 115 GHz (wavelenth 0.25 cm) and THz (wavelength 20m),the model results should be accepted with caution. The model itself is unique in its flexibility of application and special numerical techniques which enable it to compute types of ray paths which some models cannot handle. Furthermore, the code is structured in a modular, 'top down' fashion to allow for ease in modification and program maintenance. It has the capability to utilize user input atmospheric data or data from the USAFETAC archived weather tapes. Actual ray plotting is not provided. Instead, added information on the net atmospheric refractive effect such as range error is included in ouput along with a summary of the input parameters.
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摘要 :
This report describles the theory and use of the USAFETAC ray trace model RAYTRA. In this model atmopheric refraction is calculated using geometric optics and a single atmospheric profile. This program allows the user to define an...
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This report describles the theory and use of the USAFETAC ray trace model RAYTRA. In this model atmopheric refraction is calculated using geometric optics and a single atmospheric profile. This program allows the user to define an arbitarary path geometry in the atmosphere anywhere from the Earth's surface to space. In its present form ionospheric effects are ignored. Its use is restricted to frequencies between 30KHz(wavelength 10 km) and 1500 Hz (wavelength 0.2 m). For frequencies between 115 GHz (wavelenth 0.25 cm) and THz (wavelength 20m),the model results should be accepted with caution. The model itself is unique in its flexibility of application and special numerical techniques which enable it to compute types of ray paths which some models cannot handle. Furthermore, the code is structured in a modular, 'top down' fashion to allow for ease in modification and program maintenance. It has the capability to utilize user input atmospheric data or data from the USAFETAC archived weather tapes. Actual ray plotting is not provided. Instead, added information on the net atmospheric refractive effect such as range error is included in ouput along with a summary of the input parameters.
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The frequency and distribution of ocular refractive errors among middle-aged and older people were obtained from a nonclinical population holding a variety of blue-collar, clerical, and technical jobs. The 422 individuals ranged i...
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The frequency and distribution of ocular refractive errors among middle-aged and older people were obtained from a nonclinical population holding a variety of blue-collar, clerical, and technical jobs. The 422 individuals ranged in age from 35 to 69 years and were volunteers for several vision research studies conducted primarily at the FAA Civil Aeromedical Institute in Oklahoma City, Oklahoma. Data include frequency of various spherical (hyperopic or myopic) and astigmatic refractive errors, including differences in refractive errors in pairs of eyes. These data, together with information provided by other investigators, will allow a realistic assessment of the distribution of refractive errors and expected visual acuities in the adult population. (Author)
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