EVALUATION OF LENSES FOR USE IN ALL-SKY PHOTOMETERS
LOS ALAMOS NATIONAL LAB NM
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For maximum performance, an all-sky photometer should have a large light-collection area and a narrow spectral passband however, for a given size of photometer, these parameters cannot be optimized simultaneously. Three compromise lens designs are evaluated here LASL-2, a 0.43-in.-focal-length, f 2.8, 160 degrees-field-of-view lens for use with a 2-in.-diam. photomultiplier tube and, for use with 5-in.-diam. photomultiplier tubes, LASL-5 a 2.1-in.- focal-length, f4.0, 120 degrees-field-of-view lens and EGG-5, a lens with a nominal 120 degrees field of view, which can be used with or without an ND2 filter covering the central part of the first element. The effective on-axis entrance-pupil areas and the relative response curves as a function of wavelength and incidence angle were measured, and the results are reported. Therefore, LASL-5 photometers are recommended for systems like the Los Alamos Air Fluorescence Detection System, which for optimum performance require wide- field photometers with narrow, well defined, spectral passbands.
- Optical Detection and Detectors