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Applied Optics

Applied Optics


  • Vol. 38, Iss. 3 — Jan. 20, 1999
  • pp: 441–450

Feasibility of an airborne TV camera as a size spectrometer for cloud droplets in daylight

Howard K. Roscoe, Tom A. Lachlan-Cope, and John Roscoe  »View Author Affiliations

Applied Optics, Vol. 38, Issue 3, pp. 441-450 (1999)

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Photographs of clouds taken with a camera with a large aperture ratio must have a short depth of focus to resolve small droplets. Hence the sampling volume is small, which limits the number of droplets and gives rise to a large statistical error on the number counted. However, useful signals can be obtained with a small aperture ratio, which allows for a sample volume large enough for counting cloud droplets at aircraft speeds with useful spatial resolution. The signal is sufficient to discriminate against noise from a sunlit cloud as background, provided the bandwidth of the light source and camera are restricted, and against readout noise. Hence, in principle, an instrument to sample the size distribution of cloud droplets from aircraft in daylight can be constructed from a simple TV camera and an array of laser diodes, without any components or screens external to the aircraft window.

© 1999 Optical Society of America

OCIS Codes
(010.3920) Atmospheric and oceanic optics : Meteorology
(120.3930) Instrumentation, measurement, and metrology : Metrological instrumentation
(120.4640) Instrumentation, measurement, and metrology : Optical instruments

Original Manuscript: March 30, 1998
Revised Manuscript: August 14, 1998
Published: January 20, 1999

Howard K. Roscoe, Tom A. Lachlan-Cope, and John Roscoe, "Feasibility of an airborne TV camera as a size spectrometer for cloud droplets in daylight," Appl. Opt. 38, 441-450 (1999)

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