Laser Polar Nephelometer for Airborne Measurements of Aerosol Optical Properties

G. W. Grams; A. J. Dascher; C. M. Wyman

doi:10.1117/12.7971772

1 February 1975 Laser Polar Nephelometer for Airborne Measurements of Aerosol Optical Properties

G. W. Grams, A. J. Dascher, C. M. Wyman

Author Affiliations +

Optical Engineering, Vol. 14, Issue 1, 140185 (February 1975). https://doi.org/10.1117/12.7971772

Abstract

A nephelometer has been developed for airborne measurement of polar scattering diagrams of atmospheric aerosols. The nephelometer light source is a modulated heliumneon laser; a digital synchronous photon counter is utilized to measure scattered-light intensity. The system has been designed for airborne measurements on a pressurized aircraft using outside air ducted through a 5-cm diameter airflow tube; the sample volume is that which is common to the intersection of the collimated source beam and the detector field of view within the airflow tube. The instrument has been flown on the NASA Convair 990 airborne laboratory to obtain data on the complex index of refraction of atmospheric aerosols. Particle sizing devices were operated simultaneously to determine the aerosol size-number distribution. Calculated values of the angular variation of scattered-light intensity were obtained by applying Mie scattering theory to the observed size distribution function and assuming different values of the complex index of refraction of the particles. The calculated values were then compared with data on the actual variation of the scattered-light intensity obtained with the polar nephelometer. The most probable value of the complex refractive index was taken to be that which provided the best fit between the experimental light-scattering data and the polar scattering diagrams calculated from the observed size distribution function.

Citation Download Citation

G. W. Grams, A. J. Dascher, and C. M. Wyman "Laser Polar Nephelometer for Airborne Measurements of Aerosol Optical Properties," Optical Engineering 14(1), 140185 (1 February 1975). https://doi.org/10.1117/12.7971772

Published: 1 February 1975

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available