# Accession Number:

## AD0767310

# Title:

## Electromagnetic Beam Fields,

# Descriptive Note:

# Corporate Author:

## NAVAL RESEARCH LAB WASHINGTON D C

# Personal Author(s):

# Report Date:

## 1973-08-31

# Pagination or Media Count:

## 30.0

# Abstract:

An electromagnetic beam is defined using mathematical properties of the associated angular spectrum of plane waves. It is found that the usual paraxial theory for the Hermite Gaussian or Laguerre Gaussian beams, produced by some lasers, can be replaced by a more general theory which is precise according to Maxwells equations. In this theory the beams exhibit an amplitude distribution over any plane normal to the direction of propagation which can be described using prolate spheroidal wave functions. As the degree of collimation is increased, these beams asymptotically take on the familiar Gaussian amplitude cross section. However, as the divergence from focus is increased, these beams asymptotically approach modified dipole fields. It is found that two, mutually exclusive, classes of beam fields exist. For each beam in one class there is always a complementary beam in the other class. As the degree of collimation is increased, complementary beams become almost identical. Complementary beams contain electromagnetic components which are related to one another in the same manner as between the fields of similar electric and magnetic multipoles. Author

# Descriptors:

# Subject Categories:

- Optics