The complex dispersion relation of capillary waves on water has been m
easure in a wavelength regime (lambda approximately 1-2 cm) of interes
t to radar imaging. Two noninvasive sensors: a capacitive wave height
antenna and a one-dimensional scanning laser slope gauge, are used to
study the alteration of surface tension and surface elastic modulus in
the presence of monomolecular surface films. On a static water surfac
e, these sensors are compared to accepted standard techniques. The sur
face tension results are compared to a Wilhelmy plate while the elasti
c modulus results are compared to equations of state obtained by Langm
uir trough techniques. The sensors are then employed to measure the re
sponse of surface film properties to surface areal strains for film pr
essures and strain rates, which are comparable to natural films in the
presence of ship-generated surface currents. In the experiments repor
ted in this paper, only insoluble surfactants are used. The monolayer
surface films considered in this study are found to exhibit higher cla
stic modulus (approximately 8 mN/m) at small surface pressure (pi less
-than-or-equal-to 1 mN/m) than expected from previous work reported in
the literature. The response of these films to surface strain is cons
istent with our static surface measurements. The modulation of film pa
rameters is found to be in phase with internal wave-generated oscillat
ory surface strain with periods on the order of 9 s. This implies that
the film conforms to the strained water surface with negligible slipp
age in this regime. These measurements demonstrate the capability of t
his approach to continuously monitor surface films in situ with detect
or system response time of the order of 1 s. The technique is suited t
o large or deep containers and is applicable to sheltered ocean enviro
nments.