Boresight error in the conical scan method of autoboresighting a laser beam on a specular point-target.

While autoboresighting a laser beam on a specular point-target, the automatic tracking is set to the highest degree of precision by accurately estimating the beam position on the target. A serious degradation in the prediction of miss-distance in such autoboresightings (for example, by conical scan tracking) would arise if boresight error is encountered due to various sources of statistical fluctuations in the system. Typically, beam-intensity fluctuations (resulting from beam propagation through a turbulent atmospheric medium), imperfections in the trans-receive optical scanners, random variations in the nutation-drive signal, etc., are the main sources of boresight errors in the tracker system. Presently, for a conical scan tracker which uses a laser beam on a specular point-target, expressions for the mean and variance of boresight error are derived by considering various possible random parameters in the system concerned.

Noninvasive beam-wave spectrometric instrumentation for measuring dielectric constant at microwave frequencies.

From the characteristics of the reflected Gaussian beam-wave for oblique incidence, measured with a spectrometer arrangement, the dielectric properties of a selectively exposed region of a dielectric slab are ascertained at microwave frequencies. For this purpose, a focused (Gaussian) microwave beam is launched from a suitable applicator to irradiate obliquely a selected protion of the test dielectric and the complex reflection coefficient is measured and analyzed. Further, the magnitude of the angular shift involved in the direction of the reflected beam is also used to calculate the dielectric constant. Application of this method to noninvasive measurements of dielectric properties of selective partial-bodies of commercial dielectrics and biological substances is discussed.

Noninvasive beam-wave reflectometric instrumentation for measuring complex permittivity of dielectric materials at microwave frequencies.

A noncontact and nondestructive method of measuring at microwave frequencies the complex permittivity of a selected region in a dielectric slab is described. For this purpose the test dielectric sample is irradiated with a focused (gaussian) microwave beam by means of a suitable applicator. From the characteristics of the reflected beam wave measured at a reflectometric bridge arrangement, the complex permittivity of the exposed region is determined. Some theoretical and experimental results analysing the test conditions are presented. Application of this method to biological in vivo (or in vitro) measurements of dielectric properties of bones and tissues, with selective partial-body microwave irradiation, is discussed.