Far Infrared Physics

We demonstrate terahertz (THz) frequency imaging through use of a single quantum cascade laser (QCL) device for both generation and sensing of THz radiation. Detection is achieved by utilising the effect of self-mixing in the QCL, and specifically by monitoring perturbations to the voltage across the QCL induced by light reflected from an external object back into the laser cavity. Self-mixing imaging offers high sensitivity, a potentially fast response, and a simple, compact optical design, and we show that it can be used to obtain high-resolution reflection images of exemplar structures. © 2010 Optical Society of America

This communication reports the results of calculation of cold shield shading effects in a linear detector array for an elliptical aperture geometry with varying major-to-minor axis ratio. The results suggest that an elliptical aperture geometry is a better design than a rectangular aperture.

Many of the standard considerations for the modeling of infrared target acquisition of stationary targets in a single field of view must be altered when considering target acquisition in the actual battlefield. Sensors are scanning, targets are moving, and a complex background is present. A metric is needed to determine acquisition efficacy which is considerably more complex than the standard analysis. In this paper, we will discuss several of the issues involved. The use of a single detectable frequency to model the target acquisition process is not sufficient. We consider the replacement of this model with one consisting of an integral of the target spectrum, taking into account the spatial frequency modulation transfer function dependence of the imaging system. Psychophysical experiments are presented; the results of this experiment verify our approach that the maximum spatial frequency criterion is not sufficient to determine the target acquisition probability.