High pass optical filter

Abstract

A microstructure device having a array of deep lamellar structures resembling parallel plates has sharp high pass cut-off behavior associated with incident TE polarized radiation. When two such microstructures are disposed in an orthogonal orientation, they act like a 2-D array of rectangular waveguides with the cut-off behavior determined by the separation of the respective parallel plates. Another embodiment of the present invention employs a linear drive to articulate the array of coupled parallel plates to tune the filter to the operative incident radiation relatively independent of the angle of incidence. The microstructure finds application placed proximate the focal plane of an array of radiation sensitive material so that very high resolution multispectral images may be generated. When the array is articulated by a linear actuator, a preselected cut-off frequency may be tuned so that multispectral imaging occurs independent of the imaging technology employed, with applications for remote sensing of chemical agents, satellite surveys of agricultural resources, meteorological conditions, or environmental quality. When disposed in a gas absorption cell, opposing an IR source and proximate an IR detector the tunable filter can be used for gas analysis.