Hss, Inc.

Marion P Shuler, Jr

Willem Brouwer

Harold S Stewart

An instrument for responding to backscattered or backreflected radiation from a path through a medium in which a beam of electromagnetic radiation is transmitted along the path, and a receiver system is arranged to receive backscattered radiation returning along the path substantially coaxially with the beam, the receiver system including detection means for the backscattered radiation and equalizing means for producing a substantially equal response regardless of the point of backscatter along the path. The equalizing means comprises a passive radiation transmission structure interposed in the path of return prior to the detection means, the passive structure having a substantially constant acceptance solid-angle for the returning radiation from points over the range of the path whereby radiation reaching the detection means from various points along the path does not vary in intensity due to the different distances of the points from the detection means. The passive structure is shown in the form of a full circular hole and a doughnut-shaped hole in an opaque plate, with the return beam focused to fill the hole out to a range of interest. Other passive structures are illustrated by a Fabry-Perot filter combined with a telescope and a bundle of opaque walled tubes. Transmissivity of a medium out to a point r is determined by the ratio of the integral of power from r to an outer limit range L in which the passive structure is still functional, as numerator, over the integral from the instrument to limit L as denominator. The coaxial array is shown achieved by use of a beam splitter, the beam from the source proceeding via the beam-splitter outwardly, the beamsplitter sized so that all return signal reaching the detector is treated equally by the beam-splitter. A multiple beam-splitter is shown by which multiple beams from a single source are produced, with the respective returns concentrated on a single detector.

Growing community of inventors

Boston, MA, United States of America

Marion P Shuler, Jr