Controllable interferometer

US4999013A · kind A · utility

Assignee

• Hartmann & Braun Aktiengesellschaft · DE

Inventors

• Michael Zoechbauer · Oberursel, DE
• Walter Fabinski · Kriftel, DE

Key dates

• Filing date: Apr 14, 1989
• Grant date: Mar 12, 1991
• Expiry date: Apr 14, 2009

Classification

• Technology area (CPC G): Physics
• CPC primary: G01N2201/067
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

Interferometric equipment for detecting a substance having a structure preferably a periodic or quasiperiodic absorption spectrum; the equipment includes a source of radiation, a path for that radiation that includes a sample cell with the substance to be detected, an interference filter and a detector, and is improved in that the interference filter is constructed as an electrically tunable filter, including a plate or cell element with semitransparent reflective boundaries serving as electrodes; an electrical voltage is applied to said electrodes such that the transmission characteristics of the filter is varied and the amplitude of the voltage as applied to these electrodes is an indication of that variation; and the thickness of the plate or cell is selected to meet one of the following criteria (i) a distance between the interference lines produced equals a distance of absorption lines within a periodic absorption spectrum of said substance; (ii) the equipment causes a line to be separated from the radiation having a bandwidth which is small as compared with a spacing between two absorption lines of the substance to be found (iii) the equipment causes a line to be separated fr…