The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 01, 1985
Filed:
Oct. 19, 1981
Norman E Pedersen, Wilmington, MA (US);
Panametrics, Inc., Waltham, MA (US);
Abstract
A photometric detection method and apparatus employ a variable beam modulation device, such as a planar oscillating disk whose reflectance and transmittance with respect an incident beam of electromagnetic radiation vary with disk angular position, to form, from an incident beam of radiation, two amplitude modulated correlated component beams. Preferably the amplitudes of the component beams vary sinusoidally, 180.degree. out of phase. In one illustrative embodiment, one of the component beams passes through a sample fluid, which absorbs a portion of the radiation at a wavelength characteristic of a selected component. The second component beam passes through a reference path and provides a reference signal relative to which changes in the sample fluid are measured. A feedback mechanism is provided to automatically adjust for variations which can occur while the apparatus is operating. The component beams are combined and are directed onto a detector which produces an output proportional to the intensity of the combined beam. By properly selecting the parameters of the system, the AC component of the combined signal, if any, provides a sensitive measure of the presence generally and if calibrated the relative density, of the selected sample fluid.