High Photometric Accuracy in an Optical Null, Double-Beam Infrared Spectrophotometer

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To date, optical null infrared spectrophotometers have been capable of double-beam photometric accuracies of no better than 0.5% to 1.0%. When operated in the double-beam mode, optical null instruments measure the transmittance of a sample by optically attenuating the reference beam until its energy equals that of the sample beam. This operation is usually performed automatically by a servosystem which constantly repositions an optical attenuator (comb) in the reference beam to obtain a null balance condition. A pen servosystem then follows the comb movement from a linear potentiometer geared to the comb.

Document Type: Short Communication

DOI: http://dx.doi.org/10.1366/000370268774384614

Affiliations: 1: Beckman Instruments, Inc., Fullerton, California 92634 2: Beckman Instruments, Inc., Fullerton, California 92634; present address: Honeywell Radiation Center, Lexington, Massachusetts

Publication date: September 1, 1968

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