OPTICAL NULL METHOD SPECTROPHOTOMETERS

摘要

An optical null method spectrophotometer with which the difference between the intensity of a test sample beam representing the quantity of light transmitted through a test sample and the intensity of a reference sample beam representing the quantity of light transmitted through a reference sample is detected and amplified to drive a servo mechanism to thereby displace an optical attenuator inserted in the path of the reference beam, so as to vary the reference sample beam until the test sample beam and the reference sample beam are balanced with each other to thereby obtain transmission spectra or absorption spectra of the test sample, characterized in that separate means is provided for producing an electrical signal proportional to the variation in the reference sample beam resulting from the displacement of the optical attenuator and that the electrical signal produced by the separate means is recorded by a recorder.