Self-normalizing single-beam laser spectrometer

摘要

Self-normalization of laser spectrometers is provided by I"/I laser modulation and detection. A single tunable diode laser is frequency modulated by a high S/N ratio triangle wave, mechanically chopped, passed through an isothermal in-line gas and reference chamber absorption cell, and synchronously detected to provide the I" and I signals. The preferred embodiment discloses isotopic ratio measurements. The invention has application to quantitative trace gas measurements generally.