Hydrogen Sensor Based on Tunable Diode Laser Absorption Spectroscopy

Tunable Diode Laser Absorption Spectroscopy of Oxygen

Self-mixing interference effects in tunable diode laser absorption spectroscopy

We report the effects of self-mixing interference on gas detection using tunable diode laser spectroscopy. For very weak feedback, the laser diode output intensity gains a sinusoidal modulation analogous to that caused by low finesse etalons in the optical path. Our experiments show that self-mixing interference can arise from both specular reflections (eg cell windows) and diffuse reflections ...

A Bayesian Approach for Gas Concentration Reconstruction Based on Tunable Diode Laser Absorption Spectroscopy

We address the problem of 2D reconstruction of the gas concentration map from its 1D path averages based on Tunable Diode Laser Absorption Spectroscopy (TDLAS). This problem is challenging because typically only a very small number of paths are available. In addition, a path may not be set up to our desirable configuration. These challenges result in a large percentage of unobserved pixels in t...

Balloon-borne tunable diode laser absorption spectrometer

A balloon-borne tunable diode laser absorption spectrometer capable of in situ measurement of the concentrations of several stratospheric trace gases simultaneously in the same parcel of air is described. Laboratory tests show present detection limits of 1.5 ppbv for NO and 0.5 ppbv for N02 under stratospheric conditions. This instrumentwas flown in July 1983 to make the first tunable diode las...

Use of diffuse reflections in tunable diode laser absorption spectroscopy: implications of laser speckle for gas absorption measurements

The use of diffusely scattering materials as a means of eliminating interference fringes has been investigated. Their use introduces laser speckle that can contribute a random, rather than periodic, uncertainty to gas measurements. We have established a method for quantifying the uncertainty due to speckle and investigated ways of reducing it. We characterised the speckle at 823nm allowing the ...