We report a compact, portable, low power tunable diode laser based sensor for a fast, non-intrusive measurement of
temperature on airborne-based vehicles. The proposed sensor design avoids common problems in existing sensors such
as adiabatic compression of the ambient airstream, thermal inertia of the sensing element, and impinging cloud particles.
These effects are quite common in the conventional temperature sensors used in most aerial vehicles for ambient
temperature measurements. The molecular oxygen transitions are measured using a 765 nm wavelength range vertical
cavity surface emitting laser in the spectral region of two closely spaced oxygen transitions, centered at 13069.95 cm-1and 13068.07 cm-1 respectively, according to HITRAN database.
Another advantage of the proposed sensor design is that it can simultaneously detect additional trace gas species along
with in-situ temperature measurements. For example, in this design we detect carbon dioxide concentration using a 2000
nm wavelength laser. The two laser beams are co-aligned and coupled into a single 20 cm multipass cell. The absorption
signal (from both carbon-dioxide and oxygen) was detected simultaneously on a 2 micron photodetector. Second
harmonic (Nf, N=2) detection, using wavelength modulation spectroscopy was employed to enhance the sensitivity of
measurements. The sensor can readily be miniaturized and consumes less than 2 W of power, ideal for use of unmanned
aerial systems and other airborne platforms.