Abstract. NASA Compact Airborne Formaldehyde Experiment (CAFE) is a
nonresonant laser-induced fluorescence instrument for airborne in situ
measurement of formaldehyde (HCHO). The instrument is described here with
highlighted improvements from the predecessor instrument, COmpact
Formaldehyde FluorescencE Experiment (COFFEE). CAFE uses a 480 mW, 80 kHz
laser at 355 nm to excite HCHO and detects the resulting fluorescence in the
420–550 nm range. The fluorescence is acquired at 5 ns resolution for 500 ns
and the unique time profile of the HCHO fluorescence provides measurement
selectivity. CAFE achieves a 1σ precision of 160 pptv (1 s) and 90 pptv (10 s) for [HCHO] = 0 pptv. The accuracy of CAFE, using its
curve-fitting data processing, is estimated as ±20 % of [HCHO] + 100 pptv. CAFE has successfully flown on multiple aircraft platforms and is
particularly well-suited to high-altitude research aircraft or small air
quality research aircraft where high sensitivity is required but operator
interaction and instrument payload is limited.
In-situ measurement of water-vapor in fire environments using a real-time tunable diode laser based system
