Novel optical method for background reduction in resonant photoacoustics.
We report a new way of reducing the background originated by window absorption in resonant photoacoustics. The technique employs a secondary light source that is absorbed by the window but not by the gas sample. This auxiliary source is modulated 180 degrees apart from the one used to probe the gas. This way the window is heated almost uniformly during each cycle, thus lessening the associated background signal. We tested the scheme on a photoacoustic setup, conceived to measure NO(2), which is excited by an array of blue light-emitting diodes. Another array of near-infrared, light-emitting diodes served as the secondary light source. With the addition of this cancelling method, the detection limit was decreased to 4% of the previous reached without it.
González
Martín
M
Laboratorio Láser, Facultad de Ingeniería, Universidad de Buenos Aires, Paseo Colón 850 (1063) Buenos Aires, Argentina.
Santiago
Guillermo
G
Slezak
Verónica
V
Peuriot
Alejandro
A
D000162:Acoustics / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005740:Gases / Q000032:analysis*; D008029:Lighting / Q000295:instrumentation*; D055095:Optics and Photonics / Q000295:instrumentation*; D010783:Photometry / Q000295:instrumentation* / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D005740:Gases