Ammonia sensing system based on wavelength modulation spectroscopy

• Autor(a) principal: Carlos Duarte Viveiros
• Data de Publicação: 2015
• Outros Autores: João Ferreira, Susana Oliveira Silva, Ribeiro,J, Flores,D, José Luís Santos, Orlando Frazão, José Manuel Baptista
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://repositorio.inesctec.pt/handle/123456789/7244; http://dx.doi.org/10.1007/s13320-015-0242-3

A sensing system in the near infrared region has been developed for ammonia sensing based on the wavelength modulation spectroscopy (WMS) principle. The WMS is a rather sensitive technique for detecting atomic/molecular species, presenting the advantage that it can be used in the near-infrared region by using the optical telecommunications technology. In this technique, the laser wavelength and intensity were modulated by applying a sine wave signal through the injection current, which allowed the shift of the detection bandwidth to higher frequencies where laser intensity noise was typically lower. Two multi-pass cells based on free space light propagation with 160 cm and 16 cm of optical path length were used, allowing the redundancy operation and technology validation. This system used a diode laser with an emission wavelength at 1512.21 nm, where NH<inf>3</inf> has a strong absorption line. The control of the NH<inf>3</inf> gas sensing system, as well as acquisition, processing and data presentation was performed. © 2015, The Author(s).